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Summary 1.Fire is an important process in Mediterranean-ecosystem shrublands, and prescribed burning is often used to manage these ecosystems. Analyses of past fire regimes are required to interpret biotic responses to fire, as well as to assess the degree to which management interventions have been able to influence the fire regime. 2. We used a spatial data base of fires within 10 protected areas covering >720 000 ha to examine the frequency, seasonality, size and cause of fires over four decades. Our study covered five fire climate zones and a range of mountain fynbos shrubland types. We examined whether regular prescribed burning would be necessary to rejuvenate the vegetation, and also to reduce the incidence and extent of wildfires. 3. Cumulative fire frequency distributions indicated that the probability of fire was not strongly affected by post-fire age, with 50% of the area experiencing a successive fire within 10-13 years after the previous fire in most areas. This suggests that the accumulation of fuel did not limit the occurrence of wildfires, and that regular prescribed burning would not necessarily reduce the risk of wildfires. 4. Inland zones experienced more severe fire weather than coastal zones (35% vs. 11-19% of days with high to very high fire danger, respectively). Despite these differences, fire return periods were similar (10-13 years), suggesting that the availability of ignitions, and not fuel or weather, limited the occurrence of wildfires. 5. Despite a policy that promoted prescribed burning, a relatively small area (between 4AE6% and 32AE4% of the area of all fires) burned in prescribed burns. Seasonal restrictions for safety and ecological reasons, the imperative to integrate planned fires with invasive alien plant treatments and unplanned wildfires have all contributed to the relatively small area that burnt in prescribed burns. 6. Synthesis and applications. Recurrent wildfires, and not prescribed burning, are providing sufficient opportunities for fire-stimulated regeneration in fynbos ecosystems. Because of this, and because burning to reduce fuel loads is unlikely to prevent wildfires, there should be less pressure to conduct prescribed burning. The predicted growth in human populations in all areas is expected to increase the number of ignition opportunities and the frequency of fires, with detrimental consequences for biodiversity conservation and the control of invasive alien trees. Fire frequency should thus be monitored and steps should be taken to protect areas that burn too frequently.

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We characterised the historical fire regime (1900–2010) in eastern coastal fynbos shrublands, which occur in a poorly studied part of the Cape Floral Kingdom (CFK). Natural (lightning-ignited) fires dominated the fire regime. Fire seasonality decreased from west (Outeniqua region) to east (Tsitsikamma region) within the study area, and between the study area and further west in the CFK. This is consistent with a west–east climatic gradient in the CFK, where rainfall is concentrated in winter in the west, and evenly distributed across months in the east. Median fire return intervals (FRIs) (1980–2010) were broadly comparable to other fynbos areas but estimates varied widely depending on whether or not the data were censored (16–26 years with and 8–13 years without censoring). FRIs appeared to be shorter in the Tsitsikamma, where rainfall and plant growth rates are higher, than in the Outeniqua. The total area burnt annually has increased significantly since 1980, coinciding with an increase in weather conducive to fires, suggesting that fire regimes may be responding to climate change. Frequent recurrence of very large fires and the virtual absence of vegetation in older post-fire age classes are potential causes for concern in achieving fynbos conservation objectives.

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