Drought release and post-drought changes in herbaceous compositionand diversity in two land uses subjected to selective bush control in asemi-arid Kalahari savanna

Land degradation due to bush encroachment and drought threatens the well-being of land users and forage production in the semi-arid savannas of southern Africa. This study aimed to analyse how herbaceous vegetation in the Kalahari savanna can recover from drought, and how this is affected by previously implemented bush control measures. We compared plant species composition and diversity of the herbaceous layer across a drought-release (2021) and post-drought (2022) year within two land use types (game and livestock) in bush-encroached and controlled areas, respectively. Diversity decreased significantly during the post-drought year. Annual species dominated in the drought-release year, which were replaced by perennial forbs and dwarf shrubs in the post-drought year. Selective bush control enhanced herbaceous species abundance and richness due to decreased competition. The species richness was higher in the game ranch compared to the cattle farm during the drought-release year. Herbaceous abundance, however, increased on the cattle farm. The management strategies, feeding behaviour and animal movement may have contributed to these differences in these two contrasting land use types. This study showed that herbaceous plant communities can recover rapidly after a drought period and in areas where bush control was applied.

Automated summary

Land degradation caused by bush encroachment and drought has negative impacts on land users and forage production in southern African savannas. This study examined the recovery of herbaceous vegetation in the Kalahari savanna after a drought, and the effects of previous bush control measures. Results showed that diversity significantly decreased in the post-drought year, with annual species being replaced by perennial forbs and dwarf shrubs. Selective bush control enhanced herbaceous species abundance and richness. Differences in herbaceous abundance and species richness were observed between game and livestock areas, likely due to management strategies, feeding behavior, and animal movement. This study highlights the rapid recovery of herbaceous plant communities after drought and the benefits of bush control measures.