The role of linear structures in agricultural landscape in the maitenance of xerothermic species

The aim of the study was to evaluate the role of different types of linear structures in the preservation of four xerothermic species (Centaurea scabiosa, Euphorbia cyparissias, Melampyrum arvense, and Salvia verticillata) and two weeds (Euphorbia exigua and Thymelaea passerina). Observations were conducted in the agricultural landscape of Western Volhynia with fields of different land use intensity (a large-scale farming system and small traditional arable fields). The total length of the studied structures was 4760 m and the following five categories of structures were distinguished: field road verges adjacent to large (1) and small fields (2), field margins between the patches of xerothermic grasslands as well as large (3) or small fields (4) and balks (5). The distribution and abundance of species mentioned above were recorded there. The survey showed that linear habitats are not suitable for all the studied species; margins between arable fields and grasslands were the most important habitats for both grassland and weed species. Factors responsible for their abundance and distribution along these margins included the following: type of farming system, exposure of the margin, and soil moisture. Grassland species occupied habitats adjacent to small traditional fields with other than southern exposure; weeds were more abundant in drier microhabitas