王华1" 欧阳志云1 郑华1 王效科1 倪永明2 任玉芬1"

（1 中国科学院生态环境研究中心城市与区域生态国家重点实验室，北京； 2北京自然博物馆，北京）

摘要：2009年4月-9月，应用热消散技术测定了北京市常见树种银杏、七叶树、玉兰、刺槐、油松、雪松的树干液流，并将液流与总辐射和水汽压亏缺数据进行逐行错位分析，探讨不同树种树干液流与蒸腾驱动因子之间的时滞效应。结果表明：6个树种树干液流（J_S）的变化与总辐射(R_S)和水汽压亏缺(D)显著相关，且J_S均滞后于R_S，提前于D；J_S与R_S之间最大相关系(0.74-0.93)通常比J_S 与R_S之间最大相关系数（0.57-0.79）高，表明日尺度上J_S在很大程度上依赖于R_S的变化。除油松外，其他树种J_S与R_S之间时滞范围（10-70min）比 J_S与D之间时滞范围（47-130min0短，其中刺槐、油松和雪松种间差异显著；城市树种J_S与蒸腾驱动因子之间的时滞主要受树形（胸径、树高、冠层投影面积、边材面积）以及夜间水分补充量的影响，而与树种无关

关键词:城市树种,热消散探针法,树干液流,时滞

应用生态学报 2009, 20(9) 2111-2117 

Time lag characteristics of stem sap flow of common tree species during their growth season in Beijingdowntown.WANG Hua¹;OUYANG Zhi-yun¹;ZHENG Hua¹;WANG Xiao-ke¹;NI Yong-ming²;REN Yu-fen¹

(1 State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China,|2 Beijing Museum of Natural History, Beijing 100050, China)

Abstract: From April to September in 2008, the stem sap flow velocity (Js) of several common tree species (Ginkgo biloba, Aesculus chinensis, Magnolia denudata, Robinia pseudoacacia, Pinus tabulaeformis and Cedrus deodara) inBeijingwas measured by thermal dissipation method. Cross-correlation analysis was used to estimate the time lag between the stem sap flow and the driving factors of canopy transpiration among the tree species. The Js of the six tree species was significantly correlated with the total radiation (Rs) and vapor pressure deficit (D), and the Js was lagged behind Rs but ahead of D。 The maximum correlation coefficient of  Js with Rs (0.74-0.93) was often higher than that of Js with D (0.57-0.79), indicating that the diurnal Js was more dependent on Rs than on D. The sampled tree species except P. tabulaeformis had a shorter time lag of Js with Rs (10-70 min) than with D (47-130 min), and there existed significant differences among R. pseudoacacia, P. tabulaeformis, and C. deodara. The time lag between the Js and the driving factors of canopy transpiration was mainly correlated with the tree features (DBH, tree height, canopy area, and sapwood area) and the nocturnal water recharge, regardless of tree species.

Keywords: urban tree species   thermal dissipation method   stem sap flow   time lag