Environmental heterogeneity compensates the potential homogenising effect of abandonment of grazing in a sub-Mediterranean mountain landscape

ABSTRACT Background Anthropogenic mountain grasslands undergo major changes in their composition and structure after abandonment of their use as pastures or hay meadows. Distinct plant community-types may develop in habitats that differ in environmental conditions, such as soil water availability; however, few studies have addressed this issue in abandoned anthropogenic grasslands. Aims To quantify the effects of topographic factors and variables related to soil water availability on α and β taxonomic diversity (TD) and functional diversity (FD) to assess the role of landform heterogeneity in shaping vegetation structure. Methods We classified the vegetation of long-abandoned central Apennine pastures and related their species composition and diversity to environmental variables. Results We identified four community-types whose distribution was related to topographically determined soil water availability. The species composition of drought-tolerant communities on south-eastern slopes with shallow soils was largely similar to that of anthropogenic grasslands. Resource-poor conditions were related to enhanced α-TD and β-TD and reduced α-FD for traits related to temporal niche differentiation and resource acquisition strategies. Conclusion In long-abandoned sub-Mediterranean grasslands, landform heterogeneity guarantees a certain level of TD and FD at the landscape scale, contrasting the assumed role of abandonment of grazing on homogenisation of vegetation features.