Temperature Sensitivity in Individual Components of Ecosystem Respiration Increases along the Vertical Gradient of Leaf-Stem-Soil in Three Subtropical Forests

Temperature sensitivity (Q(10)) of ecosystem respiration (ER) is a crucial parameter for predicting the fate of CO2 in terrestrial e cosystems under global warming. Most studies focus their attention in the variation of Q(10) in one or two components of ER, but not in the integration or comparison among Q(10) in major components of ER. Vertical and seasonal variations in individual components, including leaf respiration, stem respiration and soil respiration, of ER were observed synchronously along the gradient of leaf-stem-soil over a 2 year period in three forest stands dominated by masson pine, loblolly pine and oak, respectively, in a subtropical forest ecosystem of central China. We found that Q(10) in individual components of ER increased along the vertical gradient of leaf-stem-soil. The vertical pattern of Q(10) in individual components of ER was ascribed to variations of diurnal temperature range (DTR) and activation energy (Delta H-a). These results suggest that a vertical pattern of Q(10) in individual components of ER along the gradient of leaf-stem-soil should be taken into consideration in process-based models that simulate respiratory carbon flux in terrestrial ecosystems.