Fire, grazing and climate shape plant–grasshopper interactions in a tallgrass prairie

Abstract

Species interactions are integral to ecological community function, and the structure of species interactions has repercussions for the consequences of species extinctions. Few studies have examined the role of environmental factors in controlling species interaction networks across time. We examined variation in plant–grasshopper network structural properties in response to three major grassland drivers: periodic fire, ungulate grazing and climate. We sequenced a plant barcoding gene from extracted grasshopper gut contents to characterize diets of 26 grasshopper species. Resulting grasshopper species’ diets were combined with long-term plant and grasshopper surveys to assemble plant–grasshopper networks across 13–19 years for six watersheds subjected to varying fire and grazing treatments. Network modularity, generality and predicted grasshopper community robustness to plant species loss all increased in grazed watersheds. Temperature decreased predicted grasshopper community robustness to plant species loss. Grasshopper communities were found to be vulnerable to climatic warming due to host plant loss. However, intermediate disturbance from ungulate grazers may maintain grasshopper diversity and buffer community robustness to species loss. Our results suggest that climate and disturbance shape the structure of ecological interaction networks and thus have many indirect effects on species persistence though direct effects on interaction partners. A plain language summary is available for this article.