Plant-herbivore-climate interactions in dynamic northern and alpine environments

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Ecologists have long debated how various factors determine when and where predators (top-down forces) or resources (bottom-up forces) or abiotic influences (e.g. weather and climate) will be predominant in different ecosystems. Increasingly it seems that complex trophic interactions can lead to unexpected outcomes, and that external, abiotic forcing can override biotic interactions in strongly seasonal environments.  Being able to better predict the responses of northern and alpine environments to disturbance at different scales is essential for developing viable strategies for conserving biodiversity, restoring degraded habitats, and managing the consequences of climate change. My research program is focused on understanding plant-herbivore-climate interactions in northern alpine environments. The focal study areas for this research program are located in the mountains of the southwest Yukon, in the Ruby Ranges east of Kluane Lake (61° N, 141° W). This proposal further develops several research themes that are integrated into a long-term (since 1995) program, including (1) Evaluation of the demographic, behavioural and physiological responses of alpine herbivores (invertebrates and vertebrates) to inter-annual variation in climate, especially seasonal snow cover; (2) Determination of the effects of resource availability and predation risk on the behaviour and demography of mammalian herbivore populations (pikas, marmots, ground squirrels), as model system for testing the predictions of the trophic exploitation models; (3) Measurement of the responses of alpine vegetation to different levels of natural and experimental herbivory and interannual variation in climate, at physiological, demographic and community levels; (4) Construction of regional models to assess the influence of landscape-level processes (e.g. snow, treeline and shrubline dynamics, etc) on biodiversity and ecosystem processes; and 5) Development of mechanisms for ensuring sustainability of northern and alpine environments, through long-term monitoring, education, outreach, and integration of scientific and community-based knowledge.