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期 刊 ：应用生态学报 2009年 20卷 09期 页码：2111-2117

关键词：城市树种；热消散探针法；树干液流；时滞；

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

摘 要 ：

2008年4—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之间最大相关系数(0.74～0.93)通常比J_s与D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(10～70 min)比J_s与D之间时滞范围(47～130 min)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.

Abstract:

From April to September in 2008, the stem sap flow velocity (Js) of se
veral common tree species (Ginkgo biloba, Aesculus chinensis, Magnolia denudata,
 Robinia pseudoacacia, Pinus tabulaeformis and Cedrus deodara) in Beijing was m
easured by thermal dissipation method. Cross-correlation analysis was used to e
stimate the time lag between the stem sap flow and the driving factors of canopy
 transpiration among the tree species. The Js of the six tree species was
significantly correlated with the total radiation (Rs) and vapor pressure
deficit (D), and the Js was lagged behind Rs but ahead of D.
 The maximum correlation coefficient of Js with Rs (074〖KG-*2〗-
〖KG-*7〗093) was often higher than that of Js with D (057〖KG-*2
〗-〖KG-*7〗079), indicating that the diurnal Js was more dependent on
Rs than on D. The sampled tree species except P. tabulaeformis had a
shorter time lag of Js with Rs (10〖KG-*2〗-〖KG-*7〗70 min)
than with D (47〖KG-*2〗-〖KG-*7〗130 min), and there existed significant di
fferences among R. pseudoacacia, P. tabulaeformis, and C. deodara. The t
ime lag between the Js and the driving factors of canopy transpiration was
 mainly correlated with the tree features (DBH, tree height, canopy area, and sa
pwood area) and the nocturnal water recharge, regardless of tree species.

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