Estimating grassland production loss due to fire for a semi-arid climate

Abstract

Accidental, runaway veld fires cause enormous fodder flow problems in dry regions. It was the objective of this study to estimate the short-term (one year) impact of fire over 10 growing seasons (1995/96 – 2004/05) on the productivity (aboveground phytomass and litter) of a semi-arid grassland ecosystem. Fire caused a 41% decrease in basal cover over the first season following burning. On average over the study period the seasonal aboveground phytomass and litter production were decreased significantly, from 1 536 to 1 150 kg/ha and 111 - 42 kg/ha, respectively by fire. Seasonal production losses due to fire varied between 238 and 444 kg/ha. The relationship between aboveground phytomass production loss due to fire and two independent variables, namely seasonal rainfall and fuel load (aboveground phytomass plus litter) before burning, was investigated. One year after an accidental fire the production losses can be accurately (79%) estimated if the fuel load before burning is known. In general, the higher the fuel load before burning, the greater the production loss due to fire. The relationships can also serve as a simple empirical model for managers to determine short-term production loss due to unplanned fires in a semi-arid grassland. This information can serve as a scientific guideline in court cases in estimating production losses in claims for damages caused by fires.

Keywords: Aboveground phytomass production; basal cover, fuel load; litter

South African Journal of Animal Science Vol. 36 (5) 2006: pp.38-41