Plant communities of cultivated fields of the Podlaski Przełom Bugu mesoregion. Part 5. Root crop communities of light soils

This present paper, focused on root crop communities of light soils, is a part of the wide range characteristics of segetal communities of the Podlaski Przełom Bugu (Podlasie Bug River Gorge) mesoregion. On the basis of 160 phytosociological relevés made according to the Braun-Blanquet method, phytocenoses representing the Panico-Setarion alliance were distinguished. Most often, patches of the association Echinochloo-Setarietum were recorded in the study area. Heterogeneous habitat conditions affect its floristic diversity. Two subassociations of the phytocenosis, divided according to the species composition into 9 lower syntaxa, were identified on light soils. The following subassociations were distinguished: Echinochloo-Setarietum setarietosum glaucae in a typical variant and a variant with Juncus bufonius, both with subvariants with Digitaria ischaemum, as well as a typical variant of Echinochloo-Setarietum typicum, a variant with Juncus bufonius and a subvariant with Oxalis stricta in the typical and wet variant. Another association found in root crops on light soils of the Podlaski Przełom Bugu mesoregion is Digitarietum ischaemi. Its patches were observed in cultivations on light, acidic, poor soils. The characteristic feature of this community is the occurrence of numerous acidophilous species. In habitat conditions typical for the Podlaski Przełom Bugu mesoregion, Digitarietum ischaemi is differentiated into the typical and wet variant. Quite frequent patches of the Setaria pumila-Setaria viridis community were noted in intermediate habitat conditions, between those characteristic for Digitarietum ischaemi and Echinochloo-Setarietum