Controls on soil carbon loss with permafrost thaw in Alaskan peatland ecosystems

Authors

C C. Treat, University of New Hampshire - Main Campus
M Bhagat, University of New Hampshire - Main Campus
Julie Talbot, University of New Hampshire - Main CampusFollow
Ruth Varner, University of New Hampshire - Main CampusFollow
Andrew S. Grandy, University of New Hampshire - Main CampusFollow
S Ewing, Montana State University-Bozeman
Wilfred M. Wollheim, University of New Hampshire - Main CampusFollow
Steve Frolking, University of New Hampshire - Main CampusFollow

Abstract

High latitudes are experiencing effects of climate change such as soil warming, thawing permafrost, altered hydrology, and longer growing seasons due to warmer temperatures. An estimated 50% of the global below-ground soil organic carbon pool (SOC) is stored in high latitudes and a significant amount is found in peatlands. Using an experimental approach, we quantified release of methane (CH₄) and carbon dioxide (CO₂) from soil cores from northern permafrost peatlands and explored mechanisms responsible for SOC mineralization in response to temperature and soil moisture. We conducted experiments using replicate cores from two boreal and two tundra peatland sites with intact permafrost to represent Alaskan peatlands. Cores were exposed to a range of temperature and moisture to represent typical field conditions, and we measured production of CO₂ and CH₄. We also characterized total microbial biomass, dissolved organic carbon, and peat chemistry. In these incubations, CO₂ production over 30-days ranged from 1.20 to 394.5 umol CO₂ g^-1 and CH₄ production over 30-days ranged from -0.134 umol CH₄ g^-1 (net uptake) to 2.167 umol CH₄ g^-1. All soil types demonstrated similar rates of potential C production at lower temperatures. However, at high temperatures, arctic active layer soils showed higher rates of potential CH₄ production and boreal active layer soils showed higher rates of potential CO₂ production. Differences in potential C fluxes between ecosystems (boreal vs. arctic peatlands) and depths (active layer vs. permafrost) at higher temperatures are likely due to inherent differences in peat properties, microbial biomass, and redox status. Therefore, the response of soil C mineralization to climate change will vary by ecosystem type and depend on the magnitude of temperature increase.

Department

Earth Sciences, Earth Systems Research Center

Publication Date

12-2012

Journal Title

Fall Meeting, American Geophysical Union (AGU)

Publisher

American Geophysical Union Publications

Document Type

Conference Proceeding

Recommended Citation

Treat, C., Bhagat, M., Talbot, J., Varner, R., Grandy, S., Ewing, S., Wollheim, W. & Frolking, S. (2012), Controls on soil carbon loss with permafrost thaw in Alaskan peatland ecosystems, Abstract B21D-0414 presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec.