SUSTAINABLE FORESTS: WATER AND RESOURCE USE IN THE MANUBI FOREST

 

Mark Gush, Willem de Lange, Peter Dye and Coert Geldenhuys
Council for Scientific and Industrial Research (CSIR), Natural Resources and Environment, University of the Witwatersrand, School of Animal, Plant and Environmental Sciences, ForestWood cc

 

Abstract:

In the debate around resource use of indigenous forests compared to woodlots or plantations of introduced species, the question of relative water-use associated with either argument is an important yet poorly understood issue. This is because, while the water resource impacts of introduced tree species has historically been a priority research area, there has been little research on the water-use of indigenous trees and forests. Similarly, information on the economic value of biomass products from indigenous forests has not been extensively quantified. A study on the water-use, growth and economic value of the biomass of indigenous trees, solicited,funded and managed by the Water Research Commission with co-funding from Department of Environmental Affairs – Working for Water, is being undertaken by the CSIR towards addressing this knowledge gap. This paper presents preliminary findings from this project, based on research conducted in the Manubi State Forest in the Eastern Cape. The transpiration (water-use) of indigenous Ptaeroxylon obliquum (Sneezewood) and Millettia grandis (Umzimbeet) trees were compared against that of an adjacent coppicing Eucalyptus grandis plantation by measuring stem sap flow in selected trees over a year. Additional environmental measurements at the site included weather variables, soil moisture, total evaporation and biomass increments. Economic information on the value of resources from the forest and plantation were quantified by means of interviews with local inhabitants. Results showed that the indigenous tree species, and the indigenous forest as a whole, used less water than the introduced plantation trees, although growth rates were slower. Products from the indigenous forest were sought after, and valued to a greater extent than those from the plantation due to their quality, durability and cultural significance, but were under-priced. The study confirms the value and importance of ecological infrastructure such as indigenous forests, from both environmental and socio-economic perspectives. The wider (national scale) applicability of the methods applied and results obtained is also discussed.

 

Presentation Topic
SUSTAINABLE FORESTS: WATER AND RESOURCE USE IN THE MANUBI FOREST
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