PARENT SESSION
Contributed Oral Session 148: Biogeochemistry: Nutrient Dynamics
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 511 B, Level 5, Palais des congrès de Montréal
Effects of land use and climate on carbon dynamics in Southeastern US.
Chen, Hua *,1, Tian, Hanqin 1, Liu, Mingliang 1, Zhang, Chi1, Pan, Shufen1, Melillo, Jerry2, 1 School of Forestry and Wildlife Sciences, Auburn, AL, USA2 The Ecosystems Center, Woods Hole, MA, USA
ABSTRACT- Southeast is thought to be the largest carbon sink across the six major bioclimatic regions of the conterminous United States. Land use and cover change (LUCC) and climate dynamics are the two potentially most important factors to be responsible for this carbon sink. The objectives of this study is to examine how cropland abandonment, forest harvest, forest regrowth and climate affect terrestrial carbon storage in southeastern US. We have compiled and developed the historical annual cropland gridded data set of southeastern US between 1850 and 2002 with a spatial resolution of 8 km. Meanwhile, we have compiled the average monthly temperature, precipitation, radiation gridded data set with the same spatial resolution. These data sets have been used as input of the Terrestrial Ecosystem Model (TEM) to simulate the effects of LUCC and climate on carbon fluxes and storage in the region. According to the preliminary analysis, our results indicate that cropland area decreased more than 50% and forest land area increased more than 50% from 1850 to 2002 in the region. Forest regrowth after cropland abandonment has resulted in a carbon uptake. The forest harvest and regrowth cycles within managed forests in the region are estimated using statistical models and a bookkeeping model. Carbon has accumulated in wood products and logging debris. Effects of fire disturbance on carbon storage in this region have been estimated. The climate shows much milder effects on carbon fluxes and storage than land use change in this region. The southeastern region of US became a net carbon sink since 1940, although the magnitude of the carbon sink varies over space and time.
Key words: cropland abandonment, forest harvest, fire disturbance, TEM