Clonal Diversity of Aspen (Populus tremula) in Glen Affric

Aspens growing beside the River Cannich in Glen Cannich

A research project in 1998 by Stephen Lees, a student at Edinburgh University, produced some useful and interesting information about the aspen stands in Glen Affric.

Using isozyme analysis, a scientific method of 'fingerprinting' trees from the tissues of their buds, he was able to identify individual clones of aspen. His results showed that, contrary to previous assumptions we have had, aspen stands in the glen generally contain more than one clone, with the size of the stand being related to the number of different clones within it. In some stands, he found evidence of young aspen suckers, or ramets, growing off root systems which had no visible surviving parent trees, thereby confirming an unusual characteristic of aspen - that its roots can continue living after the death of the above-ground part of the tree.

His research also revealed that aspen ramets were still being grazed in most of the stands he studied, and we have used those results to help us plan a variety of measures for protecting the ramets in a subsequent phase of our aspen project.

Here is Stephen's summary of his work, from his thesis document:

Summary

Trees for Life, a charity organisation based in Findhorn, have placed emphasis on the role of aspen (Populus tremula) as an underrepresented species in the Glen Affric Caledonian Forest Reserve; an example of a native woodland remnant which they aim to conserve and restore.

The aim of this study was to provide information on the genetic diversity of existing aspen stands in the area with respect to clone numbers, and to use this information to examine the structure of existing stands. This information was used to provide guidance in the estimation of clonal diversity in stands not studied and to provide guidance in the planting of new stands.

This study will also provide a further part of the research effort which is required to bring the knowledge of aspen up to the same standard as that of other native tree species.

Genetic diversity was measured using starch gel-electrophoresis on dormant bud material. Four enzyme systems were assayed. The number of clones in each stand was assessed and from this their diffusion within each stand could be estimated.

A regression showed stand size was a highly significant predictor of genotypic diversity. When findings from a previous survey of a larger stand of Scottish aspen were included, a strong linear relationship on log transformed values was seen.

From data of clonal diversity, stand age, field observations and a review of literature it was found that current stands were at least 2 or 3 generations old, and estimated that asexual growth is supplemented by sexual reproduction when favourable conditions occur.

Aspen - related pages

• Aspen Information Resource

Back to Scientific Research in the Caledonian Forest

Last updated: 25 August 2010