Topological differentiation of vegetation of the Lublin-Volyn geobotanical district

Abstract

The position of the Lublin and Volyn (Volhynian) uplands within the geobotanical zonation system is ambiguous and disputable. An analysis of the syntaxonomical diversity and landscape distribution of the egetation of the Lublin and Volyn uplands revealed their similarity, and we consider this whole territory as the Lublin-Volyn geobotanical district of hornbeam-oak, oak forests, and steppe meadows. This district differs from the adjacent territories and is classified within the Central European mixed forests ecoregion. Typical and diagnostic syntaxa have been identified, and ecological-coenotic profiles have been constructed to characterize the distribution patterns of shrub-forest and herbaceous vegetation within the landscape. Based on calculations of phytosociological indicators for the main ecological factors, graphical patterns of their variation were developed. It was determined that the characteristic forests of the district, Tilieto-Carpinetum (Carpinion betulis), are represented by four variants (T.-C. var. galeobdolosum; T.-C. var. hepaticosum; T.-C. var. caricosum pilosae; T.-C. var. isopyrosum). The district is also characterized by the presence of syntaxa associated with carbonate soils, both of the marsh type (Caricion davallianae) and the meadow-steppe type (Cirsio-Brachypodion, Festucion valesiacae), with the dominance of Carex humilis and Stipa capillata. Using DCA-analysis, the correlation between ecological factor indicators and the distribution of plant communities within the ecological space has been established, forming six fields distributed along three vectors: by moisture (aquatic and marsh communities), xerophytism, and chemical properties of soils (meadow-steppe communities), as well as the structure of coenoses with a specific ombroregime (forest communities).