HR: 11:05h
AN: B52A-04    [Abstracts]
TI: Interactions Between Temperature and Nutrient Availability in Mediating Microbial Respiration in High Arctic Polar Semi-desert Soils
AU: * Holland, K J
EM: holland@lifesci.ucsb.edu
AF: University of California, Santa Barbara, Dept. Ecology, Evolution, and Marine Biology University of California, Santa Barbara, CA 93106-9610 United States
AU: Sullivan, P
EM: anpfs@uaa.alaska.edu
AF: University of Alaska, Anchorage, Environment and Natural Resources Institute University of Alaska, Anchorage 707 A St., Anchorage, AK 99501 United States
AU: Wallenstein, M
EM: wallenstein@lifesci.ucsb.edu
AF: University of California, Santa Barbara, Dept. Ecology, Evolution, and Marine Biology University of California, Santa Barbara, CA 93106-9610 United States
AU: Arens, S
EM: setharens@yahoo.com
AF: University of Alaska, Anchorage, Environment and Natural Resources Institute University of Alaska, Anchorage 707 A St., Anchorage, AK 99501 United States
AU: Schimel, J P
EM: schimel@lifesci.ucsb.edu
AF: University of California, Santa Barbara, Dept. Ecology, Evolution, and Marine Biology University of California, Santa Barbara, CA 93106-9610 United States
AU: Welker, J M
EM: afjmw1@uaa.alaska.edu
AF: University of Alaska, Anchorage, Environment and Natural Resources Institute University of Alaska, Anchorage 707 A St., Anchorage, AK 99501 United States
AB: Field respiration measurements in high arctic polar semi-desert in northern Greenland suggest a divergence in respiration rates of microbial communities in fertilization treatments at temperatures above 4°C. We hypothesized that this divergence could be attributed to either greater temperature responsiveness of microbial communities in nitrogen fertilized treatments, or to increased substrate availability in nitrogen fertilization treatments at higher temperatures. Microbial respiration responses to labile substrate addition were equal across fertilization treatments, suggesting that microbial communities had similar temperature sensitivities. To determine whether substrate availability differed between fertilization treatments, we measured ¹³CO₂ of respiration at four temperatures. With increased temperature, rates of CO₂ efflux increased and isotopic signatures of respired carbon became lighter, suggesting increasing turnover of more recalcitrant C at higher temperatures. Respiration of nitrogen fertilized soils had lighter ¹³CO₂ signatures than ambient soils, suggesting that nitrogen might increase turnover of more recalcitrant soil carbon. These data suggest the divergence in CO₂ efflux in the nitrogen fertilization treatments could be mediated by increasing availability of recalcitrant carbon.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: Fall Meeting 2005