涡度相关技术及其在陆地生态系统通量研究中的应用

通量观测是定量描述土壤-植被-大气间物质循环和能量交换过程的基础。涡度相关技术作为直接测量植被冠层与大气间能量与物质交换通量的技术手段, 已经逐步发展成为国际通用的通量观测标准方法。随着涡度相关技术在全球碳水循环研究中的广泛应用, 长期连续的通量观测正在为准确评价生态系统碳固持能力、水分和能量平衡状况、生态系统对全球气候变化的反馈作用、区域和全球尺度模型的优化与验证、极端事件对生态系统结构与功能影响等方面的研究提供重要数据支撑和机制理解途径。通过站点尺度通量长期动态观测, 明确了不同气候区和植被类型生态系统碳水通量强度基线及其季节与年际变异特征。通过多站点联网观测, 在区域和全球尺度研究生态系统碳通量空间变异特征, 揭示了区域尺度上温度和降水对生态系统碳通量空间格局的生物地理学控制机制。该文概括地介绍了涡度相关技术的基本原理、假设与系统构成, 总结了涡度通量长期联网观测在陆地生态系统碳水通量研究中的主要应用, 并对通量研究发展前景进行了展望。

Eddy covariance technique and its applications in flux observations of terrestrial ecosystems

Carbon (C) and water cycles are the most critical processes in terrestrial ecosystems, which links the materials and energy flows through the pedosphere-biosphere-atmosphere integration. Most attention has been paid to the responses of C and water and their feedbacks to global climate change. Flux observation is the basic pathway to quantify the rate of material and energy exchange across soil-plant-atmosphere continuum. As an only technique can directly measure the carbon, water and energy fluxes between vegetation and atmosphere, eddy covariance (EC) technique has been considered as a standard method for flux observation internationally. With broad applications of EC technique on global C and water cycles, long-term flux observations provide scientific data on assessing ecosystem C sequestration capability, water and energy balance, and ecosystem feedback to climate change; optimizing and validating models on regional and global scales; and understanding responses of ecosystem functions to extreme events. Based on long-term flux observation in individual site, scientists have described the seasonal and inter-annual dynamics, and quantified the baseline rates of ecosystem carbon and water fluxes across different climate and vegetation types. With the development of regional and global flux networks, researchers further understood the spatial patterns of ecosystem carbon and water fluxes and their climatic control mechanisms at regional and global scales. This paper briefly introduces the basic principles, hypothesis and instrument system composition, summarizes the major applications of EC observation on C and water fluxes in terrestrial ecosystems, and finally discusses future directions of EC observation network.