Oral Session # 12: Biogeochemistry I: Carbon Dioxide Cycling.
Presiding: D Markewitz
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 204.

Effects of a pulsing water addition to soil on CO2 efflux.

Kim, Donggil*,1, Mu, Shou Guo1, Lee, Dowon1, Chai, Namyi2, Kim, Joon2, 1 Department of Environmental Planning, Seoul, Seoul, Korea2 Department of Atmospheric Science, Seoul, Seoul, Korea

ABSTRACT- The objectives of this study was to examine how an abrupt increase of soil water by rainfall affects soil respiration. We measured soil respiration and various environmental factors in deciduous, coniferous and mixed forest sites over two years. We also conducted mesocosm experiments to clarify how a pulse of water addition to soil affects CO2 evolution. Based on the field measurements, we derived a regression model to estimate soil respiration with soil temperature. However, observed values of soil respiration were higher just after summer rainfall events (about 15∼30%) than model predictions in the deciduous and mixed forest sites, and an opposite tendency was observed in the coniferous forest sites. A mesocosm experiment showed that increase of soil respiration after rapid increase of soil water content had significant positive correlation with soil temperature in the range of 10 and 20 degrees C. On the other hand, soil respiration decreased with increasing water content at 4 degrees C. Also soil respiration was positively correlated with organic matter content in the range of 10 and 20 degrees C. Our results indicate that the effects of an abrupt increase of soil water on CO2 efflux is dependent on temperature and soil organic matter in fields.

Key words: Soil water content, Soil respiration, Rainfall