Does human-induced heterogeneity differently affect diversity in vascular plants and breeding birds? Evidences from three Mediterranean forest patches

Abstract

Human-induced disturbances induce heterogeneity at patch and landscape scale, affecting plants and animals differently. In this study, we analyzed the diversity of three oak forest patches (one of them recently coppiced) in Mediterranean Central Italy. Vascular plants were censused on a raster of squares of 10,000 m2. Breeding birds were censused with the point-sampling method. In the three wood patches studied, we observed a clear pattern in diversity with similarities and differences between plants and birds. A mature wood patch (Foglino North) showed the highest total number of species (a measure of γ-diversity at wood patch scale) both for birds and plants but, at level of mean species richness (an averaged measure of α-diversity at sampling point scale), birds showed values significantly different among wood patches with the lowest value in the recently coppiced wood patch (Armellino); on the contrary, the plants did not show differences among patches. In the coppiced wood patch, birds showed the highest value of species turnover among sampling points (a measure of β-diversity at wood patch scale), while plants showed the lowest value. Data suggest that when comparing a coppiced wood patch to a mature wood patch, human-induced heterogeneity developed by coppice management may affect diversity in vascular plants and breeding birds differently at different hierarchical level (i.e., α-, β-, γ-level). This human-induced heterogeneity may decrease the α-diversity values in birds, while it may favor an increase in plants. Moreover, with coppice management, species turnover among sites (a measure of β-diversity) may decrease in plants while may increase in birds. We hypothesize that this different pattern may be due to intrinsic characterization of these two taxa (different number of species, sessile vs. vagile strategies of dispersion, different scales of the assemblages) and to different methods of sampling them.