【摘要】 以长白山阔叶红松林为研究对象,利用Raupach提出的局地近场理论(localizednearfield,LNF)耦合垂直风速标准差σw(z)和拉格朗日时间尺度TL(z),建立林冠内CO2源汇强度和平均浓度廓线之间的关系.结果表明,拉格朗日模型能准确、稳定地模拟林冠与大气之间CO2的交换特征.模拟值比涡动相关系统实测值高出约15%,与实测值的相关性为89%,这种差异可能主要来自于输入的浓度廓线的波动以及大气稳定层结造成的涡动相关观测系统误差.在近地面层,由于土壤呼吸作用,整个时间段都为CO2源.林冠层的CO2源汇强度变化较为复杂,其日变化经历了源-汇-源的转变过程.林冠与大气间CO2通量交换明显受大气稳定度影响.更多还原

【Abstract】 Estimating the scalar source/sink distribution of CO₂ and its vertical fluxes within and above forest canopy continues to be a critical research problem in biosphere-atmosphere exchange processes and plant ecology. With broadleaved Korean pine forest in Changbai Mountains as test object, and based on Raupach’s localized near field theory, the source/sink and vertical flux distribution of CO₂ within and above forest canopy were modeled through an inverse Lagrangian dispersion analysis. This model correctly predicted a strong positive CO₂ source strength in the deeper layers of the canopy due to soil-plant respiration, and a strong CO₂ sink in the upper layers of the canopy due to the assimilation by sunlit foliage. The foliage in the top layer of canopy changed from a CO₂ source in the morning to a CO₂ sink in the afternoon, while the soil constituted a strong CO₂ source all the day. The simulation results accorded well with the eddy covariance CO₂ flux measurements within and above the canopy, and the average precision was 89%. The CO₂ exchange predicted by the analysis was averagely 15% higher than that of the eddy correlation, but exhibited identical temporal trend. Atmospheric stability remarkably affected the CO₂ exchange between forest canopy and atmosphere.更多还原