Species Interaction Networks in the Boreal Forest: Structure, Assembly, Function, and Responses to Disturbance

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All species in nature interact with subsets of the other species in their community, both through trophic interactions (predator-prey or host-parasite relationships) and non-trophic interactions (e.g., semiochemicals released by one organism that modify behaviour of other organisms). The structure of this complex network of interactions determines how a fluctuation in the population size or behaviour of one species can send ripple effects through the entire community. Research has shown that interaction networks are not randomly structured, and that certain network architectural features confer important properties, such as network stability or function, the latter referring to a diverse range of ecosystem processes, for example, primary production, decomposition, plant pollination, or natural enemy control of herbivores.******However, there are still major knowledge gaps as to how these network structural patterns assemble, how network structure confers specific important functions, and how to quantify interactions and interaction strengths for diverse guilds of arthropod generalist predators and omnivores. Furthermore, only one recent study has attempted to map out all trophic and non-trophic interactions in an ecosystem, and the patterns that emerged from this comprehensive description generated such interesting hypotheses that further attempts to completely describe all the interactions in other ecosystem types seem like a very worthwhile endeavour, and will facilitate the testing of the findings from this initial study, generate new hypotheses, and test the generality among systems. My long-term research objective is to understand how ecological interaction networks assemble and change through ecosystem development, how they respond to anthropogenic and natural disturbance, and how network structure is related to ecosystem function. This knowledge will be critical for improved conservation of ecosystem functions and services, since species interactions underlie many important ecosystem functions.******To achieve this objective my proposed research will:***1. Measure differences in quantitative herbivore-parasitoid network structure at different stages of forest community assembly following disturbance, and relate network structure at different stages of forest succession to magnitude and stability of top-down control of herbivores by parasitoids.***2. Investigate how boreal forest Lepidoptera-parasitoid quantitative food web structure changes during forest tent caterpillar outbreaks and compare the strength of parasitoid top-down control of all Lepidoptera species in outbreak areas versus non-outbreak areas.***3. Quantify diet and seasonal nutritional limitation of a habitat generalist omnivorous ant, and how these change with land use intensity and vegetation cover type.***4. Assemble all available trophic and non-trophic interaction data for all known taxa in Alberta's boreal forest and construct the first complete' boreal forest interaction network.**