The genetic management of native species in Scotland

Changes in forestry policy have increased the importance and extended the scope of genetic management of native species. Recent debate on genetic management prescriptions has been conducted with insufficient access to sound scientific information. This paper attempts to remedy this by: (1) presenting an overview of genetic variation and the processes which control it; (2) reviewing current measures; and (3) proposing a range of improvements to policy and practice. Genetic variation in Scottish tree and shrub populations is a neglected field of research, except for Scots pine (Pignus sylvestris). Some useful information can be provided by considering the history, ecology and biology of species together with genetic theory. Current patterns of variation reflect both the historical origins as demonstrated by biochemical markers) and adaptation through natural selection (as indicated by provenance research). Existing populations probably still retain significant elements of adaptive variation; though this will vary according to species, with some showing close correlation between patterns of adaptive variation and environmental factors and others being more plastic. Indigenous genepools have been modified by fragmentation, changes in the forest environment, and introduction of foreign material, much of which is maladapted to upland sites. With some exceptions, the levels of genetic variation in existing indigenous populations comprise an adequate basis for restoring and expanding native woodland. The current undiscriminating use of continental provenances needs to be strongly discouraged; but equally restricting choice of seed sources to the most local provenances can also be inappropriate. Use of Scottish material from the same region and similar site type as the planting site needs to be encouraged. Current genetic management measures are rudimentary and fail to address adequately key issues of provenance choice, genetic conservation, seed supply or provision of selected or improved material, especially in broad leaves. Changes in legislation, regulation, seed supply, advice and research are proposed to address these shortcomings. The need for more provenance research is highlighted.