title: [Time lag characteristics of stem sap flow of common tree species during their growth season in Beijing downtown].
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) 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.
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. huawang_st@rcees.ac.cn
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Zhi-yun
authors.initials: ZY
authors.lastname: Ouyang
authors.forename: Hua
authors.initials: H
authors.lastname: Zheng
authors.forename: Xiao-ke
authors.initials: XK
authors.lastname: Wang
authors.forename: Yong-ming
authors.initials: YM
authors.lastname: Ni
authors.forename: Yu-fen
authors.initials: YF
authors.lastname: Ren
mesh_terms: D002681:China; D002947:Cities; D017753:Ecosystem; D018547:Plant Stems / Q000378:metabolism*; D018526:Plant Transpiration; D014197:Trees / Q000145:classification / Q000254:growth & development* / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water