Fire frequency increased significantly since 1970 in multiple fynbos protected areas in the Boland Mountains of the Cape Floristic Region

Fire regimes are changing along with global change in many parts of the world, which may adversely affect the persistence of plant species. We assessed a 55-year fire history in five protected areas (jointly 125 000 ha) in the heart of the hyperdiverse Cape Floristic Region of South Africa in terms of the cause, seasonality, size, and frequency of fires, and for potential changes over time. The fire regime in the fire-prone fynbos shrublands of the Boland Mountain Complex was characterised by a predominance of unplanned man-made fires (>75% of the area burnt) in summer and autumn. Average fire return intervals (FRIs) ranged between 11 and 16 years, but were significantly shorter in the latter half (1998-2024) than in the first half (1970-1997) of the study period. At least 50% of the study area, and of threatened vegetation types which occupy half of the study area, have burnt manifold at short FRIs (<12 years) when immaturity of obligatory-reseeding overstorey Proteaceae species is likely to have compromised post-fire recovery of plant diversity. The consistency and magnitude of increases recorded in fire frequency is of utmost concern for the persistence of the hyperdiverse flora containing many local endemic and threatened species. The nature and extent of the impacts on the vegetation require further evaluation. Managers should aim to prevent and suppress fires, particularly man-made and out-of-season fires, in young post-fire vegetation and in areas where healthy populations of slow-maturing, threatened, and endemic species are known to occur.