Post-wildfire regeneration of rangeland productivity and functionality – observations across three semi-arid vegetation types in South Africa

Abstract

Wildfires can have significant impacts on rangeland productivity and functionality causing substantial economic losses to affected farmers. In August 2011, such wildfires swept through the North West province of South Africa, destroying large areas of grazing and farm infrastructure. There is little information available on how the regional semi-arid rangelands respond to fire. In order to increase knowledge on short-term regeneration capacities of burned rangelands, the recovery of grass phytomass, composition and diversity as well as the frequency distribution of patch types (i.e. grass-, litter- and bare patches) were assessed in the growing season following the fire. Burned and unburned sites were compared in two regional grasslands and one savanna type receiving between 480 and 700 mm rainfall y⁻¹. Fire significantly reduced phytomass production, and lowered the grazing capacity and potential grazing days across vegetation types. In general, grass diversity, composition and relative frequencies remained unaffected documenting an overall good regeneration potential of the grass sward. An increased proportion of bare patches and decrease of litter indicated that the post-fire environment lost functionality with respect to erosion control, nutrient cycling and water infiltration. Gained insights provide valuable baseline information for future impact assessments and research into the fire dynamics of investigated vegetation types.

Keywords: aboveground phytomass, grass diversity, grazing capacity, grazing days, impact assessment

African Journal of Range & Forage Science 2013, 30(3): 161–167