Response of herbaceous vegetation in the southern kalahari following a prolonged drought

Abstract

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.