Question: How does the frequency of heathland fire events affect population growth rates of two woody shrub species, Ulex gallii and U. minor?
Location: Dry heathland on the south coast of England, UK.
Methods: The population dynamics of U. gallii and U. minor were modelled at each phase of the heathland cycle – pioneer, building, mature and degenerate – using periodic matrix products to investigate the response to different fire regimes.
Results: Population growth rates of both Ulex species declined under annual burning. Initially, as the time between burns increased, population growth rate increased for both species. Maximum population growth rates for each Ulex species were achieved under a 16-yr fire return interval. Fire return intervals > 16 yr resulted in declining population growth rates.
Conclusions: A species-specific critical fire frequency can be predicted, the minimum fire return intervals permitting persistence were 4 yr for U. minor and 3 yr for U. gallii. These patterns are similar to those reported for a range of woody plant species within savanna environments.
Nomenclature: Stace (1997).