Influence of tree stand age and management on the species diversity in Estonian eutrophic alvar and boreo-nemoral Pinus sylvestris forests

The influence of tree stand age, silvicultural management and several habitat variables on species diversity was analysed in Calamagrostis site type alvar forests and Hepatica site type boreo-nemoral forests. On the community scale, the herb-layer species richness appeared to be determined mostly by forest soil and light conditions. However, the number of bryophyte species growing on tree stem bases and on decaying wood was dependent on management intensity and forest site quality class. On the same substrate types the number of lichen species was promoted only by tree species diversity. On the 1 m(2) quadrat scale, diversity and density of tree layer, species richness of bush layer and soil pH have significant layer-specific effects on species richness. Bryophyte diversity increases together with increasing shade and moisture in forest ground vegetation, while an increase of herb-layer diversity is connected with lightness. Therefore, maintenance of the small-scale species richness of forest ground vegetation cannot be achieved by uniform management practice.