ИСТИНА

The vegetation of the Valdai National Park was studied with particular attention to the meadows of the class Molinio-Arrhenatheretea. These ancient meadows have formed due to centuries of agrarian use of the forest lands in the region. According to the methodology of the EDDG group, permanent sample plots of the grassland communities of the аssociation Anthoxantho-Agrostietum (alliance Cynosurion cristati, order Arrhenatheretalia) were established in 2017. The species composition monitoring was carried out in these plots annually. It was revealed that each year, the communities are characterized by high values of the total cover and the height of the herb layer (respectively, 75-100% and 80-120 cm). Due to the absence of haymaking and grazing, all plots are characterized by a thick litter layer. The number of species in the plots varies from 75 to 22. A tendency for decreasing species diversity was observed over the years. The group of constant species for every year on the plot is relatively small (from 8 to 30%). The maximum values are reached by a group of episodically occurring species that appear or disappear in different years or single species, found only in one of the four years of observation. This high species turnover maintains a high level of biological diversity of post-forest meadows in the region. In addition, on all plots, expansion of trees and shrubs, as well as invasive species, is very rare, which indicates that owing to long-term anthropogenic evolution, meadows of the National Park retain their own succession status. They are conservative with respect to the introduction of new species (including alien ones) and can withstand forest overgrowth after the end of land use (haymaking and grazing). Thus, it is necessary to note the high importance of meadows for conserving natural biodiversity and cultural heritage in the Novgorod region.