The effects of an induced short-term drought period on the spatial variations in soil respiration measured around emergent trees in a typical bornean tropical forest, Malaysia

Our previous studies documented how soil CO2 efflux, one of the main carbon pathways in forest ecosystems, is affected by soil moisture and forest structure in an aseasonal tropical rainforest in Borneo, Malaysia. In this study, we clarify the effect of short-term drought treatment on the spatial variation of soil CO2 efflux in a forest, and to interpret the changes in soil CO2 efflux caused by root activities. Experimental plots (15 m radius) were established around six emergent trees and a drought treatment was conducted for three of the six plots. Soil CO2 efflux was measured along with environmental factors and root biomass, respiration and production in each plot. Soil CO2 efflux at 0.5 m of the emergent trees was nearly three times higher than at 5 and 10 m away from the trees. Root respiration and biomass had no correlation with the spatial variation. Soil water content decreased by nearly 30 % during the drought treatment, although soil CO2 efflux was unchanged between drought and control plots. Our result suggests a strong spatial variation exists in soil CO2 efflux around emergent trees, but short-term severe drought has little effect on it.