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The increasing frequency of global drought events poses a significant threat to the stability of grassland ecosystems' functionality. The Inner Mongolian grasslands stand out as one of the world's most drought-prone regions, facing elevated drought risks compared to other biomes. An in-depth comprehension of the impact of drought on grassland ecosystems is paramount for their long-term sustainability. Using the Standardized Precipitation Evapotranspiration Index (SPEI) from 1982 to 2018, this study identified various drought events within the Inner Mongolian grasslands, encompassing moderate drought, severe drought, and extreme drought. The resistance of the vegetation to the different drought conditions, assessed through net primary productivity (NPP) as a metric (reflecting its capacity to maintain its original level during drought periods), was examined. The research findings indicated that the period from 2001 to 2018 witnessed a substantial increase in both the frequency and the extent of drought events compared to the period from 1982 to 2000, particularly concerning severe and extreme droughts. The areas most severely impacted by extreme drought were the Xilingol League and the Alxa League. From 1982–2000 to 2001–2018, under moderate drought conditions, vegetation resistance exhibited a minor decrease in the central and eastern regions but experienced a slight increase in the western region. In contrast, under severe drought conditions, the western region saw a significant decrease in vegetation resistance. Remarkably, under extreme drought conditions, the western region showed a substantial increase in vegetation resistance, while the central and eastern regions experienced a slight decrease. Across all three drought conditions, as precipitation levels declined, the resistance of the meadow–steppe–desert ecosystems demonstrated a high–low–high distribution pattern. The temperate desert steppe exhibited a minimal vulnerability to drought, boasting resistance levels exceeding 0.9. Notably, extreme drought had the most pronounced impact on the temperate meadow steppe, temperate steppe, and temperate desert steppe, particularly within the temperate meadow steppe category. Given these findings, the authorities responsible for grassland management should prioritize regions characterized by frequent drought occurrences and low drought resistance, such as Ulanqab City, the Xilingol League, and the western part of Hulun Buir City. Safeguarding steppe ecosystems is of paramount importance for stabilizing vegetation productivity and land carbon sinks, especially under the anticipated exacerbation of climate conditions in the future. [ABSTRACT FROM AUTHOR]

• VCI showed an increasing trend in China from 2001 to 2020. • The time lag and cumulative effects of drought on VCI increased with latitude. • Warming and decreased precipitation at high altitudes improved vegetation growth condition. Vegetation can reduce the adverse effect of climate change. Under the frequent droughts and global warming, it is critical to clear vegetation dynamics and response to climatic variables. However, it is unclear how drought and climatic variables affect vegetation dynamics. In this study, we used the vegetation condition index (VCI) to examine vegetation dynamics in China between 2001 and 2020. The average annual value of VCI had increased during the period of 2001 to 2020, and 90.63% of the study regions had a rising trend in VCI. A large portion of the area had a 3-month time lag between VCI and temperature and precipitation. The time-lag response of VCI to drought was mainly 9 months, with a cumulative effect on drought of 1 month and 12 months. The VCI of evergreen needleleaf forests (ENF), deciduous needleleaf forests (DNF), deciduous broadleaf forests (DBF), and mixed forests (MF) in northern China displayed long time-lag response to drought. Except for DBF in the north and DNF in the central south regions, the cumulative effect of drought on other forest VCI was great in northern China. Except for DNF, DBF, and MF in the central south and DBF in the southwest regions, drought had less time-lag effects on VCI for ENF, evergreen broadleaf forests (EBF), DNF, and MF in southern China. The cumulative effect of drought on VCI of forests in southern China was short. The responses of various types of the grassland and shrubland to drought were similar as those of forests. However, the time-lag effect of drought on grassland and shrubland VCI was shorter than that of forests, making the grassland and shrubland more vulnerable to the short-term cumulative effects of drought. The result of this study can help us understand how the vegetation responds to climate change and drought under global warming scenarios. [ABSTRACT FROM AUTHOR]