EFFECT OF DOUGLAS FIR ON PLANT COMMUNITIES IN FOREST ECOSYSTEMS COMPARED TO OTHER TREE SPECIES

The study focuses on the preliminary evaluation of the effects of Douglas fir (Pseudotsuga menziesii /Mirb./ Franco) on the plant communities of the herb layer of forest ecosystems. It was performed in different regions of the Czech Republic: School Training Forests of Kostelec nad Cernymi lesy, Krtiny, Hurky, and Hranice. The plant communities were described using standard phytocoenological relevees in older forest stands with well developed ground vegetation, i.e. in stands of Douglas fir, Norway spruce and especially of other broad-leaved tree species; 44 plots were sampled in total. The results confirmed acidification effects of Norway spruce and revealed some effects of Douglas fir, supporting plant communities including more nutrient, especially nitrogen demanding species. Because of limited number of studied plots, the results have to be understood as preliminary.