Measurement of response of leaf litter respiration to rainfall using the automatic chamber system

Soil respiration is sum of CO2 efflux from various components (e.g. root for autotrophic respiration; leaf and root litter, and SOM for heterotrophic respiration). Each respiration process has specific characteristics responding to environmental conditions (e.g. water condition, temperature). Especially, heterotrophic respiration is highly affected by wetting and drying event during and after rainfall event. The greatest temporal variability in water condition may occur in or near the leaf litter layer, and this will affect the variation in leaf litter respiration (RLL) and therefore soil respiration. We measured RLL using automated chamber system to examine response of RLL to wetting and drying event due to rainfall and compared with the response of soil respiration. Observations were performed at Kiryu Experimental Watershed (KEW) located in central Japan from March to December 2011. To examine temporal changes in RLL, we used automated dynamic chamber system. We used four chambers to respectively measure RLL, soil respiration and CO2 efflux from mineral soil. For leaf litter and mineral soil chamber, we replaced organic soil inside chamber with weathered granite soil of an equal depth, and the acrylic board was buried just below the base of chamber to prevent from other CO2 efflux sources (e.g. root and soil organic matter). During non-rainy day, RLL showed a diurnal pattern, which is corresponding to the diurnal changes in temperature. RLL was beginning to increase within a few hours from starting time of rainfall and showed peak values during rainfall. The rate of increase and decrease of RLL during rainfall were higher than that of soil respiration. The responses of each component of soil respiration to rainfall would be different.