Data from: Climate variability and community stability in Mediterranean shrublands: the role of functional diversity and soil environment

1.Understanding how different factors mediate the resistance of communities to climatic variability is a question of considerable ecological interest that remains mostly unresolved. This is particularly remarkable to improve predictions about the impact of climate change on vegetation.

2.Here we used a trait-based approach to analyse the sensitivity to climatic variability over nine years of 19 Mediterranean shrubland communities located in southwest Spain. We evaluated the role of functional diversity and soil environment as drivers of community stability (assessed as changes in plant cover, species diversity and composition).

3.The studied shrubland communities were strongly sensitive to inter-annual variability in climate. First, colder and drier conditions caused remarkable decreases in total plant cover but increased functional diversity, likely because the reduction of plant cover after harsh climatic conditions promoted the expansion of functionally dissimilar species in the new open microsites; although communities returned to their initial values of plant cover after nine years, changes in functional diversity and structure persisted over time. Second, drier and colder conditions favoured the predominance of shrubs with a conservative resource-use strategy (i.e. with higher dry matter content in leaves, stems and roots), bigger seeds and a more efficient use of water.

4.The most functionally diverse communities were the most stable over time in terms of species diversity, likely because a higher number of functionally dissimilar species allowed compensatory dynamics among them.

5.Communities inhabiting more acidic and resource-limited environments were less variable over time, probably because they were mainly constituted by slow-growth, stress-tolerant species that are potentially better adapted to harsh climatic conditions.

6.Synthesis: This study highlights the utility of a trait-based approach to evaluate how plant communities respond to climatic variability. We could infer that the increased frequency of extreme climatic events predicted by climatic models will alter the functional structure of shrubland communities, with potential repercussions for ecosystem functioning. Our results also provide new insights into the role of functional diversity and soil environment as buffers of the climate impact on woody communities, as well as potentially useful information to be applied in ecologically-based management and restoration strategies.

1. 厘清不同因子如何调控群落对气候变异的抗性，是生态学领域广受关注且尚未完全解决的科学问题，该问题的解析对于优化气候变化对植被影响的预测工作具有重要价值。
2. 本研究采用基于功能性状的研究方法，对西班牙西南部19个地中海灌丛群落展开了为期9年的气候变异敏感性分析，并评估了功能多样性与土壤环境作为群落稳定性驱动因子的作用（群落稳定性以植物盖度、物种多样性及群落组成的变化进行评估）。
3. 本研究涉及的灌丛群落对气候年际变异具有显著敏感性。其一，冷干气候条件会导致群落总植物盖度显著下降，但功能多样性却有所提升，这可能是因为极端气候条件下植物盖度降低后，为功能型迥异的物种在新生裸露微生境中的拓殖提供了空间；尽管9年后群落的植物盖度恢复至初始水平，但功能多样性与群落结构的变化却持续存在。其二，冷干气候条件更有利于采用保守型资源利用策略的灌木占据优势——这类物种通常具有更高的叶、茎及根干物质含量、更大的种子，且水分利用效率更高。
4. 功能多样性最高的群落，其物种多样性随时间推移的稳定性也最强，这可能是因为功能型差异较大的物种越多，群落内物种间的补偿动态就越容易发生。
5. 栖息于酸性更强、资源更受限环境中的群落，其随时间的变化幅度更小，这可能是因为这类群落主要由生长缓慢、耐胁迫的物种构成，而这些物种更适应极端气候条件。
6. 研究总结：本研究凸显了基于功能性状的研究方法在解析植物群落对气候变异响应机制中的应用价值。我们可推断，气候模型预测的极端气候事件频率增加，将改变灌丛群落的功能结构，进而对生态系统功能产生潜在影响。本研究结果还为理解功能多样性与土壤环境作为气候影响对木本群落的缓冲因子提供了新视角，同时可为基于生态学原理的群落管理与修复策略提供潜在的实用参考信息。