Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Biology

Supervisor

Dr. R Greg Thorn

2nd Supervisor

Dr. Zoë Lindo

Joint Supervisor

Abstract

Peatlands have an important role in global climate change through sequestration of atmospheric CO2. Climate change is already affecting these ecosystems, including both above- and below- ground communities and their functions. Fungi play a central role in these communities. As a result, there is concern that altered fungal community function may turn peatlands from carbon sinks to carbon sources, greatly exacerbating the impacts of climate change. In order to gain a better insight into effects of climate change on the structure and function of these carbon sequestrating ecosystems, this thesis focuses on diversity and structure of fungal communities in natural environment in boreal peatlands and in mesocosm experiments to better understand the main and interactive effects of multiple drivers of climate change (increased temperature, elevated CO2, lowered water table) on fungal communities, and their function. The results of these studies suggest that moisture content of peat is probably one of the key factors driving changes in community composition of fungi in boreal peatlands under natural conditions. However, the effects of water table drawdown is likely to appear as a short-term effect. Following this short-term effect of water table drawdown, fungal groups are mainly affected by increased temperatures over a longer period of time, such that increased temperatures of 4 and 8°C above ambient conditions provoke a compositional shift in communities of fungi towards decomposers and vascular plant root-associates. These findings are valuable in providing a broader conceptual context of climate change and its consequences for carbon dynamics of boreal peatlands.

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