Climatic extremes, such as severe drought, are expected to increase in frequency and magnitude with climate change. Thus, identifying mechanisms of resilience is critical to predicting the vulnerability of ecosystems. An exceptional drought (<1st percentile) impacted much of Southern Africa during the 2015 and 2016 growing seasons, including the site of a long-term fire experiment in Kruger National Park, South Africa. Prior to the drought, experimental fire frequencies (annual, triennial, and unburned) created savanna grassland plant communities that differed in composition and function, providing a unique opportunity to assess ecosystem resilience mechanisms under different fire regimes. Surprisingly, aboveground net primary productivity (ANPP) recovered fully in all fire frequencies the year after this exceptional drought. In burned sites, resilience was due mostly to annual forb ANPP compensating for reduced grass ANPP. In unburned sites, resilience of total and grass ANPP was due to subdominant annual and perennial grass species facilitating recovery in ANPP after mortality of other common grasses. This was possible because of high evenness among grass species in unburned sites pre-drought. These findings highlight the importance of both functional diversity and within-functional group evenness as mechanisms of ecosystem resilience to extreme drought.

中文翻译：

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南非热带稀树草原极端干旱后生态系统功能的快速恢复

随着气候变化，极端气候事件（例如严重干旱）的频率和幅度预计会增加。因此，确定复原力机制对于预测生态系统的脆弱性至关重要。在 2015 年和 2016 年的生长季节，异常干旱（<1%）影响了南部非洲的大部分地区，包括南非克鲁格国家公园的长期火灾试验地点。在干旱之前，试验性火灾频率（每年、三年和未燃烧）创造了组成和功能不同的稀树草原植物群落，为评估不同火灾状况下的生态系统恢复机制提供了独特的机会。令人惊讶的是，在这次异常干旱之后的第二年，地上净初级生产力 (ANPP) 在所有火灾频率中都完全恢复。在被烧毁的地方，恢复力主要是由于每年的 forb ANPP 补偿了减少的草 ANPP。在未燃烧的地点，总和草 ANPP 的恢复力是由于次优势的一年生和多年生草种在其他常见草死亡后促进了 ANPP 的恢复。这是可能的，因为干旱前未燃烧地点的草种之间的均匀度很高。这些发现强调了功能多样性和功能组内均匀度作为生态系统抵御极端干旱的机制的重要性。这是可能的，因为干旱前未燃烧地点的草种之间的均匀度很高。这些发现强调了功能多样性和功能组内均匀度作为生态系统抵御极端干旱的机制的重要性。这是可能的，因为干旱前未燃烧地点的草种之间的均匀度很高。这些发现强调了功能多样性和功能组内均匀度作为生态系统抵御极端干旱的机制的重要性。