HR: 12:05h
AN: B42B-07    [Abstracts]
TI: Greenhouse Gas Exchange and Biogeochemistry of Fertilized Canadian Plantation Forests
AU: * Basiliko, N
EM: nathan.basiliko@ubc.ca
AF: University of British Columbia, Department of Forest Sciences, 2424 Main Mall, Vancouver, BC V6T1Z4 Canada
AU: Grayston, S J
EM: sue.grayston@ubc.ca
AF: University of British Columbia, Department of Forest Sciences, 2424 Main Mall, Vancouver, BC V6T1Z4 Canada
AU: Roy, R
EM: realroy@uvic.ca
AF: University of Victoria, Department of Biology, PO Box 3020 Station CSC, Victoria, BC V8W3N5 Canada
AU: Mohn, W W
EM: wmohn@interchange.ubc.ca
AF: University of British Columbia, Department of Microbiology, 300-6174 University Blvd. , Vancouver, BC V6T1Z3 Canada
AU: Yolova, V
EM: vyolova@yahoo.com
AF: University of British Columbia, Department of Forest Sciences, 2424 Main Mall, Vancouver, BC V6T1Z4 Canada
AU: Prescott, C
EM: cindy.prescott@ubc.ca
AF: University of British Columbia, Department of Forest Sciences, 2424 Main Mall, Vancouver, BC V6T1Z4 Canada
AB: Canada's ratification of the Kyoto Protocol in 2002 has raised questions of the role of ecosystem management as a tool to temporarily reduce the net greenhouse gas burden of the forestry industry and potentially generate emission offset credits. We examined growing season methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) fluxes, soil nutrient chemistry, and microbial biomass and CH4-oxidizing bacterial communities in 20-year-old sub-boreal lodgepole pine and maritime hemlock plantations under control conditions and simulated operational fertilization with N (200kg urea-N per ha, applied twice) and N, P, K, and micronutrients. CH4 uptake was significantly greater in the lodgepole pine site than in the hemlock site (152-221 and 57-81 micrograms CH4 consumed per square meter per hour), and there were no significant differences among treatments at either site. Among sites, treatments, and sampling times, CH4 uptake correlated positively with NH4 concentrations and negatively with extractable organic N:P quotients, indicating that this process may potentially be limited by nutrient availability to the CH4-oxidizing bacteria. N2O efflux was measured sporadically at a few flux collars, but was not significantly different from zero at any site, treatment, or time. Soil respiration (CO2 efflux) rates were faster in the hemlock than lodgepole pine site (243-409 and 100-266 milligrams CO2 per square meter per hour), and significant treatment differences were observed at individual times, though with fertilized plots exhibiting both faster and slower rates than controls. Soil respiration correlated significantly with microbial biomass C and N and NO3. Within each site, soil respiration, but not CH4 uptake, was positively correlated with soil temperature. New experiments examining the short-term effects of fertilization on greenhouse gas exchanges are underway, and both short and long-term effects will be evaluated in relation to changes in C storage in plant biomass, litter, and soil organic matter under the same fertilized and control conditions.
DE: 0428 Carbon cycling (4806)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: Fall Meeting 2005