Metagenomic Assessment of Mycorrhizal Fungal Community Dynamics and Plant Productivity in Warming Alaska Peatlands
Team: Jim Bever, Jeffrey White, Ursel Schütte, Indiana University
Climate models suggest that global air temperatures will rise at unprecedented rates during this century. The impacts will likely be greatest in the Arctic where recent observations show temperatures already increasing at a rate twice that of temperate regions. Emissions of greenhouse gases (CO2 and CH4) are increasing in boreal environments, including from thawing permafrost soils. These soils contain organic carbon equal to about 35% of the global soil pool. Arctic warming is likely to drive a positive feedback – increasing greenhouse gas emissions leading to greater temperature increases.
Indirect effects include changes in plant community composition and productivity, which will likely influence the amount of greenhouse gases released into the atmosphere from boreal peatlands. Permafrost thaw can affect both plant community composition and productivity. An important unknown in boreal ecosystem feedbacks is how mycorrhizal fungi living in close association with plants may respond to permafrost thaw and in turn affect plant productivity and net carbon exchange. Mycorrhizal fungi form symbioses with 70-90 % of plant species and may either positively or negatively impact plant productivity and hence, the amount of carbon sequestered by the plant community.
We have begun work in permafrost areas in the Bonanza Creek Long Term Ecological Research (LTER) station outside of Fairbanks, Alaska. Here we are collaborating with other groups investigating how carbon flux in arctic tundra is influenced by permafrost thaw. The goal of this project is to determine the role of mycorrhizal fungi in soil carbon dynamics of arctic ecosystems. We study how mycorrhizal fungal communities affect plant productivity using a combination of traditional growth assays and next generation molecular methods. Metagenomic analysis involves isolating DNA from mycorrhizal fungal cells associated with plant roots. We measure mycorrhizal fungal community composition, including arbuscular, ecto- and ericoid mycorrhizal fungi, using bar coded 454 pyrosequencing in collaboration with the Center for Genomics and Bioinformatics at Indiana University.