Assessment of degradation in forested areas of Tanzania: a case study of Tanga, Morogoro, Pwani and Dar-es-salaam regions

Masters Thesis

Study was conducted to assess the level of degradation in the forested areas in Tanzania particularly on eastern zone regions (Tanga, Pwani, Morogoro and Dar es salaam). Three vegetation types were taken into consideration where both volume and biomass removed was determined. The NAFORMA data was used where a total of 1413 plots with stumps were used. The study revealed that montane forest lost 48.47+8.2 m3/ha, lowland forest 22.27+2.25 m3/ha and woodland forest 13.77+1.39 m3/ha. The weighted mean volume and biomass removed was 15.67 m3/ha and 11.02 t/ha respectively. Average volume and biomass lost in woodland forests were 13.7 m3/ha and 9.77 t/ha respectively. The most harvested species in woodland were found to be Brachystegia sp. 2.57 m3/ha followed by Commiphora sp. 1.5 m3/ha while other remaining species account for 9.63 m3/ha. Average volume and biomass lost in lowland forests were 22.27 m3/ha and 14.88 t/ha respectively. The most harvested species in the lowland forest were found to be Brachystegia sp. 5.5 m3/ha followed by Combretum sp. 3.4 m3/ha and other remaining species contributed about 13.37 m3/ha. On the other hand average volume and biomass lost in montane forests were 48.46 m3/ha and 33.69 t/ha respectively where as the most degraded species in montane forest were found to be Ocotea usambarensis 14 m3/ha followed by Olea usambarensis 3 m3/ha and other remaining species 31.4 m3/ha. Volume removed in the woodland forest is contributed mostly by charcoal making 2.92 m3/ha followed by timber extraction 2.09 m3/ha, the remaining volume 8.76 m3/ha include other drivers of degradation. For lowland and montane forests, timber extraction is the most driver of degradation where about 5.03 m3/ha (22.5%) and 14.82 m3/ha (30.57%) respectively were extracted.