Short-Term Responses of Southern African Semi-Arid Rangelands to Fire: A Review of Impact on Soils

Abstract

Knowledge of the impact of fire in arid and semi-arid sweet rangeland areas and the role it can play in sustainable utilization of the rangeland ecosystem is limited. This review uses a South African case study (experimental plot data) to elevate the research (soil quality and seed bank dynamics) on short-term fire responses in a semi-arid climate. The impact of a decrease in basal cover and plant density due to fire, especially on the hydrological characteristics of the ecosystem was clearly shown. Fire increase soil temperatures and soil compaction, and decrease organic matter, which lowers soil-water content and infiltration ability. Much of the influence of these variables had not been completely reduced two growing seasons after the fire. Reduction of organic matter after only one fire is a cause of concern due to maintenance of soil fertility. Fire caused a flush of seedlings from the soil seed bank over the first season following the fire. Low seedling survival with burning can be ascribed to poor basal cover and resultant change in microclimate. Fire also negatively influenced species richness. The enormous impact of fire on soil characteristics and seed bank dynamics, over the short-term, underscores the importance of purposeful burning in semi-arid rangelands. It is clear that over the short term, fire could strongly influence the sustainability of the ecosystem in the drier areas.