Aridity mediates how grazing affects ground-dwelling arthropod abundance through changes in plant community properties in Mongolian grasslands

Abstract

In dryland ecosystems, grazing and increasing aridity (aridification) are major drivers of biotic community modification. Although some studies have indicated that the effects of grazing on plant communities change with aridity, the effects on ground-dwelling arthropod communities remain unclear. This study examined (1) aridity-dependent grazing effects on plant communities (plant species richness and community-weighted mean [CWM] of plant height) and ground-dwelling arthropod communities (abundances of herbivores, detritivores, and omnivores) and (2) the variation in interlinkages among grazing, plant communities, and ground-dwelling arthropod communities for steppe and desert steppe in a wide aridity range of Mongolian grasslands. The abundance of herbivores was enhanced by grazing, regardless of aridity. In contrast, with increasing aridity, the negative effects of grazing on the abundance of detritivores weakened, and the abundance of omnivores, mostly that of ants, shifted from positive to negative. A grazing-induced decrease in the CWM of plant height exhibited positive effects on the abundance of omnivores and negative effects on that of detritivores in the steppe; however, these effects were not observed in the desert steppe. Conclusively, this study highlights how aridity mediates the effects of grazing on plant and arthropod communities, providing insights into the changing dynamics of dryland ecosystems.