Print PagePlant diversity patterns are structured by ecological processes operating at multiple scales over space and time. Despite that the importance of dispersal and habitat heterogeneity in structuring and maintaining plant diversity is increasingly recognized, the effects of landscape context and habitat quality are seldom studied simultaneously. Most studies have focused on species diversity in a set of similar habitats, often depicting the landscape as a binary template and eluding the potential role of adjacent habitats on plant diversity. Yet, communities are open systems linked to surrounding communities through reciprocal dispersal likely to affect species' extinction, colonization and coexistence at both local and regional scales. We investigate how changes in management and landscape context affect plant community structure in semi-natural pastures and adjacent forests. Using 25 island landscapes, we examine the effect of grazing management and the proportion of open land in the surrounding landscape on composition and diversity of species assemblage in plant communities. Specifically, we (1) investigate the effect of spatial proximity and habitat quality on species composition in grassland communities and (2) test hypothesized relationships between species assemblage structure and change in management and landscape context at both habitat and landscape scales.
Results/Conclusions
Our results highlight the importance of habitat quality and species sorting on species assemblage in heterogeneous landscapes, but also the role of dispersal between adjacent habitats in structuring and potentially promoting species coexistence in local communities. Structural equation models show clear difference in the response of grassland communities inhabiting contrasting habitats. While reduced area of open land and cessation of livestock grazing induce compositional shift without direct effect on species diversity in open pastures, we observe substantial change in spatial turnover, composition, and species diversity in adjacent forests. These results suggest that diversity, as well as its spatial structure, is influenced by inflow from adjacent habitats affecting species coexistence and communities’ capacity to track abiotic and biotic changes across space and time. In conclusion, our study highlights the influence of adjacent habitats on structuring local species assemblage and maintaining diversity at both local and regional scales through the interplay of species sorting, mass effect, and spatiotemporal storage. It especially stresses the importance to consider multiple scales when assessing and managing diversity in heterogeneous and dynamic landscapes.
