Quantifying fuelwood biomass in savanna woodlands of southern Africa

نویسندگان

  • C. Paradzayi
  • H. J. Annegarn
چکیده

Most rural communities in southern Africa rely on fuelwood or charcoal to meet their domestic energy demands. These energy sources are readily accessible and often the only affordable means. Nevertheless, rising population densities and poverty levels are exerting pressure on unprotected natural woodlands. In many electrified communities, high costs of electricity have prevented a move away from dependency on bio-energy. Quantitative data on available woody biomass is lacking, influencing negatively on energy planning policy and implementation. Conventional ground-based biomass assessment methods are tedious and time-consuming. Species heterogeneity of savanna woodlands poses challenges for both optical and radar remote sensing platforms. Optical remote sensing techniques are constrained by atmospheric conditions as well as spectral resolution to distinguish different tree species and woody biomass densities in large-scale applications. Although satellite borne radar remote sensing offers greater opportunities for quantifying above-ground biomass, it is inhibited by the medium spatial resolution and long repeat cycles of current platforms. A combination of allometric equations and vegetation parameters from synthetic aperture radar (SAR) data can be used to quantify standing biomass. However, allometric equations are often site specific and difficult to extrapolate to landscape scales. This paper will discuss opportunities and challenges faced by natural resource practitioners when attempting to assess and quantify woody biomass in southern African savannas. The data needs and current availability of appropriate imagery will be presented in the context of the VW Foundation Bio-fuels Modeling Project, covering Zambia, Mozambique and South Africa. Biomass energy in low-income communities Biomass, mostly in the form of charcoal and fuel wood, is the predominant source of bioenergy in low income of rural and urban households in southern Africa [Banks et al., 1996; Wamukonya and Jenkins, 1994]. In Mozambique, biomass (charcoal and firewood) provides up to 80% of energy consumption while 87% of rural households in Zambia use fuelwood for cooking [Brouwer and Falcão, 2004; Chidumayo, 2002]. Many rural households in South Africa use mainly fuelwood and paraffin for cooking and space heating. In some cases, rural settlements derive approximately up to 90% of their domestic energy from wood [Banks et al., 1996]. Rising population growth and persistent poverty are increasing pressure on forest and woodland resources, thereby, threatening their sustainable utilisation. Signs of resource depletion as indicated by the distance of preferred species from households [Howells et al., 2003] are beginning to show in certain communal woodlands that are not subject to rigorous management regimes. Policymakers in most developing economies lack knowledge about the factors that determine energy choices by rural consumers [Von Maltitz and Scholes, 1995; Banks et al., 1996].

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تاریخ انتشار 2008