Transcriptional Changes Underlying the Degradation of Plant Community in Alpine Meadow Under Seasonal Warming Impact

Global warming is exhibiting a seasonal trend, while different seasons have different warming variations. However, the impact of seasonal warming on plants remains unclear. This study employed Open Top Chambers (OTCs) to simulate future seasonal warming scenarios in alpine meadow. The study examined plant community dynamics following long-term seasonal warming. The transcriptional and physiological responses of two dominant species (Kobresia pygmaea and Stipa purpurea) were examined. Results suggest that seasonal warming effects are correlated with both the duration of warming and the season which warming occurs. A long annual warming duration, especially growing season warming, made plants confront various stresses. K. pygmaea adopted a stress-avoidance strategy, showing a negative response, and leading to population decline or disappearance. This kind of dieback had also been observed in other Cyperaceae species. Meanwhile, due to positive responses, S. purpurea adopted a stress-tolerance strategy and overcame the impact of warming, partially gained the dominance over Cyperaceae species. Overall vegetation coverage and plant community diversity decreased over the years. These results reveal the impact of seasonal warming to plants, explaining the reasons for changes in plant communities under seasonal warming and providing new insights for future plant conservation under seasonal warming. Seasonal warming exerts distinct effects on plant communities compared to year-round warming. This study demonstrates that warming during the growing season, particularly in summer and autumn, imposes significant stress on alpine meadow plants. The negative response of Cyperaceae species emerges as a critical factor driving community degradation under seasonal warming. These findings advance our understanding of the ecological impacts of seasonal warming and elucidate potential mechanisms underlying plant community decline. They also provide a theoretical foundation for grassland management and conservation strategies in the context of future global seasonal warming scenarios.