Woody cover in wet and dry African savannas after six decades of experimental fires

Abstract

Summary: Fire is an integral process in savannas because it plays a crucial role in altering woody cover of this globally important biome. In this study, we examine the long-term effects of varying fire frequencies over a 60-year time period in South Africa. We analyse the effects of fire exclusion and of experimental burns every 1, 2 and 3 years on woody cover, tree abundance and stem structure on a wet and dry savanna. Increased fire frequency did not display a consistent effect on woody cover. The presence of fire, irrespective of frequency, was much more influential in lowering tree abundance in the wet savanna than the dry savanna. In the dry savanna, fire was more effective in greatly increasing coppicing in trees, when compared to the wet savannas. Synthesis. The effects of fire on three measures of savanna woody vegetation differed between wet and dry experimental sites. We suggest that vegetation responses to fire are dependent on local conditions, which are likely influenced by rainfall. Therefore, we suggest that management strategies should take account of whether a savanna is a wet or dry system when implementing fire management regimes. We examined the effects of varying fire frequencies over a 60-year time period upon woody vegetation on a wet and dry savanna. We suggest that vegetation responses to fire are influenced by regional differences in rainfall. Therefore, management strategies should take account of whether a savanna is a wet or dry system when implementing fire management regimes.