Aspen Report

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Edited by Peter Cosgrove and Andy Amphlett
2002


3
The Biodiversity and Management of Aspen woodlands:
Proceedings of a one-day conference held in
Kingussie, Scotland, on 25th May 2001


CONTENTS:

Foreword and overview
Peter Cosgrove and Andy Amphlett . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

The ecology and history of Aspen woodlands
Peter Quelch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Fungi and Aspens: Promoting biodiversity, Aspen friends and foes
Ernest and Valerie Emmett . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

The importance of Aspens for lichen
Les and Sheila Street . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Bryophytes on Aspens
Gordon Rothero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Aspen, a vital resource for saproxylic flies
Graham Rotheray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

The Large Poplar Longhorn Beetle, Saperda carcharius in the Scottish Highlands
Tracey Begg and Iain MacGowan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Byctiscus populi, a leaf rolling weevil dependent on Aspen
Jon Mellings and Steve Compton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

The importance of Aspen for Lepidoptera
Mark Young . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Beavers: Aspen heaven or hell?
Dave Batty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Colour photographs insert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i - viii

Variation in Aspen in Scotland: genetics and silviculture
Bill Mason, Eric Easton and Richard Ennos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Improving the availability of native Aspen for use in northern Scotland
Mark Banham and Paul Young . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Woodland management measures for Aspen woodlands
Denis Torley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Agri-environment management measures for Aspen woodlands
Alison McKnight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Delivering action: how Aspen fits into the UK Biodiversity Action Planning process
Peter Cosgrove . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

The Trees for Life Aspen Project
Alan Watson Featherstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

The management of Invertromie wood, Scotlands fourth largest stand of Aspen
Tom Prescott . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Habitat fragmentation
Iain McGowan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Aspen in myth and culture
Anne Elliott . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Delegate discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Delegates list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85



4
Foreword

Peter Cosgrove

Cairngorms Biodiversity Officer, Cairngorms Partnership, 14 The Square, Grantown-on-Spey,
Morayshire, PH26 3HG. E-mail: [email protected]

Andy Amphlett

The Royal Society for the Protection of Birds (RSPB), Abernethy Forest Nature Reserve, Forest
Lodge, Nethybridge, Inverness-shire, PH25 3EF. E-mail: [email protected]

These proceedings are the result of hard work and enthusiasm of many individuals and organisations
involved in action and research into the biodiversity and management of Aspen woodlands
in the UK. This interest and effort culminated in a one-day conference held at The Duke of
Gordon Hotel, Kingussie in the heart of Aspen country on Friday the 25th May 2001. Over 120
people interested in the biodiversity and management of Aspen woodlands attended the conference.

The quality of both the presentations and the poster sessions convinced the organisers of the
need to publish this material as a fitting permanent record of the conference. Most of the papers
in these proceedings were presented in one form or another at the conference, with a small number
of additional important papers invited from other contributors. It is hoped that these proceedings
have captured the expertise and interest of the various specialists and enthusiasts that
was so evident on the 25th May 2001. In particular, it is hoped that these papers will stimulate
further positive action and research into the biodiversity and management of Aspen woodlands
in the UK.

As a focus for future action, Trees for Life have offered to establish and host a web-site and central
information resource on Aspen that is easily accessible to land managers, researchers and
the general public. If you would like to become more involved in Aspen action please visit Trees
for Lifes website: http://www.treesforlife.org.uk

Finally, we would like to thank the sponsors and partners; Aberdeenshire Council, Butterfly
Conservation, Cairngorms Local Biodiversity Action Plan, Cairngorms Partnership, Forest of
Spey Project, Forestry Commission, Highland Council and the Highland Local Biodiversity Action
Plan Partnership, RSPB, Scottish Natural Heritage (SNH), and Woodland Trust Scotland, who
came together to make this conference happen. We are very grateful to the proceedings authors
and photographers who contributed their time and efforts so freely. In particular, special thanks
are due to Tom Prescott of the RSPB, and to Anne Elliott and Peter Beattie of SNH for organising
such a successful and enjoyable event.


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Overview

As a woodland type, or as a significant component of other woodlands, Aspen is restricted, in
the Scottish Highlands, to a very limited number of sites mainly in the North-east. Here its local
abundance, in parts of Badenoch and Strathspey especially, making a striking contribution to the
landscape, seems at odds with its lack of formal recognition in current national vegetation classifications.

With one exception, the papers in these proceedings concentrate on Aspen in the North east
Highlands, where the conference and fieldtrip were held. Links could and should be made with
Scandinavian ecologists, who view Aspen, especially old individual trees, as keystone components
in preserving biodiversity in boreal forests. There, Aspen is a focus of current research, e.g.
as part of the University of Helsinkis Biodiversity in Boreal Forests project
(http://www.helsinki.fi/science/biobof/).

In the Scottish Highlands, Aspen is particularly associated with well drained, often moist, mineral
soils. Here it was a very early post-glacial colonist (before Scots pine) and has persisted in
mixed woods with Birch, Hazel, Willow and Rowan, which are probably of great antiquity. It also
occurs more rarely, as stands within the native pinewoods.

As a tree species, Aspen is widespread across the British Isles appearing to be especially frequent
in South-east England (Perring and Walters 1962). Examination of a selection of recent
county Floras from England which map Aspen at the tetrad scale reveals Aspen to be very frequent
in some areas, ranging from just 8% of tetrads in Devon (Ivimey-Cook 1984) to 35% in
Kent (Philp 1982) and a remarkable 41% in Sussex (Hall 1980). Do large Aspen stands occur
outside the Highlands? The scant descriptions in these Floras make it hard to place Aspen into
an ecological context, but the resource seems to be very large elsewhere, warranting more
attention.

Rare species confined to, or with nationally important populations on Aspen include flies, moths,
beetles, fungi, lichens and mosses, as described in subsequent papers. In terms of practical
nature conservation, a number of these species are in need of emergency first aid. The invertebrates,
as is so often the case, are in the greatest need of targeted (and monitored) management.
They include a number of species with critically low populations which utilise relatively
ephemeral components of the total Aspen resource, e.g. the decaying cambial layers under the
bark of large diameter logs on the ground, or the foliage of Aspen suckers less than 1m high. A
number of lichens and one moss are similarly restricted to just a few individual Aspen trees,
though in the medium term they may be able to persist on these trees.

In a turn around from usual situations, these proceedings lack information (with one notable
exception - European beaver) on the vertebrate fauna associated with Aspen. For example, we
appear to know next to nothing about the bird species and communities associated with Aspen
in this country. Elsewhere in Europe, Aspen woodland and its dead wood resources attract several
species of hole nesting birds, including various species of woodpeckers, some of which are
absent from the UK. Aspens are also used by other, perhaps unexpected, species such as
Capercaillie (Tetrao urogallus). The Bird species of UK Aspen woodlands paper has yet to be
written, but breeding records of Buzzard (Buteo buteo), Great spotted woodpecker
(Dendrocopus major) Redstart (Phoenicurus phoenicurus) and Redwing (Turdus iliacus) from the
afternoon fieldtrip suggests it is an area worthy of further investigation.

For all of these Aspen dependent species, chance events or uninformed management could be
devastating for local populations. All require regular population and distribution monitoring and
habitat management trials aimed at securing populations. It is beholden on specialists, advisors
and site managers to consider the implications of any proposed actions (or inaction) on other
taxonomic groups or habitats. Mellings and Compton report the apparent loss of the BAP wee-
vil, Byctiscus populi, at one site due to the removal (for unspecified conservation reasons) of


6
Aspen scrub. Though statistically unlikely, creation of dead wood to increase potential breeding
sites for threatened Diptera could lead to a loss of a similarly threatened lichen or moss.
Practically, we either accept that risk (not recommended!) or we ensure that adequate baseline
surveys are carried out prior to management, and that site managers know the exact location of
important trees. Unfortunately, the current lack of skilled field lichenologists and bryologists is a
critical problem for facilitating informed management decisions.

Peter Quelchs goal of protecting, regenerating and expanding all existing Aspen woods, stands
and trees, as well as planting into new areas deserves support. However, it has to be remembered
that it will be decades before some components of the overall Aspen habitat will have
increased, e.g. large diameter trees and snags. Clonal variation is almost certainly a significant
determining factor for the epiphyte communities of Aspen and quite plausibly for other groups
e.g. Diptera. New plantings of Aspens should follow the protocol adopted by Trees for Life
(Watson) and include material from as wide a range of locally occurring clones as possible.

Much attention has centred on the importance of the largest Aspen stands, as being the only
instances whereby natural processes can maintain a continuity of supply of key micro-habitats.
Rothero highlights the possible significance of smaller stands and wayside Aspens for
bryophytes, and Coppins et al. (2001) have demonstrated the outstanding importance of some
small Aspen stands for lichens. Such examples should be targeted for survey and conservation.

Given that Aspen will sucker so freely, it is obvious that exclusion or other control of grazing animals
will be an important tool to expand existing stands. Complete exclusion of browsers may
not be desirable, as the maintenance of successional habitats with associated pollen and nectar
sources may be of value to foraging adult invertebrates. Aspen stands occur in a wide variety
of contexts and important habitats may occur within the bounds of a projected Aspen expansion
zone. Complete exclusion of grazing from such areas may be damaging to other interests.
Again, adequate survey prior to formulating management plans is required.

Several contributors discussed and highlighted the grants and financial assistance available to
land managers to progress practical action for Aspen and its dependent species. Specific examples
of the practical work carried out to date are presented, including the challenges of reconnecting
isolated Aspen stands to facilitate important ecological processes, such as species dispersal
or gene flow. As a number of authors point out, we are only just beginning to identify and
understand the complex biodiversity associated with Aspen in the UK, and clearly much is still
waiting to be discovered.

Finally, Anne Elliotts paper illustrates that interest in Aspen is not just the domain of ecologists
and specialist researchers. Aspen has strong cultural links for the people of the Scottish
Highlands and their support will be crucial if any action for Aspen is to be successful. We should
not lose sight of the fact that Aspen woodlands are a beautiful and striking feature of the
Highland landscape, and worthy of conserving for that reason. Indeed it can be argued that
Aspen helps improve the quality of life for local residents and helps make the Highland area special
for visitors and tourists.

Aspen seems to have survived as an ancient remnant up to now largely by default, rather than
by design. These proceedings provide compelling evidence of why this situation should change
and how Aspen conservation and management should move up the UK conservation agenda in
the future.


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References

Coppins, B., Street, S. and Street, L. 2001. Lichens of Aspen woods in Strathspey. Report to British
Lichen Society and SNH.
Hall, P.C. 1980. Sussex Plant Atlas. An Atlas of the distribution of wild plants in Sussex. Booth Museum
of Natural History.
Perring, F.H. and Walters, S.M. 1962. Atlas of the British Flora. 2nd. Edition (1976). EP Publishing.
Philp, E.G. 1982. Atlas of the Kent Flora. Kent Field Club.
Ivimey-Cook, R.B. 198). Atlas of the Devon Flora. The Devonshire Association.


8
The ecology and history of Aspen woodlands

Peter Quelch

Native Woodland Adviser, Forestry Commission, Whitegates, Lochgilphead, Argyll, PA31 8RS.
Email: [email protected]

Introduction

This paper gives a quick overview of Aspen, both as a tree species and as a rare woodland type
in Scotland. The ecology of Aspen is well covered by Rick Worrell, along with other selected
papers and booklets. Much has been written about the folklore of Aspen (Elliott, this volume) and
why it is such an enigmatic and well loved tree.

This paper will examine where Aspen occurs naturally in todays landscape, and then to ask if
we are satisfied with the status quo. If we are not, what greater part could Aspen play in
Scotlands woods and forests, and what actions should be considered on its behalf? At present,
Aspen is a well liked but Cinderella species, somewhat neglected, and yet with an unrealised
potential. Recognition of its values for biodiversity have emphasised Aspens importance, and
this gives the context for this paper.

Aspen in the Biodiversity Action Plan (BAP) process

Simple woodland classifications tend to label woodland types by their dominant tree species, i.e.
Oakwoods, Birchwoods, Pinewoods and so on. We can therefore recognise Aspen woods
where locally Aspen predominates in certain stands of semi-natural broadleaves in Badenoch
and Strathspey, alongside Birch, Rowan, Hazel, Sallow and Alder.

The UK BAP process uses such a classification in selecting the main native woodland types and
allocating targets for action (for an overview of woodland classifications see Hall and Kirby,
1998). But what is the status of those native woodland types which are not given BAP plans?

- Birchwoods after many years of discussion it has now been agreed that upland
Birchwoods should have their own Habitat Action Plan (HAP).

- Hazel is not covered separately in the BAP process, despite some lobbying on behalf of
the western coastal hazelwoods, which are exceptionally rich habitats for oceanic
bryophytes and lichens. Certain rare lichens characteristic of this habitat, (e.g. Arthothelium
macounii, or Pseudocyphellaria norvegica) then become surrogates in the BAP process for
the habitat they depend on, since they have been given Species Action Plans (SAP).

- Juniper this native shrub species is covered by having its own SAP, but no HAP.

- Aspen is mentioned in the SAPs for three invertebrate species which depend on it as a
habitat, (Hammerschmidtia ferruginea, Byctiscus populi and Epione parallelaria), and two
bryophytes (Orthotrichium sp.), but Aspen has neither its own HAP or SAP. Aspen woodlands
are however recognised as important habitats in some Local Biodiversity Action
Plans (LBAP), e.g. the Cairngorms LBAP.

Aspen in woodland classifications

In the National Vegetation Classification (NVC) (Rodwell 1991), Aspen is described as a component
of upland Ashwood (W9b), but even then only occurring rarely. Aspen is also mentioned as
an infrequent component in several lowland woodland types: W5, W6, W8, W10, and W16.

Aspen woodlands are not recognised as a distinct woodland type in either NVC, or in the
Peterken Stand Type classification (Peterken 1993), where Aspen is associated with the
Rowan/Birch stands of Type 12A. Rackham (1986) recognises Aspen woodlands as a subset of
Peterkens Birch/Hazel woods, at least for East England. In their classic survey of native


9
pinewoods, Steven and Carlisle (1959) record Aspen as rare or occasional in most of the
pinewoods they surveyed, but never abundant. Interestingly they record more than usual Aspen
in Glen Strathfarrar pinewoods, which appear to be one of the most natural woodland remnants
in the country today.

Aspects of Aspen ecology

Like Birch and other successful colonisers, Aspen can tolerate a wide range of soil types, from
lime-rich sites to acidic heaths (for example, Aspen suckers are spreading onto acidic heath at
Crannach pinewood, Bridge of Orchy). Like Oak and Ash, Aspen actually prefers good well
drained mineral soils, a site type that it finds in greater areas in Badenoch, Strathspey and
Deeside. While sites that it occupies are often moist, it is not a wet woodland species in the same
way as Alder or the Willows, or even Bird cherry. Aspen grows at a wide range of altitudes, from
sea level (coastal Aspen at Assynt and on Rum) to high altitude gullies almost to the tree-line.

Aspen history

Aspen has an ancient history in Scottish woodlands, being a very early coloniser, arriving with
Birch, Sallow and Rowan during the pre-Boreal period 10,000 years ago, earlier than Hazel, and
before Scots pine began to dominate. All this happened well before Oak, Alder, Ash, Elm and
Holly joined the flora. I see Aspen not so much as a rare and neglected woodland type, but more
as a tree species which is now under-represented as a component of natural woodland types in
Scotland, despite its ancient lineage. I also find it significant that Aspen is host to so many specialist
species, despite the fact that the tree itself is not now very common or in extensive stands.
To me this dependency indicates a very long ecological association, and this is backed up by
the history of Aspen in Scotland.

Aspen and ancient woodlands

Aspen seems to be strongly linked to ancient woodland sites, both in Scotland and in England
where it is also a somewhat rare component of usually ancient woodlands (Rackham 1986,
1990). Indeed, I would go further and suggest that Aspen in Scotland is actually an ancient
woodland indicator species. Most examples that I find are linked to ancient woodlands, large or
small. For example, I recently came across Aspen in the Ryvoan Pass (Glenmore Forest) in a very
mixed old-growth stand at high elevation, alongside veteran Scots pine, Juniper and Rowan, as
well as very old grey Sallow and Alder. Aspen has strong connections, not only with ancient
woodland patches, but sometimes to the tiny woodland refugia of the most natural origins.

Aspen in Europe

In Europe and Scandinavia, where Aspen is more abundant, it is usually as a component species
of the northern sub-boreal temperate forest zone (Worrell 1996), rather than as a woodland dominant
on certain soil types (compared to say, Oak or Beech). Its natural place seems to be in the
small group of broadleaved associates in northern coniferous forests, along with Birch, Rowan,
Sallow, and Alder, where together they typically occupy about 15-20% of the forest, alongside
the Pine and Spruce (Peterken 1996).

Reasons for current distribution of Aspen

Why has Aspen survived where it is to be found today even sometimes after all other tree species
have gone? The reasons for Aspens ability to survive, albeit in low numbers, include:

- Aspen is actually a poor coloniser (in modern times at least), for while it can produce viable
seed this is a rare occurrence.

- Aspen trees are dioecious, so individual trees and even whole clones are either male or
female. As individuals become separated from the opposite sex, it is not surprising that
Aspen does not reproduce well in its currently fragmented condition.


10
- Nevertheless, Aspen is very good at self-perpetuation on a local scale by producing masses
of suckers in response to felling, windthrow, fire or other disturbance. It seems that vegetative
reproduction keeps Aspen going in the same locality almost indefinitely.

- While grazing animals do eat the suckers (it is more palatable than Alder, but less so than
Ash and Elm), sufficient survive to grow into new trees, unless grazing pressure is kept at
very high levels.

- Aspen is not an inherently rare species like the various Whitebeams for example, partly
because it has wide soil and altitude tolerance.

- Aspen has not traditionally been a valuable species for its timber, bark, or coppice shoots
(unlike Oak and Hazel) and so has not been deliberately protected or cultivated.

- Aspen has probably been reduced in status partly through poor seeding ability (compared
to Birch and Sallow), combined with susceptibility to grazing, but also an inability to form
veteran trees (unlike Oak, Holly, Ash, Pine and Alder, which can all survive as stems of
many centuries age). Long-lived trees have more time in which to set viable seed and produce
new generations during lulls in grazing pressure. The reason why Aspen cannot live
a long time and form a huge hollow and ancient stem must surely be that the soft white
wood is not durable against rot fungi (unlike Oak and Pine for example).

- If it were not for its suckering ability, Aspen may well have been lost entirely from Scotland.

Are we happy with Aspens current distribution?

So, apart from the relatively small number of Aspen dominated woods in Badenoch, Strathspey
and Deeside, Aspen is a survivor in small patches over most of Scotland. It is found on the sea
cliffs of the west coast, in ancient grazed pinewoods in the central Highlands, in remote refugia
like the lochside screes of Loch Muick, in the Border cleugh woodland remnants, and in the forgotten
corners of many an ancient woodland.

Should Aspen be left alone to inhabit these sparse niches - the remote and craggy woodland
refugia? Should Aspen continue to be treated as a somewhat enigmatic tree rarity, a minor
species, mainly of interest to woodland historians and romantics as a ghost of the once great
natural woodlands? Or does Aspen have a wider role in Scottish woods and forests?

A possible new scenario for Aspen?

Lets look again at the role Aspen plays in, for example, central Swedish forests, where Aspen
forms a constituent of the broadleaved component of the mixed pine/spruce forests, along with
Birch, Sallow and Alder.

Why could we not encourage both Birch and Aspen as a normal component of Scottish upland
forests, up to a proportion of say 25%, rather than the current five or 10% normal maximum?
The biodiversity and landscape benefits would be high, and Aspen timber grown in forest conditions
is (like other Poplars) straight and utilisable, though not of high value (less than Birch, similar
to Alder?). Birch and Sallow regenerate profusely, Alder readily coppices even in the face of
moderate deer numbers, while Aspen suckers after felling. So the species in this group can perpetuate
themselves at low cost, and all are relatively fast growing.

Conclusion

I think that Aspen would be sold short if we continued to confine it to woodland refugia and
regard it as a rarity. There is evidence that it was once a great component of Scottish natural
woodlands, and there seems to be no good reason why, with help, it could not be so again. It is
time for a Comeback Code for Aspen!


11
Actions needed to bring Aspen back into its rightful place could include the following:

- Protecting, regenerating, and expanding where possible, all existing Aspen woods, stands
and trees.

- Careful planting of Aspen (of both sexes) into some degraded semi-natural woodlands
where it is missing

- Planting Aspen into forestry restock areas in sufficient numbers, that Aspen becomes a
self-perpetuating component of a group of mixed broadleaves which between them would
cover 15-25% of the gross area of many upland and lowland conifer forests.


References

Ennos R, Worrell R, Arkle P, Malcolm D, 2000. Genetic variation and conservation of British native trees
and shrubs, Technical Paper 31, Forestry Commission, Edinburgh.

Hall JE, Kirby KJ, 1998. The relationship between Biodiversity Action Plan Priority and Broad Woodland
Habitat Types, and other woodland classifications, JNCC Report 288, Joint Nature Conservation
Committee, Peterborough.

Peterken G, 1993. Woodland conservation and management, Chapman and Hall, London.

Peterken G, 1996. Natural woodland, Cambridge University Press, Cambridge.

Rackham O, 1986. The history of the countryside, Dent, London.

Rackham O, 1990. Trees and woodland in the British landscape, Dent, London.

Ratcliffe P, 1999. Aspen woodlands: a case for conservation, paper to the Native Woodlands Advisory
Panel for Scotland, Forestry Commission, Edinburgh.

Rodwell J, 1991. British Plant Communities, Vol I, Woodlands and Scrub, Cambridge University Press,
Cambridge.

Steven and Carlisle, 1959. The native pinewoods of Scotland, University of Aberdeen.

Trees for Life, 2001, Aspen information and papers, on www.treesforlife.org.uk

Worrell R, 1995. European Aspen (Populus tremula L.): a review with particular reference to Scotland, I
Distribution, ecology and genetic variation, Forestry 68(2), pp 93-105; II Values, silviculture and utilisation,
Forestry 68(3): 231-243

Worrell R, 1996. The Boreal Forests of Scotland, Technical Paper 14, Forestry Commission, Edinburgh.

Worrell R, Gordon AG, Lee RS, McInroy A, 1999. Flowering and seed production of Aspen in Scotland
during a heavy seed year, Forestry 72(1): 27-34


12
Fungi and Aspens: Promoting Biodiversity

Aspen friends and foes

Ernest and Valerie Emmett

Drumlins, Newtonmore Road, Kingussie, Inverness-shire, PH21 1HD.
E-mail: [email protected]

It has been estimated that about 80% of all the organic energy on the Earth is locked up in wood
of various kinds. This enormous store of energy is under constant attack, both when the trees
are alive and more so when they are dead: from fungi, bacteria, insects and smaller animals.
(Ryvarden 2001).

Foremost in the relationships with trees are the fungi and these play several different roles, not
all of them detrimental to the health of the tree and some also provide food for insects and
other invertebrates, as well as mammals.

The fungi can be classified under three main headings:

Categories of Forest Fungi

Mycorrhizal
Endo- Important for most (all?) plants
Ecto- Important for most trees, e.g. Aspen

Saprophytes or Detrivores Litter decomposers

Pathogenic/parasitic Principal causes of tree death

The Mycorrhizal species are essential for the healthy growth of the tree. These fungi are of
two sorts: endo-mycorrhizal and ecto-mycorrhizal. The hyphae of the latter sheath the
trees roots and, by breaking down material in the forest soil, they provide the tree with nitrogenous
and other nutrients, including mineral trace elements. In exchange, the fungus receives
carbohydrates manufactured by the tree during photosynthesis. Endomycorrhizal species are
the most widespread, but their presence is not revealed by the formation of fruitbodies on the
soil surface. These fungi enter the plant root cells forming specialised inclusion bodies, where
exchange of nutrients occurs.

With Aspens, the ectomycorrhizal fungi are more important, and fairly specific associates in this
category include familiar toadstool shaped fungi such as Leccinum aurantiacum, Leccinum
duriusculum and Lactarius controversus. These are the friends of the Aspen, helping it to grow.

The second group of fungi are the Saprophytes and these include both host specific and cosmopolitan
species. They are the litter decomposers, reducing fallen leaves, twigs and other
already dead woody material to humus, a principal part of forest soils. These fungi include some
that look like familiar toadstools with lamellae (gills). Others are poroid fungi (the Polypores),
releasing their spores from pores instead of lamellae.

Some others that help to decay the woody material look rather like paint splashes and sheets of
fungal tissue adhering to the surface but loose at the edges; and yet others form hard warty
growths on twigs and branches. These are the Corticioid fungi. They do not have lamellae or
pores; instead, they form amorphous sheets of spore bearing tissue covering the surface of logs
and twigs.


13
Examples of detrivores specific to Aspen are the Polypores: Ceriporiopsis anaerina, Antrodia
malicola and mellita, and the Corticioid: Peniophora polygonia. The two Antrodias mentioned
have not yet been found in Britain, but it is hoped that they will be found in Scotland.

The cosmopolitan species are legion; for example, many Mycena species. One that was found
in an Aspen grove on The Royal Society for the Protection of Birds (RSPB) Insh Marshes
Reserve last November may be a new species for science requiring description.

