Wang Hua, Ouyang Zhi-yun, Zheng Hua, Wang Xiao-ke, Ni Yong-ming, Ren Yu-fen
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Ying Yong Sheng Tai Xue Bao. 2009 Sep;20(9):2111-7.
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) in Beijing was measured by thermal dissipation method. Crosscorrelation 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.
2008年4月至9月，采用热扩散法测定了北京几种常见树种（银杏、七叶树、白玉兰、刺槐、油松和雪松）的树干液流速度（Js）。运用互相关分析估算了树种间树干液流与冠层蒸腾驱动因子之间的时间滞后。六种树种的Js与总辐射（Rs）和水汽压差（D）显著相关，且Js滞后于Rs但超前于D。Js与Rs的最大相关系数（0.74 - 0.93）通常高于Js与D的最大相关系数（0.57 - 0.79），表明日间Js对Rs的依赖性大于对D的依赖性。除油松外，采样树种的Js与Rs的时间滞后（10 - 70分钟）比与D的时间滞后（47 - 130分钟）短，刺槐、油松和雪松之间存在显著差异。无论树种如何，Js与冠层蒸腾驱动因子之间的时间滞后主要与树木特征（胸径、树高、冠层面积和边材面积）以及夜间水分补给相关。
