Grant: Discovery Grants Program - Individual

There is broad recognition that boreal forests are under pressure from climate change, but many impacts are gradual and may only be manifest through complex biotic interactions and variable ecosystem dynamics. To date, limited research has focused on answering `how' and `why' questions related to climate change responses, which typically require targeted and long-term investigation. In the Kluane Lake region, southwest Yukon, where the boreal ecosystem has been studied intensively since 1977, we will assess if and how plant-herbivore and predator-prey interactions have shifted from climate change. Using new remote sensing products to reconstruct historical changes to snow conditions (snow depth, hardness) and shrub cover (abundance and biomass), we will characterize long-term environmental change in the 500km^2 study region (1950-present). In our intensive study area (30km^2), we will conduct drone-based surveys to track fine-scale changes in snow and vegetation, with emphasis on snow conditions, plant phenology and shrubification. Snowshoe hares, the primary herbivore and keystone species in the boreal ecosystem, will be tracked intensively using GPS telemetry and accelerometry to reveal fine-scale responses to snow and shrubs, for example, how hares alter their foraging behaviour and anti-predator activity in response to spatiotemporal seasonal variation in snow and shrub cover. The primary predators in the system, Canada lynx and coyotes, will be instrumented and tracked in tandem with hares and drone-based snow/vegetation surveys to provide fine-scale, tri-trophic (plant-herbivore-predator) assessment of responses. Specifically, predator and hare tracking will reveal variation in movements, interspecific interactions, and hare predation in response variable snow and shrub profiles. Because coyotes are invasive to northern boreal forests and, unlike most native species, should respond favourably to many climate-mediated environmental changes, this work will assess their impacts on the boreal ecosystem, including density-dependent predation on hares and possibly contributing to attenuation of the famous Canada lynx-snowshoe hare population cycle. Previous work on plants, hares and predators on site provides a unique opportunity to conduct temporal comparisons to infer longer-term changes in key measures. Finally, we will analyze archived data from the Kluane system and open access time series data for > 5000 animal populations worldwide, to assess global prevalence, intensity and numerical features of cyclic attenuation in relation to the climate forcing hypothesis, as indicated by remote sensing products. This work is of primary relevance to academic communities (who have been trying to understand drivers of predator-prey and hare-lynx population cycles for >100 years) and broader society (who rely on healthy ecosystems and a sustainable and predictable boreal forest).