The Poroid and Corticioid fungi are among the dominating species in the decay of Aspens. In
two Norwegian studies of the species occurring on cut and fallen logs, it was found that most of
them were Polypores and Corticioids (Table 1).

Table 1. Taxonomic diversity of wood decaying fungi on Aspen

Locality and Number of species

South Norway (Andersen - 1995) 123 Logs

Polypores 21 (14.2%)
Corticioids 64 (42.6%)
Agarics 43 (29%)
Heterobasidio-mycetes 16 (10.3%)
Other 6 (3.9%)

Total 155

South Norway (Hermansen 1974 - 76)

Polypores 31 (27.7%)
Corticioids 81 (72.3%)
Agarics
Heterobasidio-mycetes
Other

Total 112

Note that in one of these studies, the Aspen logs yielded 155 species of fungi, an indication of
the value of lying timber for biodiversity.

The diversity of the fungal species increases as the wood decay proceeds: in the early stages of
decay relatively few fungi colonise the wood, but as defensive substances are removed by early
colonisers, a succession of species become involved. By the last stage, when the trunk is losing
its shape completely, a great number of species have inhabited the former tree, during its
decay cycle.

Some of the rarer fungi fruit only sporadically, with long gaps of many years between appearances
of the sporocarps, although they are presumably present throughout in the vegetative
state. In several long-term studies, while some species fruited regularly, others were only recorded
once. It has also been found that some fungi can only invade decaying wood after a pioneer
species has overcome the woods armoury of defensive chemicals and started the partial decay.
(Niemelet al. 1995).

So far, nearly 100 species of fungi have been recorded on or with Aspen in Britain (Table 2), by
members of the British Mycological Society mostly in England, reflecting where most mycologists
live or collect and where Aspen is not considered a common tree. The authors anticipate
increasing the number of species recorded from Aspen in the coming years.

The third group, the Pathogenic fungi, are especially interesting, and include several species
that are specific to Aspen. They are not friends of the Aspen but do great things for biodiversity.
They include the group known as Rusts, as well as larger poroid fungi, the Polypores, often
referred to as Bracket fungi.

Aspen is the host for several species of Rust (Melampsora spp.), which cause decay spots on
the leaves and some will blacken and kill the growing tips of new shoots. Heavy infestation can
result in defoliation of the Aspen. These fungi thus reduce the growth rate of the tree and obviously
are detrimental to the life cycle of insects that feed on the young leaves and growing shoot


14
tips, such as the Dark-bordered beauty moth (Epione vespertaria).

A spectacular flower parasite is Taphrina johansonii, and this obviously interferes with seed production
where it occurs. It is probably of limited significance in Badenoch and Strathspey, where
flowering is rare although in 2001 the trees were flowering and the Taphrina was found locally
in Strathspey.

Another small parasite is the Ascomycete, Encoelia fascicularis, which can be found erupting like
small brownish black cups from the bark of living trees and on fallen branches on the ground.
This fungus causes carbonising rots.

The wood decaying parasites include a significant Polypore, Phellinus tremulae, which is responsible
for the death of most Aspens. It is a white rot type fungus, decomposing both the lignin
and the cellulose. The wood from decayed trees has little economic value. Sporocarps can be
found erupting as wedge shaped brackets from the trunks of Aspens, or else as a coating on
the underside of branches at the point where they emerge from the main trunk the branch
creepers.

This fungus, which is the most serious pathogen of Aspen, was previously not recorded from
Britain until last year, when it was found for the first time on the RSPB Insh Marshes Reserve
(Emmett and Emmett 2001) and so it is not even on the Red Data List for fungi. It was thought
that Britain did not have any Aspen trees large enough to support it. In Fennoscandia, where
Aspen is much more common, it usually occurs on large and old trees. In Badenoch, however,
it has been found on comparatively young trees the diameter at breast height of the smallest
of the infected trees measured so far, is under 20cm and the largest is about 50cm.

Since the first recording of Phellinus on the Insh reserve, it has been found at many sites in the
Badenoch and Strathspey area: at three places in Kingussie, at Kincraig, at Loch an Eilein on the
Rothiemurchus estate, Granish near Aviemore, at two sites near Grantown on Spey and westwards
towards Laggan, and it has also been found on the RSPB Abernethy Forest reserve and
across the Cairngorm massif near to Balmoral. It is likely to be found at other Aspen sites and
this has been confirmed from other areas; for example, recent records from Glen Affric (Watson-
Featherstone this volume).

The Aspens that grow on the poorer soils, for example on stony moraines, seem to produce
sporocarps more readily than those that grow on the richer, damper sites closer to water bodies.
These findings confirm similar ones made by mycologists in Finland and Norway.

The problem in recording fungi is that most of them are ephemeral and there may not be a friendly
mycologist on hand when a fungus fruits! Fortunately, Phellinus tremulae is perennial, the fruit
bodies are persistent and one can see the annual growth phases on the fruit bodies. They are
not easy to spot in the early stages of their growth though, often looking like a thumbnail on the
trunk. The fungus is typically a parasite of living trees, but fruit bodies remain alive for a few years
after the death of the host tree. It is said not to form new fruit bodies on dead trunks (Balaban
and Kotlaba 1970). The current authors, however, have observed fruit bodies that have apparently
formed after trees have fallen.

Entomologists hunting rare saproxylic insects in decaying Aspens, record a sweet smell in the
soft decay material that the larvae feed on. Cultures of the Phellinus are unusually interesting in
that they emit a sweet smell like Oil of Wintergreen, due to the presence of methyl benzoate,
methyl salicylate, benzyl alcohol, linalool and ethyl benzoate (Collins and Halim 1972). It is likely
that mycelium of the Phellinus is present in the decomposing sapwood which is home to the larvae
of these invertebrates, and contributes these compounds to the mixture of smells.


15
References:

Ballaban, K. and Kotlaba, F. 1970. Atlas drevokaznych hub. 136 pp Praha.

Collins, R. and Hallim, A. 1972. An Analysis of the odorous constituents produced by various species of
Phellinus. Canadian. J. Microbiology. 18: 65-66.

Emmett, E.E. and Emmett, V.E. 2001. Phellinus tremulae, a new British Record on Aspens in Scotland,
Mycologist 15:3 105-106.

Niemel T. 1974. On Fennoscandian Polypores. III. Phellinus tremulae (Bond.) Bond. and Borisov, Ann.
Bot. Fennici 11: 202-215. 1974

Niemel T., Renvall, P. and Penttil P. 1955. Interactions of fungi at late stage of wood decomposition.
Ann. Bot. Fenn. 32: 141-152.

Ryvarden, L. 2001. An Introduction to Wood-rotting Fungi, Biological Institute, University of Oslo, Norway.
(For work by Andersen and Hermansen, see Ryvarden 2001)


Table 2. Species of fungi recorded in association with Aspen

Source: British Mycological Society Fungus Recording Database

Arcyria cinerea Armillaria bulbosa Auricularia mesenterica
Badhamia panicea Bjerkandera adusta Bolbitius vitellinus
Boletus erythropus Brevicellicium olivascens Byssomerulius corium
Ceriporiopsis aneirina Chalara cylindrosperma Clitopilus prunulus
Comatricha nigra Coprinus disseminatus Cortinarius
Cortinarius crocolitus Cortinarius decipiens Creopus gelatinosus
Crepidotus cinnabarinus Crepidotus mollis Cristinia rhenana
Cryptodiaporthe populea Cryptosphaeria populina Cylindrobasidium laeve
Cyrtidula hippocastani Daedaleopsis confragosa Dothiora sphaerioides
Drepanopeziza Encoelia fascicularis Enteridium lycoperdon
Epicoccum nigrum Exidia nucleata Flammulaster carpophiloides
Ganoderma applanatum Gymnopilus junonius Hebeloma
Hebeloma sacchariolens Hymenoscyphus caudatus Hymenoscyphus immutabilis
Hyphodontia gossypina Inonotus radiatus Kirschsteiniothelia aethiops
Laccaria laccata Lasiosphaeria ovina Leccinum aurantiacum
Lactarius controversus Leccinum duriusculum Leccinum fuscoalbum
Leccinum populinum Lenzites betulina Leucostoma niveum
Leucostoma persoonii Linospora ceuthocarpa Macrotyphula juncea
Massarina emergens Melampsora allii-populina Melampsora epitea var. epitea
Melampsora larici-populina Melampsora populnea Mitrophora semilibera
Mollisina acerina Mycena acicula Mycena galericulata
Mycena pura Nemania serpens Oxyporus populinus
Panus conchatus Patellariopsis clavispora Peniophora lycii
Peniophora polygonia Peziza udicola Phaeocalicium praecedens
Phanerochaete velutina Phellinus ferruginosus Phellinus tremulae
Pholiota squarrosa Phomopsis putator Physarum robustum
Platystomum compressum Pleurotus ostreatus Polydesmia pruinosa
Rosellinia aquila Scopuloides hydnoides Stictis radiata
Taphrina johansonii Taphrina populina Tomentella crinalis
Trametes pubescens Trichoderma viride Tricholoma fulvum
Tricholoma populinum Troposporella fumosa Tympanis spermatiospora
Typhula setipes Uncinula adunca var. adunca Valsa sordida
Venturia macularis Xerocomus subtomentosus


16
The importance of Aspens for lichen

Les and Sheila Street

c/o Flaxfield, High Road, Havenstreet, Ryde, Isle of Wight, PO33 4DL
E-mail: [email protected]

Aspens differ greatly, both structurally and chemically, from the majority of Highland woodland
trees and in particular from Birch and Scots pine. In Strathspey, especially, they provide a very
important niche substrate for epiphytes that is otherwise virtually absent. One hundred and thirty
species of lichen and 12 lichenicolous fungi have been recorded on Aspen in Strathspey (Table
1).

The bark of Aspens can be both fissured and smooth. The characteristic diamond-shaped
rough parts provide a coarse substrate favouring some species such as the strap-like green
Ramalina spp. some of them up to 25cm long. The smooth areas host a different suite of lichens
such as Lecidella elaeochroma and Pertusaria or Arthonia spp. which are crustose. Older trees
tend to be more rough and fissured, and bark on the oldest can even superficially resemble that
of Oak. Scots pine, for example, cannot host these species and birches and pines typically hold
the genera Bryoria, Usnea and Hypogymnia, which, themselves, are less common upon Aspens.

Different parts of each Aspen can also provide a variety of microhabitats. On the lower parts of
the trunk, usually overgrowing bryophytes, are lichens such as Peltigera membranacea, a doglichen,
so-called because the Velcro-like rhizinae attaching it to its substrate are said to resemble
dogs teeth. At the other end of the tree, small lichens such as Rinodina sophodes subsist
on small twigs.

The most significant feature of Aspen bark is its low acidity. Whereas Scots pine and Birch are
typically around pH 3.2-3.5 (ranges respectively 3.4-3.8 and 3.2-5.0), Aspen bark is pH 5-6
(Mikko Kuusinen, Annales Botanici Fennici, 1994). Interestingly, some Strathspey Aspen clones
host lichen epiphytes more typical of acidic substrates, while others hold those favouring more
neutral or alkaline conditions. Further research may reveal the reason for this being natural variation
in bark pH. There is also evidence that Aspens probably provide a naturally enriched substrate.
Therefore, species that prefer nutrient-rich, basic habitats grow on them such as
Xanthoria parietina (probably the best-known British lichen occurring as orange splodges on
most old asbestos roofs) and Physconia distorta, a whitish-grey placodioid species with pruina
that resemble caster sugar. Both of these have prominent jam-tart shaped apothecia (fruiting
bodies). It can be noted that the Xanthoria plants show a preference for the western facing sides
of Aspens and one method of quickly spotting Aspen stands from afar is to look for any tree
sporting orange lichens.

The longest established stands, as with most woodlands, are those which have the richest lichen
assemblages. At Invertromie (Strathspey), the Aspen seminar study area, there appear to have
been a succession of pulses of vigorous Aspen regeneration. One is presently underway following
some fencing to exclude deer and rabbits. Another occurred in the late 1980s when sheep
grazing ceased and at least two others; one around 30-50 years ago and another, earlier one,
are evident resulting in the varied age structure seen today.

The most species rich Aspen stands hold some very scarce and endangered lichens. The Aspen
seminar field trip study area at Invertromie, for example, revealed one new UK lichen species
Arthonia patellulata, another not seen for over 150 years with the apposite specific name
Lecanora populicola and two more lichens, each confined to less than 20 UK sites. One is
Sclerophora pallida, a vulnerable Red Data Book (RDB) lichen resembling minute ginger coloured
pinheads which is found on the dry under-hangs of boughs and trunks. The other a RDB (vulnerable)
and Schedule 8 (legally protected) rarity called Pannaria ignobilis. This has an oddly
disjunct distribution from Norway to the Mediterranean and is found locally in central Scotland.


17
Another interesting feature is the presence of several lichens normally considered more oceanic
or western in their distribution. Examples include Pannaria conoplea, Degelia plumbea and
the large, leafy lungworts Lobaria pulmonaria and L. scrobiculata which are relatively common
along the western seaboard of Scotland from Argyll to Assynt, but scarcer well inland amid the
central Highlands of Scotland (F Dobson, Lichens [distribution maps], 2000). These species and
others demonstrate yet another important feature in that they are all closely associated with, and
some confined to, ancient woodlands. Ecological indices have been developed defining lichen
species linked to native pinewoods and western Scottish broadleaved woods and it may be possible,
in future, for a similar version to be developed providing better evaluation of the ecological
continuity of Aspen woods. It is clear already from the range of bryological, lichenological and
entomological taxa present, that many Aspen woods show strong evidence of very long ecological
continuity.

Each taxonomic group speaker used the Aspen seminar as a forum to make a plea for feedback
from delegates and lichens are no exception: an extremely rare species resembling a small dark
pinhead about a millimetre long called Phaeocalicium praecedens apparently exists only on
Aspen twigs. If something resembling this is found, please collect and send a small sample specimen
provided there is plenty locally present to Sheila Street.

The study of lichens associated with Aspens in Britain is in its infancy. Only recently, Brian and
Sandy Coppins discovered the first UK occurrence of a species called Bacidia igniarii on Aspen.
Further research in Strathspey since the Aspen seminar has revealed a yet more diverse lichen
flora living upon Aspens including two more new species to the UK: Caloplaca ahtii and (once it
is confirmed) Rinodina laevigata plus the best UK population of the attractive, and now rare, RDB
critically endangered Schedule 8 lichen Caloplaca flavorubescens. This research is also beginning
to provide insight into the processes involved with this special and complex symbiotic association.
Judging by the diverse range of specialist epiphytes or invertebrates that these Aspen
stands sustain, they are evidently ancient ecosystems requiring further study.

Further reading and key references

Coppins, B. and Coppins, A. M. 2000. Thoughts on aspen and its present and future role as a habitat for
other organisms (unpublished).

Coppins, B. and Coppins, A. M. 1990. Forest of Glentanar Lichens (unpublished).

Coppins, B., Street, S. and Street, L. 2001. Lichens of Aspen woods in Strathspey. Unpublished report to
the British Lichen Society and Scottish Natural Heritage.

Dobson F. S. 2000. Lichens. Richmond Publishing.

Heden H. and Ericson L. 2000. Epiphytic macrolichens as conservation indicators: successional
sequence in Populus tremula stands. Biological Conservation 93: 43-53.

Hereford and Worcester County Council incentive tree planting scheme leaflet (1987) The Black Poplar.

Humphries C. J., Press J. R., and Sutton, D. A. 1981. Trees of Britain and Europe Country Life Books.

Kuusinen M (1994) Epiphytic lichen flora and diversity on Populus tremula in old growth and managed
forests of southern and middle boreal Finland, Annales Botanici Fennici 31:245-260.

Moberg R and Holmen I (1990) Lavar, Interpublishing AB, Sweden.

Nature Conservancy Council. 1988. Keys to woodland NVC vegetation communities

Ripple W and Larsen E. 2000. Historic aspen recruitment, elk and wolves in northern Yellowstone national
Park USA Biological Conservation 95: 361-370

Steven H M and Carlisle A (1959) Native Pinewoods of Scotland. Hartnolls.

Trees for Life 2000. Caledonia Forest Species Profile Aspen.


18
Table 1. Strathspey Aspen Lichen species list

Annotations:
Column 2: Status
RDB (CE) = Red Data Book species (Critically Endangered)
RDB (V) = Red Data Book species (Vulnerable)
Sch. 8 = Listed on Schedule 8 of the Wildlife and Countryside Act
Nr = Nationally rare species (recorded in only 15 or fewer 10km squares)
Ns = Nationally scarce species (recorded in only 16-100 10km squares).
Other status details are written in full or annotated with superscript references.

Column 3: Substrata
Pp = Populus tremula
Al = Alnus glutinosa
B = Betula spp.
C = Corylus avellana
J = Juniperus communis
L or ~L = lignum
S = Salix spp.
Sb = Sorbus aucuparia
T = terricolous
Sx = saxicolous
-by = on bryophytes
-st = on stumps
-tw = on twigs or thin branches

Column 4: Relative abundance (RA)
D = Dominant, A = Abundant, F = Frequent, O = Occasional, R = Rare

Species Status Substrata RA

Arthonia mediella Ns Pp R
A. muscigena Ns Pp-by R
A. patellulata Nr new to UK Pp R
A. punctiformis Pp,C O
A. radiata Pp,C O
A. subfuscula Nr Pp R
A. vinosa Pp R
Bacidia absistens Ns Pp R
B. arceutina Pp O
B. igniarii Nr Pp O
B. naegelii Pp O
B. rubella Pp O
B. vermifera RDB(CE) Nr Pp R
Biatoridium delitescens RDB(V) Nr Pp R
Bryoria fuscescens Pp,B,Sb,L F
Buellia disciformis Pp,B,C,Sb F
B. griseovirens Pp,C O
B. punctata Pp R
Calicium glaucellum Pp,L R
C. viride Pp O


19
Species Status Substrata RA

Caloplaca ahtii Nr - new to UK Pp R
C. cerina Pp F
C. cerinella Ns Pp F
C. cerinelloides Ns Pp O
C. ferruginea Ns Pp F
C. flavorubescens RDB(CE) Sch.8, Ns Pp R
C. obscurella Pp O
Caloplaca phlogina Pp R
Candelariella xanthostigma Pp R
Catillaria nigroclavata Ns Pp O
Catinaria neuschildii RDB(V) Nr Pp R
C. aff. atropurpurea Ns Pp R
Chaenotheca chrysocephala Pp R
C. furfuracea Pp R
Chrysothrix candelaris Pp,B,Al F
Cladonia chlorophaea Pp O
C. coniocraea Pp- and B-by F
C. fimbriata Pp-by R
C. glauca Pp,B R
C. pyxidata Pp base F
Cliostomum griffithii Pp R
Collema occultatum Ns Pp R
Degelia plumbea Pp O
Evernia prunastri Pp,B,C, Sb F
Fuscidea arboricola Ns Pp R
Hypocenomyce scalaris Pp R
Hypogymnia physodes Pp,B,C,S,Sb A
H. tubulosa Pp, B F
Lauderlindsaya acroglypta Ns Pp O
Lecania cyrtellina Ns Pp R
L. sambucina Nr Pp R
Lecanora carpinea Pp,C F
L. chlarotera Pp A
L. confusa Pp R
L. conizaeoides PpL R
L. expallens Pp, B, C A
L. persimilis Ns Pp O
L. populicola [RDB(EX)]Nr Pp O
L. pulicaris PpL,B F
L. rugosella Ns Pp F
L. sambuci Ns Pp O
L. symmicta Pp R


20
Species Status Substrata RA

L . turgidula PpL R
Lecidella elaeochroma Pp,C A
f. soralifera Pp-tw R
L. lobificans Pp O
L. umbricola Ns Pp R
Lobaria amplissima (as
Dendriscocaulon
umhausense the
cyanobacterial morph) Pp R
L. pulmonaria Pp,C R
L. scrobiculata Pp,Sb R
Lopadium disciforme Ns Pp R
Megalaria grossa Pp A
Micarea nitschkeana PpL R
Mycoblastus fucatus PpL,C O
Nephroma laevigatum C,Pp O
Ochrolechia androgyna Pp,Sb A
O. microstictoides Pp,JSb O
O. szatalaensis Ns Pp O
O. turneri Pp R
Opegrapha herbarum Pp R
O niveoatra Pp O
O. ochrocheila Pp R
O. rufescens Pp R
Pannaria conoplea Pp R
P. mediterranea Pp-fallen R
P. ignobilis RDB(V), Sch.8, Ns Pp R
P. rubiginosa Pp R
Parmelia exasperata Pp,B-tw F
P. glabratula subsp. glabratula Pp,Al A
P. saxatilis Pp,B,C,Sb A
P. subaurifera Pp, B, F
P. sulcata Pp, B, Al,C A
Parmeliella triptophylla Pp O
Peltigera collina Pp,C R
P. membranacea T,Pp-by O
P. praetextata PpL,T-by F
Pertusaria amara Pp,Al,C,Sb A
P. coccodes Pp R
P. coronata Ns Pp O
P. flavida Pp,Sb R
P. hemisphaerica Pp,Sb R
P. leioplaca Pp, C F


21
Species Status Substrata RA

P. pertusa Pp,A,B F
P. pupillaris PpL,J,Sb R
Phaeophyscia orbicularis Pp F
Phlyctis argena Pp,C,Sb A
Physcia adscendens Pp O
P. aipolea Pp A
P. leptalea Pp O
P. stellaris Pp O
P. tenella Pp A
Physconia distorta Pp, C A
Platismatia glauca Pp,B,C,J,Sb, L A
Pseudevernia furfuracea Pp,B,J,Sb,L F
Pyrrhospora quernea Pp R
Ramalina farinacea Pp,Al,C A
R. fastigiata Pp R
R. fraxinea Pp F
Rinodina efflorescens Ns Pp,Sb O
R. ? levitate Pp-tw R
R. sophodes Pp-tw O
Schismatomma graphidiodes RDB(V) Sch.8, Nr Pp R
Sclerophora pallida RDB(V) Ns Pp,Sb R
Scoliciosporum chlorococcum Pp O
Sphaerophorus globosus Pp,Al,B,Sb R
Sticta limbata Pp R
Tephromela atra Pp F
U. hirta Pp,B O
U. subfloridana Pp,B,C,J,Sb F
Xanthoria parietina Pp A
X. polycarpa Pp O

Lichenicolous fungi (all on lichens growing on Aspen in Strathspey)

Arthonia subfuscicola in apothecia of Lecanora carpinea, not previously recorded in UK since 19th century
Arthonia sp. in apothecia of Lecanora populicola. Similar to A. intexta in having 12-septate ascospores
Dactylospora parasitaster associated with Biatoridium delitescens
Laeviomyces pertusariicola on Pertusaria leioplaca
Lethariicola sp. on Pertusaria coronata. Possibly the same undescribed species as previously found in
Scotland on Pertusaria hymenea
Lichenodiplis lecanorae on Caloplaca cerinella and Lecanora persimilis
Muellerella lichenicola on Tephromela atra
Phaeosphaerobolous alpinus on Lecanora carpinea
Phoma physciicola on Physcia stellaris
Stigmidium congestum in apothecia of Lecanora chlarotera
Stigmidium pumilum on Physcia aipolia
Vouauxiella lichenicola on Lecanora chlarotera
The Biodiversity and Management of Aspen Woodlands


22
Other microfungi on Aspen

Amphisphaerella dispersella on Aspen bark
Dasyscyphius corticalis on Aspen bark
Hysterographium elongatum on Aspen lignum
Lahmia kunzei on Aspen bark
?Melaspilea cf. proximella on Aspen bark
Teichospora sp. on Aspen bark

Notes on Priority lichens and species new to the British Isles

Arthonia patellulata Apparently the first correctly reported finds of this Aspen specialist in
the British Isles. Previous records have proven to be other species,
although there is a 1968 record from Braemar that may be correct.

Bacidia vermifera Status: RDB(CE). Previously recorded only from two 10km squares in
Britain, both in Strathspey, one of which was Abernethy in 1980s. The
finds during this survey increases the number of squares to four, and the
first UK reports from Aspen.

Biatoridium delitescens RDB(V) species, previously recorded from six 10km squares (four of
which are Scottish). Not previously reported on Aspen from the UK.

Caloplaca ahtii A recently described lichen from Fennoscandia and Alaska, where it is
mainly found on Aspens. All the Scottish material is without apothecia.

Caloplaca flavovirescens RDB(CE) and Schedule 8 lichen sparsely known from only a handful of
isolated wayside trees, mostly Ash. Widely recorded in the 19th century,
but now declined almost to extinction. Clais Eich and another site near
Rothiemurchus are believed to be easily their best UK locations.

Catinaria neuschildii RDB(V). The find at Kinchurdy is the fifth 10km square record in the UK,
and the first from Aspen. Previous records are from Juniper and Oak.

Lecanora populicola Until this survey RDB(EX). Not recorded in UK for over 150 years when it
was last seen at Coltishall, East Norfolk. Seen at four sites.

Pannaria ignobilis RDB(V) and Schedule 8. The discovery on a single old Aspen at
Invertromie is the first and only record from Strathspey, and the first in the
UK from Aspen. Its main populations are in the Great Glen and Strath
Glass.

Rinodina laevigata * If the identity is confirmed, this will be its first Scottish record and the first
in Europe outwith Fennoscandia.

