摘要
The available methods for studying C uptake of forest and their problems in practices are reviewed, and a new approach to combining sap flow and 13C techniques is proposed in this paper. This approach, obtained through strict mathematic derivation, combines sap flow measure-ment-based canopy stomatal conductance and 13C discrimi-nation to estimate instantaneous carbon assimilation rate of a forest. Namely the mean canopy stomatal conductance (gc) acquired from accurate measurement of sap flux density is integrated with the relationship between 13C discrimination (?) and Ci/Ca (intercellular/ambient CO2 concentrations) and with that between Anet (net photosynthetic rate) and gCO2 (stomatal conductance for CO2) so that a new relation be-tween forest C uptake and ? as well as gc is established. It is a new method of such kind for studying the C exchange be-tween forest and atmosphere based on experimental ecology.
The available methods for studying C uptake of forest and their problems in practices are reviewed, and a new approach to combining sap flow and ^13C techniques is proposed in this paper. This approach, obtained through strict mathematic derivation, combines sap flow measurement-based canopy stomatal conductance and ^13C discrimination to estimate instantaneous carbon assimilation rate of a forest. Namely the mean canopy stomatal conductance （gc） acquired from accurate measurement of sap flux density is integrated with the relationship between ^13C discrimination （A） and G/Ca （intercellular/ambient CO2 concentrations） and with that between Anet （net photosynthetic rate） and gco2 （stomatal conductance for CO2） so that a new relation between forest C uptake and A as well as gc is established. It is a new method of such kind for studying the C exchange between forest and atmosphere based on experimental ecology.
基金
supported by the National Natural Science Foundation of China(Grant Nos.30428022&30270239)
the Natural Science Foundation of Guangdong Province(Grant No.031265)
the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KSCX2-SW-133&KZCX-SW-01-01B-05)
the Knowl-edge Innovation Foundation of South China Institute of Botany(Grant No.20022110)
Wang Kuan Cheng Education Foundation.
关键词
碳同位素
稳定性
碳同化
热量消散探测
电导系数
sap flow, stable carbon isotope, C assimilation, Granier＇s thermal dissipation probe, mean canopy stomatal conductance.
