THE EFFECTS OF SHADE ON THE PLANT-COMMUNITIES OF RIDES IN PLANTATION WOODLAND AND IMPLICATIONS FOR BUTTERFLY CONSERVATION

During 1985-6 the vegetation in the rides (forest tracks) of eight Eng lish lowland woods, planted on ancient woodland sites was surveyed. Sh ade was measured in each transect by hemispherical photography. Dicoty ledonous species richness and the majority of dicot plant species decl ined as shade increased. The results for individual species compare fa vourably with Ellenberg's (L) value in most cases, and a method is sug gested for modifying Ellenberg's data in the light of new information. The woodlands contained species of both open and shaded habitats and communities were influenced by soil acidity. Because shade in woodland rides increases as the trees mature, theory states that there will al most certainly be a reduction in plant species diversity. Butterfly po pulations would also be adversely affected, partly because of the redu ction in direct sunlight, and partly because their larval foodplants d ecline in both quantity and quality since they are generally associate d with low to moderate shade.