HR: 08:15h
AN: GC11B-02    [Abstracts]
TI: CH4 AND CO2 FLUXES FROM THE ARCTIC TUNDRA DURING THE BIOCOMPLEXITY MANIPULATION EXPERIMENT
AU: * Zona, D
EM: dzona@sciences.sdsu.edu
AF: Global Change research Group, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, United States
AU: Walter, O C
EM: oechel@sunstroke.sdsu.edu
AF: Global Change research Group, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, United States
AU: Kochendorfer, J
EM: jkoch@ucdavis.edu
AF: University of California, Davis Atmospheric Science Section, 139 Hoagland Hall, Davis, CA 95616, United States
AU: Salyuk, A
EM: san@poi.dvo.ru
AF: Laboratory Arctic Research,V.I.Il'ichev Pacific Oceanological Institute, 43 Baltiyskaya St., Vladivostok, 690041, Russian Federation
AU: Hastings, S
EM: shastings@sunstroke.sdsu.
AF: Global Change research Group, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, United States
AU: Paw U, K
AF: University of California, Davis Atmospheric Science Section, 139 Hoagland Hall, Davis, CA 95616, United States
AU: Harazono, Y
EM: yoshi44ybb@yahoo.co.jp
AF: IARC, UAF, 930 Koyukuk Drive, Fairbanks, AK 99775, United States
AB: Previous research involving long-term, replicated chamber studies have demonstrated strong linkages between the tundra carbon cycle and thermal and soil hydrologic processes at local (centimeter to meter) scales and individual land cover units. Soil water content is particularly important in that it can potentially affect all of these variables. Alteration of local hydrology will, therefore, have a profound and complex effect on soil respiration, methanogenesis and the associated rates of decomposition and mineralization and consequently on carbon fluxes. Methane is an effective greenhouse gas that has a warming potential about 23 times that of CO2. The wetland regions of the world (especially the ones located in the boreal and low Arctic) were major accumulation sites of organic materials under anaerobic conditions and could be a significant source of global CH4 and CO2. Wet sedge ecosystems appeared to be the dominant Arctic and subarctic sources of methane. It is important to note, however, that the large majority of these measurements were performed with the use of flux chambers. While chambers have the advantage of effectively characterizing different vegetation and micro-topographic sites, they have the disadvantage of being discrete (non-continuous) measurements in time and space. In addition to this the installation of chambers in the soils disrupts the integrity of the surface and could significantly impact the gas fluxes. This research presents the results of a three years large scale manipulation performed to investigate the response of the arctic tundra carbon balance to wetting and drying at various levels of biological organization (microbial to landscape ecology) and over multiple spatial and temporal scales over an area of approximately 50 hectares of coastal tundra. The manipulation experiment was conducted in the BEO (Biological Experimental Observatory), in Barrow, Alaska, in a drained lake basin that was dived in three parts by the placement of dikes separating three areas in which water was pumped to create three different water table heights. During the baseline years (2005 and 2006) before the placement of the dikes the three areas showed similar fluxes and the ecosystem was a source of CH4 of around 2 mg m-2 hr-1. The use of micrometeorological instead of chamber measurements allowed investigating the effects of flooding and drying on CH4 fluxes over large areas without disturbances on soil and vegetation. Our results indicate that the process of methane release is more complicated than expected and that sites with considerably different water table depths were very similar sources of CH4 fluxes of about 2 mg m-2 hr-1. Within the natural ranges observed, and the manipulations performed, areas with different water table depths were characterized by very similar fluxes. This raises the possibility that the response of net methane emission is more complicated than previously thought and raises uncertainties concerning the estimation of the methane release in response to drying or wetting of the Arctic and makes less clear the actual impact of Climate Change on methane and carbon dioxide fluxes of the Arctic tundra.
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
DE: 1630 Impacts of global change (1225)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting