Carbon-flux and Microbial Community Dynamics in Low-Arctic Tundra

Purpose: Effects of anthropogenic climate change have now been reported in all of the earth's biomes (Rosenzwieg et al. 2008) but Arctic regions, which sustain the highest rates of warming (Trenberth et al. 2007), have been particularly perturbed (Post et al. 2009). The stability of terrestrial Arctic ecosystems is of immediate concern because tundra soils store a disproportionally large share of the earth's C, and increased microbial decomposition of this C will feedback to climate on decadal timescales (Schuur et al. 2009). Soil microbes are central to the C balance of terrestrial ecosystems because of their dual role as decomposers of soil organic matter and as determinants of plant community diversity (van der Heijden et al. 2008), which in turn controls the quality and quantity of C inputs to soils (De Deyn et al. 2008, Bardgett et al. 2008). Yet, despite the importance of Arctic soils in the global C cycle, we know very little of the impacts of climate change on Arctic soil microbial communities, and even less of how these changes will feedback to the stability of tundra plant communities. In "Carbon-flux and Microbial Community Dynamics in Low-Arctic Tundra" we address critical gaps in our understanding of the role of soil microbial communities in the response of an Arctic ecosystem to climate change. Objectives: 1) To assess the ecological role of mycorrhizal networks (MNs) in plant interactions in a Low-Arctic tundra ecosystem; 2) To determine the effects of warming and increased nutrient availability on the ectomycorrhizal (ECM) fungal community of a tundra shrub that is responsive to these climate change factors; 3) To determine the effects of climate warming on Arctic soil fungi and bacteria over time; 4) To assess the role of the mycorrhizal symbiosis in determining C-allocation to tundra plant rhizosphere organisms.