Spatial and temporal characteristics of Urumqi City desert grasslands gross primary productivity and its response to climate change

The desert grasslands, integral to Xinjiang’s dry and semi-dry terrestrial ecosystems, fulfil ecological functions like water cultivation, wind erosion resistance, and carbon sequestration. However, once desert grasslands are destroyed, they are not only unable to feed livestock, regulate the regional climate, and maintain ecological balance but also become the source of sandstorms and dust storms. With the intensification of climate change, preserving the ecological stability and vitality of Urumqi desert grasslands is gaining importance. Consequently, conducting a long time-series desert grassland observation is necessary. Therefore, we can further explore the spatial and temporal characteristics of desert grasslands in Urumqi, assess the existing environmental strain on these areas, and forecast the progression of their ecological health. This research aimed to explore the spatiotemporal dynamics of the Urumqi desert grassland GPP across various spatial dimensions. Our research utilized the MODIS-MOD17A2H GPP and meteorological data (including precipitation and temperature) spanning 2001 to 2020, employing Theil-Sen Median trend analysis and the Mann-Kendall (MK) significance test. Additionally, we examined how desert grasslands react to climatic shifts, such as changes in temperature and precipitation. The results showed that: 1) From 2001 to 2020, Urumqi desert grassland Gross Primary Productivity (GPP) averaged 94.26 g·(m²·a)⁻¹ over several years, with a slight gradual increase in the annual average GPP. 2) Across all districts and counties, the GPP of desert grasslands exhibited a slight increase. And varying hydrothermal factors led to the highest growth rate in the Shuimogou District, succeeded by the Shayibake District, and was the lowest in the Dabancheng District. 3) The response of desert grassland to precipitation was higher than the temperature, indicating that precipitation is the main climatic limiting factor affecting the growth of desert grassland. 4) In future, some areas of Urumqi desert grassland will be degraded while the foothills will improve locally. Consequently, it is imperative to adopt suitable safeguarding and restoration management measures for the deteriorated regions in Urumqi, including synthetic rehydration or enhancements in re-seeding. The research findings serve as a guide to understanding the evolution and effective utilization of the desert grassland ecosystem in Urumqi.