Comparison of four EVI-based models for estimating gross primary production of maize and soybean croplands and tallgrass prairie under severe drought

REMOTE SENSING OF ENVIRONMENT

卷:162

Article

Dong, Jinwei^1,2  Xiao, Xiangming^1,2,3  Wagle, Pradeep^1,2  Zhang, Geli^1,2  Zhou, Yuting^1,2  Jin, Cui^1,2  Torn, Margaret S.⁴  Meyers, Tilden P.⁵  Suyker, Andrew E.⁶  Wang, Junbang⁷  Yan, Huimin⁷  Biradar, Chandrashekhar⁸  Moore, Berrien, III⁹ 

[1] Univ Oklahoma, Dept Microbiol & Plant Biol, Norman, OK 73019 USA

[2] Univ Oklahoma, Ctr Spatial Anal, Norman, OK 73019 USA

[3] Fudan Univ, Inst Biodivers Sci, Shanghai 200433, Peoples R China

[4] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Dept Atmospher Sci, Berkeley, CA 94720 USA

[5] NOAA, Atmospher Turbulence & Diffus Div, ARL, Oak Ridge, TN 37831 USA

[6] Univ Nebraska, Sch Nat Resource, Lincoln, NE 68583 USA

[7] Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China

[8] Int Ctr Agr Res Dry Areas, Consultat Grp Int Agr Res, Amman 11195, Jordan

[9] Univ Oklahoma, Coll Atmospher & Geog Sci, Norman, OK 73019 USA

关键词: Gross primary production (GPP);    Drought;    Light use efficiency (LUE);    Vegetation Photosynthesis Model (VPM);    Temperature and Greenness (TG) model;    Greenness and Radiation (GR) model;    Vegetation Index (VI) model;   

DOI  :  10.1016/j.rse.2015.02.022

来源: Elsevier

【 摘 要 】

Accurate estimation of gross primary production (GPP) is critical for understanding ecosystem response to climate variability and change. Satellite-based diagnostic models, which use satellite images and/or climate data as input, are widely used to estimate GPP. Many models used the Normalized Difference Vegetation Index (NDVI) to estimate the fraction of absorbed photosynthetically active radiation (PAR) by vegetation canopy (FPAR(canopy)) and GPP. Recently, the Enhanced Vegetation Index (EVI) has been increasingly used to estimate the fraction of PAR absorbed by chlorophyll (FPAR(chl)) or green leaves (FPAR(green)) and to provide more accurate estimates of GPP in such models as the Vegetation Photosynthesis Model (VPM), Temperature and Greenness (TG) model, Greenness and Radiation (GR) model, and Vegetation Index (VI) model. Although these EVI-based models perform well under non-drought conditions, their performances under severe droughts are unclear. In this study, we run the four EVI-based models at three AmeriFlux sites (rainfed soybean, irrigated maize, and grassland) during drought and non-drought years to examine their sensitivities to drought. As all the four models use EVI for FPAR estimate, our hypothesis is that their different sensitivities to drought are mainly attributed to the ways they handle light use efficiency CLUE), especially water stress. The predicted GPP from these four models had a good agreement with the GPP estimated from eddy flux tower in non-drought years with root mean squared errors (RMSEs) in the order of 2.17 (VPM), 2.47 (VI), 2.85 (GR) and 3.10 g C m(-2) day(-1) (TG). But their performances differed in drought years, the VPM model performed best, followed by the VI, GR and TG, with the RMSEs of 1.61, 232, 3.16 and 3.90 g C m(-2) day-1 respectively. TG and GR models overestimated seasonal sum of GPP by 20% to 61% in rainfed sites in drought years and also overestimated or underestimated GPP in the irrigated site. This difference in model performance under severe drought is attributed to the fact that the VPM uses satellite-based Land Surface Water Index (LSWI) to address the effect of water stress (deficit) on LUE and GPP, while the other three models do not have such a mechanism. This study suggests that it is essential for these models to consider the effect of water stress on GPP, in addition to using EVI to estimate FPAR, if these models are applied to estimate GPP under drought conditions. (C) 2015 Elsevier Inc All rights reserved.

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