Comparison of weed communities organization factors in the Leningrad Region and the Republic of Bashkortostan

This paper considers the results of the ordination analysis of weed communities in two regions – the Leningrad Region (LR) and the Republic of Bashkortostan (RB). The dataset includes 1726 relevés of the weed communities executed by the authors during 2000–2018 in cereal and root crops. The calculation of the ecological statuses of communities on 9 scales of D.N. Tsyganov is carried out for ecological characteristics of habitats. The values of the scales corresponding to climatic factors (thermoclimatic scale, cryoclimatic scale, aridity-gumidity scale), edafic factors (salt regime, soil acidity, nitrogen richness, variability of moistening) as well as scales of soil moisture and lightning are attracted to the analysis. The communities ranges on each scale are determined. The detrended correspondent analysis (DCA-ordination) with CANOCO 4.5 software package is used for the identification of ecological patterns of species and communities distribution and definition of the main drivers. It is demonstrated that the sets of the scales reflecting main ecological drivers significantly differ for the compared regions. Only the thermoclimatic scale and the scale of variability of moistening are common for both regions. The scales of nitrogen richness, variability of moistening and cryoclimatic influence generally on floristic composition differentiation in the LR. The scales of aridity-gumidity, the salt regime, lightning, moistening and soil acidity determine the floristic differentiation in the RB. A large number of scales in RB are defined by a variety of zonal vegetation types in the region which are connected with landscapes of forest, forest-steppe and steppe zones as well as a mountain-forest belt of the Southern Ural. The zonal vegetation of LR belongs only to subzones of the southern and average Taiga. The exception is the lightning scale which high values of correlation are connected with a considerable share of sunflower and corn in cultivated crops in RB.