The Effects of Fire in FelledHakea sericeaand Natural Fynbos and Implications for Weed Control in Mountain Catchments

Abstract

Dense stands of the alien shrub Hakea sericea were felled and later burned accidentally under severe weather conditions. The recovery of the natural vegetation was monitored for 19 months on 12 permanent plots. Cover increased slowly to 13% and 42 species were recorded. Data were collected at a similar but uninvaded site burnt in the same fire. Mean cover on 12 plots at this site 19 months after the fire was 34% and the total number of species was 95. Sprouters were adversely affected at the invaded site, where species regenerating from seed stored in the soil predominated. Sprouters were dominant at the uninvaded site. Fire behaviour was simulated using Rothermel's fire model. Simulated fire intensity at the invaded site was particularly high (79 700 kW/m). Managers should attempt to burn felled hakea under conditions that will lead to less intense fires to reduce the adverse effects caused by high fuel loads. Fire behaviour prediction models should prove useful in this regard. Alternative control strategies for dense stands should also be investigated.