Rate of Microsuccessions: Structure and Floristic Richness Recovery after Turf Transplantation in Alpine Plant Communities

摘要

Reciprocal transplantations of turf pieces have been conducted in alpine plant communities of the northwestern Caucasus. The changes in floristic richness and successional rates have been registered for 25 years. The study objects were plant communities located in a toposequence from ridges to deep depressions along the gradients of an increase in the snow cover thickness and a decrease in the growth season: alpine lichen heaths (ALHs), Festuca varia grasslands (FVGs), Geranium—Hedysarum meadows (GHMs), and snow bed communities (SBCs). The results of the study confirm the hypothesis about the approach of the floristic richness of transplanted pieces to that of the background acceptor community. It is shown that variability reduces during successionif turf pieces from different communities are transplanted into a common community. In particular, this is obvious in the case of SBCs, where the floristic richness of turf pieces transplanted from ALHs and GHMs has been noticeably reduced. The resultsalso show that the more different are the donor and acceptor communities, the higher is the rate of their changing. However, the assumption of a higher succession rate in more productive communities has not been confirmed. On the contrary, the communities with initially low productivity changed more rapidly than those with high productivity. It is found that turf pieces transplanted to upper plots of the toposequence have a higher rate of alteration in comparison with those transplanted to lower plots,which may be related to the longer growth season, which indicates a more prolonged period of high functional activity, and, hence, more time for the effects of competition, seed transfer, etc. In general, the rate of succession decreases as the time since the moment of transplantation increases, especially in communities with low productivity.