Sap-flow measurement and scale transferring from sample trees to entire forest stand of Populus euphratica in desert riparian forest in extreme arid region

作     者：JianHua Si 1, Qi Feng 1, HaiYang Xi 1, ZongQiang Chang 1, YongHong Su 1, Kai Zhang 1,2 1. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China. 2. Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China. 

作者机构：Chinese Acad Sci Cold & Arid Reg Environm & Engn Res Inst 320 Donggang West Rd Lanzhou 730000 Gansu Peoples R China China Meteorol Adm Inst Arid Meteorol Lanzhou 730020 Gansu Peoples R China 

出 版 物：《Research in Cold and Arid Regions》 (寒旱区科学（英文版）)

年 卷 期：2009年第1卷第3期

页      面：258-266页

学科分类：0907[农学-林学] 08[工学] 0829[工学-林业工程] 09[农学] 0705[理学-地理学] 

基　　金：supported by the National Natural Science Foundation of China (40725001 40501012) drought mete-orological scientific research fund projects (IAM200707) the Knowledge Innovation Program from the Chinese Academy of Sciences (KZCX2-XB2-04) 

主　　题：sap flow heat-pulse technique sapwood area scale transferring extreme arid region Populus euphratica 

摘      要：Understanding how the transpiration of this vegetation type responds to environmental stress is important for determining the wa-ter-balance dynamics of the riparian ecosystem threatened by groundwater depletion. Transpiration and sap flow were measured using the heat-pulse technique. The results were then projected up to the stand level to investigate the stand’s water-use in relation to climate forcing in the desert riparian forest in an extreme arid region. This study took place from April through October 2003 and from May through October 2004. The experimental site was selected in the Populus euphratica Forest Reserve (101o10 E, 41o59 N) in Ejina county, in the lower Heihe River basin, China. The sapwood area was used as a scalar to extrapolate the stand-water consumption from the whole trees’ water consumption measured by the heat-pulse velocity recorder (HPVR). Scale transferring from a series of individual trees to a stand was done according to the existing natural variations between trees under given environmental conditions. The application of the biometric parameters available from individual tree and stand levels was proved suitable for this purpose. A significant correlation between the sapwood area and tree diameter at breast height (DBH) was found. The prediction model is well fitted by the power model. On the basis of the prediction model, the sapwood area can be cal-culated by DBH. The sap-flow density can then be used to extrapolate the stand-water use by means of a series of mathematical models.