Estimation of grassland productivity in the period 1978-2021 and prediction under different climate scenarios in the period 2021-2100 in the Qinghai-Tibet Plateau in China

In the context of the future global warming trend, the complexity and diversity of climate change will have varying effects on grassland productivity. However, the response of grassland productivity to various climatic changes remains unknown. We investigated the impact of climate change on the grassland NPP of the Qinghai-Tibt Plateau(QTP), estimated grassland productivity over the QTP from 1978 to 2021, and predicted grassland NPP under the future climate scenarios SSP245 and SSP585 (SSP stands for Shared Socioeconomic Pathways). According to the SSP245 (2021 -2100) scenario, global average temperatures will rise by 2.7 & DEG;C by the end of the century. However, under the SSP585 (2021 -2100) scenario, the rise will be 4.4 & DEG;C). The simulation results were analyzed using spatiotemporal statistics and compared with the base period (1978 -2021). The results revealed the following: (1) In both the SSP245 and SSP585 scenarios, the grassland NPP of the QTP decreased from southeast to northwest, with higher NPP values primarily located in the east and south of the QTP and lower NPP values concentrated in the northwest. (2) Compared to the base period, the NPP of grassland in the QTP showed a downward trend under the SSP245 and SSP585 scenarios, and the NPP values of SSP245 and SSP585 decreased by 13 % and 23 %, respectively, compared to the base period (1978 -2021). (3) Temperature and precipitation were negatively correlated with NPP in the SSP245 scenario, while under the SSP585 scenario, both temperature and precipitation positively correlated with NPP. The temperature correlated more strongly with NPP than precipitation in future climate scenarios. Therefore, we proposed strengthening grassland ecosystem protection measures in the QTP, adopting corresponding protection mechanisms based on climate change and vegetation growth environment in different regions, and implementing key protection measures in the northwest of the QTP to increase vegetation coverage and enhance man-made effects to offset the negative impact of climate change.

Automated summary

In the future global warming trend, the impacts of climate change on grassland productivity are uncertain. This study investigated the effect of climate change on grassland NPP in the Qinghai-Tibet Plateau and predicted the NPP under different climate scenarios. The results showed a decrease in NPP from southeast to northwest of the plateau, and a decline in NPP under both SSP245 and SSP585 scenarios compared to the base period. Temperature and precipitation had different correlations with NPP in the two scenarios. To mitigate the negative impacts of climate change, it is important to strengthen grassland ecosystem protection measures and implement region-specific protection mechanisms.