Schismatomma graphidiodes This internationally rare RDB(V) and Schedule 8 species has its known
world headquarters on the Oaks at Cawdor Wood near Nairn. Otherwise,
it is known from only a handful of scattered, mostly Scottish localities.

* currently awaiting formal confirmation


23
Bryophytes on Aspens

Gordon Rothero

Strolonag, Glenmassen, Dunoon, Argyll, PA23 8RA. E-mail: [email protected]

Introduction

Away from the oceanic woodlands of the west, where there is a rich and interesting bryoflora on
all broadleaf species, interest in epiphytic bryophytes has tended to centre on those tree species
known to have base-rich bark, particularly Fraxinus excelsior, Acer pseudoplatanus, Ulmus
spp, Salix spp and Sambucus nigra. These tree species often have a good assemblage of
bryophytes, particularly when growing in relatively open sites, hence the value of wayside and
parkland trees. To my knowledge, Aspen has mainly been celebrated as the host species for the
single British record for Orthotrichum gymnostomum and it has certainly been undervalued.

Orthotrichum gymnostomum

Orthotrichum gymnostomum is a small, yellow-green, blunt-leaved moss which has a scattered
distribution over much of northern and central Europe and also records from south-west Asia,
Afghanistan and Newfoundland (Hill et al. 1994). Though it has been found on the bark of a number
of different tree species throughout its range, most records come from species of Populus
and through northern Europe most records are from old Populus tremula (Nyholm, 1979). In this
sense, in Europe at least, it is probably more host-specific than other epiphytic bryophytes.
Though sporophytes are apparently rare throughout its range, the plant does produce large
numbers of gemmae, specialised means of vegetative reproduction, on its leaves, a feature it
shares with the closely related Orthotrichum obtusifolium.

The solitary British record dates from 21st June 1966 when it was collected by J Dransfield in
company with H.J.B. Birks and H.H. Lees near Loch an Eilein in the Rothiemurchus forest (Perry
& Dransfield 1967). A small tuft consisting of about 15 stems was not recognised in the field and
was collected. At first it was thought that the plant was Orthotrichum obtusifolium, but closer
examination showed it to be Orthotrichum gymnostomum. After the discovery, other Aspens
were searched but no further cushions were found. It would seem that the only cushion in that
area had been collected, a sobering observation.

The site of the host Aspen for the 1966 record is not obvious from the description. The habitat
description talks of open pine-birch woodland with occasional Aspens on a north-facing slope
at about 800ft in altitude (Perry & Dransfield 1967), but unfortunately the six-figure map reference
delineates a hectare on a south-facing slope near the loch margin. Perry and Dransfield
opine that, given the frequency of Aspen in the Aviemore area, Orthotrichum gymnostomum
should turn up elsewhere in the vicinity. Thirty five years on, that hope has yet to be realised and
the plant is now classified as extinct in the Bryophyte Red Data Book (Church et al. 2001).

A number of competent bryologists have visited the Loch an Eilein area over the years and
searched Aspens without success, but few have ventured further afield. Before giving up hope
completely, it seemed a sensible idea to spend a small amount of time visiting some areas of
Aspen in Strathspey and this suggestion was incorporated into a wider survey of Priority
bryophytes in Scotland, commissioned and funded by Scottish Natural Heritage. Other than the
original locality, the sites to be visited were selected from a database of significant stands of
Aspen compiled by the Malloch Society. It seemed sensible to look at as many Aspens as possible
so only large stands were selected; at Invertromie, Insh, Torcroy, Creagan Breugach near
Inverton, Speybank by Kincraig, Tomnagowan and Boat of Garten.

I had no more success at Loch an Eilean than other bryologists; the most likely site seemed to


24
be Creag an Fhithich, the closest north-facing slope to the map reference with a few scattered
Aspens, but a wider search was also made. Moving on to the other Aspen woodlands, two
things were immediately apparent; Aspens had a much more diverse epiphytic bryophyte flora
than I had realised, and searching all Aspens in a large woodland was not possible in the time
available. Certainly more than 50% and probably more than 75% of the Aspens in the woods
were checked, and it was the more bryophyte-rich trees that were targeted. On this basis I am
reasonably convinced that Orthotrichum gymnostomum does not occur in the woodlands I visited.
The general diversity of the flora is discussed below.

Orthotrichum obtusifolium

At Invertromie, one Aspen produced a small, blunt-leaved Orthotrichum species but this proved
to be the closely related Orthotrichum obtusifolium. This species is very close to Orthotrichum
gymnostomum and requires some familiarity with the group to distinguish it in the field. It has the
same neat cushions with blunt leaves and differs mainly in the character of the leaf margins, plain
or erect in Orthotrichum obtusifolium and curled in over the leaf surface in Orthotrichum gymnostomum.
There are also critical differences in cell ornamentation that require a microscope but
are diagnostic (Smith 1978).

The initial disappointment was hardly justified as Orthotrichum obtusifolium is listed on Schedule
8 of the Wildlife and Countryside Act and, prior to this survey of Aspens in Strathspey, had just
one extant site in Britain, at Leith Hall near Huntly. The woodland at Insh produced a further tiny
stand of Orthotrichum obtusifolium but disappointingly, no more populations were found at the
other sites visited. A third locality was found on a group of Aspens at Inveruglas by David
Chamberlain, walking back to Insh village from a visit to the site at Invertromie. During the Aspen
day afternoon fieldtrip, I found a further small stand close to the original tree at Invertromie and
a subsequent search by David Long has revealed further stands, including one large one, on
three more trees.

Orthotrichum obtusifolium, as the distribution map shows, has a much longer history in Britain
than Orthotrichum gymnostomum.


25
Map 1. Showing the Distribution of Orthotrichum obtusifolium in the British Isles
(not available in text format)

Orthotrichum obtusifolium was widespread in Britain in the 19th century, though it has always
been rare. The reasonable presumption has been made that most of the English localities were
casualties of increasing air pollution, though with a rare species, chance events will always play
their part. Of the four relatively recent (post-1960) sites, three are in Scotland (Cortachy in Angus,
Fochabers and Leith Hall). At Cortachy the plant grew on parkland Elms which all seem to have
succumbed to Dutch Elm disease, and this may also have been the fate of the Elm on which it
was recorded at Fochabers. At Leith Hall there is a healthy population on some eight trees, both
Elm and Sycamore, and this remains the best British population. At the English site in Norfolk, a
single tuft was found on an elder twig in 1989, and shades of Orthotrichum gymnostomum was
collected and has not been seen again.

The new populations near Insh have increased both the geographical spread of recorded localities
and the number of host species. Historically, Ash has been the most favoured substrate in
Britain followed by Elm and Sycamore, but in northern Europe and North America, Orthotrichum
obtusifolium shows a marked preference for Aspen, so its occurrence on this tree in Scotland
should be no real surprise. The sites at Invertromie and at Inveruglas are in relatively open wood-


26
land where light levels in summer remain quite high and all historic records come from similarly
open sites. It may well be that further survey work on Orthotrichum obtusifolium, and possibly
Orthotrichum gymnostomum as well, should target smaller stands of Aspen on more open sites
rather than areas of woodland with a complete canopy.

Other bryophytes on Aspen

The survey of large numbers of Aspen revealed that a good proportion of mature trees have an
excellent epiphytic flora. Table 1 gives a list of bryophytes recorded from Aspen in Strathspey in
2000 and no doubt more could be added.

Table 1. Bryophytes recorded on Aspen in selected woodlands on Speyside in 2000

Liverworts
Frullania dilatata Frullania fragilifolia Frullania tamarisci
Metzgeria furcata Radula complanata

Mosses
Dicranum scoparium Dicranum fuscescens
Homalothecium sericeum Hypnum andoi
Hypnum cupressiforme Leucodon sciuroides
Orthotrichum affine Orthotrichum lyellii
Orthotrichum obtusifolium Nationally rare, Schedule 8
Orthotrichum speciosum Nationally rare
Orthotrichum stramineum Orthotrichum striatum
Orthotrichum tenellum Syntrichia laevipila
Ulota bruchii Ulota crispa
Ulota drummondii Ulota phyllantha
Zygodon conoideus Zygodon rupestris
Zygodon viridissimus var viridissimus

Apart from the excellent diversity of species, there are three important conclusions to be drawn
from the list. The first is a simple observation, that Aspens in Strathspey are the centre of distribution
for the nationally rare moss Orthotrichum speciosum. Given the restricted distribution of
recent records of this species (see Map 2), its abundance on many Aspens in the woods visited
is quite remarkable. The robust cushions with clearly visible capsules are a feature of most of the
better trees, sometimes forming large stands. The second is that three of the mosses which
occur regularly on Aspen in the area, Ulota drummondii, Ulota phyllantha and Zygodon
conoideus, are Atlantic bryophytes (see Hodgetts 1997), an affinity which is also reflected in the
lichen flora.


27
Map 2. Showing the distribution of Orthotrichum speciosum in the British Isles
(not available in text format)

The third observation is more subtle, but could be of considerable importance. The loss of Elms
to disease, and the general loss of wayside and parkland trees over the past 100 years, has
deprived epiphytic bryophytes of favoured sites, so much so that some species, like
Orthotrichum obtusifolium but also Orthotrichum pallens and Orthotrichum pumilum are now
endangered in Britain (Church et al. 2001). It may be that Aspens on open sites in the east of
Scotland could have populations of these species that have been overlooked. Even if this does
not prove to be the case, the substrate that Aspens provide for a good assemblage of regionally
important species, which might otherwise be in decline, is a worthwhile discovery.

One further observation of epiphytic populations on Aspens is puzzling. Though some Aspens
are clothed in a variety of epiphytic mosses, species which are known to need bark of a reasonably
high nutrient status, others are almost devoid of bryophytes, except those which can


28
cope with nutrient-poor conditions. So we have Aspens, close together and experiencing similar
light and nutrient regimes, some having a flora similar to Ash or Elm and others to Birch or
Alder. A similar situation seems to exist with the epiphytic lichen flora. One obvious explanation,
given the structure of Aspen woodland, is that this may be a clonal difference, some trees being
genetically different to others. Another possible explanation may relate to the sort of fungal infestation
that the Aspen is subject to. Aspens seem particularly prone to damage and most large
trees show signs of fungal invasion; does this affect the nutrient status of the bark or the run-off?

Conclusion

It is clear from the survey of a limited number of Aspens in 2000 that the importance of the
species for epiphytic bryophytes has been distinctly under-estimated. Though Orthotrichum
gymnostomum was not refound, the discovery of three new populations of Orthotrichum obtusifolium,
the abundance of Orthotrichum speciosum and the diversity of epiphtyic mosses on
Aspen fully justify the survey. Any increase in Aspen woodland will benefit bryophytes, and this
is as true of smaller groups of trees as of larger woodlands, so there is a different emphasis here
compared with the entomological interest. The epiphytic interest of the larger Aspens should be
borne in mind when considering the management of the woodland for insects which require
dead wood but sensible precautions should prevent any possible conflict.

References

Church, J.M., Hodgetts, N.G., Preston, C.D. & Stewart N.F. 2001. British Red Data Books. Mosses and
liverworts. Peterborough, JNCC.

Hill, M.O., Preston, C.D. & Smith A.J.E. 1991. Atlas of the Bryophytes of Britain and Ireland, Vol 3 Mosses
(Diplolepidae). Harley Books.

Nyholm, E. 1979. Moss Flora of Fennoscandia II Musci; fascicle 4. Swedish Natural Science Research
Council.

Hodgetts, N.G. 1997. Atlantic bryophytes in Scotland. Botanical Journal of Scotland. 49: 375-386.

Perry, A.R. & Dransfield, J. 1967. Orthotrichum gymnostomum in Scotland. J. Bryol. 5: 218-221.

Smith, A.J.E. 1978. The Moss Flora of Britain and Ireland. Cambridge University Press.


29
Aspen, a vital resource for saproxylic flies

Graham Rotheray

National Museums of Scotland, Chambers Street, Edinburgh EH1 1JF.
E-mail: [email protected]

Saproxylic organisms are those that depend on dead wood at some stage in their life cycle. They
vary from woodpeckers to fungi, but the most biodiverse groups are Coleoptera (beetles) and
flies (Diptera). Over most of Europe saproxylic organisms are under threat, due to the removal of
woodland cover and impoverishment of what remains (Speight 1989).

Over the past 12 years, members of the Malloch Society have been involved in a study of saproxylic
Diptera in Scottish woodlands. In comparison with Coleoptera, Diptera are poorly known
(Rotheray et al. 2001), and part of our aim was to redress this imbalance. Our emphasis was on
finding breeding sites and rearing larvae.

During the study we visited over 300 woodlands throughout Scotland. We obtained 2061
records of 258 species in 32 families. Two hundred and six species were reared, many for the
first time. We reared 53 red-listed species. In addition, we recorded nine species new to Britain
and 10 new to science, which further demonstrates how poorly known this fauna is (Rotheray et
al. 2001).

Most records came from common and relatively widespread boreal trees such as Silver birch,
Betula pubescens E., Scots pine, Pinus sylvestris L. and also from Ash, Fraxinus excelsior L.
However, another tree species was also important, Aspen, Populus tremula L. For example, we
found that for red-listed and other significant species (defined here as new to Britain, new to
science), Aspen was the third most important tree species after Birch and Pine of 22 tree
species examined. It had three Red Data Book (RDB) category 1 endangered species reared
from it, including the UK BAP Priority species, Aspen hoverfly Hammerschmidtia ferruginea
(Fallen) (Diptera, Syrphidae) (Table 1). No other tree species had as many RDB 1 species associated
with it (Rotheray et al. 2001). Altogether a group of 39 species were reared from Aspen,
of which 14 were red-listed or otherwise significant.

Many of the red-listed and significant Diptera associated with Aspen appear to be confined to it.
We did not rear them from any other tree species. Possibly these species will use other Willows
and Poplars (Salicaceae) in different geographical regions, but this does not appear to be the
case in Scotland. Thus, Aspen has a rich, specialised and unique fauna of saproxylic Diptera
associated with it.

Table 1. Rare and notable insects bred from Highland Aspen

Species and Status**

Ecataetia christiei (Dipt.Scatopsidae) New species
Mycetobia obscura (Dipt. Anisopodidae) New to Britain
Lonchaea hackmani (Dipt. Lonchaeidae) New to Britain
Medetera freyi (Dipt. Dolichopodidae) New to Britain
Hammerschmidtia ferruginea (Dipt.Syrphidae) RDB 1 (UK BAP)
Homalocephala biumbratum (Dipt.Ottitidae) RDB 1
Strongylophthalmyia ustulata (Dipt.Tanypezidae) RDB 1
Tachypeza heeri (Dipt.Hybotidae) RDB 2
Tachypeza truncorum (Dipt.Hybotidae) RDB 3
Medetera inspissata (Dipt.Dolichopodidae) RDB 3
Brachyopa pilosa (Dipt.Syrphidae) RDB 3
Gnophomyia viridipennis (Dipt. Tipulidae) Notable
Clusoides apicalis (Dipt.Clusidae) Notable
Stegena coleoptrata (Dipt.Drosophilidae) Notable
Lonchaea peregrina (Dipt.Lonchaeidae) Notable


30
Systenus pallipes (Dipt.Dolichopodidae) Notable
Xylota tarda (Dipt.Syrphidae) Notable
Criorhina ranunculi (Diptera Syrphidae) Notable
Saperda carcharius (Col. Cerambycidae) Notable

** The status rating of the Dipteran species is based upon Falk (1991) and that of Saperda carcharius on
Hyman and Parsons (1992).

The most important microhabitats used for breeding by saproxylic Diptera include tree-holes,
exudations of tree sap, decaying sap under bark and decaying sapwood and heartwood. With
the exception of exuding tree sap which is associated with live trees, all these microhabitats are
found in stumps and live and dead trees and branches. Although some tree species exhibit a
tendency to have more of one type of microhabitat than others, (e.g. tree-holes in Beech, decaying
sapwood in Birch), all were features of most of the 22 tree species examined, including
Aspen.

For saproxylic Diptera associated with Aspen, the most important microhabitat was decaying
sap under bark. When a tree or branch dies one of the first stages in the decay process is bacterial
decomposition of the cambial layers between the bark and the sapwood. In Aspen this
process results in the gradual build-up of a dark, oily, pungent-smelling layer under the bark, and
it often includes the inner layers of the bark. This decay process is common to all trees, but in
no other species did we find a layer as thick and wet as in Aspen.

This layer develops patchily at first but will eventually, under suitable conditions of shade and light
and perhaps other as yet unknown features such as the state of fungal decay within the wood,
encompass the entire underside of the bark. Eventually the bark separates from the sapwood,
cracks and this lets in air. Bacterial decomposition of the sap ends at this point and the oily layer
dries out and becomes unsuitable. The dynamics of this decay process are unclear, but the initial
build-up takes about two years and lasts for another three years or so. The thickness of the
oily layer depends on the thickness of the branch or tree. In branches below about 10cm, the
oily layer of decay is too thin to provide a breeding site for most of the important Diptera.

It is within this oily layer of trees and branches above 10cm diameter that most of the important
saproxylic Diptera dependent on Aspen breed. Their larvae either feed directly on the bacteria or
acting as predators feeding on other insect larvae. A key characteristic of this particular microhabitat
is that it is dynamic and does not last long. Thus, for populations of saproxylic Diptera, a
continuous input of fresh fallen or dead wood is required.

A particular feature of the important saproxylic Diptera associated with Aspen is their geographical
distribution. Most of them are confined to just 14 sites in north-eastern Scotland. These sites
contain large stands of Aspen, above 4.5 hectares. Although Aspen is widespread in Scotland
it is only in the north-east that such large stands exist. The survival of these Diptera may thus be
explained. It is only in these large stands that there is enough Aspen to provide a sufficient input
of new fallen or deadwood for breeding.

Few of these vital stands are protected and some have sustained damage in the past few years.
One particular problem is grazing by rabbits and deer which often remove the bark of fallen wood
thus ruining the breeding site. Another problem is competition from faster growing conifers and
removal of fallen wood by people. An additional potential threat is the plan to release beaver into
Scotland with their preference for eating Aspen (Batty this volume).

Measures are required to protect these core Aspen stands if this rich community of saproxylic
Diptera is to be conserved. In the short-term, continual inputs of wood can be created by felling
one or two trees per year. Aspen stands are often characterised by wind-blown trees lying on
their sides, but still alive attached by their root plate. Trees such as these are perhaps good candidates
for felling to provide an increase in breeding potential. Over the long-term, Aspen stands


31
can be protected from grazing with fencing as has been started at the Royal Society for the
Protection of Birds (RSPB) Reserve at Invertromie (Prescott, this volume). Such protection should
enable the fast-growing Aspen to recover and offers the potential to extend Aspen stands and
link them up to create a fully functioning ecological unit, C McGowan, this volume).

This is all the more urgent, given recent assessments of the abundance of Aspen dependent
saproxylic Diptera. These reveal them to be at a low point in numbers due to the lack of suitable
fallen wood in many stands.

Some may argue, why bother to conserve insects such as these flies in the first place? It should
be understood that just because these organisms are flies does not mean they lack significance.
Scottish Aspen is unique for the richness of its associated saproxylic flies. Many are rare in not
only a British but also a European context. Some are accorded the highest level of threat within
the RDB and one is a UK Biodiveristy Action Plan Priority species. If such a wealth of uniqueness
and rarity is not worth saving, what is? However, there is another aspect to the saproxylic
Diptera associated with Aspen that is important. When Aspen spread north following the retreat
of the ice about 10-11,000 years ago, many insects that depended on it also moved north.
Some of these have separated from populations of the same species further south to varying
degrees. Some vary just in ecology, like the hoverfly Brachyopa pilosa. In southern Britain, this
species breeds in association with Oak, Beech and Poplar, but in Scotland it appears to be
restricted to Aspen. It seems that this species has undergone a change in Scotland and is therefore
special and adds to the biodiversity of the British Isles. Other insects appear to have gone
one further step and speciated with the new species becoming dependent on Aspen. For example,
we discovered a new species of scatopsid (small black flies) confined to Aspen, Ectaetia
christii. This new species is very similar to a widespread southern species, Ectaetia clavipes to
which it is most closely related (Rotheray and Horsfield 1997). All of these features make Scottish
Aspen and its saproxylic Diptera special and important to European natural history. This deserves
to be recognised as such and treated accordingly.

Acknowledgements

I am very grateful to fellow members of the Malloch Society who helped discover the significance
of Scottish Aspen for saproxylic Diptera. These include Geoff Hancock, Steve Hewitt, David
Horsfield, Iain MacGowan, David Robertson and Kenn Watt. I am also grateful to Scottish Natural
Heritage, World Wide Fund for Nature and to the RSPB for financial support. All of us are very
grateful to Tom Prescott of the RSPB who has already done much to ensure the survival of
Aspen and its dependent flora and fauna in Scotland.

References

Graham Rotheray, Geoff Hancock, Steve Hewitt, David Horsfield, Iain MacGowan, David Robertson and
Kenn Watt. 2001. The biodiversity and conservation of saproxylic Diptera in Scotland. Journal of Insect
Conservation In Press.

Rotheray, GE Horsfield D. 1997. Ectaetia christii sp. n., a Scottish species similar to Ectaetia flavipes
(Diptera, Scatopsidae). Dipterists Digest 4: 41-4.

Speight, MCD. 1989. Saproxylic Invertebrates and their Conservation. Nature and Environment Series,
No. 42. Strasbourg: Council of Europe.

Falk S., 1991. A Review of the scarce and threatened flies of Great Britain (Part 1) Research and Survey
in Nature Conservation No.39, Nature Conservancy Council, Peterborough.

Hyman P.S and Parsons M.S., 1992. A review of the scarce and threatened Coleoptera of Great Britain
(Part 1), UK Nature Conservation No. 3, Joint Nature Conservation Committee, Peterborough.


32
The Large Poplar Longhorn Beetle
Saperda carcharius in the Scottish Highlands

Tracey Begg

Department of Zoology, University of Glasgow. E-mail: [email protected]

Iain MacGowan

Scottish Natural Heritage, Battleby, Redgorton, Perth. E-mail: [email protected]

The Large Poplar longhorn beetle Saperda carcharius (Linnaeus) (Cerambycidae), is classified as
a notable A species considered to occur in 30 or fewer 10km Grid Squares of the National Grid
(Hyman and Parsons, 1992). In the Scottish Highlands, the known distribution of this species has
recently been extended from four to 13 10km squares (MacGowan and Begg In Prep.).

Larvae of Saperda carcharius are found in trunks of Aspen (Populus tremula) the preferred larval
tree, but other Poplar species, Salix and occasionally Quercus may be utilised (Uhthoff-
Kaufmann, 1991).

Saperda probably spends 2-4 years as a larva within an aspen tree (Hyman and Parson, 1992),
after which the adults emerge during July and August. Adults may be found until October. During
the emergence period, frass and wood fibres are ejected through a circular hole in the bark
formed by an enlargement of the oviposition site. This makes it possible to determine where larvae
are present and adults have emerged.

Studies conducted at two sites, Invertromie in Strathspey and a site in Deeside during the emergence
period in 2000, revealed that where trees had emergence holes, or showed signs of larval
activity, the tree circumference (measured at chest height) was within the range 13-187cm.
The mean circumference was 47.4cm.

The circumference of over 200 Aspen trees across the Scottish Highlands was measured and
showed that the mean circumference for aspen overall lies in the 81-90cm circumference size
range. This demonstrates that Saperda carcharius is selecting for smaller trees.

Within each aspen stand, most activity was found to be on trees at the edge of the stand, next
to open ground with only a few sites being found within dense cover. Trees found bordering
walls, fences or along road verges commonly had an abundance of emergence holes, possibly
due to the open aspect consistent with these sites.

Where conditions are favourable and grazing pressure is low, Aspen regenerates by producing
suckers from the parent tree, giving rise to dense stands of young trees. These trees are used
by Saperda larvae. Although larval activity does not directly kill the host tree, it no doubt weakens
it by allowing the entry of damaging tree diseases, fungal attack and by weakening the stem,
making it more susceptible to wind blow and other damage.

The thinning of Aspen stands to produce relatively open stands of larger trees is, in general, a
benefit to the other insects and lichens associated with Aspen. By being an agent in the thinning
process, Saperda carcharius acts in an ecologically beneficial manner and plays an important
role in the ecology of Aspen stands.

References

Hyman and Parsons. 1992. A review of the scarce and threatened Coleoptera of Great Britain, Part 1, UK
Nature Conservation Series Number 3, Joint Nature Conservancy Council, Peterborough.

MacGowan, I. and Begg, T. 2001. Notes on the distribution, status and ecology of the large poplar longhorn
beetle, Saperda carcharius (Linnaeus) (Cerambycidae) in the Scottish Highlands. In Prep.

Uhthoff-Kaufmann, R. R. 1991. The distribution and occurrence of the genus Saperda F. (Col. Lamiidae)
in Great Britain. Entomologists Record 103: 129-134.


