Local Tree Cover and Regional Climate Hierarchically Shape Ant Communities in Mediterranean Dehesas

Mediterranean dehesas are open agroforestry systems in which tree configuration and climatic regime condition the organisation of biodiversity. In these landscapes, ants are commonly used as ecological indicators, although the relative importance of local versus regional factors in structuring their communities remains poorly defined. Ant assemblages were sampled using pitfall traps at 15 farms in southern Spain, and the influence of environmental variables defined at two spatial scales was analysed: microhabitat, distinguishing between areas under tree canopy and open areas, and farm as a unit representative of the regional context. The multivariate analyses applied (dbRDA, PERMANOVA and variance partitioning) reveal a hierarchical organisation of community assemblages. At the local scale, community variation was primarily explained by structural attributes of the tree layer, particularly canopy cover and distance to trees. At the farm scale, environmental predictors explained a modest proportion of community variation, with strong overlap among climatic, vegetation and structural variables. Overall, the structure of ant communities in dehesas follows a scale-dependent pattern, in which climate sets the regional framework and tree structure modulates assemblage organisation at a fine scale.