Soil drying weakens the positive effect of climate factors on global gross primary production

Abstract

Global warming and the fertilization effect of carbon dioxide (CO2) have led to a general increase in gross primary production (GPP). Although soil drying (SD) may limit this increase, its limiting effect has not been confirmed and quantified. Hence, we evaluated the impact of SD and climate factors on GPP. From 1997 to 2017, GPP showed a slight downward trend but began to rise after 2011. In SD zones, 19% of the GPP change was attributed to SD, and CO2 concentration in climate factors was the climate factor that contributed the most (24%) and accounted for the main control area (9%). Surprisingly, the negative contribution of SD to GPP offset 35% of the positive contribution area of the climate factors. In addition, SD and climate factors explained 1% and 23% of the GPP increase, respectively, but in areas where GPP decreased, the SD area exceeded that of climate factors by 1.2 times, further highlighting the importance of SD in the GPP drive mechanism. Compared with previous studies, we further quantified the contribution of SD and climate factors to GPP, which improved our understanding of the global pattern of total carbon absorption and its response to SD and climate factors.