Transpiration and water use efficiency of tree species and stands in Korean montane forests

TERRECO WP 1-04

Abstract 2011: Tree water use in temperate deciduous forests in South Korea was determined by sap flow methods. Quantifying water use from natural mixed temperate forest is challengeable due to its complexity of diverse tree species and forest structure. And also examining the seasonal forest transpiration along an elevation gradient and investigating the most significant driver of transpiration is difficult, since geology and climate alter with increasing elevation. In this study, we selected five dominant species in Gyebangsan (Mt.) to examine species-specific effects on estimating stand transpiration and obtained two different sap flow methods for overstory and understory trees to investigate contribution of understory to overall stand transpiration in Gwangneung forest. We also selected four study plots at three different levels of elevation in Haean Basin to compare forest transpiration along an elevation gradient. For all study sites, maximum stand transpiration occurred during June when the foliage was maximized. As a result of study on multiple species in mixed deciduous stands, tree water use was strongly correlated with tree diameter at breast height for all measured species. Thus, water use traits of diverse species could be generalized with tree size characteristics. Secondly, understory transpiration contributed about 24 % of the total stand transpiration, implying that the understory layer should be considered on forest stand transpiration studies. And tree water use efficiency of Quercus mongolica increased with increasing elevation because of greater water stress at higher elevation. These studies of forest transpiration with ecological gradients and variations can strengthen modeling and scenario simulations of climate change and its impact on forest water cycle.

Keywords: tree water use, sap flow, allometric scaling, temperate deciduous forest, forest stand transpiration, elevation gradient

project description in detail from proceedings of 2011 TERRECO Science Conference GAP