Species composition modulates seedling competitiveness of temperate tree species under hemiboreal conditions


Mixed stands are advised for reduction of impacts of natural hazards, and species composition can largely affect sustainability and productivity of the stands. Early development of a stands after a stand-replacing disturbance can have considerable legacy effects on growth via alterations in the diversity-productivity relationships. Accordingly compatibility of growth and competitiveness of different species is one of the key issues for susceptibility of mixed stands. A two-year chamber experiment was conducted to assess early growth and intra- and inter-specific competition for light and soil resources among the seedlings of temperate tree species simulating the predicted effect of warming (presuming optimal moisture regime). Five species, which have high economic importance or potential to become so in the eastern Baltic region (Scots pine, Norway spruce, silver birch, red oak, and European beech) were studied. Among the studied species, European beech had the fastest height growth and competitiveness, suggesting ability to concur a stable niche outside its natural range, particularly under increased temperature. Beech also maintained high competitiveness despite the damages suffered during the overwintering, supporting legacy effects of early development and suggesting invasive properties. Among the studied, Norway spruce had the slowest growth and suffered the highest competition, which is in line with predicted changes in forest composition. Scots pine, silver birch, and red oak showed intermediate growth and competitiveness, particularly when growing together, suggesting balanced development and optimal productivity of such mixed stands. Nevertheless, growth and competitiveness of these species was reduced by increased temperature, indicating negative effects of warming..

Forest Ecology and Management