Revisiting the main driving factors influencing the dynamics of gross primary productivity in the Mongolian Plateau

Abstract

By contributing to what is considered as the world's largest carbon flux, global climate change has been significantly altering terrestrial vegetation gross primary production (GPP) at a global level. Thus, a robust understanding of the main driving factors influencing GPP change is neccessary for increasing terrestrial carbon sequestration potential of a region. In this study, we conduct an analysis of the main driving factors that have influenced GPP change in the Mongolian Plateau in the 1982–2018 period. The results of our analysis indicate that the GPP of the plateau's total vegetated area has witnessed both growth and decline (of 51.16% and 48.48%, respectively) over the past 37 years, with the latter occurring mainly across northern Mongolia and northeastern Inner Mongolia. Water availability, temperature, and solar radiation are deemed the most crucial climatic factors behind GPP change in 51.21%, 15.51%, and 18.63%, respectively, of the plateau's total vegetated area, according to a nonlinear Granger causality test. These three factors also explain up to 31%, 25.20%, and 17.21% of GPP change in 82.78%, 64.23%, and 69.96%, respectively, of the plateau's total vegetated area, as 34.52%, 31.57%, and 48.62% of the total vegetated area affected by the abovementioned driving factors concomitantly exhibit time-lag effects. The average intensity and extent of the effects of extreme climate indices on GPP change are lesser than the effect of general climate change; up to 21.31% and 22.35% of the GPP change can be explained by the extreme precipitation and temperature in 47.41% and 34.33%, respectively, of the plateau's total vegetated area. Moreover, the standardized total effects of this study's structural equation model (SEM) show that precipitation has the greatest impact on the GPP change (0.42), followed by snow water equivalent (SWE) (–0.11), solar radiation (0.08), and soil moisture or near surface temperature (0.07). Overall, our study provides new insights into the effects of the aforementioned driving factors on GPP change in the Mongolian Plateau, which will be helpful in mitigating the adverse effects of future climate change in the region.