Fine-scale vegetation mapping reveals shrub survival and recruitment patterns over 27 years in arid Karoo rangeland

Unpredictable rainfall in arid regions results in drier and wetter periods that influence the vegetation dynamics of these systems. Change in such drylands manifests slowly; therefore, long-term vegetation studies are necessary to provide insight into changes over time. The fine-scale mapping of individual plants in permanent plots in arid dwarf shrubland in 1997 and 2024 revealed that individuals of many species in Succulent Karoo shrubland survive for at least three decades. A preceding favourable weather event resulted in shrub recruitment, while a protracted drought resulted in significant mortality. There was no difference between the number of individuals that persisted from 1997 until 2024 (older individuals) and those that recruited after 1997 (younger individuals). Recruitment under nursed conditions occurred more often than in the open. The four consistently common plant species, Aizoon fruticosum, Osteospermum sinuatum, Pteronia pallens and Ruschia spinosa, differed in lifespan, recruitment site and abundance of recruited individuals. Differences in grazing management, ranging from grazing exclusion to moderate grazing, did not influence survival among common succulent and non-succulent shrubs. These arid shrublands appear to include shrub species that show slow continuous recruitment as well as event-driven episodic recruitment, and others that show demographic inertia, lagged responses and event-driven recruitment.