33
Byctiscus populi, a leaf rolling weevil
dependent on Aspen

Jon Mellings

Centre for Biodiversity and Conservation, University of Leeds, Leeds LS2 9JT.
E-mail: [email protected]

Steve Compton

Centre for Biodiversity and Conservation, University of Leeds, Leeds LS2 9JT.
E-mail: [email protected]

Introduction

Byctiscus populi (Coleoptera: Attelabidae) is an attractive, metallic green or coppery coloured
leaf-rolling weevil associated with Aspen Populus tremula and occasionally Poplars. Fowler
(1891) stated that B. populi was found on young Aspens, and Morris (1999) refers to anecdotal
evidence that these weevils prefer young growth of suckering and regenerating trees to large,
mature individuals. The UK range of B. populi appears to have declined in the past few decades.
It is classified as Red Data Book 3 rare and UK Biodiversity Action Plan (BAP) - Priority listed
species (Morris, 1999). In accordance with recommendations in the UK Species Action Plan,
research was initiated in 2001 at the University of Leeds, the designated Lead Partner for this
species. Former and extant sites are being resurveyed to update records, and thereby establish
a picture of the species current status. Since ecological knowledge of B. populi is largely anecdotal,
priority is being given to field and laboratory-based research to examine aspects of its biology
and habitat requirements. These findings will be used to advise on practical management
actions to aid recovery of B. populi. Here we discuss the current UK distribution of B. populi,
describe some initial findings regarding its biology and habitat requirements and suggest possible
causes for its decline.

Ecology

Field studies were carried out during summer 2001 at Monkwood (just north of Worcester,
Worcestershire), which supports a strong population of B. populi. Comparative studies were also
carried out by Lianne Evans (University of Leeds) and Dmitry Telnovs in Latvia, where B. populi
is still common.

Besides Aspen, B. populi is said to be associated with White poplar (Populus alba) and Black
poplar (Populus nigra) (Hyman and Parsons, 1992). However, in the UK and Latvia it appears to
occur almost exclusively on Aspen. Field observations and captive rearing of Latvian and UK
specimens have provided a reasonably complete picture of its lifecycle.

Emergence of adults, mating and oviposition

The adult insects appear from May onwards, when they can be seen feeding on the leaves of
Aspen. Mated females lay batches of between one to four eggs in cigar-like rolls formed from
one, or occasionally two, Aspen leaves, with more eggs deposited in longer leaves (Evans,
2001). The larger, longer leaves found at the growing tips of Aspen suckers are the favoured
oviposition sites, with plants as short as 30cm utilized. Trees above two or three metres are used
more rarely than smaller individuals. As many as four individuals, both females and more rarely
males, may cooperate in the rolling of a single leaf roll. This suggests that some rolls may contain
the eggs of more than one female. The rolls are sometimes detached almost immediately, or
may remain on the trees for several weeks.


34
From egg to larvae

Eggs of captive-reared Latvian beetles took an average of just under four days to hatch. The first
instar larvae then proceeded to feed on the wilted leaf roll from within. Usually at this point the
leaf was still attached to the food-plant. The number of larval instars remains undetermined, but
mature larva of 4-6mm in length, vacated the roll after an average of around 16 days. It is possible
that larvae occasionally complete their development while the roll is still attached to the tree.

Prepupa, pupation and emergence

In common with B. populis slightly larger sister species B. betulae, larvae were found to pupate
in pupal chambers in the soil at a depth of between 560mm. A prepupal stage lasts up to four
weeks, followed by a comparatively short pupation, lasting less than a week in some cases.
Whereas B. betulae overwinter as adults in the pupal chamber (Bily, 1990), captive-reared B.
populi specimens emerged above the soil surface and began feeding shortly after.

Number of broods and hibernation of the adults

In Monkwood, B. populi adults were observed rolling leaves throughout the summer between
May and the beginning of August, when suckers were still seen to be producing fresh leaves.
The peak activity was around the end of June, when both beetles and leaf rolls were very numerous.
It is likely that the beetle is bivoltine or even continuously brooded through the summer.
Captive-reared beetles provided with a choice of rough pieces of bark and soil in outdoor conditions
in late October 2001, settled beneath the soil and within cracks in the bark and appeared
to enter diapause. Whether any final generation adults overwinter as adults in their pupal cells,
as described for B. betulae, is unknown.

Distribution

Internationally, B. populi occurs over the whole of the Palaearctic region, being fairly common in
central Europe (Harde, 1998). In the UK, Morris (1999) stated There are post-1970 records from
east Sussex and east Kent, but historically it was more widely distributed, being recorded from
much of southern England northwards to east Norfolk, east Gloucestershire and
Worcestershire. Now considered to be rare and declining, it is clear from Fowlers (1891) summary:
very local, but not uncommon where it occurs, that B. populi was patchily distributed
even at the end of the 19th century.

A meeting on the conservation of UK BAP phytophagous beetles, funded by English Nature, was
held in London in February 2001. It became evident that B. populi has continued to decline, having
probably become extinct at two of the seven sites for which post 1980 records were available.
Ian Menzies, who had regularly recorded the species at Bookham Common Special Site of
Scientific Interest (SSSI), Surrey, noted that he had recorded no further specimens since 1991.
Similarly, four miles away at Wisely Common, Peter Hodge reported the beetles recent demise
as a result of extensive clearance of pioneer Aspen scrub, removed for conservation purposes!

Four possible post-1990 B. populi site records are available, two of which are based on our surveys
this year. The first is Oversley Wood, a Forestry Commission site in Warwickshire. Here the
most recent of several records since 1987 was made by Lane & Forsythe in May 1999 (Lane &
Forsythe, 1999). They beat a single specimen from Aspen and described the Oversley population
as small and vulnerable. Aspen is one of the dominant species in sections of this site and
our 2001 site visits found several leaf rolls on ride-edge aspen suckers, though no adults were
seen. This suggests the population is still extant at Oversley, but remains very small.

The second recent B. populi site record was added by Darren Mann (pers. comm.), who found
the beetle at Wappenbury Wood (a Warwickshire Wildlife Trust Reserve approximately 30km
from Oversley Wood) during the 1990s. Aspen suckers proliferate along rides at Wappenbury,
though conservation efforts have apparently reduced their abundance in recent years. Leaf scars


35
consistent with B. populi were found during our 2001 site visit, but we failed to confirm the continued
presence of the beetle.

Orlestone Forest, a Kent Wildlife Trust-managed ancient woodland, near Ham Street was visited
in mid-August 2001. B. populi had last been recorded at the site in 1972, with records dating
back to the mid-1960s. No adult beetles were found, but two leaf rolls, almost certainly created
by B. populi, were discovered in a sunny, ride edge location. Interestingly, the habitat at this
site was very similar, in terms of vegetative composition, structure and management, to
Monkwood, another site where the beetle survives.

Morris (1990) has described Worcestershire as a blank spot because of the apparent underrecording
of Coleoptera there. We investigated two woods in the county where there were old
(1950s) records for B. populi, one of which was Monkwood, where we found what may be currently
the strongest UK population of this species. This wood is a Worcester Wildlife Trust
Reserve and SSSI. An ancient coppice woodland, and once a Harris brush wood, it is now
managed jointly by the Worcester Wildlife Trust and Butterfly Conservation. Leaf rolls were
noticed even before the site was entered, on low aspen suckers at the woodland boundary adjacent
to the road. Subsequent searches within the wood revealed a number of discrete patches
of Aspen sucker growth along ride edges and in areas of recently-coppiced Hazel (Corylus avellana).
B. populi adults and leaf rolls were found in reasonable numbers on virtually all the patches
of pioneer, ride-edge Aspen throughout the site. In contrast, the beetle and its rolls seemed
largely absent from mature trees (although rolls sometimes occurred on the lower branches of
standards in sunny conditions). More tellingly, where aspen suckers occurred as an understorey
in areas heavily shaded by mature trees, B. populi was almost always absent.

The second site in Worcestershire, which has recently been acquired by Worcester Wildlife Trust,
was Randen Wood, between Bromsgrove and Kidderminster, where the beetle appears to have
been lost. Aspen was present in this wood in small isolated patches, but the woodland canopy
was closed, allowing little light to penetrate. There was no sign of recent management and no
evidence that B. populi was present.

The contrasting fortune of the beetle at the two Worcester sites and its distribution within
Monkwood and elsewhere provides strong indications of the habitat needs of B. populi and the
management required for it to persist. Small Aspens, growing in sunny, sheltered conditions are
what this species requires. The Dark-bordered beauty (Epione vespertaria) appears to have very
similar habitat requirements to B. populi. This moth is known mainly from Aspen sites in
Scotland, and it would be well worth looking for B. populi at these sites, even though it has not
been recorded previously north of the border. Suitable small Aspens are typically found along
woodland rides at the English sites, but in Latvia they are also a common feature of roadside
verges, derelict land, footpaths and other habitats, hence the beetles much greater abundance
there. Perversely, maintenance of open rides is important for the persistence of this species, but
thorough ride clearance that results in the elimination of Aspen suckers and bushes deprives it
of suitable host plants.

Acknowledgements

Our work on Byctiscus populi has been funded by the English Nature.

References

Bily, S.,1990. A colour guide to beetles, ed. London: Hamlyn.

Evans, L. 2001. A study on Byctiscus populi (L.1758) (Attelabidae) in Latvia and implications for conservation
management in the UK. Unpublished MSc. project, University of Leeds.

Fowler, W.W., 1891. The Coleoptera of the British Isles, vol 5. London: Reeve and Co.

Harde, K.W. and Severa, F., 1998. A Field Guide in Colour to Beetles. Leicester: Blitz Editions.


36
Hymen, P.S. and Parsons, M.S., 1992. A review of the scarce and threatened Coleoptera of Great Britain,
Part 1. Peterborough: JNCC.

Lane, S.A. and Forsythe, T.G., 1999. Noteworthy beetles found in Warwickshire (VC 38) in 1999. The
Coleopterist, 9: 102 104.

Morris, M.G., 1999. Byctiscus populi (a leaf-rolling weevil) Action plan. In UK Biodiversity Group Tranche
2 Action Plans, Vol 5: Invertebrates (March 1999). Peterborough: JNCC.

2001, Minutes of meeting on phytophagous beetle conservation, Royal Entomological Society, London.
(unpublished).


37
The importance of Aspen for Lepidoptera

Mark Young

Centre for Ecology, University of Aberdeen, Culterty, Newburgh, Ellon, Aberdeenshire, AB41
6AA. E-mail: [email protected]

Introduction

The species of Lepidoptera that use Aspen as a larval foodplant are summarised by Emmet
(1991), who lists all British Lepidoptera and their life histories. Depending on interpretation of the
use made of Aspen by generalist feeders, there are around 40 moth species regularly found on
the tree in UK overall, about 25 in Scotland and, of these, 26 are specialised Aspen feeders in
UK, whereas only about 14 are mainly confined to Aspen in Scotland (Table 1). Southwood
(1961) originally counted the number of herbivorous insects on British tree species, (although this
analysis has been upgraded recently for Lepidoptera by Young (1997)). By this reckoning, Aspen
harbours a rather modest total, compared with Oak, Birch and Sallow, for example. However,
the number found on different trees is positively correlated with the abundance and distribution
of each tree and, although Aspen is widespread, it does not compare with other forest trees in
its abundance, nor in the tendency to form extensive woodland. Its apparency to moths is relatively
low. In Scotland, every large stand of Aspen tends to have a regular attendance of 10-12
moth species, which form a distinct assemblage.

Table 1. Species of Lepidoptera associated with Aspen in Scotland, including only species feeding
mainly or exclusively on Aspen.

(Data from Emmet, 1991).

A. Number of species regularly feeding on Aspen in UK 40 species
in Scotland 25 species

Number of species specialising on Aspen in UK 26 species
in Scotland 14 species

B. Species feeding mainly or exclusively on Aspen in Scotland
Ectoedemia argyropeza (Zell.) larvae mine in petiole & leaf
Stigmella assimilella (Zell.) larvae mine in leaf
[Paraleucoptera sinuella (Reutti) larvae mine in leaf (? extinct)]
Anacampsis populella (Cl.) larvae in folded/rolled leaves
Ancylis laetana (Fabr.) larvae in folded leaf
Epinotia cinereana Haw larvae in folded/spun leaves
E. maculana (Fabr.) larvae in spun leaves
[Gypsonoma nitidulana (L. & Z.) larvae in spun leaves (extinct?)]
G. sociana (Haw.) larvae in spun leaves
Tethea or (D. & S.) (Poplar Lutestring) larvae in flat-spun leaves
Lobophora halterata (Hufn.) (Seraphim) larvae free on leaves
Epione vespertaria (Linn.) (Dark-bordered Beauty) larvae free on young regrowth
Pheosia tremula (Cl.) (Sallow Prominent) larvae free on leaves
Clostera curtula (Linn.) (Chocolate Tip) larvae in spun leaves
Orthosia populeti (Fabr.) (Lead-coloured Drab) larvae on catkins then leaves
Acronicta megacephala (D. & S.) (Poplar Grey) larvae in spun leaves

Characteristic species on Aspen

Since Aspen is closely related to other Poplars, and reasonably closely related to Salix spp., it is
not unexpected to find that it shares a number of species with them. The Pale prominent
(Pterostoma palpina) and the Poplar hawk (Laothoe populi) are examples of species which will
readily use most Sallow and Poplars species, whereas the Swallow prominent (Pheosia tremula)


38
and the Poplar grey (Acronicta megacephala) are restricted to Poplars. However, the latter illustrates
an interesting feature in that it is apparently restricted to Aspen and does not use other
Poplars in the north of its UK range. This extra specialisation applies to several species. Finally
there are some species, such as the Seraphim (Lobophora halterata) and the Lead-coloured
drab (Orthosia populeti), that are always restricted to Aspen.

Most tree species have some moth larvae that feed on the bark, flowers or that bore into the
twigs. However, all Aspens specialised feeders use only the leaves, except that the Leadcoloured
drab also feeds on the flowers at first. It is traditionally believed that the flat petiole, leading
to the trembling of the leaves, makes it difficult for insect herbivores to remain attached to
Aspen leaves, and it may not be coincidence that most species live between spun or folded
leaves. For example, the Poplar lutestring (Tethea or) uses a series of strong silk pads to attach
one leaf on top of another and Ancylis laetana makes a neat chamber of a folded leaf.

Even small stands of Aspen will harbour the commoner species of moth, especially those that
will also use Sallow or other Poplars. However, it is only Aspen woodlands of a significant size
that include the rarer, specialist species. The Chocolate-tip (Clostera curtula) is found locally only
in the larger Aspen woods. No-one knows how large such a woodland needs to be for this
species to survive, but it is clear that it is associated with mature trees, as is the Lead-coloured
drab. As will become clear below, other species require regenerating growth and so there is a
clear conservation need for large stands of Aspen that include both mature and regenerating
stems. The majority of the species that live on Aspen can apparently survive in rather generalised
woodlands, but the rare species described below clearly need very much more specialised conditions.

The Dark-bordered beauty and its conservation

The Dark-bordered beauty (Epione vespertaria) has always been a rare species but is now very
localised indeed and, by nature of this localisation, must be considered threatened in UK. Its
English and southern Scottish localities are already published in the literature and so can be safely
repeated here, whereas its northern Scottish localities are referred to by a generalised name
(Table 2).

At Strenshall Common, Yorkshire and Newnham Bog, Northumberland Dark-bordered beauty
larvae are known to feed exclusively on Creeping willow (Salix repens) and they have been confirmed
recently from these sites, but not from the small handful of other historic English sites. At
Adderstonlee Moss, Roxburgh it is also assumed that S. repens is the foodplant, in the absence
of Aspen, but no larvae have been found to confirm this. Nor has the adult moth been seen there
recently, but it must be admitted that the few recent searches have been in less than ideal conditions
(K.P. Bland, D.A. Barbour, pers. comm.).

Table 2. Sites for the Dark-bordered beauty (Epione vespertaria) in UK since 1990.
(Editors note: excludes details of newly discovered Deeside site)

1. Strenshall Common, Yorkshire
Larvae recently found on Salix repens.

2. Newham Bog, Northumberland
Larvae recently found on Salix repens.

3. Adderstonlee Moss, Roxburgh
No recent sightings, larvae presumed to feed on Salix repens. (No Aspen present).

4. Near Balmoral, Aberdeenshire
Larvae recently found exclusively on low regrowth of Aspen. Adults also seen.

5. Near Grantown, Strathspey
Adults recently found. Larvae presumed to feed on low regrowth of Aspen.

(No Salix repens present).


39
In contrast, at the Balmoral and Grantown sites, the larvae feed exclusively on Aspen
(Leverton et al., 1997) and are confined to regenerating shoots. There is no clear height above
which such growth becomes unsuitable, but recently larvae were found on shoots of less than
50cm height and at the Balmoral site the moths are seen only where there is abundant suckering
of less than 1m height. At Balmoral, this regrowth has been favoured by irregular cutting
of a roadside verge and by the recent clearance of mature woodland to create a pylon wayleave.
At Grantown, intermittent grazing seems to have allowed regrowth, although the number of
available shoots is very low there and only a small number of moths have been found. The colony
seems to be in serious danger.

Visits have been made to several possible sites, near those on Deeside and Speyside, but so far
with only limited success. In summer 2001, a new site on Deeside was discovered, taking the
total to three sites in the Cairngorms. Suitable regeneration of Aspen does occur in places near
the known sites and there is no convincing reason why these should not be used. However, a
successful site will have to have had a continuity of regrowth always available and the adult
females are rather sluggish, so that colonisation may only be possible over short distances.

The clear conservation priority is to secure management of the existing sites, so as to maintain
and extend the availability of suitably low growing shoots; and then, secondly, to consider the
suitability and security of other nearby sites, with a view to possible introductions.

Species in need of relocation

Finally, there are two species that used to be found on Aspen in Strathspey but are now apparently
extinct. Urgent survey work is needed to relocate these, or to confirm their absence.
Gypsonoma nitidulana was found until 1911 on old Aspens near Aviemore but has not been
seen in Britain since then. Its relocation may seem to be a hopeless cause but there are ample
examples of other species that have been rediscovered after such an interlude such as Ethmia
pyrausta, recently re-recorded after over 100 years (Smith and Young, 1997). G. nitidulana is
rather nondescript and its relocation will require collection of larvae by a specialist.

Paraleucoptera sinuella, by contrast, should be reasonably easily recorded, for its larvae make
rather characteristic leaf blotches. It was recorded by Bankes, a well-known and reliable lepidopterist,
in an Aspen spinney near Aviemore Railway Station in 1910 and it survived there until
the 1950s, since when it has inexplicably vanished. It was also found in 1945 near Grantown,
indicating that it was not wholly restricted to one site. Abroad, it ranges from Europe to Japan
and is often rather common on other Poplars and Salix spp., as well as Aspen. The adult is generally
found in June and again in August, and the larvae in July and September but there may be
only one generation per year in Scotland. Adults are tiny white moths, with minute gold streaks
on the wings, but the larvae form oval blotch mines on the leaves. These are 1-1.5 cm long and
0.5-0.8 cm wide when fully formed and are at first brown but then later black. The larval droppings
(the frass) are placed at the centre of the mine, often in a spiral array of fine grains, leaving
clear margins to the mine. However, old mines go black and indistinct as the leaves decay.
Furthermore, there are other insects that also mine Aspen leaves and so confuse matters. Once
the larvae are fully fed, they emerge from the mine and spin a small and sparse rectangular white
silk web on a leaf within which they form a dense yellowy-white cocoon, in which to pupate. No
other insects form such a spinning and its presence is diagnostic for this species. There is a real
hope that P. sinuella will be refound in Strathspey in future, by searching for its mines and
cocoons.

Conclusions

Conservation of Aspen feeding Lepidoptera requires a general effort to provide a continuity of all
ages of tree, in sufficiently large stands to provide for the larger, specialist species. The Dark-bordered
beauty has more specialised and exacting requirements, however, and its three remaining
sites in northern Scotland will need careful management, to sustain the continuity of regenerat-
ing growth. It has survived by accident so far, but we must now act deliberately to secure its
future.


40
References

Emmet, A.M. 1991. Chart showing the Life History and Habits of British Lepidoptera. In: Emmet, A. M.
and Heath, J. The Moths and Butterflies of Great Britain and Ireland. 7:2. Harley Books, Colchester.

Leverton, R., Young, M.R. and Barbour, D. 1997. Epione paralellaria D. & S. (Lep.: Geometridae) and its
association with Aspen (Populus tremula) in the Scottish Highlands. Entomologists Record & Journal of
Variation. 109: 49-55.

Smith, R. and Young, M.R. 1997. The rediscovery of Ethmia pyrausta (Pallas, 1771) (Lepidoptera:
Ethmiidae) in Britain. Entomologists Gazette 48 (2): 85-87.

Southwood, T.R.E. 1961. The number of species of insect associated with various trees. Journal of Animal
Ecology 30: 1-8.

Young, M.R. 1997. The Natural History of Moths. T. & A.D. Poyser, London.


41
Beavers: Aspen heaven or hell?

Dave Batty

SNH Casework Support Officer, Kilmory Industrial Estate, Kilmory, Lochgilphead, Argyll,
PA318RR. E-mail: [email protected]

The paper will provide a background to the ecology of European beavers, discuss their potential
impact on woodland in general and on Aspen in Scotland in particular.

European beaver

The European beaver, Castor fiber, is Europes largest rodent (average weight c 25kg), and is a
separate species from the North American beaver Castor canadensis. It has a semi-aquatic
lifestyle, and inhabits freshwater, either slow-running rivers or lochs. They generally use water as
their main means of travel and are only occasionally found more than c60m from water.

Beavers are social animals and live in family groups consisting of the two parent animals plus the
young of the year and sometimes the young of the previous year. The number of animals in a
group varies, but an average of 3.8 has been recorded. The group occupy a territory around their
lodge, which they defend against other groups. They also use a larger home range, which they
might share with other neighbouring groups.

Beavers normally have their young in May-June, and most litters are either two or three young.
The young stay with the parents until they are sexually mature and ready to disperse from the
home territory, usually at around two years old just before the new young of the year are born.
However, the dispersing young may return to the home territory if they fail to find a suitable area
elsewhere.

European beavers tend to live in natural holes in banks or excavate burrows with an underwater
entrance. Where the banks are not high enough, the Beavers may construct bank lodges consisting
of a burrow covered by piles of wood. The lodge contains a vestibule and, typically, one
nesting chamber above water level.

Beavers build dams from a variety of materials including wood, mud and sometimes stones. The
main reason for dam building is to raise the water level and keep the entrance to their burrow or
lodge below the water surface. This reduces the chances of predation and danger to the young.
Beavers will also excavate canals to facilitate the transport of material. This can increase their
potential feeding range.

Beavers are herbivores, feeding entirely on plant material. They eat an extremely wide range of
herbaceous and woody plants, with at least 149 and 80 species recorded respectively. During
the late spring and summer they mainly eat herbaceous plants, especially aquatic ones, and take
a wide range of grasses, forbs, ferns, shrubs and leaves. The bark and leaves of trees and
shrubs forms only a small part of their diet.

Where the preferred herbaceous plants are not available, Beavers will utilise more woody
species. This change is most obviously seen in the autumn and winter when woody plants form
the vast majority of the diet. Beavers will store branches underwater in the autumn for use in the
winter when other food is not available. Trees and shrubs are used for their foliage and their bark,
especially in the winter. There is a marked preference for hardwoods, especially Aspen, Birch,
Willow, Rowan, Oak, Alder and Ash.

Beavers tend to focus their activities around their burrow or lodge and this influences their foraging
behaviour. They travel by water and generally feed up to 100m from the waters edge but
most is carried out within 20-60m. Most of their preferred trees and shrubs are harvested near
the waters edge. However, observations from Norway indicate that Beavers will travel up to
200m or more to use Aspen, and it is considered that any accessible Aspen within 500m may


42
be at risk of some exploitation. In addition, any Aspen within c 30m of the water would be vulnerable
to heavy exploitation. It should be noted that Beavers can only use stands of Aspen that
are accessible to them and that they are not as athletic as sheep or deer!

Most trees and shrubs felled are less than 10cm in basal diameter, in Finland the mean being
c3cm and in Norway the majority <5 cm. The result is that the vast majority of the hardwoods
will then coppice naturally, providing other browsing species are not present, to provide another
potential crop for the Beavers to harvest in the future. Experience from re-introductions to
Brittany and Poland is that the Beavers coppice the woodland rather than clear fell. Although the
majority of trees used are small, Beavers are capable of felling trees of greater diameter, up to
1m. Where Beavers have been re-introduced, there has been a range of young regeneration and
old mature trees, so the potential situation of just mature Aspen trees has not occurred.
Therefore, given Beavers predilection for Aspen, it would be advisable to have a range of trees
of different ages and sizes in an area.

Re-introduction proposal

The European beaver was once widespread across Europe, including Scotland and the rest of
Britain, and northern Asia to Siberia. It probably occurred in Scotland until the early 16th century
when it was hunted to extinction for its fur. It suffered a similar decline in Europe until by the
19th century there were only a few populations remaining in Norway, Germany and France.
However, through legal protection, translocation and re-introduction it has now been successfully
returned to much of its former range.

Scottish Natural Heritage (SNH) is now considering the re-introduction of European beaver to
Scotland because:

- It is listed on the EC Habitats Directive;

- It is recognised as being a keystone species in the ecology of woodland and freshwater
systems;

- It would benefit biodiversity; and,

- Since humans were responsible for its extinction in Scotland, it has been argued that there
is a moral responsibility to redress the loss.

