BROAD-LEAVED FORESTS OF THE UPPER PLATEAU OF THE VOLGA UPLAND
Background. The upper plateau of the Volga Upland occupies the eastern part of the Penza region. The features of the lithogenic base of the upper plateau of the Volga upland, the rugged terrain create a variety of ecological conditions, which is reflected in the species composition and structure of phytocenoses. Within the upper plateau of the Volga upland, all landscapes are united in the group of erosion-denudation upland plains (EDR). Information about the broad-leaved forests of this territory is not numerous, so this publication aims to analyze their current state within the boundaries of the Penza region. Materials and methods. The investigation of the flora composition and structure of broad-leaved forests was carried out in route and stationary studies on sample areas of 100 m2. The structural diversity of the communities was estimated by the ratio of ecologic-coenotic groups of species in the composition of the vegetation cover. The classification of communities was carried out according to the dominant principle, taking into account ecological and coenotic groups (ECG), as well as in accordance with the principles of floral classification. All descriptions were processed according to the ecological scales of D.N. Tsyganov. Ordination of geobotanical sites was performed by indirect gradient analysis. Results. Modern broad-leaved forests in the landscapes of erosion-denudation plains are not widespread and account for about 20 % of the total forest area of the area. Five groups of associations have been identified: Querceta nemoro-herbosa (Q-Nm), Querceta boreo-nemoro-herbosa (Q-Br_Nm), Querceta nemoro-pine-herbosa (Q-Nm_Pn), Querceta nemoro-prato-steppe-herbosa (Q-Nm_Md-St), Querceta nemoro-nitro-herbosa (Q-Nm_Nt). It is noted that the selected classification units are associated with the types of terrain and terrain elements, and the peculiarities of their ecology are noted. The growth of rare species in the area is noted. According to the ecologic-floristic classification, broad-leaved forests are represented by 2 classes, 3 orders, 4 unions and 5 associations. Conclusions. The formation of broad-leaved forests of the upper plateau of the Volga Uplands to a large extent and for a long period of time took place under the influence of economic activity. The overwhelming majority of communities are secondary, coppice. Forests dominated by Quercus robur of seed origin occupy very small areas and have survived in areas where felling is difficult. The species composition of communities and their structure, on the one hand, are directly or indirectly related to human activities, and on the other, are determined by the peculiarities of the lithogenic base of the upper plateau of the Volga Upland. The classification of broad-leaved forests using the ecologic-coenotic approach makes it possible to assess their successional state.