Fire Behaviour in South African Fynbos (Macchia) Vegetation and Predictions from Rothermel's Fire Model

Abstract

(1) South African fynbos (sclerophyllous shrubland) vegetation is fire-prone, and fire is important in fynbos management. No data on fire behaviour in fynbos are presently available. (2) The behaviour of fourteen experimental fires in fynbos tall open shrublands is described. Rates of spread ranged from 0.04 to 0.89 m s-1, flame lengths from 2 8 to 7.0 m and fire intensities from 515 to 20 709 kW m-1. (3) The fire behaviour is compared to predictions from Rothermel's fire spread model, which uses fuel characteristics and environmental conditions to predict fire spread and intensity. Predictions of rate of spread and flame length were good but fire intensity was underestimated where biomass and fire hazard were high. (4) The results are compared to fire behaviour in other shrubland ecosystems. Rates of fire spread and fire intensity are greater in fynbos than in Scottish heathland, and are equivalent to those reported for Californian chaparral. (5) The inclusion of fire danger indices and predictions based on Rothermel's model in fynbos fire records will enhance their value. The model can also be useful in fire research, particularly in homogenous vegetation, and represents an improvement on techniques such as the measurement of fire temperature.