Use of a vegetation index model to estimate gross primary production in open grassland
Use of a vegetation index model to estimate gross primary production in open grassland
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DOI：
10.1117/1.jrs.6.063532
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发表时间：
2012
影响因子：
1.7
通讯作者：
Chaoyang Wu
中科院分区：
文献类型：
--
作者：
Chaoyang Wu
卫星遥感观测为区域和全球监测陆地生态系统提供了重要工具。本文利用通量测量和250m中分辨率成像光谱仪(MODIS)图像对最近开发的植被指数(VI)模型进行了评估，该模型估计了开阔草原的总初级生产力(GPP)。测定了两个植被指数，即两波段增强植被指数(EVI2)和归一化植被指数(NDVI)，作为光合作用有效辐射吸收分数(F APAR)和光能利用率(LUE)的指标。标准的MODIS GPP产物与通量测量的GPP具有中等的相关性，决定系数(R2)为0.5 6，均方根误差(RMSE)为15.4g Cm−2 8d−1。结果表明，VI模型能较好地估算GPP，对EVI2×EVI2×光合作用有效辐射(PAR)、NDVI×EVI2×PAR和NDVI×NDVI×PAR的R2分别为0.80、0.82和0.81。潜在的原因是EVI2和NDVI都是fAPAR(R2分别为0.43和0.53)和LUE(R2分别为0.52和0.46)的潜在代用品。初步分析将有助于未来GPP模式的空间改进。
Observations from satellite remote sensing provide important tools for regional and global monitoring of terrestrial ecosystems. This article evaluated a recently developed vegetation index (VI) model that estimates gross primary production (GPP) in an open grassland using flux measurements and 250-m moderate-resolution imaging spectroradiometer (MODIS) images. Two VIs, the two-band enhanced vegetation index (EVI2) and the normalized difference vegetation index (NDVI), were tested as indicators of both fraction of absorbed photosynthetic active radiation ( f APAR ) and light use efficiency (LUE). The standard MODIS GPP product was moderately correlated with flux-measured GPP as indicated by the coefficients of determination ( R 2 ) of 0.56 and a root mean square error (RMSE) of 15.4 g C m − 2 8 d − 1 . In comparison, results suggested that the VI model can provide improved estimates of GPP, with R 2 of 0.80, 0.82, and 0.81 for EVI 2 × EVI 2 × photosynthetically active radiation (PAR), NDVI × EVI 2 × PAR , and NDVI × NDVI × PAR , respectively. The underlying reason was that both EVI2 and NDVI were potential proxies of f APAR ( R 2 of 0.43 and 0.53, respectively) and LUE ( R 2 of 0.52 and 0.46, respectively). The primary analysis will be helpful for spatial improvements of future GPP models.