Disentangling patch and landscape constraints of nested assemblages

2014AbstractThe role of the matrix for the functionality of residual patches and therefore for species persistence has been recentlyrecognised. However its influence on assemblage structure and composition is still unclear. We studied the effect of both patchand matrix attributes on community assemblage structure and composition in a fragmented landscape of central Italy. We usedbird assemblages as a study model. Birds were sampled in 24 wood patches and distribution patterns were analysed consideringboth assemblage and guild-level responses. Patch composition and structure together with landscape patterns quantified with GISwere used as explanatory variables. The assemblages appeared to be strongly influenced by the landscape context, both in terms ofcomposition and configuration. The functional connectivity of the patches, in terms of amount of neighbouring borders betweenwoods and hedgerows, the shape of the woods in the matrix, together with the age of the patches, expressed as tree diameter,acted as the essential determinants, and even if the assemblages presented a significant nested structure, seven out of 40 speciesshowed an idiosyncratic distribution. The study of the association between functional guilds and environmental parametershighlighted the influence of ecological constraints on the occurrence of unexpected presences and absences, suggesting theability of some species to perceive and exploit matrix habitats. The matrix holds the capability to at least mitigate the effects ofisolation and habitat loss, and the semi-natural elements of the mosaic may represent a biodiversity reservoir in an otherwisedeprived landscape.