Estimation of the gross primary production of an old‐growth temperate mixed forest using eddy covariance and remote sensing
Estimation of the gross primary production of an old‐growth temperate mixed forest using eddy covariance and remote sensing
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DOI：
10.1080/01431160802372143
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发表时间：
2009-01
影响因子：
3.4
通讯作者：
J. B. Wu;Xi Xiao;D. Guan;T. Shi;C. Jin;S. Han
中科院分区：
文献类型：
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作者：
J. B. Wu;Xi Xiao;D. Guan;T. Shi;C. Jin;S. Han
来自CO2通量站点的连续通量数据可用于提高我们对叶物候的理解，并验证基于卫星的碳循环模型的算法。在这项研究中，我们进行了模拟的植被光合作用模型（VPM）使用增强植被指数（EVI）和陆地表面水分指数（LSWI）来自8天的中分辨率成像光谱仪（MODIS）的表面反射率产品，以及站点特定的空气温度，生物温度和光合有效辐射（PAR）数据。2003-2005年，将VPM估算的初级生产力（GPP）与中国东北一个古老的温带混交林通量塔的野外观测结果进行了比较。EVI时间序列与GPP的指数关系（R2 = 0.74，n = 6 7，p<0.0 1）比归一化植被指数（R2 = 0.6 2，n = 6 7，p<0.0 1）强，表明不同时期叶片的光能利用效率不同。与通量塔GPP相比，VPM预测的GPP很好地捕捉了生长季节的开始，并且它们的季节动态在生长高峰期的阶段方面基本一致，而生长季节的结束日期比现场测量的早8-16天。在2003年至2005年的三个观测年中，根据通量塔观测估计的年度森林GPP从1312 g C m−2（每平方米碳的克数）到1490 g C m−2不等，这与基于VPM的年度GPP相差不到10%。这些结果表明，卫星驱动的VPM有可能扩大CO2通量塔站点森林的GPP，这是区域尺度碳预算研究的关键问题。
Continuous flux data from CO2 flux sites can be used to improve our understanding of leaf phenology and validate the algorithms of satellite‐ based carbon cycling models. In this study, we conducted a simulation of the Vegetation Photosynthesis Model (VPM) using the Enhanced Vegetation Index (EVI) and the Land Surface Water Index (LSWI) derived from the 8‐day Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance product, as well as site‐specific air temperature, biological temperature, and photosynthetically active radiation (PAR) data. Gross primary production (GPP) estimates derived from the VPM were compared with field observations of a flux tower in an old temperate mixed forest in northeastern China during 2003–2005. Time series data for the EVI have a stronger exponential relationship with the GPP (R 2 = 0.74, n = 67, p<0.01) than those for the Normalized Difference Vegetation Index (NDVI) (R 2 = 0.62, n = 67, p<0.01), indicating a different light use efficiency during the different stages of foliage development. In comparison to the flux tower GPP, the VPM‐predicted GPP captured the onset of the growing season well, and their seasonal dynamics were generally consistent in terms of phase in the peak growing season, while the end date of the growing season was 8–16 days earlier than that of field measurements. The annual forest GPP estimated from the flux tower observations varied from 1312 g C m−2 (grams of carbon per metre squared) to 1490 g C m−2 in the three observation years from 2003 to 2005, which is less 10% different from the VPM‐based annual GPP. These results demonstrate the potential of the satellite‐driven VPM for scaling up the GPP of forests at the CO2 flux tower site, a key issue for the study of the carbon budget at regional scales.