European aspen (Populus tremula L.): a review with particular reference to Scotland I. Distribution, ecology and genetic variation

European aspen ( Populus tremula L.) has attracted relatively little research attention in Britain. Interest in the species has increased in recent years because of efforts to restore and extend native woodland, of which aspen is an infrequent but important component species. This paper draws together information from British, European and Russian literature on the ecology and genetics of aspen. The species is distributed throughout Britain in many different types of woodland. It is particularly common in the Scottish Highlands and Islands where it occurs on a diverse range of sites from sea cliffs to near the treeline. It is associated with a distinct insect fauna, several species of which are considered endangered. Information is lacking on several fundamental aspects of the ecology and genetics of aspen in Scotland including seed production, growth rates, genetic variation and its conservation value and status in native forest ecosystems. Some useful information on these topics is presented from studies of aspen elsewhere in Northern Europe, particularly Norway.