The structure of ancient native pinewoods and other woodlands in the Highlands of Scotland

A sun ey was carried out in the Highlands of Scotland of the tree species, tree density, stand structure, and field or ground layer cover in ancient native pinewoods and other woodlands (primarily plantations). The trees in ancient native pinewoods were largely Scots pines but the western sites also had a high proportion of birch, Other woodlands largely comprised planted Scots pine, Sitka spruce, lodgepole pine, larches and Douglas fir. The sizes of the trees were greater in ancient native pinewoods than other woodlands, but some ancient native pinewoods had small trees reflecting recent regeneration or planting. The density of live trees in other woodlands was about 10 times higher than in ancient native pinewoods. The density and percentage of dead trees was also higher in other woodlands. The low density of trees in the ancient native pinewoods has allowed trees to develop deep and broad crowns. The other woodlands were characterised by pre-thickets and thickets. Tree species diversity was,greater in other woodlands than ancient native pinewoods, Also, other woodlands had a greater structural variety in terms of stand types, but less variation within stand types, compared with ancient native pinewood. Calluna vulgaris and Vaccinium spp. comprised most of the field layer in the ancient native pinewoods whilst bryophytes, other plants and dead needles made up most of the ground cover in other woodlands. Ancient native pinewoods are generally regarded as biologically richer than plantations, largely due to the differences in stand age and the field layer. However, comparative studies are lacking for many tare. (C) 1999 Elsevier Science B.V. All rights reserved.