Some years ago, SNH began to examine seriously the possibility of returning European beaver
back to Scotland. SNH commissioned work on the suitability of habitats in Scotland to support
Beaver and also on the effects of Beavers on hydrology, fish and woodland habitats in Europe.
A national consultation was carried out in 1998 to ascertain the views of everyone who might
have an interest in the subject. Based on that, SNH decided to go ahead, in principle, with a trial
re-introduction which would be in a limited area for a specific period of time. Interest from the
Forestry Commission led to an assessment of their holdings in Scotland and Knapdale Forest in
Argyll was identified as the most suitable area for a trial. A fully planned trial is proposed with
monitoring to determine, amongst other things:

- How the Beavers behave in Scotland;

- Impact on woodland habitat;

- Impact on other wildlife interests; and,

- Impact on water quality.

The trial would last for five years, but if insurmountable problems were encountered during that
period the trial would be curtailed prematurely. If the trial proceeds, it is intended that Beavers
will be captured in autumn 2002, spend six months in quarantine and then be released in spring
2003. The trial would end in 2008. After the five years, there will be an assessment to help provide
information for an informed decision on whether a wider-scale Beaver re-introduction should


43
take place. At this stage there will be wide consultation.

The trial will be taken forward by SNH in partnership with Forest Enterprise, Scottish Wildlife Trust
and Argyll and Bute Council.

SNH will make a final decision over the trial in autumn 2002. However, approval will then be
needed from the First Minister, as Beavers are not currently part of the native UK fauna and as
such a licence is required under the Wildlife and Countryside Act 1981 to release them into the
wild.

Potential impact on Aspen

It has already been noted above that Aspen is a favoured food for Beaver and that they will preferentially
select it. This could put more pressure on an already restricted resource, both in terms
of quantity and quality. However, at present Aspen is under pressure from grazing animals; both
domestic (sheep and cattle), and wild (primarily deer, rabbits and hares). A key question is how
to reduce or eliminate any extra threat from Beavers?

Direct methods would include the identification of areas of Aspen at high risk from Beavers due
to their proximity to water and their accessibility to Beavers. These areas could be easily fenced
against Beavers, and, if of high value, might need to be fenced against other animals as well.
Relatively low stock-proof fencing should be adequate, avoiding potential significant problems of
fence collisions for woodland grouse. Given that Beavers burrow for other purposes, it would
probably be sensible to have an apron of netting on the ground to deter burrowing, especially in
soft ground.

If there are concentrations of Aspen along particular river systems, an alternative method would
be not to re-introduce Beavers to that catchment. Beavers usually travel via water and experience
from the continent is that it can take some time for Beavers to move from one catchment
to another one.

However, perhaps the best method for dealing with a potential threat to Aspen from a Beaver reintroduction
is to increase the quantity and quality of the Aspen resource, be it areas of Aspen
woodland or Aspen stands in other woodland types. In this way the aim would be to manage
existing Aspen and create new Aspen areas such that if/when Beavers arrived there would be
sufficient habitat for both the Beaver and Aspen. The proposed trial re-introduction of European
beaver to Scotland could be used as the publicity to raise the profile of Aspen with the public,
land owners and managers, and also the bodies which could provide the funds for its management
and expansion. European beaver could be used as an Aspen flagship species to heighten
awareness.

If the trial went ahead, it would be 2008/2009 before any decision could be made about any
wider re-introduction of European beaver to other parts of Scotland. This provides considerable
time to begin the active management and expansion of the Aspen resource in Scotland, and to
look at ways of improved funding for this work through, for example, Woodland Grant Scheme
and agri-environment schemes. If this work took place, and the decision was made not to proceed
with a wider re-introduction, then the net result would still be both a raising of awareness
of Aspen and a considerable expansion in the Aspen resource.

The return of European beavers to Scotland might be hell for an individual Aspen, but potentially
heaven for the Aspen resource as a whole. It is for people with an interest in Aspen to decide
how they want to view Beavers, either as a problem or, more sensibly, as an Aspen opportunity.


44
Further reading:

Collen P. 1997. Review of the potential impacts of re-introducing Eurasian beaver Castor fiber L. on the
ecology and movement of native fishes, and the likely implications for current angling practices in
Scotland. Scottish Natural Heritage Review 86.

Conroy J. and Kitchener A. 1996. The Eurasian beaver (Castor fiber) in Scotland: a review of the literature
and historical evidence. SNH Review 49.

Gurnell A. 1997. Analysis of the effects of beaver dam-building activities on local hydrology. SNH Review
85.

Kitchener A. and Lynch J.M. 2000. A morphometric comparison of the skulls of fossil British and extant
European beavers, Castor fiber. SNH Review 127.

Macdonald D., Maitland P., Rao S., Rushton S., Strachan R. and Tattersall, F. 1997. Development of a protocol
for identifying beaver release sites. SNH Research, Survey and Monitoring Report 93.

Reynolds P. 2000. European beaver and woodland habitats: a review. SNH Review 126.

Scott Porter Research & Marketing Ltd. 1998. Re-introduction of European Beaver to Scotland: results of
a public consultation. Scottish Natural Heritage Research, Survey and Monitoring Report 121.

Webb A., French D.D. and Flitsch, A.C.C. 1997. Identification and assessment of possible beaver sites in
Scotland. Scottish Natural Heritage Research, Survey and Monitoring Report 94.


45
Variation in Aspen in Scotland:
genetics and silviculture

Bill Mason

Forest Research, Northern Research Station, Roslin, Midlothian, EH25 9SY.
E-mail: [email protected]

Eric Easton and Richard Ennos

Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, The
Kings Buildings, Mayfield Road, Edinburgh, EH9 3JU.
E-mail: [email protected]

Introduction

European Aspen (Populus tremula L.) is a widely distributed tree species in the northern temperate
zone with a range stretching from Scandinavia to north Africa and from Britain to Japan.
While the species is found throughout Britain, it is commonest in northern Scotland (Worrell,
1995a). However, a tendency to grow in small groves on the edges of woodland, a lack of regular
seed production (Ennos et al., 2000), plus a palatability to grazing, have meant that the total
area of Aspen woodland in Britain is estimated at around 500ha (J. Gilbert FC, pers. comm.) and
woods of more than 1ha are rare. As a consequence, there have been very few studies of the
silviculture and genetics of Aspen in Britain (Worrell 1995 a, b) and knowledge of appropriate
management to favour this species is limited. The lack of knowledge is the more unfortunate
because the importance of the species for both nature conservation and landscape interests is
considerable (see other papers in these Proceedings). The purpose of this paper is to summarise
some recent studies which provide useful guidance to those interested in increasing the area of
Aspen woodland, either through natural colonisation or through planting.

Propagation of Aspen

The recent upsurge of interest in Aspen partially stemmed from recommendations that it be
accepted for planting in the Native Pinewood schemes of the late 1980s (Hollingsworth and
Mason, 1991). An average of 9ha of Aspen has been planted per year in Scotland since 1996
under the Woodland Grant Scheme (D. Wright, FC pers. comm.). Concern was expressed that
the only Aspen material that could be purchased from nurseries in Britain at the time was of nonnative
origin and probably not well adapted to Scottish conditions (Ennos et al., 2000). A small
research project was carried out in the late 1980s to look at the possibilities of propagating
Aspen by cuttings. This resulted in recommendations to excavate root sections in the field during
the dormant season, place them in a heated greenhouse to promote suckering, and root the
detached shoots as softwood cuttings in a mist house (Hollingsworth and Mason, 1991). Trials
have generally shown high rooting percentages using this method (ie 90-100% rooting under
mist) but there has been appreciable clonal variation in the number of shoots m-1 of root, and in
growth after rooting (Hollingsworth and Mason, 1993).

Although seed production by Aspen in Scotland is infrequent, there have been two recent reports
of successful seed collections in Strathspey (Worrell, 1995b; Worrell et al., 1999). In addition,
some of the native Aspen material offered by commercial nurseries in Scotland has been through
at least one multiplication cycle in vitro before being grown on for forest planting (R.S.D. Ogilvy,
Christie-Elite pers. comm.).

Distribution in Scotland

As a result of increasing confidence in the ability to propagate native Aspen, the next question
was where could suitable locations of Aspen be found in Scotland. Discussions resulted in a
small Forestry Commission/Scottish Natural Heritage project being established in 1992 with nine


46
objectives (see Table 1). Some of these objectives are discussed in more detail below.

Worrell (1995a) recorded some 500 sites in Scotland where Aspen had been reported in the early
1990s. These locations1 are plotted in Figure 1 together with a further 100 sites recorded since
the original survey; the 40 sites identified by Wilson et al. (2000) are included. The results indicate
particular concentrations of Aspen in Perthshire, Deeside, Badenoch, Strathspey, Easter
Ross and eastern Sutherland, with lesser frequency elsewhere. The recorded distribution was
divided into eight zones as shown in Figure 1. This used the boundary between Regions of
Provenance 10 and 20 (see Herbert et al., 1999) as the first divider, with subsequent divisions
along major watersheds.

Investigations of Scottish Aspen using genetic markers

Once the range of the distribution of Aspen in Scotland had been ascertained, it became possible
to undertake genetic analysis to find out more about the population biology and genetic variability
of Aspen in Scotland. As indicated earlier in this volume, the reproductive biology of Aspen
in Scotland is very different from that of most other native tree species. Flowering of the species
is rare, and significant seed set is found at distant and irregular intervals (Worrell 1995a, Worrell
et al., 1999). Seed is short lived, and the disturbed and open conditions required for seedling
establishment are rarely found. Sexual propagation of the species is presently very problematic.
On the other hand, the species has a remarkable ability to persist and spread via root suckers,
so that individual genotypes have the potential to be extremely large and long lived. The management
of native Aspen woods for conservation requires an understanding of how these special
features have affected the level and distribution of genetic variation within Scottish Aspen
populations. Two studies using genetic markers were therefore conducted to investigate these
topics (Easton 1997).

The objective of the first study was to look at the native Aspen resource in the whole of Scotland
and assess its genetic variability relative to that of other tree species within their natural ranges.
Three main questions were addressed:

- Has the Scottish population retained genetic variability despite its reduced powers of sexual
reproduction?

- How is this genetic variability now distributed among the regions within Scotland?

- Is there any evidence that restriction of sexual reproduction has led to inbreeding within the
resource?

The study was based on analysis of enzyme genetic markers. This represents genetic variation
that is not affected by natural selection (selectively neutral variation [Ennos et al., 2000]), and is
not involved in adaptation. This is important to remember when interpreting the results that were
obtained.

Dormant Aspen buds were sampled from a total of 275 individuals across Scotland (Figure 2)
and scored for their genotype at eight enzyme loci. Measures of genetic variability at these loci
were very similar to those found for other long lived woody perennials, though rather lower than
for other Populus species (Table 2). Analysis of data coming from the six regional populations in
Scotland (Wester Ross, Sutherland, Strathspey, Deeside, Perthshire and Southern Scotland)
showed that less than 2% of the genetic marker variation was accounted for by differences
between these regions. An unexpected finding, however, was that significantly fewer heterozygous
genotype were found than would be expected in an outcrossing dioecious species like
Aspen (Inbreeding coefficient within populations FIS = 0.153, P< 0.001).

1 These locations are held on a database at Forest Research - Contact the senior author for more details.


47
These results are consistent with postglacial invasion of Scottish Aspen under conditions where
sexual reproduction was widespread and seed dispersal and establishment were unrestricted. It
appears that this initial genetic structure and variability has been largely retained despite fragmentation
and reduction of sexual reproduction as a consequence of vegetative persistence over
long periods of time. During this period, limited sexual reproduction of the species has taken
place among an increasingly related group of individuals, leading to a significant level of inbreeding
in the population as a whole.

Having obtained a broad picture of genetic variation in Scottish Aspen, a second study was conducted
to determine the extent and pattern of clonal diversity within native Aspen woodlands.
The questions of interest were whether woodlands comprise single or multiple clones, and, if
multiple clones are found, do they differ from one another in ecologically significant ways. The
study was conducted in Tomnagowan wood, Strathspey, the largest Aspen dominated woodland
in Scotland. Within a 7ha sample area, 198 stems of Aspen were mapped and scored for
their genotype at seven variable enzyme genetic markers. Stems were also scored for the extent
of leaf flushing in June (Figure 3), and for their sex in spring of 1996, an exceptionally prolific year
for Aspen flowering (Easton 1997).

Within the sample area, 21 different clones could be identified. These ranged in size from single
stems to individuals spreading over 100m. The clones identified in this manner showed very different
leaf flushing scores. Individuals within each of the putative clones were all of the same sex
and the sex ratio was 3.33:1 male:female, significantly greater than the 1.5:1 ratio normally found
within Scotland. These data indicate that high clonal diversity exists within native Aspen populations,
and that clones differ widely in important ecological characteristics. In future conservation
programmes aimed at restoring or recreating Aspen woods, this clonal diversity must be included
within planting stock.

Studies of natural stands

Matthews (1993) carried out a small study comparing growth rates, ages, site characteristics,
and incidence of fungal pathogens on 30 sites in northern Scotland, 15 in Wester Ross and 15
in Badenoch and Strathspey. A total of 226 trees was sampled. The oldest tree was 120 years
old; only 2% of trees were more than 100 years old with 36% being 50-100 years, and the
remainder less than 50 years. The largest tree in Wester Ross was 19m tall by 91cm dbh compared
with 25mx39cm in Badenoch and Strathspey. The best growth was found on clay loam
and sandy loam soils and the poorest on sands. The incidence of bacterial canker (Xanthomonas
populi) was relatively low overall (7%), but increased with age to nearly 20% in trees older than
70 years. Similarly, the incidence of butt and heart rots increased with age with the percentage
of infected stems exceeding 50% for trees older than 50 years. Height-age relationships were
interpreted to predict potential site indices (i.e. dominant height) at age 50 ranging from 6-18m;
the former were more characteristic of exposed sites in Wester Ross and the latter of sheltered,
fertile sites in both regions. Assuming that the appropriate yield models (Hamilton and Christie,
1971) are those for sycamore, Ash and Birch rather than those for hybrid Poplars (Worrell,
1995b), then potential yields from natural unmanaged stands in the two regions range from 2-6
m3 ha-1 yr-1.

Silvicultural performance of Aspen clones

Once satisfactory propagation techniques had been devised for Aspen, and a range of locations
had been identified, a further stage was to examine the variation in growth rates and other parameters
in comparative trials. Five field trials have been established with this aim in Scotland since
1993. These compared a range of Aspen clones chosen systematically without selecting for
superior phenotypes with selected hybrid Poplar cultivars and, in some cases, selected clones
for an Aspen breeding programme in Sweden (see Table 3). The trials were established using
normal forestry methods in deer-fenced enclosures. The results after six years are briefly


48
described below. Analyses are based on standard analysis of variance procedures with survival
percentages first transformed to the arc-sine scale.

Bush 30 and Cowal 11

These were both small trials with a limited range of Aspen clones. At Bush, mean survival after
six years was over 95% with no significant difference between clones. By contrast at Cowal, survival
was only 75% overall, largely because of vole damage; there were significant differences
(p<0.05) among the Aspen clones for survival with a range of 40-100%. Height growth after six
years showed very highly significant (p<0.001) differences between the Aspen clones (see Table
4); the best clone at each site originated from Tummel in Perthshire. At the more fertile Bush site,
the Aspen clones performed less well than the hybrid poplar standards, but this trend was not
significant at the more oceanic site in Argyll.

Moray 43

There were very highly significant differences (p<0.001) between clones for height, survival and
diameter. Survival here was also affected by vole damage with a mean value of c 70% and a
range of 32-100%. However, perhaps of more interest is to examine the difference between
zones (Table 5). The highest survivals were found in material from the southern Scottish zones (1
and 2), with best growth from clones of the east-central Scotland zone (3). However, the
favourable performance of the latter will have been influenced by the fact that the best clone was
from zone 3. This was the same Tummel clone which had grown well in the Bush and Cowal trials.
The standards generally grew better at this site than the Aspen clones.

Kilmichael 37

Again, very highly significant differences occurred between clones (p<0.001) for survival percentage,
height and diameter growth after six years. Survival was higher than at Moray, with a
mean of 92%; the standards ranged from 23-57%, while the Swedish Aspen clones all had
100% survival. Comparisons between the different zones are shown in Table 6. The best survival
is from zone 8 (northern Scotland) and the poorest is from zone 4 (Argyll). The best height and
diameter growth is again in zone 3, but once again the mean figure for this zone is increased by
the vigorous growth of the Tummel clone. The surviving standards were taller than the average
of the Aspen clones. However, the most vigorous growth was shown by the selected Swedish
Aspen clones.

Aberfoyle 9

Data is only available for the first three years after planting, when initial establishment could still
be having an effect, so only preliminary results are noted here. Survival was generally 100%, with
only five clones showing some losses (20% in each case). There were very highly significant
(p<0.001) differences in height growth, with the Scottish Aspen ranging from 86-266cm. By contrast,
the Swedish clones varied from 287-446cm. The fast growing Tummel clone was not
included in this trial.

General

These five trials comprise the first systematic attempt to examine variation in establishment and
growth rate in Scottish Aspen. Results are encouraging, since they suggest that good survival
can be obtained, except where vole damage is a problem, and average height of 1.5-3.0m can
be anticipated within six years, depending upon site quality. The possibility of improving growth
rates by selection of superior clones, if timber production is an objective, is indicated by the vigorous
growth of the Tummel clone at four of the sites and by the vigour of the selected Swedish
material on the two sites where it has been planted. Examination of zonal performances at the
Moray and Kilmichael sites does not provide conclusive evidence that local origins of Aspen are
necessarily the best adapted.


49
Conclusions

The results reported in this paper only serve to re-emphasise Worrells view (1995b) that
Fundamental questions concerning [Scottish Aspens] ecology and silviculture remain largely
unanswered. Over the last decade, progress has been made in two main areas. Firstly, we can
be reasonably confident that native Aspen can be reliably propagated by cuttings and that this
material will establish well and grow vigorously in the field without special attention. Given that
we can also be more optimistic about obtaining seed from native Aspen (Worrell et al., 1999),
there should therefore be no justification for using plants of non-native origin in native woodland
restoration or creation schemes.

The other main area of progress is that we understand more about genetic variation in Scottish
Aspen, both at a national level and in terms of the occurrence of clones within particular woodlands.
As far as the former is concerned, we now know that there is appreciable genetic marker
variability within the Scottish resource, little variation between the main regions of the Scottish
population, and a low but significant level of inbreeding. This suggests that Scottish Aspen has
been derived postglacially from a single source that was freely sexually reproducing at that time,
but has since survived chiefly by vegetative propagation. The study of clonal variability has highlighted
the need to use a mixture of clones when seeking to establish any sizeable areas of
Aspen woodland. We would suggest a minimum of 10 clones in woods of 0.5-1.0ha, 15 clones
in those of 1.0-5.0ha and >20 clones in those greater than 5.0ha. Within such schemes, the
clones could be planted randomly (mimicking the situation expected with establishment from
seed) or in pure blocks of perhaps 500-1000m2 to mimic the patterns that are now found after
the extensive vegetative spread of individuals in our few large Aspen woods.

Apart from these two areas, our understanding of the silviculture and dynamics of Aspen in
Scottish woodlands is still rudimentary. The improved growth of the clone from Tummel indicates
that there is improved vigour (i.e. 3.5-5.0m height at six years) in the Scottish population that
could be exploited for timber production. This suggests that the growth rates of 6-10m3 ha-1 yr-
1 quoted by Worrell (1995b) for Aspen in Norway on 40-60 year rotations could also be achieved
in Scotland. The improved vigour observed with the small group of selected Swedish clones also
suggests that there is a real possibility of increasing the productivity of Aspen stands where these
are being used for timber. However, more systematic, comprehensive and longer-term trials
would be necessary to confirm this potential for improved growth. Such trials could also consider
other aspects of adaptive variation, such as salt tolerance of clones growing close to the
sea (for use in reclamation schemes), and timing of bud burst and leaf senescence.

A further area of interest is the potential use of Aspen as a species for mixture in stands of nonnative
conifers. The species tendency to grow in clumps, its vigorous early height growth and
its tolerance to gleyed soils all suggest a potential role in enhancing biodiversity within spruce
plantations. However, to date no experiments have been established to ascertain desirable patterns
of mixture with non-native conifers.

A further limitation is our ignorance of stand dynamics in existing Aspen woodland. Worrell
(1995a) cites MacGowan (1991) as indicating that woods of >4.5ha are desirable to provide a
complete range of habitats for specialist Aspen invertebrates. Both Worrell (1995a) and
Matthews (1993) suggest that trees over 100-120 years of age are rare and that older trees tend
to be at risk from fungal pathogens. Based upon first principles and observations in the field, we
propose that sustainable Aspen stands should contain a minimum of three age classes, each in
discrete homogeneous cohorts. These would be an area of old trees perhaps 80-120 years of
age characterised by abundant deadwood, a younger age range of perhaps 30-50 years which
could be exploited selectively for a range of timber products, and a young cohort of perhaps 5-
10 years to provide a successor stand. It is this last category which is so often absent in existing
Aspen stands as a consequence of inappropriate grazing management.


50
In summary, we believe that these results give preliminary indications of the methods and potential
for developing an expanded Aspen resource in Scotland, both as a component of native
woodland and of restructured plantation forests. However, there is a considerable challenge for
both researchers and forest managers if this potential is to be realised.

Acknowledgements

Dr Rick Worrell was responsible for the initial compilation of Aspen sites in Scotland with help
from many individuals. Mike Hollingsworth propagated the material used in the field trials which
have been managed by Forest Research at the Newton, Cairnbaan and Bush field stations.
David Brown was responsible for collecting root sections from different parts of Scotland in 1993.
The Swedish Aspen clones were kindly provided by Martin Werner and colleagues from
Skogforsk, Ekebo. Statistical analysis and advice was provided by Ian White and Alvin Milner.
Glenn Brearley provided the figures. The comments of Richard Thompson, Colin Edwards and
Sam Samuel are gratefully acknowledged.

References

Easton, E. P. 1997. Genetic variation and conservation of the native Aspen (Populus tremula L.) resource
in Scotland. Unpublished Ph.D. thesis, University of Edinburgh.

Ennos, R.A., Worrell, R., Arkle, P., and Malcolm, D.C. 2000. Genetic variation and conservation of British
native trees and shrubs: current knowledge and policy implications. FC Technical Paper 31, FC Edinburgh.

Hamilton, G., and Christie, J.M. 1971. Forest Management Tables. FC Booklet 34, HMSO, London.

Herbert, R., Samuel, C.J.A. and Patterson, G.S. 1999. Using local stock for planting native trees and
shrubs. FC Practice Note 8, FC Edinburgh.

Hollingsworth, M.K., and Mason, W.L. 1991. Vegetative propagation of Aspen. FC Research Information
Note 200, FC Edinburgh.

Hollingsworth, M.K., and Mason, W.L. 1993. Vegetative propagation of native Aspen update. Native
Woodlands Discussion Group Newsletter 18.

Matthews, P. 1993. Growth rates, site indices and their environmental correlates for naturally occurring
stands of European Aspen (Populus tremula) in 2 proposed Scottish provenance regions. Unpublished
MSc thesis, University of Aberdeen.

Wilson, S. McG., Malcolm, D.C., Rook, D.A. 2000. Locations of populations of Scottish native trees.
Scottish Forestry Trust, Edinburgh. 108pp.

Worrell, R. 1995a. European Aspen (Populus tremula L.): a review with particular reference to Scotland I.
Distribution, ecology and genetic variation. Forestry 68: 93-106.

Worrell, R. 1995b. European Aspen (Populus tremula L.): a review with particular reference to Scotland II.
Values, silviculture and utilisation. Forestry 68: 230-243.

Worrell, R., Gordon, A.G., Lee, R.S., and McInroy, A. 1999. Flowering and seed production of Aspen in
Scotland during a heavy seed year. Forestry 72: 27-34.


