The burning of fuelwood in South Africa: When is it sustainable?

Fuelwood harvesting is considered sustainable when consumption is equal to or less than production. An empirical model was developed to estimate potential fuelwood production from savannas. The model is based on the observation that in semiarid savannas, biomass production is linearly dependent on rainfall. Woody basal area is linked to mean annual precipitation, and aboveground woody biomass is proportional to basal area. Production averages 4% of standing woody biomass and is corrected to exclude stems that are too small for harvesting. The model assumes that the entire area consists of seminatural savanna. Corrections for the land lost as a result of land transformation and degradation would have to be included. Data on land loss can most effectively be obtained from satellite imagery, with appropriate ground calibration. The model is based on limited data sets but in most instances has been validated against independently collected data. The model yields a reasonable prediction at a national and regional level, but estimates for limited areas or specific points on the ground may differ substantially from the predicted values. Model results indicate a potential for sustainable fuelwood production at the national level, but specific regions are using fuelwood at nonsustainable levels.