Local and landscape drivers of ground-dwelling ant diversity in agroecosystems of Dry Chaco

Abstract

In mosaic landscapes, environmental heterogeneity has been pointed out as an outstanding driver of emergent biodiversity patterns. Whether environmental heterogeneity elicits an increasing, decreasing or hump-shaped response of biodiversity depends on species, scale and type of agricultural land use and management. In this study, we analyzed ground-dwelling ant diversity in agroecosystems of Southern Dry Chaco (SDC) at local and landscape scales. We carried out the study along a gradient of agriculture intensification, taking into account five land-use and land-cover (LULC) classes: fallow lands, secondary forests, pastures, woody crops and herbaceous crops. We analyzed ant species richness and community composition in relation to local environmental heterogeneity as well as to landscape compositional heterogeneity. Changes in ant community composition were mainly related to species replacement along the LULC gradient, with fallow lands and secondary forests harboring the highest ant species richness. Biotic heterogeneity, promoted by vegetation, explained the pattern of ant diversity at local scale, whereas dissimilarity between neighboring LULC types explained ant species richness at landscape scale. Our findings highlight the importance of promoting natural and semi-natural vegetation as well as managing landscape compositional structure to enhance ant diversity in agroecosystems of the SDC.