FIRE AND BUSH ENCROACHMENT IN ITHALA GAME RESERVE
Paul Gordijn and Dave Ward

South African Environmental Observation Network (SAEON),Grasslands-Forests-Wetlands Node, University of KwaZulu-Natal, School of Life Sciences

 

Abstract:
The ingression of woody plants into savannas, known as bush- or shrub- encroachment, has become a global concern. Bush encroachment has been associated with a decrease in rangeland palatability. In addition, the increase in woody biomass has consequences for climate change, carbon sequestration, rangeland hydrology and nutrient cycling. As a result of these large changes in ecosystem functioning with bush encroachment, biodiversity may be threatened.Fire has been acknowledged as a key factor in managing woody vegetation in savannas. This study assessed the role of fire in determining the total density, structure and composition of woody vegetation in Ithala Game Reserve, northern KwaZulu-Natal, South Africa. We surveyed woody vegetation in comparable areas with different fire frequencies. In Combretum-dominated woodlands, there was no significant effect of fire frequency on the total density of woody individuals. In old field grasslands, the density of woody plants was greater in areas burnt annually and in areas burnt once every ten years, compared to areas burnt once every 2 to 4 years. In these grasslands, areas burnt annually were dominated by woody plants <2m in height. Herbivore and fire interactions may explain these results. Multivariate analyses also indicated a significant effect of fire frequency on woody vegetation composition. To control dominant encroaching trees such as Dichrostachys cinerea and Acacia karroo, and the development of macrophyllous thickets, an intermediate fire frequency is required (one burn every 2 to 4 years).

 

Presentation Topic
FIRE AND BUSH ENCROACHMENT IN ITHALA GAME RESERVE
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