Factors Influencing Burning by Prescription in Mountain Fynbos Catchment Areas
Abstract
SYNOPSIS The fynbos vegetation of the Cape mountains is managed by applying what is termed prescribed burning. Burns are carried out under conditions of weather and fuel that are selected to ensure a safe and efficient burn. Formal prescriptions for burning in fynbos do not exist, but air temperature and days since last rain are the most important factors currently used to select days for burning. The conditions currently favoured by managers for burning were used to define preliminary prescriptions. Strict selection for time since last rainfall currently limits the number of suitable days available but could become less important if strict attention is given to other factors. Suitable conditions of wind, temperature and humidity will also limit the number of days suitable for burning. The seasonal occurrence of prescribed conditions was examined at seven weather stations in four zones of fire climate in the fynbos biome. Burning should take place in March and April in the inland zones, but may be undertaken from November to April in the south-western coastal zone. Fires in the humid south-eastern coastal zone should take place only when the desired fire intensity can be achieved. This may be in winter or summer, but more research is needed to determine the optimum season in this zone. Suitable burning days are rare in the recommended seasons and suggestions for the efficient use of available burning days are made.