Response of total primary productivity of vegetation to meteorological drought in arid and semi-arid regions of China

Abstract

Since the beginning of the 21st century, global climate change has led to severe vegetation degradation in arid and semi-arid regions. However, the potential mechanisms by which meteorological drought affects changes in vegetation gross primary productivity (GPP) under the involvement of multiple environmental factors remain unclear. From 2007 to 2021, we utilized data on temperature (Ta), precipitation (Prec), solar radiation (SW), etc., to explore the response mechanisms of vegetation GPP to meteorological drought from seasonal and growing season perspectives. The results indicate that spring drought has the most significant impact on vegetation GPP. Summer is the peak period for GPP. Additionally, under meteorological drought conditions, GPP shows significant responses at a time scale of a 6-month lag, with the largest proportion occurring over a 5-month accumulation period. Structural equation modeling (SEM) analysis indicates that, within the mechanism of GPP variation during the vegetation growing season, the Standardized Precipitation Evapotranspiration Index (SPEI) has a total standardized effect of −0.17 on GPP. Ta and Prec indirectly promote GPP growth by significantly altering soil moisture (SM) and other indirect pathways. Prec has the most prominent promoting effect on GPP among all factors, while SPEI plays a critical role in inhibiting GPP. Moreover, we found that when Ta (12.74 °C), Prec (26.59 mm), and SW (24.87 W/m²), SPEI's influence on GPP experiences a threshold turning point. This research will contribute to strengthening future ecosystem management and mitigating the threats of climate change to ecosystems.