Landscape and habitat filters jointly drive richness and abundance ofspecialist plants in terrestrial grassland islands

Abstract

Land use changes have resulted in the loss and isolation of semi-natural habitats worldwide. In intensively used agricultural landscapes the remnants of natural flora only persist in small habitat islands embedded in a hostile matrix (Deák et al. 2016a). Species composition of small habitat islands is substantially influenced by habitat and landscape filters through persistence and dispersal traits of plant species. Due the interaction of factors acting in different spatial scales, vegetation of habitats islands can be evaluated by a complex approach considering multiple spatial scales. We sampled grassland specialist plant species, local environmental factors (habitat filter) and the landscape composition (landscape filter) of 82grassland islands in Hungary. We assessed the effects of slope, woody encroachment and disturbance, together with the level of isolation on the trait composition of grassland specialist plants. We studied the trait responses related to functional spatial connectivity (long-term dispersal ability by wind and animals) and temporal connectivity (clonality and seed bank) using model selection techniques. We found that isolation decreased the abundance of good dispersers due to the lack of directional vectors transferring seeds between suitable habitat patches. We found that clonal plants cope well with increasing woody encroachment due to their high resistance against environmental changes; however, they could not cope with high disturbance. Persistent seed bank did not support the survival of specialist species in the studied habitat islands. Steep slopes which provided favourable dry habitat conditions and environmental heterogeneity for specialist plants had an overall positive effect on their species richness. Grassland specialist plants were influenced by the interplay of landscape filters influencing their abundance, and habitat filters affecting plant species richness. Landscape filtering by isolation influenced the abundance of specialist plants by regulating seed dispersal. Habitat filters sorted species that could establish and persist at a site by influencing micro-site availability and quality (Deák et al. 2016b).

Deák, B., Tóthmérész, B., Valkó, O., Sudnik-Wójcikowska, B., Bragina, T.-M., Moysiyenko, I., Apostolova, I., Bykov, N., Dembicz, I., Török, P. (2016a): Cultural monuments and nature conservation: The role of kurgans in maintaining steppe vegetation. Biodiversity & Conservation 25: 2473–2490.

Deák B., Valkó O., Török P., Tóthmérész B. (2016b): Factors threatening grassland specialist plants - A multi-proxy study on the vegetation of isolated grasslands. Biological Conservation 204: 255-262.