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

Abstract

The influence of fire on the ecosystem in the higher rainfall “sour” rangeland areas of southern Africa has been well established; however, less information is available for arid and semi-arid “sweet” rangeland areas. Sour and sweet rangeland areas can be defined as receiving higher and lower than approximately 600 mm of rainfall, respectively. This review uses a South African case study (experimental plot data) to elevate the research on short-term fire responses in arid and semi-arid climates. Burned rangeland took at least two full growing seasons to recover in terms of above- and belowground phytomass production and water-use efficiency (WUE). The initial advantage in quality (crude protein) accompanying fire did not neutralize the reduction in half of the aboveground phytomass production and poor WUE occurring in the first season following the fire. The belowground growth was more sensitive to burning than aboveground growth. Seasonal aboveground phytomass production loss to fire which was a function of the amount and distribution of rainfall varied between 238 and 444 kg ha⁻¹ for semi-arid rangeland. The importance of correct timing in the utilization of burned semi-arid rangeland, with respect to sustained high production, cannot be overemphasized. In arid and semi-arid rangeland areas, fire as a management tool is questionable if there is no specific purpose for it, which also can increase ecological and financial risk management in the short-term.

Keywords:

• crude protein content
• hydrological cycle
• plant cover
• productivity
• root growth
• soil characteristics
• tuft mortality