Forest Evapotranspiration: Processes and Quantification
Next to precipitation, evapotranspiration (ET) is the second largest flux in forest hydrological cycles. Forest ET rates are generally higher than other vegetated ecosystems under the same climatic conditions. ET serves as the nexus of the carbon, water and energy balances in forests. Understanding ET dynamics is critical for quantifying forest–water relationships and ecosystem services (e.g. carbon sequestration, climate and streamflow flow moderation, biodiversity) at multiple scales. This chapter describes the basic ET processes, which include forest canopy and litter interception, tree transpiration and soil evaporation. Finally, practical methods for measuring and modeling ET at tree, watershed and regional levels are presented to show the challenges in accurately quantifying ET under a changing environment.
