Forage Selectivity of Semi-Free-Roaming Bison (Bison bison) in Sod-Forming Cereal Steppes in the Western Manych River Valley

摘要

Materials on the composition of forage plants in the bison diet were obtained within the enclosure of nonconsumptive use at the Rostov Nature Reserve in the summer and autumn seasons of 2018. The described area is located in the sod-forming cereal-grass steppes in the Western Manych River valley. Data on the seasonal dynamics of the composition of forage plants in the bison diet were produced via cuticular microscopic analysis of fecal samples. An electronic database was created for the plant cuticle structures typical of the species providing the floristic richness of grassland for bisons in order to identify the species of the botanical fragments in the fecal samples. Thus, the proportion of cereals in the summer and autumn diets comprised 64% and 84%, respectively. The selectivity indices of cereal species were measured as 2.1 in the summer and 4.3 in the autumn seasons. For motley grasses, it was 0.5 in the summer season and decreased to 0.2 in the autumn. The index value depends on the animals' taste preferences, the species richness in the aboveground phytomass of grassland, and the plant growth stage.