51
Table 1. Main objectives of the FC/SNH project on Aspen from 1992-1996

Objective and Comment
1. Identify over 200 locations for Aspen in Scotland Over 600 recorded see text for details

2. Review literature on Aspen See Worrell 1995a, b

3. Sex all clones at sites and consider potential See Worrell et al., 1999 for
for natural regeneration flowering and seed production

4. Make detailed observations of clones in the field No systematic measurements other than
Matthews (1993)

5. Bring two collections into domestication About 100 clones maintained at NRS

6. Investigate genetic structure of Scottish Aspen See Easton (1997) and text

7. Establish managed genepools No progress

8. Test silvicultural performance of Aspen clones See text

9. Examine adaptive variation in Aspen No progress


Table 2. Measures of genetic marker variation in the Scottish Aspen resource based on
analysis of eight enzyme loci, and a comparison of these values with those for long lived woody
perennials and other Populus species (Easton 1997)

Sample % polymorphic Alleles per locus, Gene diversity
loci
Scottish Aspen 54.5 2.00 0.174
Long lived woody perennials 49.3 1.76 0.148
Other Populus 85 2.5 0.295


Table 3. Details of comparative clonal trials of Aspen planted 1993-1997

Year planted / Location / Site details / Treatments / Design

Bush 30 p1993
NRS
Restocking site; surface water gley
10 clones (Perthshire, SE and SW Scotland) + 2 standards
Single plant plots; 10 replications

Cowal 11 p1993
Near Tighnabruaich
New planting; brown earth with gleying
8 clones (as above) + 2 standards
Single plant plots; 10 replications

Moray 43 p1994
Near Elgin
New planting; alluvial soil
44 clones from 8 zones + 3 standards
4 plant plots; 5 replications

Kilmichael 37 p1995
Near Cairnbaan
New planting; brown earth
89 clones from 8 zones + 3 standards + 7 Swedish clones
4 plant plots; 4 replications

Aberfoyle 9 p1997
Cashel, near Rowardennan
New planting; upland brown earth
72 clones from 8 zones + 6 Swedish clones
Single plant plots; 5 replications



52
Notes:

1. Standards are: P.X euramericana cv Robusta (1993-1995)
P.X interamericana cv Beaupre (1994-1995)
P. trichocarpa cv Fritzi Pauley (1993-1995)

2. Swedish clones are selected Aspens and Aspen hybrids produced in the Skogforsk programme
at Ekebo, southern Sweden


Table 4. Height growth (cm) after six years in the Bush and Cowal experiments

Mean of
Aspen clones Best Worst Standards 5% LSD
clone clone
Bush 309.6 500.3 223.5 556.0 48.1
Cowal 173.3 311.7 107.4 179.3 49.9


Table 5. Survival percentage, height growth and diameter at 0.1 m of Scottish Aspen
clones and Poplar standards after six years in the Moray experiment

Zone
Best
Parameter 1 2 3 4 5 6 7 8 Signif. clone Standards
Number of clones 7 12 5 2 3 4 3 8 - - 3
Survival (%) 83 84 79 61 51 64 48 57 *** 96 67
Height (cm) 217 224 283 189 147 201 153 177 *** 350 325
Diameter @
0.1 m (mm) 32 31 41 23 18 26 21 24 *** 64 59

Note: Comparison of zones carried out using the Wald statistic because of unbalanced data (ie different
numbers per zone). Values are 55.2, 82.4, and 60.5 for survival (transformed), height, and diameter
respectively with 7 df.



Table 6. Survival percentage, height growth and diameter at breast height (dbh) of
Scottish and Swedish Aspen clones and hybrid poplar standards in the Kilmichael experiment

Zone
Best Swedish
Parameter 1 2 3 4 5 6 7 8 Signif. clones clone Standards
Number of clones 10 10 4 9 14 12 14 16 - - 7 3
Survival (%) 91 96 95 87 94 93 93 97 * 98 100 42
Height (cm) 295 282 371 285 261 290 245 262 *** 504 694 369
Dbh (mm) 19 18 27 18 16 18 14 16 *** 42 74 28

Note: Analysis of differences between zones as for Table 5. Values for survival (transformed), height and
dbh are 15.7, 50.8, and 46.7 respectively; all with 7 df


53
Figure 1. Map showing recorded locations for Aspen in Scotland plus the eight zones into which
the distribution was divided.
(not available in text format)



54
Figure 2.Map showing the location of six regional populations of Aspen sampled in the study of genetic marker variation
within Scotland. 1 = Badenoch and Strathspey, 2 = Sutherland, 3 = Deeside, 4 = Perthshire, 5 =
Wester Ross, 6 = Southern Scotland.


55
Figure 3. Illustration showing leaf emergence score for Aspen used at Tomnagowhan wood.

1 These locations are held on a database at Forest Research - Contact the senior author for more details.


56
Improving the availability of native Aspen
for use in northern Scotland

Mark Banham

Broom Field Nurseries, Birchen, Dornoch, Sutherland. IV25 3NE.
E-mail: [email protected]

Paul Young

Woodland Officer, Woodland Trust Scotland, Henrietta Park, Balblair, Dingwall, Ross-shire. IV7
8LJ. E-mail: [email protected]

The opportunity to expand the area of Aspen in Northern Scotland has largely been missed in
the extensive native plantings of recent years due to a lack of suitable planting material. The
species rarely, if ever, produces viable seed in the north and nurseries have been unwilling to
invest in the facilities necessary to produce stock vegetatively. The current nursery catalogues list
mainly Dutch and English origin stock, which is not acceptable provenance for Highland use.

Some stock has been produced from restricted seed sources in Perthshire and using micropropagation
techniques from a Strathspey clone. Many of the latter propogules suffer from poor
apical dominance, and there appears to be reluctance to buy these in for growing on at 250
per 1000. There is also the problem of no breadth of genetic variability in such stock. As this
method only becomes economic with large runs, it is not suitable for smaller scale multiple clone
use where 10-20 separate clones are used for plantings up to 5ha.

The best method of improving the availability of northern zone origins would seem to be to produce
stock from root cuttings along the lines of Forestry Commission Research Information Note
200 Vegetative Propagation of Aspen.

There are, however, exceptional costs associated with this method of propagation to enable suitable
stocks to be made available at affordable cost to potential users (now frequently plant-forgrant
crofters). The particular costs are those associated with root collection and provision of
heated mist and wean polytunnel facilities.

Propagation Technique

Aspen roots are located in the field from suckers and lengths are dug up; this is a very laborious
process. The root lengths are wrapped to prevent damage, and at the nursery are cut into
lengths to fit compost filled boxes. They are laid horizontally and covered with further compost
at about 16m root lengths per m2.

In the spring the roots send up suckers. Surface roots with existing sucker points are the most
productive producers of cutting material. When the sucker shoots have reached several centimeters
in height, they are cut and transferred to mist and wean beds. Here automated misting
keeps the foliage moist and soil warming cables provide a rooting zone temperature of 24oC.

After three-four weeks, the cuttings are sufficiently rooted to allow potting on into cells. They are
then kept under mist for a further few days. The collected roots send up a second set of suckers,
which are left to grow on to keep the rootstock alive. These are cut the following winter and
the process is then repeated in following years. Sucker production varies greatly between clones,
but on average a 1m length of root will produce 15 suckers.

Rooting success also shows clonal variation but is typically about 70%. About 40% of pottedon
cuttings will produce a plantable 20-40cm one year plant given a reasonable growing season.
Forty percent will take two years and 20% will be culled. From these figures, it can be seen
that to produce 1,000 plants per annum, about 95m of root stock needs to be collected.


57
Root Collection

As there is such great clonal variation in suckering and rooting success, it is thought advisable
to undertake root collection over a two year period. Limited root collection from a number of
clones per zone is undertaken in the first season, and the performance of the clones monitored
to determine which stands should have further root collections in the following year.

A collection of 25m root length from each of 10 clones should be sufficient to provide planting
stock for an annual planting of about 3ha. Collection costs will vary greatly with site and access
etc, but would be in the order of 3/m assuming material could be gathered from two clonal populations
in a locality in one day.

Propagation Facilities

It is estimated that each 25m collection would require 4.4m2 of polytunnel space @ 14/m3.
Each collection would require 1.5m2 of root bed @ 14. Each collection would require 1.0m2 of
heated mist bed @ 30. There would be a fixed cost of 330 for the control units for the mist
and wean and heating components. These units would cope with the production from 10 collections.

The total cost per 10 collections is therefore estimated as:

Root collection 750
Propagation facilities 1390
2140

It is estimated that this investment would produce 2,600 Aspen per annum.

For a nursery to recover this cost over a five year period, pay 10% finance charges and seek to
make a modest 10% return on capital/available finance employed, it would be necessary to
charge 330 per 1,000 more for Aspen than for species raised from seed. At this price it
would be unlikely that Aspen could ever be planted in significant quantities where
Woodland Grant Scheme (WGS) funding is required to meet costs.

Chicken and egg

It would seem that such technical difficulties allied to high unit costs, in producing sufficient volumes
of stock at reasonable commercial rates, is prohibitive to the reproduction of this valuable
species at present (notwithstanding the work of Trees for Life and others in propagating Aspen
stock on a small scale for local use). Consequently, it is under-represented in most, if not all,
appropriate WGS schemes in the northern Highlands and elsewhere.

In the short term, it is expected that under such proposals sufficient Aspen planting stock could
be generated from sources locally to fulfil modest planting requirements over the next three years
(7,600 plants from 10 separate clonal populations).

If such clonal collection and propagation could be produced by nurseries over a wider area, sufficient
northern Scotland provenance stock could be produced within an Aspen Bank for future
planting schemes. Once set up, nurseries would be keen to expand the bank to accommodate
other clones from wider provenances. If successful, this would do much to expand this valuable
habitat in the long term.

Such local initiatives are to be welcomed. However, the start up capital costs are prohibitive to
many small regional nurseries, and such a project on a larger scale will require targeted incentives
to assure success. Whilst Enterprise companies or European Funding could be accessed
by individual nurseries in the Highlands, other sources would need to be found. This raises a
number of interesting questions, such as:


58
- Would an Aspen challenge fund be the way forward or an Inter agency funding partnership?

- Is there scope to offer sufficient incentives through the WGS at present?

- Could the Forestry Commission be persuaded to accept lower stocking densities for
Aspen planting, thereby reducing the per hectare costs to compare favourably with other
planting stock? The ability of Aspen to sucker would ensure fully stocked stands, under
favourable conditions, in the future.

Of course, even if such incentives were to be put in place, nurseries still have to produce sufficient
stock. Did someone say chicken and egg?

Reference

Hollinsworth, M.K. and Mason, W.L. 1991. Vegetative propagation of Aspen. FC Research Information
Note 2000.


59
Woodland management measures for Aspen woodlands

Denis Torley

Former Forest of Spey Officer, Denis now works for Tilhill, 43 Clachnaharry Road, Inverness, IV3
8RA. E-mail: [email protected]

The purpose of this talk is to identify how the Woodland Grant Scheme (WGS) can assist in
improving the extent and condition of Aspen stands and their associated flora and fauna.

The Forestry Commissions WGS was introduced in 1988. It aims to encourage people to create
new woodlands and forests to produce timber, improve the landscape, provide new habitats
for wildlife, and offer opportunities for recreation and sport. It seeks to encourage good management
of forests and woodlands, including their well timed regeneration, particularly looking
after the needs of ancient and semi-natural woodlands. Its current form, WGS III, is presently
under review and out to public consultation (as of May 2001).

Funding is increasingly targeted at specific priorities and it is in this context that we should look
at management incentives for Aspen.

Priorities for Aspen

From the various species accounts and subsequent discussions we can identify two broad
strategic priorities for Aspen:

- Ensure that Aspen stands are minimally isolated by improving the connectivity of sites.
Species which depend on a rare or patch woodland type may remain isolated, even in a
fairly complete network of woods. Thus, we need to look for opportunities to increase
patch size and reduce isolation.

- Enhance conditions within stands of Aspen for dependent species. Increase the size of
existing remnants and manage for continuity of structural conditions. For example, create
conditions that continue to be capable of supporting the saproxylic fauna, and carry out
management to provide a constant supply of suitable fallen timber. This means ensuring
that there are suitable areas of differing growth stages of Aspen.

What incentive mechanisms can help achieve this?

In terms of creating new woodland to improve connectivity of broadleaved woodlands, there is
a planting grant and the Farm Woodland Premium Scheme. For expanding semi-natural woodland,
the preferred method is by natural regeneration. However, where there is no suitable seed
source, planting may be appropriate.

The second priority is to improve conditions for associate flora and fauna within stands of Aspen.
This can best be achieved by ensuring that there are sufficient patch sizes of broadleaved woodland,
component stands, and critically, adequate representations of age classes within these
patches and species components to ensure a sustained supply of suitable niches.

It is worth noting that some key woods are already under management regimes to encourage
regeneration, under the WGS; for example, Invertromie, Torcroy and Inverton. However, there is
still a need to secure regeneration in other key woods and improve links between them, either
by creating new woodlands or by restructuring existing ones. In this context, one issue that must
be addressed is grazing. Larger stands are components of larger broadleaved woodlands, which
are valuable for shelter and grazing. Total livestock exclusion reduces farmers options and is not
always appropriate or even desirable. For example, Epione vespertaria absolutely needs Aspen
less than 1m in height and the most practical way to achieve this is through grazing. Until these
conditions are achieved there are a number of ways to improve conditions and these can also
be managed through, and assisted by, the WGS.


60
Woodland Improvement Grant

The Woodland Improvement Grant (WIG) is a single discretionary payment to encourage a range
of work in existing woodlands. It may be paid to undertake work that will enhance the value of
woodland for conservation, landscape or recreation.

In the context of Aspen, assistance is available for woodland owners to manage their woods in
ways that will implement the forestry aspects of Biodiversity, the UK Action Plan.

There are five UK BAP species that rely on Aspen:

1. Epione vespertaria

2. Hammerschmidtia ferruginea

3. Orthotrichum gymnostomum

4. Orthotrichum obtusifolium

5. Byctiscus populi

The WIG can assist with the following operations:

- Preparing and implementing management plans for semi-natural woods;

- Condition Survey;

- Felling to create deadwood/Creating sap runs;

- Protecting deadwood from stripping; and,

- Respacing regeneration to favour Aspen.

Grant will be paid to cover half the net cost of suitable work, up to a limit of 10,000.

For example, at Invertromie the wood was surveyed to assess its deadwood resource, and management
operations were prescribed to create a continuity of supply of fallen deadwood as a
habitat resource for the Aspen hoverfly Hammerschmidtia ferruginea. These operations, if necessary,
are easy and relatively cheap to carry out.

- Establish by survey the present availability of suitable fallen timber.

- Do you need to protect it from being stripped?

- Do you need to create more by felling, delimbing, and for how long?

- For the Dark-bordered beauty Epione vespertaria, you need to establish regeneration and
maintain areas of young regeneration either through grazing or though encouraging areas
of regeneration over a longer period. The Dark-bordered beauty is associated with suckering
Aspen <1m in height. Appropriate grazing is therefore critical.

Annual Management Grant

Annual Management Grant is an incentive to help towards some of the cost of work that is necessary
to maintain and safeguard woodlands. It is a contribution to costs to safeguard or
enhance the existing special environmental value of a wood. It provides assistance at a rate of
35 per hectare as a contribution to the costs operations such as:

- Management plans.

- Essential survey work - e.g. archaeological survey.

- Removal of invasive species.

- Control of exotic natural regeneration.

- Uneconomic thinning/felling to encourage natural regeneration.



61
- Broadleaved planting (up to 300 plants/hectare. Larger plantings should be funded
through normal grants).

- Essential monitoring of management effects - e.g. population monitoring.

- Deer and rabbit control: this is not normally eligible but exceptionally a case may be made
for (e.g.) developing a coherent management plan where this is clearly essential to
enhance the special environmental value of the woods.

Restructuring

Restructuring mainly conifer woodland through Forest Plans

Forest Plans were introduced in 1999. The Forest Plan is aimed at woodland owners who plan
to carry out felling, restocking and thinning in their woodlands over a 20-year time period. Grants
are available to help with plan preparation. The advantages of such medium term planning are
obvious. It is worth noting that the approval of Forest Plans is a competitive process and applications
are judged against set criteria, one of which is the delivery of substantial public benefit
with a high conservation interest.

When Forest Plans are going through the scoping process, it is worth establishing if there are
opportunities in existing plantations to favour current broadleaved stands with an Aspen element,
or to identify opportunities in the restructuring which will help to create stands of Aspen with links
between broadleaved stands. This is one way of establishing links in the network without planting
valuable agricultural ground.

Conclusion

Creating a network of broadleaved woodland with an Aspen component capable of supporting
the range of Aspen dependent species is a priority that the WGS can help to deliver. The ways
in which you feel it can better contribute to priorities for Aspen and its dependent communities
might form part of your response to the consultation on the review of the Woodland Grant
Scheme and the Farm Woodland Premium Scheme.


62
MANAGEMENT OPERATION RELEVANT LEVEL OF
OBJECTIVE GRANT ASSISTANCE

Expanding woods Creating new woodland Planting Grant 1350/ha
improving connectivity by planting
of existing stands

Creating new woodland Discretionary Payment 50% of capital costs
by natural regeneration and Fixed Payment plus FP of 525ha.

Farm Woodland Premium 60/ha /15 yrs
Scheme Payment unimproved land

Encouraging natural Encouraging and Discretionary Payment 50% of capital costs
regeneration in securing regeneration and Fixed Payment plus FP of 525ha.
existing woods within woodlands

Improve habitat Various Woodland Improvement 50% of net cost of
condition for species Grant (3) for eligible work up
in the UKBAP Biodiversity to 10,000

e.g. Felling to create
deadwood

Creating sap runs

Protecting deadwood
from stripping

Respacing regeneration
to favour Aspen

Safeguard or Various Annual Management 35/ha/ yr as
enhance special Grant a contribution to costs
environmental value

Management plan
/Survey work

Uneconomic thinning/
felling to encourage
regeneration

Enhancement planting
(up to 300 trees/ha.)



63
Agri-environment management measures
for Aspen woodlands

Alison McKnight

Cairngorms Farming and Wildlife Advisory Group, Morlich House, Grantown on Spey,
Morayshire, PH26 3HG. E-mail: [email protected]

Background to agri-environment schemes in Scotland

Opportunities for the management of farm woodlands through agri-environment measures have
been available in parts of Scotland for more than 10 years. For example, in the Badenoch and
Strathspey area under the Cairngorm Straths Environmentally Sensitive Area (ESA) Scheme. The
ESA was the first, and until this year, the only agri-environment scheme to address farm woodland
management. ESAs were introduced to Scotland in two phases between 1987 and 1994
to 10 designated areas, selected for their conservation importance. The Cairngorms Straths ESA
was introduced in 1994 and came to a close (for new applications) at the end of 2000. In these
six years, we have seen almost 85% farmer uptake into the scheme, which equates to nearly
300 farm plans.

Under the Habitat Scheme, a short-lived programme introduced in the early 90s to Scotland, targeting
limited farm habitats, no woodland management options existed. Similarly, under the
Countryside Premium Scheme (CPS), a competitive scheme which ran from 1994-1997, and
was available to farmers outwith ESAs, farm woodlands were not addressed, but were encouraged
to be managed under Forestry Commission (FC) schemes in all cases.

In 2001 we have seen the arrival of the Rural Stewardship Scheme (RSS), which now replaces
all previous schemes (for new applications) across the length of Scotland. The RSS contains
some limited measures for farm woodland management, but only where a current FC woodland
grant cannot be applied. Like the CPS, the scheme is again competitive amongst farmers, who
have to reach a particular points score on selected priorities before they can enter. Existing
ESAs which are managing woodland well will continue to operate for their full 10-year term, then
their owners will be encouraged to apply for RSS.

Management measures and their effectiveness

The ESA has been a very effective way of protecting and enhancing small to medium sized native
and semi-natural farm woodlands where an area (usually less than 15ha and often below 5ha) is
managed for biodiversity and regeneration.

For an ESA application, a farm is assessed for habitat quality and importance, including an
assessment of regeneration, floral diversity, bird life etc. within farm woodlands. Management
requirements are then proposed for the general protection and enhancement of the feature and
applied under the scheme. This will usually involve restricting the grazing pressure to a level that
meets the objectives, installing stock and rabbit fencing where necessary. Stock access will then
be controlled for the duration of the plan (five years) introducing limited grazing, (preferably cattle,
at no more than 1 stock/ha in the late summer/autumn). One sheep is treated as the equivalent
to one cow (in grazing density calculations) since sheep are more selective grazers, and
can damage seedlings quickly.

Dead wood must remain in the woodland, and no felling is permitted unless to benefit the regeneration
process. In return the farmer receives a management payment of 100/ha/yr plus a tier
one general incentive/good environmental practice payment of 15/ha/yr (in-bye ground) or
1.50/ha/yr (rough grazing).

The greatest advantage of the ESA was guarantee of acceptance of a plan, provided a well balanced
and effective application was made. There are approximately 2,800 participants in ESA


64
schemes across Scotland, covering around 780,000ha. Of the 1,500 participants in the CPS
(approx. figure), it is unknown how many were advised to enter into WGS at the same time.

While only a small proportion of the overall agri-environment expenditure is likely to be channelled
into woodland management, the combined expenditure under the ESAs and CPS in Scotland
has risen from 7.93m in 1997/98 to 13.76m in 1999/2000. More recent figures are as yet
unknown; however, this is proving grossly inadequate to offer all farms the opportunity to enter
environmental plans where desired. This we know from the poor success rate of CPS annual
applications, which has hovered between 30% and 40% due to the limited budget and not the
quality of applications.

The new RSS has yet to be fully explored for woodland management potential. It is hoped that
this will prove flexible enough to realistically manage farm woodlands, particularly on tenant
farms. Similarly, a conservation audit is undertaken to assess existing habitats, and proposals are
made to enhance and create a range of habitats and features.

For the wider farm habitats, the RSS offers many improved management options and prescriptions,
but generally has greater conditions for a reduced payment. This has been the net effect
of the European Rural Development Regulation, which has introduced as standard, both General
Environmental Conditions and a Standard of Good Farming Practice within the agri-environment
programme. Previously (under ESA) this had been encouraged through the small incentive payment
of tier one.

Grazing is rather more limited under RSS than ESA, with a low-level allowance being given only
once every three years, to aid ground conditions for regeneration, (special cases can however
be proposed). Additional management requirements include the removal of rhododendron where
present, the removal of exotics if threatening to the woodland interest, and the non-removal of
dead wood, which includes leaving standing dead wood.

Unfortunately, due to the RSS being competitive across Scotland, applications must qualify with
a high-ranking score, where the pass figure will be wholly dependent upon the annual number
of applications and the Scottish Executive agri-environment budget. This of course gives little
guarantee for many valuable habitats, including Aspen woodland to be managed.

Management for Aspen in agri-environment

Often Aspen will be found on farms in small clumps within birch woodland, or indeed as a few
isolated trees, and as we know the saplings appear to attract grazing quickly. Having heard the
requirements of the many Aspen-related species, it is important that we try to apply the scheme
prescription appropriately to the needs of Aspen and these associated species.

For example, limited grazing may be less appropriate in the first stages of Aspen regeneration,
where saplings are particularly palatable to stock, but could be an important tool once initial
growth has occurred to thin regeneration, or indeed meet the habitat conditions required by, for
example, the Dark-bordered beauty moth.

We have also heard that the nationally rare Aspen hoverfly depends on dead wood of a particular
age, and often where a limb is dying/dead but is attached to the root plate, this can potentially
introduce detrimental fungus to the tree. This is where a variation on the RSS prescription
standing dead wood must not be felled may be required. Fortunately, agri-environment
schemes will permit such variations where particular conservation importance exists.

Conclusion

In conclusion, while FC grants undoubtedly play the greatest role in the management of Scottish
woodlands, I believe that small farm woodlands, particularly on tenant farms, still require an
avenue to encourage management to improve woodland structures for biodiversity and future
shelter, as has been shown through the ESA. This requires compensation for loss of use, and


65
importantly the ability to retain these woods within the agricultural unit.

Agri-environment schemes run for 10 years, with a five-year break clause, thus can be easily
accommodated within a tenancy or farming partnership and in the general short to mid-term
planning of a farm. This term can also contribute significantly to the longevity and condition of
our farm woodlands.

In this first year of RSS applications, I have been delighted to find that in working closely with the
FCs Northern Conservancy, we have found a reasonably meaningful understanding where a
farm woodland would not be appropriate for WGS. This however needs greater clarifications
on a national scale for advisers.

Finally, I hope that for tenant farmers in particular, we will also see the continued inclusion of
woodland management within the RSS, and a significantly increased budget in future for the
benefit of Aspen and other flora and fauna of all farm woodlands in Scotland.


66
Delivering action: how Aspen fits into the
UK Biodiversity Action Planning process

Peter Cosgrove

Cairngorms Biodiversity Officer, The Cairngorms Partnership, 14 The Square, Grantown on
Spey, Morayshire, PH26 3HG.
E-mail: [email protected]

A brief history of recent forest biodiversity planning milestones

In 1992, the UK Government signed up to, and later ratified, the Rio Earth Summits Convention
on Biological Diversity. This single act had profound effects upon the UKs forestry industry and
how forest biodiversity conservation should be addressed. In 1993 the UK Forestry Minister
signed up to the General Guidelines for Sustainable Management of Forests and the General
Guidelines for the Conservation of the Biodiversity of European Forests at Helsinki. The Helsinki
Guidelines interpreted the Rio Biodiversity and Sustainability principals for European forest management.
This was further defined and ratified through the Lisbon Pan-European Ministerial conference
on the Protection of Forests in 1998. The UK Forest Standard was published in 1998
and this identified what the UK had signed up to in terms of our international commitments. From
this point in time, the UK forestry industry fully embraced the concept of multi-purpose forestry,
including biodiversity conservation.

The UK biodiversity planning process

Running in parallel to the biodiversity policy developments in the forestry industry, has been the
much broader process of general UK biodiversity planning. Since 1994, the UK Biodiversity
Steering Group has published a UK Biodiversity Action Plan (BAP) Strategy and series of action
plans for the UKs most declining, threatened and endangered species and habitats. However,
this is not a complete list because of a lack of data on some species (especially on degree of
decline). Unfortunately, Aspen woodland does not have a UK Habitat Action Plan, unlike for
example Upland Ash woodland, and neither does it get its own Species Action Plan (SAP), in
the same way that Juniper does. Using the conventional UK habitat listing process, Aspen
woodland is not considered a habitat in its own right, or even a priority, but it could be considered
part of other habitats such as Pine woodland, Wet woodland or Birch woodland, none
of which are particularly appropriate. For example, Birch woodland is currently defined by the
UK BAP listing process as Oak woodland without Oak; thus Aspen woodland is probably Oak
woodland without Oak and Birch! It might also be considered part of Riparian or Wet woodland,
but this is equally unsatisfactory as most Aspen stands are not wet.

