Introducing bud bank and below-ground plant organ research to South Africa: Report on a workshop and the way forward

Abstract

Bud banks are the source of vegetative reproduction of plants. They are linked to regeneration strategies of plant communities in ecosystems prone to disturbances. Bud bank research is fast moving up the research agenda as an approach to better understand the dynamics and resilience of ecosystems. Regeneration from seed is only one of a myriad of strategies that plants use to survive and flourish in ecosystems with seasonal rainfall, above-ground consumers such as fire and herbivores, or recurrent droughts. Because the vegetation dynamics, structure and function of southern African grassy biomes are driven by these disturbances, one would expect interesting below-ground regeneration strategies. However, studies on below-ground traits are underrepresented in the scientific literature, with only a few contributions pertaining to ‘below-ground bud bank’ as the main topic. Furthermore, most of these studies have been conducted in the northern hemisphere, such as in China, central Europe and the USA. Bud bank related research in the southern hemisphere is represented by one study from South American grasslands and one from savannas in Botswana. Recent papers on ‘underground trees of Africa and the underground storage organs characteristic of ‘old-growth grasslands have highlighted the importance of quantifying and describing below-ground regeneration strategies to understand the evolution of our ecosystems, and appropriate ways to manage and conserve them. The savanna and grassland biomes in Southern Africa host a high richness of herbaceous plants, particularly forbs, which are often more abundant below ground than in the standing vegetation. Below-ground bud banks comprise an important regeneration strategy for many savanna species, and yet very little is known about below-ground strategies for plant growth-form coexistence in grassy ecosystems. Considering the importance of understanding the ‘below-ground world’ for a broader comprehension of savanna ecosystem resilience in general, savanna ecologists from southern Africa and Brazil discussed the need to bring local researchers up to date with the latest approaches in regeneration strategies. In May 2019, a first hands-on workshop on how to survey bud banks and below-ground plant organs in grassy ecosystems was hosted by the Forb Ecology Research Group from the Unit for Environmental Sciences and Management, North-West University (Potchefstroom, South Africa), in collaboration with São Paulo State University (UNESP) in Brazil. This 2-day event attracted several established researchers in southern Africa and a robust community of young scientists and postgraduate students representing North-West University, University of Pretoria, University of the Witwatersrand and University of Edinburgh (Scotland). Considering the novelty of the subject and the underrepresentation of similar studies on grassy biomes in southern Africa, the workshop aimed to bring this approach to the ecological research community, broadening the understanding of the dynamics of southern African grassy biomes for improved management and conservation of these highly diverse ecosystems. The 2-day workshop covered relevant background information on bud bank related ecological research, after which delegates had the opportunity to undertake field surveying at the Unit for Environmental Sciences and Management research facility outside Potchefstroom, followed by working group sessions to analyse and interpret results. The theoretical background of the workshop highlighted the critical role of the below-ground structures in regeneration after disturbances, and the importance of a standardised approach to investigate the morphology and terminology of below-ground bud-bearing organs. Based on the available literature on the morphology and terminology of below ground bud organs, the workshop emphasised the importance of these less explored functional traits for future studies in grassland and savanna ecology. The event furthermore provided opportunities among scientists interested in grassy ecosystems to network and discuss projects and questions related to grassland and savanna dynamics and conservation. Young scientists had the opportunity to partake in such discussions to stimulate their thinking on the links between diversity, function, evolutionary history and disturbance in grassy biomes of South Africa.