Animals and the zoogeochemistry of elemental cycling

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Human activities such as harvesting and urbanization have led to the introduction and extinction of animals in many ecosystems. This introduction or loss of animals can have profound impacts on ecosystems and the many benefits ecosystems provide. For example, the introduction of moose to the island of Newfoundland has led to failed regeneration of native balsam fir forests, increased occurrence of moose-vehicle collisions and increased recreational hunting and food provisioning opportunities. Recent evidence suggests that large animals such as moose can have substantial impacts on nutrient cycling; a process that is fundamental to life, and further research is needed to better understand how changes in animal populations will impact nutrient cycling. My long-term objective is to investigate the role of animals in ecosystem nutrient cycling in order to predict the effects of human-mediated animal extinction and introduction on ecosystem nutrient cycling. Over the next five years I have two short-term objectives: I) investigate the relative and combined direct and indirect effects of herbivores on terrestrial ecosystem carbon (C) and nitrogen (N) cycling and II) investigate terrestrial herbivore impacts on freshwater ecosystem C and N cycling. To address Objective I, I propose to use mathematical models and field studies in Atlantic Canada. In collaboration Parks Canada and the Government of Newfoundland we will study 30 areas where fencing has been set-up to exclude moose across sections of balsam fir dominant forests of Atlantic Canada. This fencing will allow us to study the effects of moose on boreal ecosystem carbon and nitrogen. Moose can move large distances and frequently use habitat near streams and ponds. At high densities, however, moose can transform boreal forest communities to open grassland dominated areas. To address Objective II, I also propose to use mathematical models and field studies. The field studies will use aerial photographs and ground sampling to measure moose impacts on forests near 14 small streams and test for the potential impacts of moose on streams by measuring stream nutrients and stream animal communities. The proposed research over the next 5 years will accelerate our understanding of animal impacts on nutrient cycling with a broad approach using mathematical modelling and field studies. Applications of this work touch on management plans for large herbivores, restoration of degraded forest ecosystems and how to maintain benefits provided by ecosystems. It is of particular relevance to boreal regions in Atlantic Canada which are undergoing rapid changes in large animals such as moose and Atlantic salmon. The tools and evidence from the proposed research will help resource managers predict the effects of these changes which will improve management plans. Finally, the proposed research program will train 15 students in quantitative skills and knowledge that are highly sought after in diverse work environments.