Species and functional group asynchrony maintain the seasonal temporal stability of a temperate grassland plant community in Inner Mongolia, China

Temporal stability is a fundamental characteristic of grasslands, many of which are experiencing increased climate change and variability. Nevertheless, the influence of these climatic changes, particularly seasonal variability, on grassland stability is still poorly understood. We conducted a 29-year monitoring experimental study in a temperate grassland to explore how seasonal climate variability affect community biomass temporal stability. We used regression analysis and structural equation modeling to examine the effects of climatic and biotic factors affected on community seasonal temporal stability. We found that increased seasonal climate variability (temperature and precipitation) reduced community temporal stability by reducing species richness, suggesting that increased climate variability has a negative impact on ecosystem functioning. In addition, community temporal stability was mainly affected by species asynchrony, functional group asynchrony and dominant species stability. Under climate change, functional group asynchrony had the strongest contribution to community compensation dynamics and community stability. Based on a long-term study spanning 29 years of observational experiments, our findings demonstrate the importance of species and functional group asynchrony to stabilize grassland functioning against increasing climate variability.

时间稳定性是草原的核心特征之一，当前多数草原正经历日益加剧的气候变化与气候变异性。然而，此类气候变化——尤其是季节气候变异性——对草原时间稳定性的影响仍不甚明晰。为此，我们在温带草原开展了一项为期29年的监测实验，以探究季节气候变异性如何影响群落生物量时间稳定性。我们采用回归分析与结构方程模型，检验气候与生物因子对群落季节时间稳定性的作用。研究发现，季节气候变异性（气温与降水）的加剧会通过降低物种丰富度削弱群落时间稳定性，这表明气候变异性增强会对生态系统功能产生负面影响。此外，群落时间稳定性主要受物种异步性、功能群异步性及优势种稳定性的调控；在气候变化背景下，功能群异步性对群落补偿动态与群落稳定性的贡献最为显著。基于这项长达29年的长期观测实验，本研究证实，物种与功能群异步性在抵御日益加剧的气候变异性、稳定草原生态系统功能方面具有重要意义。