Determinants of grassland community structure: a comparison of the community-level consequences of species interactions and loss of biodiversity

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My research focuses on biodiversity, plant community structure and ecosystem function in the boreal forest region in southern Yukon. This includes both understorey vegetation and grasslands and provides opportunity to understand 1. how natural communities are structured, 2. what role biodiversity plays in these communities 3. how they function, and 4. how they respond to perturbations? To make the results more generalizable, and thereby contribute to the development of ecological theory, I have (or have had) parallel comparative projects in other grasslands (semi-arid grasslands of Interior British Columbia, arid annual grasslands in the Negev desert, savanna grasslands in Serengeti), and forest understorey (tropical forests in southern China). Stemming from the 4 primary questions I investigate: (i) how different plant functional groups influence plant community dynamics and ecosystem function; selected components of a plant community are removed and consequent responses monitored. (ii) if the plant communities are organized primarily by nutrient limitation (bottom-up regulation), by herbivory (top-down regulation), or by their interaction; our experiments (running for 21 years) manipulate soil nutrient levels and herbivore levels, and we then monitor the consequences on individual plant species, populations, and communities. (iii) vegetation, soil, and microbial responses to long-term experimental treatments; responses measured in the 21-yr plots. (iv) if competition has significant impacts on community structure and if the magnitude of these impacts change in predictable ways along productivity gradients? (v) the effects of scale on the responses measured in i-iv; some of these experiments will be repeated at different scales. (vi) the effects of warming, wetting/drying on community composition and ecosystem function, and how these change with productivity. (vii) how food web complexity and productivity influence the relative strength of tropic interactions, and how changes in trophic structure influence ecosystem function?