The influence of Picea abies on herb vegetation in forest plant communities of the Veporské vrchy Mts

Natural mixed beech-fir forests were quite widely replaced by spruce dominated stands in Slovakia. Given the demands on the assessment of the forest status as well as on stopping the biodiversity loss it is required to evaluate the influence of Picea abies (L.) Karst. on the species composition. In a case study from the Veporské vrchy Mts. natural beech dominated forests were compared to stands with different spruce proportion. Within three groups of relevés with no, less and more than a half proportion of Picea abies the species diversity and Ellenberg indicator values were compared. The response of particular species to the proportion of Picea abies was evaluated by partial relation in direct gradient analysis. The increasing spruce proportion causes particularly higher occurrence of acidophytes and a decrease in nitrophytes. Species with the highest positive response to spruce are mostly shallow-rooted or characteristic of natural spruce forests. Greater richness along with the highest diversity was found in mixed stands with less than a half proportion of Picea abies. The most significant difference in species composition was between natural and spruce dominated stands. However the proportion of Picea abies does not reduce the species diversity in general, it causes significant changes in the species composition. As the results show, to avoid the negative effect and loss of phytodiversity it is required not to grow spruce dominated stands out of the natural occurrence of Picea abies.