Ecohydrology of a semi‐arid forest: partitioning among water balance components and its implications for predicted precipitation changes

作者：N. Raz Yaseef, Dan Yakir, Eyal Rotenberg, G. Schiller, S. Cohen · 发表于：Ecohydrology · 年份：2009 · DOI：10.1002/eco.65 · 被引用次数：205 · 研究领域：Plant Water Relations and Carbon Dynamics、Tree-ring climate responses、Hydrology and Watershed Management Studies

Abstract The distribution of precipitation inputs into different hydrological components of water‐limited forest ecosystems determines water availability to trees and consequently forest productivity. We constructed a complete hydrological budget of a semi‐arid pine forest (285 mm annual precipitation) by directly measuring its main components: precipitation (P), soil water content, evapotranspiration (ET, eddy covariance), tree transpiration (sap flux), soil evaporation (soil chambers), and intercepted precipitation (calculated). Our results indicated that on average for the 4‐year study period,ETaccounted for 94% ofP, varying between 100% whenP< 250 mm and 85% whenP> 300 mm (with indications for losses to subsurface flow and soil moisture storage in wetter years). Direct measurements of the components of theETflux demonstrated that both transpiration and soil evaporation were significant in this dry forest (45% and 36% ofET, respectively). Comparison between ecosystemET(eddy covariance measurements) and the sum of its measured components showed good agreement on annual scales, but up to 30% discrepancies (in both directions) on shorter timescales. The pulsed storm pattern, characteristics of semi‐arid climates, was sufficient to maintain the topsoil layer wet during the whole wet season. Only less often and intensive storms resulted in infiltration to the root zone, increasing water availability for uptake by deeper roots. Our results indicate that climate change prediction...