Effect of landscape structure on the spatial distribution of Mediterranean dung beetle diversity

Landscape structure influences the distribution of animals, altering their movements and their ability to reach habitat patches. We analysed the spatial patterns of dung beetle species diversity in three differently structured natural landscapes in a Mediterranean protected area in the centre of the Iberian Peninsula. Cabaneros National Park, Central Spain. Diversity components within (alpha) and among (beta) the three main vegetation types in the reserve were compared by using a hierarchical nested design. These were forests, scrublands and grasslands embedded in three different landscapes, where each was the most dominant and structurally connected habitat. Species richness of grassland habitat did not vary across landscapes, but forest habitat showed lower species richness in the grassland-dominated landscape. Scrubland was the least species-rich habitat, but here again there was no significant variation across landscapes. However, in all cases, there was a significant influence of habitat context (configuration of habitat patches within landscape matrix) on similarity of species composition. These tended to be more similar to the dominant landscape matrix where they were embedded, rather than to the same habitat type in other landscapes. Additive partitioning of diversity showed higher than expected values of beta in all landscapes, which indicated a structured response. Highest values of beta in the grassland-dominated landscape suggest that this was the least connected landscape for dung beetles. Our results suggest that in homogeneous conditions of climate and trophic resources, landscape structure may well be more important than habitat type as a determinant of dung beetle distribution in the Mediterranean.