Disentangling seasonal vegetation effects on ecosystem evapotranspiration and water use efficiency of Mediterranean savannah-type oak forest

点击翻译按钮获取中文摘要

Water represents one of the key factors driving ecosystem productivity due to the tight coupling between ecosystem water and carbon fluxes. A functional understanding of evapotranspiration and photosynthesis is required to understand the development of water and carbon fluxes, particularly in water-limited ecosystems where global climate change is expected to intensify drought and alter precipitation patterns. The aim of this project is a detailed mechanistic evaluation of the water balance and water use efficiency of a typical Mediterranean savannahtype oak woodland. The project will focus on seasonal dynamics of over- and understorey vegetation of this two-component system and on the vegetation feedbacks on water and carbon fluxes. The study will combine (1) ecosystem and understorey measurements of net CO2 and H2O fluxes with (2) an experimental approach (trenching plot design) to disentangle major vegetation effects on water and carbon processes, and (3) a modelling approach to integrate the information gained from the different scales. Partitioning of net water fluxes into their individual components will be achieved by the use of stable isotopes. This project will deliver a process-based understanding of ecosystem water cycling and water use efficiency with a particular focus on the contribution of the understorey, which will be evaluated under consideration of future climate trends. Such improved understanding will help to develop appropriate management strategies and is needed for a risk assessment of climate change impact on Mediterranean ecosystems.