Interacting effects of climate change and grazing on temperate grasslands

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My research program examines the processes that organize plant communities and the functional consequences of different emergent assemblages on ecosystem properties. The ecosystem I study, temperate grassland, is among the most threatened ecosystems globally. Less than one percent of British Columbia's land base is grassland, and the remaining grasslands are threatened by over-grazing, non-native invasives, urban development, and global climate change; therefore my results have immediate practical value in restoration and conservation efforts. To understand the processes that control plant communities it is necessary to take an integrated, multi-scaled approach. My research will be conducted across different grassland types and over a wide range of spatial scales: from single-plant pot experiments in a controlled greenhouse setting, to multi-species microcosms, to controlled manipulations in natural grasslands, to landscape descriptive monitoring. The main goal of my research is to understand the mechanics of community and ecosystem functions in temperate grasslands to provide tools to enable their restoration and conservation. I propose to study stress (through climate change) and disturbance (grazing) and how these factors affect species composition, diversity and trophic interactions. The major stress in temperate grasslands is drought. Global climate change scenarios suggest that temperature will increase and that precipitation patterns will be altered, with a reduction in rainfall during the hottest months in the summer. The research I propose is unique. I plan to alter micro-climatic conditions in grasslands along a natural environmental productivity gradient by manipulating temperature (through open-top-chambers) and water supply (through rain shelters and water additions). In combination with these abiotic factors, an interacting effect of grazing and litter (dead plant material) manipulations will be applied. The grasslands I study are located in the Thompson Plateau in Southern British Columbia. My objectives are: 1. Test how productivity affects the stability of grasslands to perturbations of both stress (drought) and disturbance (grazing). 2 Determine the relative importance of top-down and bottom-up controls in grasslands along a natural productivity gradient, and the role of detritivores. 3 Use species traits to make predictions regarding species distribution, abundance and community composition and then relate that information to objectives 1 and 2. The methods for this proposal are divided into three separate experiments. The first is a factorial field experiment testing the effects of climate change (temperature and precipitation) in conjunction with grazing to test the resistance of the grasslands to disturbance along a productivity gradient. The second field experiment will assess the role of top-down and bottom-up processes on plant and animal community structure. Finally, plant species trait screening in the greenhouse will examine correlations between plant traits and observed patterns in the field. The projects I propose consist of a combination of small- and long-term hypothesis-driven questions. My publications and grant success demonstrate that I can plan, execute, and deliver hypothesis-driven research.