Biology session

Understanding the factors that influence the distribution of species is fundamental in biogeography, ecology and conservation biology. Several methods exist which with researchers can study the variables that determine habitat choice and these methods are often specific to habitat and taxon. Literature sources suggest that in grasslands, the horizontal and vertical composition as well as the structure of vegetation fundamentally affect animal species. In our study we aimed to identify which vegetation structural variables affect the habitat choice of grassland-specialist reptiles. The model taxa of the study are strictly grassland-specialist viper species which represent the three main filogenetical lineages of the Vipera ursinii complex: the Greek meadow viper (Vipera graeca), the Steppe viper (Vipera renardi), and the Hungarian meadow viper (Vipera ursinii rakosiensis). To study habitat selection, we collected vegetation structural data in the exact localities where vipers were found (n=122) and also in randomly selected points (n=613) in the respective habitats of the three lineages in the Tomorr and Kulmak mountains (Albania), in the Davydivka steppe (Ukraine), and on the meadows of Peszéradacs (Hungary). We photographed a 25×100-cm white board installed in a vertical position from a distance of 4 m at a height of 50 cm in each sampling point to characterize vertical vegetation structure. Applying image analysis methods, we measured the leaf area, the maximum height of the vegetation totally covered by plants (low reading), the maximum height of plants (high reading) and the foliage height diversity. We used model selection based on generalized linear mixed-effects models to test the effect of vegetation structural variables on the presence of vipers. We found that the presence of the Greek meadow viper and the Steppe viper was significantly and positively affected by the low reading. In the Hungarian meadow viper, presence depended on the high reading, leaf area and foliage height diversity. The results give helpful information for nature conservational management, thus contribute to increasing the efficiency of the protection of these vulnerable and endangered species.