Project Report

This summer I conducted a study on an existing experiment on the Tibetan Plateau investigating how climate change interacts with yak grazing to affect the forage quality of the Tibetan rangeland. Many Tibetans rely almost entirely on livestock production for food, fiber, and fuel. Further, Tibet is projected to experience the effects of climate change particularly strongly due to its high elevation and topology. One of these changes is expected to be a shift in the timing of water availability due to increased winter snowfall and decreased summer moisture due to warming. Although this region has supported grazing for more than four thousand years, it is unknown how climate change will affect the rangeland’s ability to support livestock, and how grazing will act as a feedback to affect forage quality. My study focused on how grazing would interact with changes in the timing of water availability to affect plant traits associated with palatability and nutrition content of the plant community. Plants have two main strategies that can be used to cope with grazing: tolerance and avoidance. Plant traits associated with avoidance include physical and chemical defenses such as toughness, high fiber and lignin content, short height, and increased stem to leaf ratio. These plants therefore tend to be less palatable and nutritious. Plants that are tolerant of grazing are characterized by the ability to regrow tissues after defoliation. Traits associated with this strategy involve greater allocation to photosynthesis and include higher specific leaf area, increased leaf nitrogen content, and increased belowground production, leading to greater palatability. By utilizing an experiment that uses snow additions and warming chambers to simulate changes in the timing of water availability, and crossing this with a yak grazing treatment, I was able to investigate how these factors affect community-level plant traits, with implications for how the forage quality of the rangeland will be affected by future climate and grazing scenarios. I hypothesized that a shift in the timing of precipitation toward the winter would cause the avoidance strategy to be more effective, and that grazing could act as either a positive or negative feedback. Results from this study will help to better illuminate interactions between grazing and climate change, and inform future management strategies.

National Science Foundation (NSF)
Office of International and Integrative Activities (IIA)
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Carter Kimsey
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Dev Laura L
Fort Collins
United States
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