Fast seasonal growth promotes regional stability by strengthening local temporal stability in Inner Mongolian grasslands

Zexu Nie, Yi Yuan, Hushun Zhang, Hushun Zhang, Fang Shi, Han Zhang, Han Zhang, Chao Wang

Introduction Grassland productivity stability underpins the sustained functioning of arid and semi-arid ecosystems yet identifying how regional stability emerges across local communities remains challenging because stability is multidimensional, scale- dependent, and is shaped by seasonal growth processes. Methods Here, we use satellite-derived gross primary productivity (GPP) data from 2000 to 2018 to investigate how local stability, spatial synchrony, drought resistance, recovery, and fast-growing phase characteristics jointly regulate regional stability across meadow, typical, and desert steppes in Inner Mongolia and across three observational grains (0.1°, 0.5°, and 1.0°). Results We found that regional stability was governed primarily by local stability rather than spatial synchrony, suggesting that the stabilizing role of spatial insurance was limited under broad-scale climatic constraints. At the local scale, temporal stability was more closely aligned with resistance than with recovery, while resistance and recovery showed a persistent trade-off. Mechanistically, growth rate during the fast-growing phase (FGR) linked environmental variation to stability by reflecting how efficiently vegetation converted favorable hydrothermal conditions into mean GPP. Higher FGR strengthened local temporal stability mainly through higher mean GPP, while its relationships with resistance and recovery depended on productivity variability and post-drought resource conditions. Observational grain further modified the expression of stability and the detectability of relationships among stability dimensions. Discussion These findings identify fast seasonal growth as a key pathway through which favorable hydrothermal windows are translated into local stability, with consequences for regional stability across observational grains. They also suggest that grassland monitoring and management should consider the spatial grain at which stability is assessed.