LTREB Renewal: Ecosystem Structure and Function in Palouse Grasslands

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This renewal proposal continues a long-term experimental study of grasshoppers, their enemies (predators and parasites), their food plants and nutrients for these plants in a Montana Palouse grassland ecosystem. Grasshoppers are the dominant herbivores in this ecosystem and strongly influence the ecosystem?s functioning (nutrient cycling and primary production). Previous research has showed that classic food-chain or food-web theories are insufficient to explain how grasshoppers affect nutrient cycling and primary production, because these interactions very over time within a particular habitat (vegetation type) in the ecosystem as well as spatially among the four habitats comprising this ecosystem. Ongoing experiments will be continued in order to determine how food web dynamics vary over space and time, and whether this variation is associated with natural climate cycles or with anthropogenic climate change. This study will have a number of broader impacts. First, long-term studies like this are critical to assess the effects of climate change and to forecast future impacts of climate change. Since 1908, these grasslands have experienced a 0.4 degree Centigrate increase in average daily temperature and a 30% (11.1 cm/yr) decrease in annual precipitation. The main factors (food plant availability and natural enemies) that influence grasshopper abundance and their ecosystem impacts have clearly been influenced by climate changes. Results from this study will also inform range management and conservation programs, particularly with respect to climate change and ongoing ecosystem modification. The study is integrated into an undergraduate program created by the University of Notre Dame and the Confederated Salish and Kootenai Tribes to foster better resource management and cultural exchange with Native Americans.