亚热带针叶林水碳通量的模拟及其与观测的对比研究

CEVSA模型是一个基于生理生态过程模拟植物-土壤-大气系统能量交换和水碳氮耦合循环及其对环境变化响应和适应的机理模型,在区域和全球尺度上得到广泛应用．尽管该模型在大尺度上已经应用大量的植被生产力,碳储量和叶面积测定以及遥感反演数据进行了验证,但还缺乏在冠层和景观尺度上对模型的机理过程(如对光合,呼吸和蒸散过程及其导致的水碳通量变化)模拟的检验．以近年来生态系统机理过程研究的最新进展为基础,对模型进行改进,应用一个亚热带针叶林水碳通量连续观测数据对模型模拟结果进行检验,并分析机理模拟与涡度相关观测得到的水碳通量与环境条件关系的差异．模型模拟的主要水碳通量季节变化特征均与观测值一致．对蒸散和土壤水分的模拟结果与观测值相近,分别解释了观测值90％和86％的变异性,但是模拟值系统偏低．模拟的年总光合碳固定(GPP)和生态系统呼吸(Re)接近于观测值,并且能够分别解释其观测值79％和88％的变异性．尽管净生态系统生产力(NEP)的模拟值(394 gC／m2)也与观测值(387．15 gC／m2)接近,但是它仅能解释观测值31％的变异性．与观测值相比,模拟的NEP在冬季偏低而在夏季偏高．通过与温度、水汽压差的相关分析表明,在严重的高温和缺水胁迫条件下,模型没有准确模拟生态系统光合和呼吸过程．结果证明CEVSA模型对水碳循环的模拟与植被冠层尺度水碳通量测定结果一致,但仍然需要对极端温度和水分胁迫效应的模拟作进一步的ChinaFLUX．

Construction and progress of Chinese terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation

Eddy Covariance technique(EC) achieves the direct measurement on ecosystem carbon, nitrogen and water fluxes, and it provides scientific data for accurately assessing ecosystem functions in mitigating global climate change. This paper briefly reviewed the construction and development of Chinese terrestrial ecosystem flux observation and research network(China FLUX), and systematically introduced the design principle and technology of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation system of China FLUX. In addition, this paper summarized the main progress of China FLUX in the ecosystem carbon, nitrogen and water exchange and environmental controlling mechanisms, the spatial pattern of carbon, nitrogen and water fluxes and biogeographical mechanisms, and the regional terrestrial ecosystem carbon budget assessment. Finally, the prospects and emphases of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation of China FLUX are put forward to provide theoretical references for the development of flux observation and research in China.