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

摘要

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 alpha and beta 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 alpha-TD and beta-TD and reduced alpha-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.