ИСТИНА

Semi-natural grasslands are widespread in Europe and in the forest zone connected with human activity. On the territory of Russia there was a decrease of mesic grasslands area as a result of abandonment in the past half century. The expansion of Calamagrostis epigeios is one of the threats to abandoned meadows, which can lead to a decrease in biodiversity. The state of Calamagrostis meadows is still not fully understood. Our results represent inventory of wood small-reed communities in the transition area of Polistovsky Reserve, Pskov Province, Russia. Vegetation classification was carried out by J. Braun-Blanquet approach based on 47 relevés collected in 2012, 2014 and 2018. The data was processed using cluster analysis by the method of flexible beta in PC-ORD 6.0 program, while ecological features of the syntaxa revealed were determined using ordination approach and phytoindication assessment (Landolt`s scales). The frequency of fires was identified based on the analysis of remote data using Landsat and FIRMS (Fire Information Research Management System). In order to reveal the connection between the abundance of Calamagrostis epigeios and the frequency of spring fires, the Spearman's rank correlation coefficient was calculated in Statistica v.12. A preliminary classification scheme of Calamagrostis meadows was suggested for the study area. We identified 5 associations, 6 variants related to 5 alliance, 4 order from 3 classes: Molinio-Arrhenatheretea, Epilobietea angustifolii, Artemisietea vulgaris. The ordination analysis demonstrated ecological features of the syntaxa. We showed that the formation of Calamagrostis communities is associated with regular spring fires.