第七届青年地学论坛

Abstract：Both light use efficiency (LUE) and water use efficiency (WUE) play essential roles in ecosystem production. How strongly LUE and WUE are coupled to drive the variation of resource use efficiency remain unclear. In this study, we analyzed the relationship between LUE and WUE to indicate carbon-water coupling characteristic using data from flux measurements and weather stations in the Heihe River Basin, China, where flux stations and weather stations were installed along a climatic gradient. The R² of relationship between LUE and WUE achieved 85%, and the contribution of LUE to WUE increased with higher water stress. The Pearson r between LUE and WUE significantly increased from -0.12 to 0.63 with decreasing LUE. The WUE increased with higher water stress, resulting from increasing contribution of LUE to WUE. The contribution of LUE to GPP increased as water stress increase, which would improve WUE through steeper increase of GPP. This variation of WUE drove reverse increase of GPP and decrease of actual evapotranspiration with higher water stress. The study suggested ecosystem would enhance coupling between light and water resource utilization with higher water stress. Our result help to understand the resilience of ecosystems responding to changing conditions.
 

light use efficiency,water use efficiency,carbon-water coupling,gross primary productivity,evapotranspiration,dryland