Would the obtainable gross primary productivity (GPP) products stand up? A critical assessment of 45 global GPP products

Yahai Zhang; Aizhong Ye

doi:10.1016/j.scitotenv.2021.146965

Would the obtainable gross primary productivity (GPP) products stand up? A critical assessment of 45 global GPP products

Sci Total Environ. 2021 Aug 20:783:146965. doi: 10.1016/j.scitotenv.2021.146965. Epub 2021 Apr 7.

Authors

Yahai Zhang¹, Aizhong Ye²

Affiliations

¹ State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China.
² State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China. Electronic address: azye@bnu.edu.cn.

PMID: 33866164
DOI: 10.1016/j.scitotenv.2021.146965

Abstract

Gross primary productivity (GPP) is a vital variable of the global carbon cycle, but the quantification of global GPP is subject to significant uncertainty due to the lack of direct observations at a global scale. Here, we evaluated and compared 45 GPP products in terms of their applicability to different vegetation types at various spatiotemporal scales. The results show that 44 GPP products and obsGPP (Model Tree Ensemble GPP derived from observations and named obsGPP) have similar global patterns with correlation coefficients greater than 0.8 except for NGT, where GOSIF, RS, and BESS are prominent. GPP products have the greatest variation in Suriname, with a mean 75th and 25th percentile difference value of 0.4748 (normalized), and we recommend RS, SDGVM and LPJ-wsl as they provide GPP estimates close to the average GPP. In terms of seasonal estimations, considerable disagreement occurs among the GPP products in winter, with a range from 118.76 to 314.95 gC/m²/season, among which JULES has the closest GPP value to the average GPP estimation. For studies concerning vegetation types preference is given to the LUE average GPP. The 45 GPP products are more consistent on grasslands but, have obvious differences for savannas. All GPP products have their own specific spatiotemporal scales, such as global or national scales or different seasons and different vegetation types (forest, grasslands, etc.). This study provides guidelines for selecting GPP products.

Keywords: Gross primary production; Guideline; Intercomparison; Spatiotemporal GPP products.