Contrasting Performance of the Remotely-Derived GPP Products over Different Climate Zones across China

Yanan Chen,Qing Gu,Hongfan Gu,Xuguang Tang,Rongyuan Liu,Mingguo Ma,Munan Wang,Zhi Ding

doi:10.3390/rs11161855

Abstract

Precise quantification of terrestrial gross primary production (GPP) has been recognized as one of the most important components in understanding the carbon balance between the biosphere and the atmosphere. In recent years, although many large-scale GPP estimates from satellite data and ecosystem models have been generated, few attempts have been made to compare the different GPP products at national scales, particularly for various climate zones. In this study, two of the most widely-used GPP datasets were systematically compared over the eight climate zones across China’s terrestrial ecosystems from 2001 to 2015, which included the moderate resolution imaging spectroradiometer (MODIS) GPP and the breathing Earth system simulator (BESS) GPP products. Additionally, the coarse (0.05o) GPP estimates from the vegetation photosynthesis model (VPM) at the same time scale were used for auxiliary analysis with the two products. Both MODIS and BESS products exhibited a decreasing trend from the southeast region to the northwest inland. The largest GPP was found in the tropical humid region with 5.49 g C m−2 d−1 and 5.07 g C m−2 d−1 for MODIS and BESS, respectively, while the lowest GPP was distributed in the warm temperate arid region, midtemperate semiarid region and plateau zone. Meanwhile, the work confirmed that all these GPP products showed apparent seasonality with the peaks in the summertime. However, large differences were found in the interannual variations across the three GPP products over different climate regions. Generally, the BESS GPP agreed better than the MODIS GPP when compared to the seasonal and interannual variations of VPM GPP. Furthermore, the spatial correlation analysis between terrestrial GPP and the climatic factors, including temperature and precipitation, indicated that natural rainfall dominated the variability in GPP of Northern China, such as the midtemperate semiarid region, while temperature was a key controlling factor in the Southern China and the Tibet Plateau area.

Highlights

Gross primary production (GPP) refers to the total amount of organic carbon fixed by terrestrial ecosystems through photosynthesis by green plants [1]
The study implied that both moderate resolution imaging spectroradiometer (MODIS) and breathing Earth system simulator (BESS) GPP products had a gRreemaotenSuenms.b2e01r9o, f11m, xisFsOinRgPEvEaRluReEsViInEWthe arid and semiarid Northwest China including the midtemp7eorfat1e8 semiarid region (III), the warm temperate arid region (IV), and the plateau zone (VI), which meant that these approaches reduced the ability to estimate GPP in these areas
There are significant differences in the performance of different remotely-derived GPP products. Both MODIS and BESS GPP showed an increasing trend from northwest to southeast, which is closely related to the spatial distribution of vegetation cover across China

Summary

Introduction

Gross primary production (GPP) refers to the total amount of organic carbon fixed by terrestrial ecosystems through photosynthesis by green plants [1]. It directly reflects the productivity of vegetation under specific environmental conditions and characterizes the growth characteristics and health status of terrestrial ecosystems [2]. As it is the largest and most important component of global carbon cycles, accurately evaluating the spatiotemporal dynamics of terrestrial GPP has significant implications for rational use of land resources, increase of carbon sinks, and adaptive strategy to climate change [3,4,5,6]. Different products have large biases in performance due to the structures of models and the uncertainties in various input parameters

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Methods

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Discussion

Conclusion