Sheep herding in small grasslands promotes dung beetle diversity in a mountain forest landscape

Abstract: It is assumed that the transformation of native forest into agricultural fields and grazing grasslands negatively affects biological diversity, and there are multiple cases documenting this pattern. For example, when lowland tropical forests are transformed into extensive cattle pastures, dung beetle richness, abundance and diversity decrease. However, in some cases, biodiversity may respond in the opposite direction. We describe dung beetle assemblages in a mountainous landscape where small grasslands (less than 7.5 ha) with sheep pastoralism are imbedded in a pine-oak forest matrix at the Mexican Transition Zone. We captured 14 species (1058 beetles) in 10 forest sites, and 20 species (2591 beetles) in 10 grassland sites. Generalized linear mixed models showed significantly higher values of species richness, diversity and abundance in grazing grasslands. We found 10 shared beetle species between forests and grassland sites, and a PERMANOVA revealed significant differences in species composition between habitats. Generalized linear models showed that dung beetle richness, abundance and diversity are related to dung availability, soil moisture and altitude, but not to soil hardness nor land use heterogeneity. Similarly, we did not find significant correlations between compositional dissimilarity (beta diversity) and dung availability nor land use heterogeneity. Our results document how traditional sheep herding in small grassland patches embedded in a forest matrix promotes the diversity of dung beetle assemblages, showing that biodiversity can be enhanced by human activities. Implications for insect conservation: The results of this study indicate that grassland patches embedded in the forest matrix where traditional small herds of sheep graze, contribute to increasing landscape complexity by providing a mosaic of environmental conditions that promote a high diversity of dung beetles on a regional scale.