Landscape level patterns of grasshopper communities in Inner Mongolia: interactive effects of livestock grazing and a precipitation gradient

Grasshoppers are a dominant herbivore assemblage globally and play an important role for ecosystem nutrient cycling. Yet, we lack a strong understanding of the relationship between grasshopper diversity and plant community composition at the landscape scale. Our aim was to test landscape scale relationships between plant and grasshopper communities. We used a large-scale, replicated experiment at four sites, including grazed and protected pastures across a 350 km transect and 200-400 mm precipitation gradient in the steppes of Inner Mongolia, China. We analyzed the relationships between plant and grasshopper parameters with ANOVAs and CCA. We collected 17 grasshopper species and 15,000+ individuals. The desert steppe (lowest precipitation) had the lowest grasshopper richness and diversity, but abundance was not different from the other sites. In two dry sites (desert steppe and Stipa steppe), livestock grazing decreased grasshopper diversity and increased abundance of the main pest species. In contrast, at the highest precipitation site (meadow steppe), grasshopper communities did not differ between grazing levels. Across all sites and grazing intensities, grasshopper abundance tended to be lowest and diversity highest in plant communities with intermediate levels of biomass and plant species richness. These results support the concept that appropriate land use management practices would be beneficial for increasing biodiversity, promoting grassland sustainability, and reducing outbreaks of the dominant pest grasshopper in Inner Mongolia. Our study suggests that different management approaches are necessary depending on the average annual precipitation and that the driest sites are most vulnerable to disturbance.