The severe 2014–2020 drought in the southern Kalahari of South Africa resulted in extensive herbaceous cover and standing biomass losses. Droughts are a common phenomenon in this semi-arid savanna. The plants of this region have adapted to survive extreme rainfall variability and drought events. This adaptability and the inherent resilience (i.e. the ability to recover to its original state) of vegetation in the southern Kalahari enables it to recover quickly when conditions become more favourable. Droughts in the region are, however, predicted to increase in frequency and intensity due to global climate change. The associated increased aridity may also push many species beyond their tolerance threshold, leading to permanent shifts in vegetation dynamics. The aim of this study was to determine: (i) the growth vigour, cover abundance and productivity of herbaceous plant functional groups during the drought, (ii) the rate of post-drought recovery and (iii) the relative resilience and resistance of herbaceous plant functional groups. The drought affected all herbaceous plant functional groups as growth vigour, cover abundance and productivity were extremely low during the drought. All herbaceous growth started to recover post-drought but differed in their rate of response. Annual herbaceous species were found the be remarkably resilient to drought while perennial grasses were less resilient but far more resistant to the drought. Despite the resilience and rapid recovery of herbaceous growth, compositional changes post-drought were limited due to the degraded condition of the rangeland prior to the drought. The results emphasised the importance of sound management practices in the face of climate change.

中文翻译：

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喀拉哈里南部草本植被对长期干旱的反应

2014年至2020年南非卡拉哈里南部的严重干旱导致大面积草本覆盖和生物量损失。在这片半干旱的稀树草原上，干旱是一种常见现象。该地区的植物已经适应了极端降雨变化和干旱事件。喀拉哈里南部植被的这种适应性和固有的恢复能力（即恢复到原始状态的能力）使其能够在条件变得更加有利时迅速恢复。然而，由于全球气候变化，预计该地区干旱的频率和强度将会增加。相关的干旱加剧也可能使许多物种超出其耐受阈值，导致植被动态发生永久性变化。本研究的目的是确定：(i) 干旱期间草本植物功能群的生长活力、覆盖丰度和生产力，(ii) 干旱后恢复率，以及 (iii) 草本植物的相对恢复力和抗性植物功能群。干旱影响了所有草本植物功能群，干旱期间生长活力、覆盖丰度和生产力极低。所有草本生长在干旱后开始恢复，但反应速度不同。研究发现，一年生草本植物对干旱的抵抗力非常强，而多年生草本植物的抵抗力较差，但对干旱的抵抗力要强得多。尽管草本生长具有恢复力和快速恢复能力，但由于干旱前牧场状况退化，干旱后的成分变化有限。结果强调了面对气候变化时良好管理实践的重要性。