Empirical evidence of the impact of commercial charcoal production on Woodland in the Forest-Savannah transition zone, Ghana

Abstract

The impacts of charcoal production on woodland were assessed in the Forest-Savannah Transition Zone of Ghana to facilitate policy formulation for a win-win situation for both sustainable woodland management and charcoal production. Twenty-three harvested sites in two charcoal producing communities were assessed in terms of the extent of harvested sites, changes in biomass carbon stock and tree basal area. The boundary of each site earmarked for charcoal production was mapped with a hand-held Global Positioning System, and the diameters at breast height (dbh) and the heights of trees of dbh≥5cm were measured, prior to harvest. The extent of harvested sites was compared with the Intergovernmental Panel on Climate Change criterion of “devegetation” using Wilcoxon test, while the biomass carbon and basal area of the harvested trees were compared with those of the remnant trees using Mann Whitney t-test. The median of the extent of harvested sites (M=0.23ha, P=1.00) was significantly higher than 0.05ha, the Intergovernmental Panel on Climate Change minimum criterion for “devegetation”, while the difference between median basal area of harvested and remnant trees was significantly greater than zero (Gh−Gr=2.6m2ha−1; P=0.001) at 95% significant level. The Mann Whitney test also provided sufficient evidence (n=23; Mhc−Mrc=12.07tha−1; P<0.001) against the null hypothesis that the difference between the medians of the aboveground biomass carbon in the harvested and remnant is zero at 95% significant level. On the basis of the IPCC definition of “devegetation” and the changes in basal area, it suggests that intensive charcoal production has the potential of degrading woodlands. Nonetheless, it is worth highlighting that, none of the harvested sites had zero basal area or biomass carbon after harvest, which is a significant revelation for sustainable woodland management for charcoal production. The study further revealed that the extent of harvested site is not an appropriate measure of the impact of charcoal production on woodland since it does not account for the number and sizes of the trees harvested. Therefore, the impact of charcoal production on woodland may not be as alarming as it is generally perceived when the extent of harvested site is used as a measure. The impact of charcoal production is often over-generalized and that, “devegetation” of harvested sites is an issue of post-harvest woodland management and not the impact of charcoal production per se. Therefore, the evidence of the impact of charcoal production on woodlands shown in this study should be basis for sustainable woodlands management and not basis for halting charcoal production in the study area.