凤阳山针阔混交林通量观测源区分布及特征

基于涡度相关技术的通量观测要求下垫面均匀一致，然而在实际观测中，地形往往非常复杂。尤其是丘陵山区森林植被覆盖的区域，不同植被类型的空间分布对该区域的碳通量观测影响很大。本研究利用Kljun模型和ART Footprint Tool，对浙江凤阳山针阔混交林森林生态系统2017年全年的观测数据进行分析，探究该区域涡度相关系统在不同季节、不同大气稳定度条件下的通量源区变化情况。结果表明：受地形的影响，研究区内全年盛行东北风（0-90°）和西南风（180-270°）；因此，通量的源区分布也主要在东北和西南方向；当通量贡献率达到90%时，源区长度最大不超过7000m，当通量贡献率在80%时，源区长度不超过3000m；在大气稳定条件下，其源区分布范围总是比大气不稳定条件下的源区范围广。在该源区分布范围内，主要以针阔混交林分为主，也分布有少量杉木、柳杉和毛竹等纯林，源区贡献从大到小依次为针阔混交林、阔叶林、杉木林、毛竹林、柳杉林、黄山松林。

Distribution and characteristics of flux footprint of coniferous and broad-leaved mixed forest ecosystem in Fengyang Mountain of Zhejiang, China

The flux observation based on eddy covariance requires uniform underlying surface. However, in the actual observation, the terrain is often very complex. Especially in the area covered by forest vegetation, the spatial distribution of different vegetation types has a great influence on carbon flux observation. In this study, Kljun model and Art Footprint Tool were used to analyze the observation data of coniferous and broad-leaved mixed forest ecosystem in Fengyang Mountain, Zhejiang province in 2017. We aim to explore the flux source area changes of the vorticity related system in the region under different seasons and atmospheric stability conditions. The results showed that the northeast wind (0-90°) and the southwest wind (180-270°) prevailed in the study area through 2017 due to the influence of terrain; therefore, the source area distribution of flux was mainly in the northeast and southwest directions. When the flux contribution rate reached 90%, the length of the flux footprint was less than 7000 m. When the flux contribution rate was 80%, the source area length was less than 3000 m. The source areas were larger, when atmosphere stability conditions were more stable. In the distribution range of the source area, there are mainly coniferous and broad-leaved mixed forest, but also a small number of monoculture forests such as Cunninghamia lanceolata, Cryptomeria fortunei and Phyllostachys pubescens. The contribution of the source area from the largest to the smallest is coniferous and broad-leaved mixed forest, broad-leaved forest, Cunninghamia lanceolata, Phyllostachys pubescens, Cryptomeria fortunei, Pine forest.