As described elsewhere, although Aspen is a widely distributed tree in Great Britain, pure woodland
stands are extremely rare and confined to the north and east of Scotland. Aspen woodland
supports a unique living community containing many rare and scarce species including
moths, flies, bryophytes, lichens and fungi that occur nowhere else in the UK. Whilst five of these
are listed as Priority species under UK BAP, requiring the implementation of SAPs dedicated to
their survival, many others that should be listed under the UK BAP process are not (for example,
several Red Data Book invertebrate species). Ecologically speaking, Aspen woodland on its
own or in association with Birch and Scots pine is a real habitat and has its own very distinct
flora and fauna, which is not served well by the current UK BAP process.

The Scottish Executive recently produced a policy statement called The nature of Scotland
(2001). The proposals in the document outline the single most important piece of wildlife legislation
since the 1981 Wildlife and Countryside Act. Amongst its many recommendations is for a
new statutory duty for Scottish Ministers (and competent authorities) to have special regard to
the conservation of biodiversity, the richness and variety of our species and habitats. This piece


67
of legislation is very similar to the comparable Countryside and Rights of Way Act 2000 for
England and Wales, which sets in legal terms the conserving and enhancement of biodiversity in
accordance with our Rio Biodiversity Convention commitments. It provides long overdue statutory
backing for the current BAP process in Scotland.

This approach, in a non-statutory form, has already been adopted and adapted by Local
Biodiversity Action Plans (LBAPs), with national and local partners coming together to agree
delivery of local biodiversity action across Scotland. With the proposed change to statutory powers
likely in Scotland, it is worth briefly considering what has happened south of the border,
where there has been a statutory duty on English and Welsh competent authorities towards biodiversity
conservation.

Opportunities and constraints

Initial indications suggest that anything with a UK action plan - a so-called Priority habitat or
species - potentially attracts interest, resources and action. To stop an avalanche of requests for
biodiversity action on everything, many of the statutory agencies/partners appear reluctant to put
significant resources into non-priority issues. Theoretically, this is great news for listed Priority
species and habitats but where does it leave the others? In many ways it is too early to tell from
England and Wales, but we should be aware of how the UK BAP listing process might influence
what action is possible for Aspen. As someone might have once said all habitats and species
are equal, but some are more equal than others.

Therefore, in theory at least, it should be possible to get significant resources and effort committed
to the following four (five) UK Priority Aspen species without too much difficulty:

- Epione vespertaria, the Dark-bordered beauty moth;

- Hammerschmidtia ferruginea, the Aspen hoverfly;

- Byctiscus populi, a leaf rolling weevil;

- Orthotrichum obtusifolium, the Blunt-leaved bristle moss; and,

- (Orthotrichum gymnostomum, the extinct (?) Aspen bristle moss).

Luckily the moth requires young, regenerating Aspen, the moss requires mature trees and the
hoverfly requires dead wood. Thus, three of the extant Scottish Priority species appear to require
all the basic successional stages of Aspen woodland. On the face of it, action for these three
Scottish Aspen flagship species should bring along much/most of the other Aspen interest.
However, all three species have very small and fragmented populations, effectively confined to
parts of the Cairngorms. As a result, it is likely to prove difficult to obtain resources to deliver
action in areas outwith the immediate vicinity of the localised remnant populations of the three
Aspen Priority species.

Furthermore, there is a genuine concern that it is relatively difficult to get money/resources spent
on single species (even Priority species) issues when there is so much Priority habitat management
that could get the money instead. Much of the excellent past native Pinewood work has
been done on the back of Priority habitat improvement. The Pinewood Priority flagship species,
such as Capercaillie Tetrao urogallus, help focus interest, but the management of the habitat for
a range of species is of greatest biodiversity importance and this has largely driven the successful
delivery of the UK HAP for native Pinewood.

In terms of biodiversity, the critical aspect of an Aspen community is the transition from groups
of scattered individual trees to a larger more extensive/continuous Aspen stand, which then acts
as an ecological entity. It is only these larger stands that can support the full Aspen community,
including those which depend upon a regular supply of dead wood and decaying trees for larval
development. To really deliver action, and avoid as much duplication of effort and bureaucracy
as possible, it is suggested that the key Aspen species experts come together with habitat



68
specialists to develop a hybrid action plan for the Aspen habitat and its dependent species (such as
listed in the Cairngorms LBAP). This plan could then be taken forward in an integrated manner
by the key partners.

I believe the participants of this seminar are in a unique position to take such a step forward.
However, there are four simple questions that need to be answered first before we can move forward,
and I would like to ask the seminars participants to discuss and answer these questions:

- Will action targeted specifically at the three extant Scottish Priority Aspen flagship species
deliver the goods for the remainder of the Aspen flora and fauna? Or to put another way,
is it sensible to concentrate on the three Priority species and not the habitat?

- Do we need to collectively make appropriate representations to the UK Government
regarding the (non) listing of Aspen woodland under the UK BAP?

- Regardless of the answer above, should one of the key outputs of todays seminar be a
national Aspen Action Plan?

- Finally, if you think that the development of an Aspen Action Plan is a good idea, would
you be willing to be involved in its development and implementation?



69
The Trees for Life Aspen Project

Alan Watson Featherstone

Trees for Life, The Park, Findhorn Bay, Forres, IV36 3TZ. Email: [email protected]

Introduction

Trees for Life initiated an Aspen project in 1991 as part of our work to help restore the Caledonian
Forest in Glen Affric and the surrounding areas. Our observations had shown that the species
only occurred in small stands, often widely separated from each other, and that little regeneration
was taking place because of grazing pressure, primarily by Red deer. In addition, in the light
of Aspens relatively poor ability to reproduce from seed (Worrell 1995a, b), we recognised that,
unlike other tree species such as Birch, Rowan etc, it was very unlikely to spread beyond the
sites where it was already established. To address these concerns, our Aspen project has four
main elements to it:

- Surveying and mapping of existing stands;

- Protection of ramets or suckers at existing stands to facilitate natural regeneration;

- Propagation and planting of young Aspens; and,

- Research into the ecology of Aspen.


Surveying and mapping of existing stands

Commencing in 1991, we began recording data on Aspen stands in Glen Affric, and subsequently
expanded this work to other locations, such as Glens Cannich, Strathfarrar and
Morriston, where Trees for Life also seeks to restore native forest. The information gathered at
each site includes data on: soil types; aspect; elevation; number, height and stem diameter of
trees; numbers of ramets observed; evidence of grazing; and associated vegetation and tree
species. This information is stored in a database and, to date, 195 Aspen stands have been surveyed
in this way, with the mapping continuing on an ongoing basis.

Throughout this work, it has become apparent that Aspen occurs more widely than we had first
thought, and 53 Aspen stands have now been identified in Glen Affric alone. The stand sizes vary
from some which contain only one tree to others with more than 300, and with heights which
range up to over 20m. Some of the most extensive Aspen stands, with the tallest trees, are in
riparian areas in Glen Morriston and on the Royal Society for the Protection of Birds (RSPB)
Corrimony Nature Reserve. All the data weve collected has now been transferred on to a GIS
data set for us by a student from Bangor University, and this will provide a valuable tool for planning
the strategic expansion of Aspen in the areas where we work.

The surveys have also produced some interesting data. For example, most of the Aspen stands
in Glen Affric are in south-facing rocky locations, whereas, by contrast, the majority of sites we
have observed in Strathconon are on north-facing rocky sites. However, rather than indicating
preferential growing conditions, it is likely that these observations reflect the topography in each
glen, with the sites forming the least accessible parts of Aspens former distribution, where some
trees have been able to survive because of the reduced incidence of grazing there.

Another result of our surveys has been the discovery of an Aspen site in Glen Affric which consists
only of young ramets measuring 30cm or less in height, with no evidence of a parent tree
anywhere nearby. This is an example of the ability of Aspens roots to survive underground for
many years after the death of the parent tree, with the photosynthesis from the ramets leaves
providing enough nourishment to keep them alive. This phenomenon has been known of since
the 19th century (Brset 1976; Barring 1988), and in the case of the example in Glen Affric, we
suspect that the parent tree(s) may have been drowned when the construction of the Benevean


70
dam in the 1950s raised the level of Loch Benevean by 6m, with the roots and ramets surviving
on higher ground.

The surveys have also recorded seasonal phenomena associated with Aspen. In the summer of
1999, for example, we documented widespread blackening and dying back of leaves at various
stands in Glen Affric. This was subsequently identified by Dr Adrian Newton and colleagues at
Edinburgh Universitys Institute of Ecology and Resource Management as being caused by
Venturia, an ascomycetes fungus which non-lethally infects Aspen, particularly in years of stressful
conditions such as drought. Flowering of Aspen is known to occur irregularly, and during 10
years of surveying in Glen Affric, we have observed it twice - in 1996, when Aspen flowered profusely
throughout Scotland (Worrell et al. 1999), and on a single tree in 2001.

Protection of ramets or suckers at existing Aspen stands

The surveys confirmed our casual observations that very little natural regeneration of Aspen was
occurring in any of the stands, and the ramets showed clear evidence of grazing damage which
was preventing their growth. Many stands had profuse numbers of sprouting ramets, but no
young trees whatsoever, thereby indicating that recruitment, and therefore successful regeneration
of the stands over time, was being completely inhibited.

Beginning in 1992, therefore, we instigated a programme of protection for ramets at selected
sites, using a variety of methods. These include the protection of individual ramets with tree
guards, and weve used both solid tubes and open mesh Netlon guards for this, with the latter
being preferential. In other locations, small areas containing ramets have been protected with
stock fencing, with a typical size of such an exclosure being about 3mx6m. Deer are unlikely to
jump into such a small, confined space, and these exclosures are readily erected by groups of
volunteers using recycled fencing materials, thereby keeping the costs to a minimum. In some
situations, we have also used small areas of deer fencing to protect Aspen stands, or have routed
the fence lines for larger exclosures which were planned to achieve regeneration of a variety
of tree species to specifically include Aspen stands.

Our intention with this work is to ensure that successful regeneration takes place in as many
stands as possible, and also to extend the Aspen stands. In addition, another objective, where
stands are located near one another, is to link them up to form larger contiguous areas.

Propagation and planting

In early 1992, we began work on the propagation of Aspen from root cuttings, using methods
described by the Forestry Commission (Hollingsworth and Mason 1991). Roots were initially collected
from a few sites in Glen Affric, and propagation trials were on a small scale, until the technique
had been mastered. Following successful bids for funding from the International Tree
Foundation and the Millennium Forest for Scotland Trust, a custom Aspen propagation facility,
consisting of a polytunnel containing a mist propagation unit and adjacent cold frames, was
established at Plodda Lodge, our field base near Glen Affric. Using this facility, the production of
young Aspens has been increased to its current level of between 1,000 and 2,000 plants per
year.

Roots are collected from Aspen stands listed in our database, with any given stand being left for
several years to recover before further roots are collected. The young Aspens grown from the
root cuttings are all tracked with regard to which parent stand they are derived from, and when
they are planted out, this is done in groups containing representatives of at least six or seven
parent stands. This not only provides genetic diversity within each planted group of Aspens, but
also, by statistical averages, should ensure that both male and female plants are represented in
each planting. This, in turn, should help to facilitate pollination and seed production when the
trees reach reproductive age. To ensure that the local provenance of Aspen is maintained, only
young trees grown from parent stands within a particular glen, such as Glen Affric for example,


71
will be used for planting out in that glen.

Planting has been done to both establish new Aspen stands and to enrich the clonal diversity of
existing stands, by planting trees sourced from parent stands elsewhere in the same glen.
Because Aspen is one of the most palatable trees (Worrell 1995b) for herbivores such as Red
deer, all the Aspens weve planted have been protected, either with individual tree guards, or
inside fenced exclosures. The planting sites have generally been selected on the basis of exhibiting
similar characteristics to the extant stands of Aspen, with the caveat that these conditions
may not be the preferential ones for Aspen, but just where the species has been able to survive.

There is an ongoing monitoring programme for the trees we have planted, and results in
December 2000 showed that in one area where 66 small Aspens had been planted in 1996, the
average height after four years of growth was 95cm, with individual heights ranging from 13-
180cm. In another location, one tree planted in 1993 had reached a height of 350cm by
December 2000. In future, we intend to refine our monitoring system to track the relative growth
rates of Aspens grown from different parent stands, to identify the variation between them.

Research into the ecology of Aspen

With Aspen having been little studied in Scotland until recently, research into the ecology of the
species is an important component of our project. In the past few years, several students from
Edinburgh University have carried out research into Aspen in Glen Affric for us. Isozyme analysis
has been used to fingerprint the different Aspen clones in a number of stands, and a clear relationship
was found between the size of the stand and the number of clones it contained.
Contrary to the assertions of some authors (Easton, 1998), this research found that the small
stands of Aspen studied in Glen Affric generally consisted of more than one clone. Other
research has documented the extent of grazing damage by Red deer on ramets, and weve used
the results from this to plan and implement protection measures for a number of Aspen stands
in Glen Affric.

In recent years, a unique community of saproxylic insects has been identified as being associated
with Aspen stands, and specifically with dead Aspen wood (MacGowan 1991; Watt 1998;
Rotheray, this volume). The key criteria for the survival of this community are Aspen stands with
a minimum area of c 5ha and a regular supply of dead Aspen wood. Although none of the stands
weve surveyed achieve the 5ha criterion, we commissioned a survey in May 2001 by members
of the Malloch Society to look for evidence of the Aspen-dependent saproxylic insects at selected
Aspen stands in Glen Affric and on the RSPBs Corrimony Nature Reserve in upper Glen
Urquhart. Although the results of the study were not available at the time of writing, some of the
saproxylic insect species, consistent with the size of the stands, were recorded, although the full
range of species were not present. However, we anticipate that the study will produce recommendations
for management measures to expand and link up nearby stands, so that in time
there will be adequate habitat for the whole saproxylic insect community.

During the Malloch Societys study, the rare fungus, Phellinus tremulae, which grows on Aspen
trees (Emmett & Emmett, this volume) was observed for the first time in Glen Affric. This highlights
the need for further research and study to be carried out in the area, and indeed on Aspen
throughout much of its range in Scotland.

Current work and future directions

Trees for Life has identified an area of approximately 900 square miles, to the west of Inverness
and bounded by the two main roads from Inverness to Kyle of Lochalsh, where we aim to promote
the restoration of the Caledonian Forest and all its constituent species. To this end, one of
our immediate goals is to complete the surveying and mapping of all the existing Aspen stands
in this area. By adding them to our Aspen GIS data set, we will be able to prioritise areas for both
regeneration measures and the possible establishment of new Aspen sites.


72
With the proposed trial reintroduction of European beavers to Knapdale in Argyll during 2002,
concerns have been raised about the future of Scotlands Aspen population, as it is a favourite
winter food for Beavers (Macdonald et al. 1995, Batty this volume). If the trial reintroduction is
determined to be successful, more widespread reintroductions may follow later, and Loch
Benevean in Glen Affric is a possible candidate site for this. With this perspective, we have begun
to focus some of our work with Aspen in Affric more specifically on increasing the extent of
Aspen in the area around Loch Benevean. In May and June 2001 we carried out work to establish
some new stands on the north shore of the loch, to secure natural regeneration at more of
the existing stands and to enhance some of those stands by planting young Aspens in them,
sourced from other Aspen stands in the glen.

We plan to expand this programme in the next two years to include the south side of the loch,
and our goal is to establish a robust and healthy Aspen population in the vicinity of the loch,
which would provide an adequate and sustainable food supply for any Beavers which are reintroduced
in future, without it being at risk of over-exploitation.

Similarly, we are also working to incorporate the habitat requirements of the saproxylic insect
community and of the Dark-bordered beauty moth (Young, this volume), into our plans for regenerating
and expanding Aspen in the areas where we work. We hope to follow up the Malloch
Society study in 2001 with other specialist surveys in the near future for the moths, lichens,
mosses and fungi associated with Aspen. Drawing all of these elements together, we aim to produce
a comprehensive, integrated management plan for Aspen for Glen Affric, and eventually for
the other glens where we are working to facilitate natural regeneration of the native forest.

Finally, the other area which we are currently working on is the establishment of a central information
resource on Aspen, and our intention is to host this on the Trees for Life site on the World
Wide Web, so that it is easily accessible to land managers, researchers and the public alike.

Acknowledgements

Much of the Trees for Life Aspen project has been made possible thanks to funding from the
Millennium Forest for Scotland Trust, the International Tree Foundation, Scottish Natural Heritage
and the Mercers Charitable Foundation, as well as through the enthusiastic support of our volunteers
and members. Our thanks also to the students from Edinburgh and Bangor Universities
who have carried out research projects on Aspen in conjunction with our project, and to Dr
Adrian Newton for assistance on numerous occasions. We are also grateful to Forest Enterprise,
The National Trust for Scotland, RSPB and various private landowners, who have entered into
partnerships with us, which has enabled us to carry out conservation work for Aspen on their
landholdings.

References

Barring, J. 1988. On the reproduction of Aspen (Populus tremula L.) with emphasis on its suckering ability.
Scandinavian J. of Forest Research 3: 2, 229-240.

Brset. O. Birch, Aspen and Alder: a guide to practical forestry. Norges Landbrukshogskole. As, Norway.
112 pp.

Easton, E.P. 1998. Genetic variation in Scottish Aspen, Populus tremula L. M.Phil. Thesis, University of
Edinburgh.

Hollingsworth, M. and Mason, W.A. 1991. Vegetative propagation of Aspen. FC Research Information
Note No. 200. FC, Farnham, Surrey.

Macdonald, D.W., Tattersall, F.H., Brown, E.D. and Balharry, D. 1995. Reintroducing the European beaver
to Scotland: nostalgic meddling or restoring biodiversity? Mammal Review 25: 4, 161-200.

MacGowan, I. 1991 revised 1997. The entomological value of Aspen in the Scottish Highlands. Malloch
Society Report.


73
Watt, K. R. 1998. The Hoverflies of Scotland: A local biodiversity action plan for the conservation of the
Aspen hoverfly, Hammerschmidtia ferruginea. Malloch Society Report.

Worrell, R. 1995a. European Aspen (Populus tremula L.): a review with particular reference to Scotland 1:
Distribution, ecology and genetic variation. Forestry 68: 94-105.

Worrell, R. 1995b. European Aspen (Populus tremula L.): a review with particular reference to Scotland 2:
Values, silviculture and utilization. Forestry 68: 231-244.


74
The management of Invertromie Wood,
Scotlands fourth largest stand of Aspen

Tom Prescott

The Royal Society for the Protection of Birds (RSPB), Insh Marshes Nature Reserve,
Ivy Cottage, Insh, Kingussie, Inverness-shire, PH21 1NT.
Email: [email protected]

Introduction

Aspen, (Populus tremula), is one of the most widely distributed tree species in the British Isles.
It is Scotlands only native Poplar and a characteristic species of the Scottish Highlands, but it is
only in Strathspey, Deeside and parts of Sutherland that Aspen dominated woodlands occur.
Elsewhere, Aspen tends to be found only in isolated small stands clinging to steep crags and hillsides
in remote Highland glens. Aspen also adds a unique charm to the landscape being one of
the last trees to come into leaf in the spring and has very distinctive yellow autumnal colours.

Today only 160ha of Aspen woodland remains, a scarce and very threatened resource, comprising
of only 18 stands that are larger than 1ha, of which only 25ha has any statutory protection,
(MacGowan 1992). These larger stands are true remnants of the boreal woodland that
colonised the Highlands soon after the last ice age. Invertromie Wood on the RSPB Insh
Marshes Reserve is one of these stands.

The RSPB and Aspen

The Societys interest in Aspen began in the 1990s when it became lead partner for three UK
Biodiversity Action Plan Priority Aspen dependant species:

- Epione vespertaria (formerly E. parallelaria): The Dark-bordered beauty moth

- Orthotrichum obtusifolium: The Blunt-leaved bristle moss

- Hammerschmidtia ferruginea: The Aspen hoverfly

The niche of these three species is extremely different, each one representing a distinctive stage
in the succession of an Aspen woodland. Epione requires low scrubby regenerating Aspen,
Orthotricum only grows on mature trunks, whilst Hammerschmidtia likes Aspen dead wood. All
three species should be seen as flagship species, each representing a wide range of species
across the taxa that similarly depend on Aspen. The future of Aspen conservation in the UK currently
lies with these species and this process (Cosgrove, this volume).

Invertromie Wood

The RSPBs Insh Marshes Nature Reserve in the central Highlands is primarily renowned as an
internationally important wetland (Prescott 2000). However, it is also gaining recognition for its
Aspen dominated woodland at Invertromie, Scotlands fourth largest stand of Aspen. It is around
50ha in size and is predominantly a Birch wood with an extensive Aspen component comprising
around 20%. Other species include Hazel, Bird cherry and Rowan.

Invertromie Wood came under RSPB management in 1987 and one of the first steps was to
remove the winter sheep grazing. Much of the Birch and Aspen regeneration dates to this time.
However, much of the site is overrun with Rabbits, the light sandy soils being ideal for burrowing
and the adjacent fields providing excellent feeding. Roe deer are also common and browse
the Aspen regularly. Thus, there are few signs of regeneration and the wood is slowly dying on
its feet.


75
Management for Hammerschmidtia

One of the key species at Invertromie is Hammerschmidtia, the larvae live in the wet decaying
cambium layer under the bark of recently dead Aspen feeding on the micro-organisms in this
pungent and gooey decaying layer. Hammerschmidtia requires a regular input of fresh dead
wood for its continued survival, but only Aspen stands greater than 4.5ha have a sufficient
resource. In 1999, with the support of Scottish Natural Heritage (SNH), the Malloch Society
undertook a full survey of the site for Hammerschmidtia (Rotheray 1999). This study estimated
the larval population at just 65 individuals, surviving in just two pieces of fallen timber and recommended
the following specific management proposals.


Invertromie Wood Management Proposals

Objective: To ensure that the Invertromie Aspen stands continue to support
the saproxylic fauna.

Proposals:

1. Ensure that two pieces of suitable timber (>15cm diameter) enter the dead wood system
each year. Provide these artificially if this does not occur naturally.

2. Make better use of existing dead wood by:

- Protecting fallen timber from grazing animals that may strip the bark;

- Severing root plates from fallen trees to prevent fungal competition; and,

- Felling windblown trees, snags and dead columns to the ground to reduce
desiccation;

3. Encourage and promote actions to increase connectivity between stands.

4. Reduce/exclude grazing to promote natural regeneration.

5. Discourage collecting of saproxylic fauna by entomologists.


The key action is the input of fresh dead wood into the system annually. Ideally such wood
should have a diameter greater than 15cm, as the decaying cambium layer is too thin to support
Hammerschmidtia in thinner timber. This happens naturally by wind-blow, either of whole
trees, branches or tops. However, if this is not the case the second option is to sever the rootplates
of wind-blown trees that are still alive and/or fell Aspen columns and trees whose tops
have blown out. If such timber is left in-situ, fungi slowly attack the live wind-blown trees whilst
the standing columns quickly dry out. Felling the timber in contact with the ground slows both
the fungal attack and the drying out process, thus making the best use of this scarce resource.

An annual survey at Invertromie is conducted each spring to determine the amount of suitable
fresh dead wood that has entered the system naturally and the location of new wind-blown trees
and columns. If two pieces of suitable fresh dead wood are found then no further action is
required that year. If no suitable fresh dead wood has entered the system naturally then the severing
of one or two root-plates and/or felling of columns is required. If both of these are not present,
then the final course of action is the felling of live trees. This latter scenario must be seen
as a last resort and is only sustainable providing there is sufficient regeneration.

It is often necessary to protect this fresh dead wood from browsers keen to strip-off the bark,
thus destroying the larval nurseries. This is easily achieved by stretching rabbit wire over the fallen
timber without the expense of erecting a full rabbit fence. Such netting need only be



76
temporary as it probably takes 2-3 years for the fresh dead wood to become suitable for
Hammerschmidtia and it is then only suitable for a further 2-3 years before the bark cracks and
the cambium layer dries out.

The provision of new dead wood is an emergency measure and obviously not sustainable in
the long-term without regeneration. So, during the winter of 2000/ 2001, a rabbit control programme
was instigated with the erection of around 6km of rabbit fencing and installation of 25
rabbit box traps, funded by the Forestry Commission (FC), through a Woodland Improvement
Grant. The box traps have proved to be a very effective way of controlling the Rabbits and comprise
of an underground box, beneath a tunnel through the fence, with a treadle floor. When
unset, Rabbits have free access via the tunnel through the fence and when set, Rabbits fall into
the retaining box through the false floor. The boxes are sited on existing runs between 100-500m
apart dependant on the density of Rabbits. The traps are initially set weekly and as the catch
reduces the period extended to fortnightly or more. The boxes are always set in the late afternoon
and checked first thing the following morning. Regular checking of the fence is also vital to
ensure that Rabbits are using the tunnels and not creating their own access points by digging
under the fence.

