HR: 0800h
AN: B31B-05    [Abstracts]
TI: Soil Organic Carbon and Soil Nitrogen in Chinese Soils: Textural, Climatic, and Ecological Influences
AU: * Gregg, J S
EM: gregg.jay@gmail.com
AF: Department of Geography, University of Maryland, 2181 Lefrak Hall, College Park, MD 20781, United States
AU: Wang, S
EM: sqwang@igsnrr.ac.cn
AF: Institute for Geographical Studies and Natural Resources Research (IGSNRR), 11A, Datun Road, Anwai, Beijing, 100101, China
AB: The largest terrestrial carbon pool is in the soil, 1.5 to 2.5 times that of vegetation, yet this is also the area with the most uncertainty. Limited understanding of the dynamics and spatial distribution of soil organic carbon (SOC) and soil nitrogen (SN) leads to uncertainty in the global carbon and nitrogen cycles. Regionally, SOC and SN values can be summed across sample profiles to obtain a mean estimate of SOC or SN storage. However, this approach does not effectively account for the spatial variability of SOC and SN within a region, especially when the sampling density of a region is sparse, such as in some areas of western China. This remains one of the main challenges to using regional sums to calculate the total terrestrial carbon flux. This study explores an alternative technique, estimating SOC and SN from easily obtained proxy data. Data are analyzed from the extensive Chinese national soil survey, conducted between 1979 and 1992, containing records on SOC and SN content, soil texture (sand, silt and clay composition percentages), and land cover and land use classifications for over 5000 locations throughout China. These are combined with climate variables (including mean monthly temperature and mean monthly precipitation) to estimate evapotranspiration and plant available water. This is done to determine the relationships of climatic, ecological, land use, and land cover variables to SOC and SN storage. With these relationships, estimates can be produced for SOC and SN storage from larger-scale proxy data, as well as from the effect of land cover and land use changes.
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1632 Land cover change
DE: 1818 Evapotranspiration
DE: 1865 Soils (0486)
DE: 4806 Carbon cycling (0428)
SC: Biogeosciences [B]
MN: 2007 Joint Assembly