Pathways Linking Habitat Management to Avian Functional Diversity in Intensively Managed Mediterranean Agricultural Landscapes

Agricultural intensification has simplified European agroecosystems, leading to biodiversity loss and altered ecosystem functioning. Within these landscapes, (semi)natural elements such as riparian zones may enhance biodiversity, yet the mechanisms linking habitat structure to functional diversity remain insufficiently understood. In this study, we investigated how landscape attributes and community-level processes jointly shape avian functional diversity in an intensively managed Mediterranean agricultural landscape in central Greece. Bird communities were surveyed at 60 sampling stations across riparian zones, green elements, and croplands. We quantified taxonomic and functional diversity using generalized linear models and examined direct and indirect relationships using piecewise structural equation modelling (SEM), complemented by variation partitioning and redundancy analysis. Riparian habitats supported significantly higher species richness and functional richness compared to croplands, with green elements showing intermediate values. However, functional dispersion (FDis) showed limited variation among habitat types. SEM results revealed that landscape variables influenced functional diversity primarily through indirect pathways, mediated by species richness, Shannon diversity, and functional richness. Variation partitioning further showed that functional dispersion was overwhelmingly explained by community-level attributes, with negligible independent contribution of landscape variables. These findings suggest that higher-order functional structure in bird communities is not directly associated with habitat configuration but is more strongly related to internal community organization. Our results highlight the importance of considering both taxonomic and functional dimensions, as well as indirect ecological pathways, when designing habitat management strategies aimed at sustaining biodiversity and ecosystem functioning in agricultural landscapes.