Abstract
The upper Luanhe River Basin is a significant ecological barrier guarding the Beijing–Tianjin–Hebei region in China. Quantitative measures of vegetation productivity can be used to assess ecosystem carbon sequestration capacity and monitor regional ecological environmental health. Although several vegetation productivity products have been generated, poor spatiotemporal resolution limits their application in ecosystem service assessment. In this article, vegetation net primary productivity (NPP) from 2000 to 2017 with a resolution of 30 m in the upper Luanhe River Basin was generated based on a data fusion model and the multisource data synergized quantitative (MuSyQ) NPP model. Then, the variation trend of NPP and its climate controls were analyzed. Compared with forest NPP observation data, we derived an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of 0.68 and the root-mean-square error of 81.70 gC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">.</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2.</sup> yr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . Annual NPP had a fluctuating increasing trend from 2001 to 2017, with values ranging between 3.43 and 5.00 TgC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">.</sup> yr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> , with an annual increase trend of 0.04 TgC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">.</sup> yr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . Precipitation was significantly correlated with NPP in the upper part of the Luanhe River basin, which is an important reason for the interannual variation of NPP. Grassland had a stronger correlation to precipitation than forest because it is more sensitive to precipitation. The area where the temperature is significantly correlated with annual NPP only accounts for 2% of the study area, indicating that temperature has a weak influence on NPP. Furthermore, human activities, such as forest management, fertilization, and irrigation, can change the trend of annual NPP.
Highlights
Vegetation productivity is a key indicator for estimating carbon sequestration and characterizing vegetation activity, which plays an key role in climate change and the carbon balance [1]-[3]
The main purposes in this work are (i) to present a highresolution of the leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) using a downscaling method, (ii) to obtain high-resolution time series of gross primary productivity (GPP)/Net primary productivity (NPP) based on an light-use efficiency (LUE)-based NPP model, and (iii) to analyze the spatiotemporal variation and climate controls of NPP in the upper Luanhe River Basin
The monthly GPP/NPP was calculated with the multisource data synergized quantitative (MuSyQ)-NPP model by input the land-cover data, forest biomass, meteorological data and downscaled LAI and FPAR
Summary
Vegetation productivity is a key indicator for estimating carbon sequestration and characterizing vegetation activity, which plays an key role in climate change and the carbon balance [1]-[3]. The upper Luanhe River Basin is located in the arid/humid transition zone, which is the transition zone from grassland to forest It is a significant ecological barrier for guarding the Beijing-Tianjin-Hebei region in China, and its northern part is the core part of the "Three North Shelter Forest Project" and the "Saihanba Mechanical Forest Farm". The main purposes in this work are (i) to present a highresolution of the leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) using a downscaling method, (ii) to obtain high-resolution time series of GPP/NPP based on an LUE-based NPP model, and (iii) to analyze the spatiotemporal variation and climate controls of NPP in the upper Luanhe River Basin.
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