In 2000 a survey, jointly funded by RSPB and SNH, was undertaken by the Malloch Society of
all the larger Aspen stands in northern Scotland to determine the size of the UK
Hammerschmidtia population (Rotheray 2000). This was estimated at just 300 larvae, living in
just 12 pieces of suitable dead wood, an extremely low population for an insect. Specific management
recommendations were produced for each site.

Management for Epione and Orthotrichum

Epione larvae feed on low shrubby regenerating Aspen up to around 1m in height. There are currently
only three known sites for this moth in Scotland (Young, this volume). The adult moths
often fly weakly during the day and are not strongly attracted to light.

RSPB and Butterfly Conservation are currently overseeing a survey of the main Aspen stands for
this species in the hope that more colonies await discovery. One of the targets in the Species
Action Plan is to ensure that there are 10 viable populations within the historical range by 2010,
by enhancing population sizes at known sites or by re-introducing populations to suitable locations
(UK Biodiversity Steering Group). Epione has not been recorded at Invertromie though parts
of the wood look ideal. As Aspen regenerates the area of ideal habitat will increase, making the
site a priority candidate as one of the suitable re-introduction locations. One of the main management
prescriptions will then be to coppice the Aspen to maintain a continuity of low shrubby
Aspen of a suitable height.

In 1999 Orthotrichum obtusifolium, was discovered on the bark of a single Aspen tree on the
edge of Invertromie Wood. It was then known from only one other site in Scotland but has subsequently
been found on four further Aspen trees in adjacent Aspen stands (Rothero, this volume).
Mature trees adjacent to these sites will be retained in the hope that Orthotrichum may
colonise them in the future.

Research and survey work at Invertromie

Invertromie is now becoming an important study site for Aspen and its dependant taxa and several
exciting and important discoveries have already been made. Knowledge gained and implemented
at Invertromie could prove to be invaluable at other sites where the pressure on Aspen
and its associated species are far greater.

One of the most significant discoveries was of the Aspen specific bracket fungus Phellinus tremulae,
a first for Scotland though it is now proving to be fairly widespread on suitable Aspen trees
in the area (Emmett and Emmett 2001; Emmett and Emmett, this volume). As a result of the
Aspen seminar, a great deal of interest has been shown in Aspen by lichenologists (Street and


77
Street, this volume) and a recent survey has revealed four species new to Britain and one previously
believed to be extinct, (Coppins et al. 2001).

Detailed autoecological work on the Aspen longhorn beetle, (Saperda carcharius) presented in
these proceedings was based at Invertromie. What was probably Scotlands biggest ever moth
trapping night was also held at Invertromie, when members of the British Natural History and
Entomological Society ran over 20 light moth traps in Invertromie Wood.

Several studies are in progress focusing on the saproxylic diptera, (dead wood dependant flies),
trying to find answers to key lifecycle questions to help guide future management. In contrast to
many flies, the requirements of the larval stages of Hammerschmidtia are well known compared
to those of the adult fly. Little is known about the adults behaviour or food requirements. The
lack of nectar or pollen sources within the wood may be a factor limiting the population. This is
currently being monitored through detailed observations in the field. Another crucial unknown
concerns the adults powers of dispersal. This information will prove invaluable in planning and
prioritising Aspen connectivity projects and in determining locations for the targeted provision of
fresh dead wood in other areas.

The provision and subsequent annual monitoring of fresh dead wood at Invertromie will lead to
a better understanding of the exacting larval requirements of the saproxylic fauna. This will help
in the determination of timescales and a better understanding of the processes of decay. For
example, how long does it take for new fresh dead wood to become a suitable larval breeding
media? How long do these conditions persist? What density of larvae can the timber support?
Experiments are also in progress trying to create artificial sap runs in Aspen. These occur naturally
and are used by both adults and larvae alike. This is currently proving problematic as any
sap flow induced is soon healed by the tree. Samples from natural sap runs are being tested to
identify bacterial or fungal agents that may be preventing the sap clotting and introduced into
artificially created runs in an attempt to keep them open.

The age structure of Aspen at Invertromie is being determined through mapping and coring. This
will shed light on the history of the wood as well as quantifying the future resource. The distribution
of clones is also being mapped, using both leaf burst and autumn colours to identify
clones.

Connectivity

Strathspey Aspen stands occupy a distinct zone, a band that extends from the edge of the
floodplain to the base of the heather moorland. The sympathetic management of the present
Aspen resource is paramount, but this must only be seen as a short-term measure. The longterm
and far greater challenge is to link existing stands, effectively creating Aspen corridors
between sites. Several of these stands are isolated, probably with poor genetic variation, such
corridors will allow both movement of species and genetic flow (MacGowan, this volume). Some
stands are separated by dense conifer plantations that act as an impenetrable barrier despite the
closeness of adjacent stands. So, the clearance of some conifers or creation of Aspen rides in
these plantations is a high priority. The nearest adjacent Aspen stand to Invertromie lies across
the B970 at Torcroy. A priority management objective at Invertromie is to link these two stands
by planting an adjoining corridor of Aspen along the perimeter of the adjacent fields.

The distribution of Aspen in Badenoch and Strathspey is presently being mapped and an Aspen
database created. This exercise is an essential step if the aim of linking stands is to be achieved,
as it will readily highlight sites for the creation of Aspen corridors as well as identifying barriers
(MacGowan, this volume). These can then be prioritised and targeted action undertaken by
encouraging regeneration or planting to link stands, or creating rides or restructuring plantations
to remove barriers.


78
Acknowledgements

Many people have contributed to the knowledge of Aspen and its associated species at
Invertromie. In particular I would like to thank the following for their time, enthusiasm and expertise:
Valerie and Ernest Emmett, Graham Rotheray, Iain MacGowan, Tracey Begg and Peter
MacKenzie.

Several of the projects described would not have been possible without the financial backing of
various bodies including FC, Butterfly Conservation and SNH.

I look forward to the continued use of the RSPBs Invertromie Wood as a research and survey
site for all those interested in Aspen, its associated species and ultimately its conservation and
discovering more about this wonderful and special habitat with such inspiring people.

References

Coppins, B. Street, L. and Street, S. 2001. Lichens of Aspen Woods in Strathspey. Unpublished SNH
Report.

Emmett, E.E. and Emmett, V.E. 2001. Phellinus tremulae, a new British Record on Aspens in Scotland,
Mycologist 15:3 105-106.

MacGowan, I. 1992. The entomological value of Aspen in the Scottish Highlands. Unpublished Malloch
Society Report No. 1.

Prescott, T. 2000. RSPB Scotlands Insh Marshes Management Plan (April 2000 March 2005).
Unpublished RSPB report.

Rotheray, G. E. 1999. Current status of, and Management Recommendations for, Hammerschmidtia ferruginea
at Invertromie. Unpublished RSPB Scotland report.

Rotheray, G.E. 2000. Assessment of the current condition of breeding sites for the UK BAP priority hoverfly,
Hammerschmidtia ferruginea, (Diptera, Syrphidae). Unpublished RSPB Scotland report.

The UK Biodiversity Steering Group. 1999. Tranche 2 Action Plans. Volume IV Invertebrates.


79
Habitat fragmentation

Iain McGowan

Scottish Natural Heritage, Battleby, Redgorton, Perth. PH1 3EW.
E-mail: [email protected]

One of the main threats to woodland communities throughout the British Isles has been the trend
towards a declining percentage of native woodland cover, which has led to our remaining woodlands
becoming smaller and increasingly isolated from each other by open space a process
called fragmentation.

Woodland insects associated with dead wood evolved at a time when woodland cover was
almost continuous and the amount of dead wood available was probably quite large. As a general
rule, they have not developed great powers of dispersal and when they do move to find a
new habitat to breed in they prefer to do so at a low altitude through open native woodland habitats
following a scent trail of decaying wood.

In native woodlands the wind speeds are relatively low, the humidity relatively high and, with an
open structure and varied flowering plants present, there are usually nectar sources available
either in the ground vegetation or from the trees and shrubs to provide fuel for insects flying and
dispersing. In areas of open ground, wind speeds are higher making the chances of an insect
being blown away from favourable habitats much greater, scent trails from decaying wood are
also dispersed and more difficult to follow, and nectar sources may be absent or infrequent.
Conversely, in areas of dense conifer plantations, although wind speeds are low, the density of
the trees may act as an actual physical barrier, suitable nectar sources are absent, and the overwhelming
odour of conifer resins may obscure any chance of picking up a scent trail of a decaying
native broadleaf. Accordingly, both areas of open ground and of conifer plantations will act
as a barrier to the dispersal of woodland insects.

In areas where woodland is highly fragmented, the communities of plants and insects within
them are more unstable and more likely to suffer in the short-term from local extinctions and in
the long-term from a more general extinction in the wider area. In an area such as Strathspey, a
strategic view is required of the Aspen resource to identify which Aspen stands and areas of
native woodland are fragmented, and to develop a model of how greater linkages may be
achieved. On the ground, this work will probably only proceed on an opportunistic basis as applications
for woodland grants are submitted or opportunities arise for the restructuring of commercial
conifer woodlands, but the development of a model should predict which areas have the
highest priority for such action.

Habitat fragmentation case study - Balliefurth

The map (centre page insert) shows that the important Aspen stands at Grantown (shown in red)
and the open Birch/Aspen wood matrix (shown in orange), through which it is probable that the
rare Aspen hoverfly Hammerschmidtia ferruginea can disperse, are almost encircled by commercial
forestry (shown in green) This applies in particular with regard to the route down the Spey
to the south, which leads initially to the stand at Culreach and thence on to the other important
Aspen stands in Strathspey.

In order to improve the long-term survival prospects for Hammerschmidtia and other Aspen specialist
species as part of a long-term strategic approach to creating linked woodlands in
Strathspey, consideration should be given to the removal of the conifer blockage caused by
Balliefurth Wood and for its replacement, at least in part, by an open woodland dominated by
native broadleaf species.

This, in conjunction perhaps with some additional planting of broadleaves along field boundaries,
should in time create a linkage to the Culreach stand, which with a good stock of mature Aspen


80
trees could provide suitable dead wood habitat. As a first step in a long-term process, this would
allow the major Aspen stands at Grantown to be more effectively connected to other Aspen
stands in Strathspey.


81
Aspen in myth and culture

Anne Elliott

Scottish Natural Heritage, Achantoul, Aviemore, Inverness-shire. PH22 1QD.
E-mail: [email protected]

Why include a paper on the myth and culture of Aspen in the proceedings of a conference about
Aspen biodiversity and management?

Put simply, we should not lose sight of the fact that Aspen has survived best in areas where it is
valued by the people who live there, and it will only continue to survive, and spread, with their
help. People value Aspen for many reasons, but the two main ones are its landscape and its cultural
value. In Badenoch and Strathspey the golden autumn colours of aspen are stunning, and
it contrasts beautifully with the bronze of the Birch and the sombre green of Scots pine. The cultural
value of wildlife is often overlooked, but I would suggest that it is as integral a part of its
value as its scientific interest.

The word Aspen derives from the Old English aespe or aepse, which is related to aspe in
German, asp or baevreaspe in Danish and Swedish and osp in Norwegian. The alternative
names zitterpappel in German and ratelpopulier and trilpopulier in Dutch, all mean quaking
poplar (Edlin 1964).

In Gaelic, Aspen is critheann, or critheach. The origin is crith, meaning to shake or quiver. The
saying Critheann san t-sine means like an Aspen in the blast (Dwelly, 1998). In the Gaelic language,
the letters of the alphabet are represented by trees, and Aspen signifies the letter E,
eubh. The derivation of this practice is uncertain,but it is thought that it may have acted as a
teaching aid in the oral tradition, prior to the introduction of the standardised, Latin alphabet.
Eighteen tree and shrub species are used to represent 18 letters or sounds (Edlin, 1950)*.

In Irish, Aspen is arann-aritheach (McBain, 1982) or criteac and eada (Edlin 1964). In Early Irish,
it is also crith (McBain, 1982). Aspen is also given several names in Welsh, where the proper
name is aethnen (Edlin 1964) or aethnea (Nodine 1995). McBain (1982) states that in Welsh it is
cryd, and in Old Welsh, cirt. Two Welsh colloquial names are coed tafod merched and coed tafod
gwragedd, both meaning the tree of the womans tongue (Edlin 1964).

Aspen is occasionally called the quaking tree in Badenoch and Strathspey (various pers.
comm.), or elsewhere in Scotland quaking ash or old wives tongues (Jonathan Willet, pers.
comm.). Aspens Latin name is Populus tremula, which is the name for the family, Populus, and
from the Roman tremula, meaning to tremble, or shake (Edlin 1964).

Aspen is occasionally referred to as an element in place names. Crianlarich is possibly the Aspen
tree (critheann) of the ruined house (lariach) (Darton, 1994). A Gaelic name for Aspen, crann
critheach, has given rise to Killiecrankie, wood of the Aspens, in Perthshire. In Sutherland,
Ospisdale is thought to mean Aspen valley (Edlin 1964). In England, Aspen is found as a place
name element in Aspenden in Hertfordshire, meaning valley where the Aspen trees grow, from
Old English aespe and denu. Similar cases arise with Aspley in Bedfordshire, meaning Aspen
wood or glade, and Aspull in Greater Manchester, meaning hill where the Aspen trees grow
(Mills, 1991). Espley in Northumberland and another Aspley, in Warwickshire, are further examples
(Edlin 1964).

The Greek name for Aspen is aspis, and means shield. The Celts apparently used Aspen timber
for making shields, and these shields were more than mere physical barriers between warrior and
enemy; they were imbued with additional magical, protective, qualities to shield the bearer from
psychic as well as physical harm. The magically protective nature of the shield tree extended
to the general population too and Aspen, like the rowan tree, was a popular choice of tree to
plant close to a dwelling (Trees for Life 2001). However, this may not have been the only reason


82
why Aspen was planted or encouraged next to settlements. When taken in concentrated form,
the bark of Aspen is reputed to have abortive properties and this may have been used to terminate
unwanted pregnancies in rural communities (Peter Cosgrove, pers. comm.).

Elsewhere, Aspen appears to have had a rather negative reputation. The people of Uist say that
the hateful Aspen is banned three times. The Aspen is banned the first time because it haughtily
held up its head while all the other trees of the forest bowed their heads lowly down as the
King of all created things was being led to Calvary. And the Aspen is banned the second time
because it was chosen by the enemies of Christ for the Cross upon which to crucify the saviour
of mankind. And the Aspen is banned the third time because.(here the raconteurs memory
failed him). Hence the ever-tremulous, ever quaking motion of the guilty, hateful Aspen even in
the stillest air. Clods and stones and other missiles were hurled at Aspen by the local people.
The reciter, a man of much natural intelligence, said that he always took off his bonnet and
cursed the hateful Aspen with all sincerity wherever he saw it. No crofter in Uist would use Aspen
about his plough or about his harrows, or about his farming implements of any kind. Nor would
a fisherman use Aspen about his boat or about his creels or about any fishing gear whatsoever
(Carmichael 1997)*.

The understanding in the Highlands of Scotland that Christs cross was made from Aspen
appears to be longstanding. In 1777, Lightfoot wrote The belief amongst eighteenth century
Highlanders, that the crucifix was made from Aspen, was evidenced by the fact that the leaves
are always restless.*

Aspen has an interesting place in religious superstition of the Highlands. Until recently, it was
thought that the sound of the leaves rustling in the wind was able to induce prophetic insight
(although Highland men were known to draw an analogy between the sounds and the incessant
chatter of their wives!). This perhaps reflects early, Pre-Christian beliefs the same that might be
responsible for the taboo on this plants use in farming or fishing. In Christian belief, the plant was
cursed a Gaelic saying translates to Malison be on thee, O Aspen cursed, on thee was crucified
the king of kings (Fife, 19??).

According to the Trees for Life website, folk taboos, including those against the use of Aspen for
fishing or agricultural implements, or for house building, suggest that Aspen may have been considered
a faerie tree on a par with rowan, which has similar taboos. Trees important to pagan
religions appear to have been deliberately demonised in later, Christian, teaching.

Despite these negative associations, Aspen did have some specific uses:

- Its wood was used for making matches and arrows, and as a source of timber for gunpowder
charcoal.

- The wood was reputedly used for teething rings in some parts of the Highlands, as the
wood of the cross was sacred (Jonathan Willet, pers. comm.).

- Its timber is very lightweight when dried, and very buoyant, so it was used for oars and
paddles. Its lightness also made it suitable for wagon bottoms and for surgical splints. Its
softness and lightness, though ideal for sculpting, are not suitable for use in building,
though floorboards were sometimes made of Aspen as a safety measure, as Aspen wood
does not burn easily (Trees for Life).

- Aspen was the badge of Clan Ferguson according to some (Dwelly 1998).

- It gives a yellow dye (Thompson, 1969)* and a black dye from the young leaves, and brown
dye from the bark (Jonathan Willet, pers. comm.).

- The Bach Flower Remedies recommend extracts of Aspen to treat fears and apprehensions
(Trees for Life).



83
Aspen leaves, bark and shoots are very palatable to grazing animals, and according to
Trees for Life, hand gathered Aspen leaves were fed to cattle when other food was scarce.

This short paper demonstrates some of our cultural responses to Aspen. The strength of this
response perhaps reflects its importance in the landscapes in those areas where it occurs in any
numbers.

References

Carmichael, A. 1997. Carmina Gadelica: Hymns and Incantations Collected in the Highlands and Islands
of Scotland in the Last Century. Floris Books, Edinburgh.

Darton, Mike. 1994. The Dictionary of Place Names in Scotland. Eric Dobby Publishing, Kent.

Dwelly, E. 1998. Dwellys Illustrated Gaelic to English Dictionary. Gairm Publications, Glasgow.

Edlin, H. L. 1950. The Gaelic Alphabet of Tree Names. Scottish Forestry 4: 72 75.

Edlin, H. L. 1964. Wayside and Woodland Trees. Frederick Warne and Co Ltd, London.

Fife, H. 19??. The Lore of Highland Trees. Famedram, Gartochan.

Flora Celtica. The references marked * are direct quotes from the Flora Celtica, which has a web site is
run by the Royal Botanic Gardens, Edinburgh and is highly recommended to those interested in the history
and culture of plants. The web address is www.rbge.org.uk

Lightfoot, J. 1777. Flora Scotica. B. White, London.

McBain, A. 1982. An Etymological Dictionary of the Gaelic Language. Gairm Publications.

Mills, A D. 1991. The Popular Dictionary of English Place-names. Oxford University Press, Oxford.

Nodine, M. 1995. English-Welsh Meta-Dictionary, available at www.cs.brown.edu.fun/welsh

Thompson, F. 1969. Harris tweed - The story of a Hebridean Industry. David and Charles.

Trees for Life, at www.treesforlife.org.uk, is an interesting web site for information on Aspen and trees in
general.


84
Delegate discussion

At the end of the conference, there was an open discussion on some of the issues arising from
the day. The following points (in no particular order) were made by delegates:

1. Peter Quelch suggested a brain storming day be held by interested parties to take Aspen
action forward amongst the partners after the conference.

2. Jonathan Willet thought it would be worthwhile drawing up a list of Aspen related databases
held by each group, which could be accessed by all interested parties. He also
thought that a structured plan and guidelines for Aspen management would be beneficial
rather than the current laissez faire approach.

3. Alan Finnes suggested an Aspen Action Group be formed to act as a central collection
point for information and to draft any plans thought necessary. Trees for Life offered to be
an active partner should the group come to fruition.

4. Anne Elliott highlighted the importance of grazing on Aspen woodland and suggested that
this be considered and incorporated into any future management plans.

5. Sandy Coppins felt that the pasture woodlands at Insh should not be considered as secondary
woodland but are remains of ancient woodland and are therefore of high interest.

6. Dave Phillips hoped that agri-grazed wood-pasture would be considered in the WGS
Review.

7. Colin Forrest was interested to know of any nurseries that supplied local provenance
Aspen. He also suggested that there be an information exchange between interested
groups. Adam Powell said that Trees for Life held a vast amount of data which they had
accumulated from various surveys and this could be made generally available.

8. Robin Noble asked that if there was to be a repeat of the Aspen day that it be held in
Assynt, where there is 50 years of Aspen regeneration to look at.

9. Denis Torley put forward the idea of restructuring existing conifer plantations for broadleaf
components and thereby increasing the opportunities to expand Aspen.

10. Peter Quelch felt that there needed to be a surplus of Aspen to create new stands and had
heard of a small nursery www.treetrader that may help.

11. Adam Powell suggested Christie Elite in Forres as a reputable nursery who might be able
to supply locally sourced Aspen. Trees for Life are propagating Aspen and techniques are
available from Adam.

12. Allan Stevenson suggested trying to build Aspen into the present Birchwood habitat action
plan, he felt it would be difficult to prove this was a worthy cause on its own. Forest
Enterprise have a broadleaf commitment to all their plantings and he felt the conference
was exceptionally good and should be repeated in the future.


85
The Biodiversity and Management of Aspen Woodlands

Friday 25th May 2001

at The Duke of Gordon Hotel, Kingussie

Delegates list

First name Surname Organisation

Andy Amphlett RSPB
Chris Badenoch Scottish Natural Heritage
Barbara Ballinger
Brian Ballinger
Dave Batty Scottish Natural Heritage
Peter Beattie Scottish Natural Heritage
Willie Beattie Forestry Commission
Tracey Begg RSPB
Claire Belshaw Culag Community Woodland Trust
Saranne Bish Highland Council Ranger Service
Keith Bland
Stephen Brown Forestry Commission
David Brown Borders FWAG
Jenny Bryce Scottish Natural Heritage
Brendan Callaghan Forest Enterprise
Iain Calvert Scottish Woodlands Ltd
David Carstairs Scottish Natural Heritage
Ian Collier Forestry Commission
Brian Coppins Royal Botanic Garden
Sandy Coppins Consultant Lichenologist
Peter Cosgrove Cairngorm LBAP Officer
Debbie Cowan Tayside Native Woodlands
G S Cross Macro Forest
Claire Cummings Trees for Life
Meg Dickens RSPB
Chris Donald RSPB
Joanna Drewitt Scottish Executive
Claire Dumigan Fife Ranger
Keith Duncan Scottish Natural Heritage
Siobhan Egan RSPB
Anne Elliott Scottish Natural Heritage
Ernest Emmett Mycologist
Valerie Emmett Mycologist
Richard Ennos Edinburgh University
Philip Entwistle
Hugh Fife Reforesting Scotland
Tanya Fletcher BTCV Scotland
Colin Forrest Tayside Reforesting Enterprise
Mark Foxwell Scottish Wildlife Trust


86
First name Surname Organisation
Ian Francis RSPB
Robert Furness Seafield & Strathspey Estates
Paul Gallagher Scottish Wildlife Trust
Claire Geddes
Diana Gilbert Highland Birchwoods
Patrick Green Forestry Commission
Viv Halcrow
Geoff Hancock University of Glasgow
Alan Harper Forestry Commission
Liz Holden
Eric Jackson RSPB
Gus Jones Scottish Wildlife Trust
Paul Kendall Trees for Life
Anne Kiggins Scottish Natural Heritage
Paul Kirkland Butterfly Conservation
Russell Lamont Forestry Commission
Melissa MacCosh Scottish Natural Heritage
Iain MacGowan Scottish Natural Heritage
Janette MacKay North Highland Forest Trust
James MacKenzie Shetland Ammenity Trust
Morag MacKenzie RSPB
Neil MacKenzie
Peter MacKenzie Badenoch Land Management
Ruth Maier RSPB
David Mardon National Trust for Scotland
Bill Mason Forest Research
Graham McBryer Forestry Commission
Jamie McIntyre Forest Enterprise
Alison McKnight Cairngorm FWAG Officer
Pete Moore Scottish Natural Heritage
Pete Moore RSPB
Sam Murray Reforesting Scotland
Kenny Nelson Scottish Natural Heritage
Ros Newton RSPB
Robin Noble
Dave OHara RSPB
John Parrot Scottish Native Woods
David Phillips Scottish Natural Heritage
Mollie Porter Highland Council Countryside Ranger
Adam Powell Trees for Life
Ross Preston Forest Enterprise
Tom Prescott RSPB
Neil Proctor Forestry Commission
Peter Quelch Forestry Commission
John Risby Forest Enterprise
Carol Robertson North East Native Woodlands


87
First name Surname Organisation
David Robertson
Graham Rotheray National Museum of Scotland
Gordon Rotheroe Bryologist
Alan Ross Scottish Nature
Hamish Robertson CKD Findlayson Hughes
Hannes Schnell RSPB
David Shepherd
David Sheppard English Nature
Malcolm Smith I.G.Smith & Partners
Alan Stevenson Forestry Commission
Les Street RSPB
Sheila Street Lichenologist
Ron Summers RSPB
Jenny Taylor Orkney Native Tree Group
Stuart Taylor RSPB
Denis Torley Forest of Spey Officer
Una Urquhart Marchfield Ecology
Richard Wallace Forestry Commission
Stephen Ward Scottish Natural Heritage
Alan Watson Featherstone Trees for Life
Ken Watt
Britt-Maire Wenner
Miles Wenner Forest Enterprise
Dave Whitaker Forest Enterprise
Jonathan Willet Biodiversity Officer, Stirling
Duncan Williams
Scott Wilson Consultant Forester & Ecologist
Esther Woodward Crannach Management Group
Paul Young Woodland Trust Scotland
Mark Young University of Aberdeen