FUNCTIONAL STRUCTURE OF THE GRASS-SHRUB LAYER ACCORDING TO THE ABILITY TO MYCORRHIZAL FORMATION UNDER THE INFLUENCE OF ACER NEGUNDO

Changes in the functional structure of communities under the influence of alien plants are an important, but understudied, consequence of phytoinvasions. We tested the hypothesis about changes in the probability of mycorrhiza formation in plants of the herb- dwarf shrub layer under the influence of the invasion of the alien box elder (Acer negundo L.): the participation of mycorrhizal and non- mycorrhizal herbs in communities changes equally or differently depending on the degree of dominance of A. negundo. The results of 118 geobotanical descriptions carried out in the Belarusian Polesie, the Middle Volga region, and the Middle Urals were analyzed. In each region, communities with and without the dominance of A. negundo were described. The capacity of plant species to form mycorrhiza was defined as a continuously varying value of the probability of mycorrhiza formation in a species based on information presented in the FungalRoot Database. Accordingly, mycorrhiza formation was analyzed as a functional trait in the sense used in the analysis of the functional diversity of communities. It was found that the weighted average probability of mycorrhiza formation in A. negundo- dominated communities was lower than in similar communities dominated by other tree species. This indicates a simplification of community structure and a slowing of their successional development under the influence of the alien ash maple. The results confirm that the analysis of the functional structure of communities can be a useful tool for improving the understanding of the mechanisms and conditions that contribute to the course of invasions.