Short-term Storm Responses of Soil CO2 Efflux and Hydrologic Organic Carbon Export in a Forested Watershed in the Haean Basin, South Korea

Workineh, et al.

Kangwon National University

     Abstract Number: 753
     Last modified: July 19, 2011

Abstract
Increasing rainfall variability and extremes as a consequence of climate change can affect carbon (C) storage in forest soils by altering rates of soil C losses via soil respiration and hydrologic carbon export. To investigate short-term dynamics and controlling mechanisms of soil C losses during rainfall events, we conducted high-frequency monitoring of soil CO2 efflux and streamwater export of dissolved (DOC) and particulate organic carbon (POC) in a forested watershed in the Haean Basin, South Korea. Highest increments in soil CO2 efflux relative to the rate expected from the temperature-respiration relationship occurred during spring rainfall events following the dry period. As soil moisture increased over the monsoon period, storm responses from the expected carbon flux values became weaker, particularly during small size events. Variations in soil moisture explained 33% of variations in CO2 efflux increases relative to the rate expected from the temperature-respiration relationship. DOC and POC export corresponded to storm intensity. 90% and 66% of the variations in DOC and POC exports during storm events were explained by stream discharge, respectively. The results suggest that while DOC and POC export are strongly regulated by storm-induced changes in discharge, storm responses of soil respiration are determined by complex factors including antecedent hydrologic conditions and the magnitude and intensity of storm events.

Keywords: Climate change, Dissolved organic carbon, Extreme events, Particulate organic carbon, Soil carbon, Soil respiration