Estimates of Volume and Carbon Stock Removals in Miombo Woodlands of Mainland Tanzania

Abstract

Miombo woodlands are major vegetation type covering about 93% of the forest land of Mainland Tanzania. It forms an integral part of the rural landscape in Tanzania and plays a crucial role in providing a wide range of goods and services including carbon sequestration. However, the sustainability of forest resources is mostly affected by the magnitude of its utilization. There should be a balance between the forest growth and removals. Nevertheless, the magnitude of removed volume and carbon in the country is not known. Quantification of volume, biomass, and carbon stocks removals is vital in developing effective climate change mitigation strategies, decision making, and promoting sustainable forest management. Based on the National Forest Resources Monitoring and Assessment data (NAFORMA) comprising 7,026 stumps collected from 16,803 circular plots of 10 m and 15 m radii established in Miombo woodlands of Mainland Tanzania, volume and carbon stock removals were estimated with the use of models that utilize stump diameter (SD) as the sole predictor. Results indicate that the annual volumes, aboveground biomass removed, and belowground biomass removed were 1.71 ± 0.54 m3 ha−1 year−1, 1.23 ± 0.37 t ha−1 year−1, and 0.43 ± 0.12 t ha−1 year−1, respectively. In addition, the corresponding aboveground and belowground carbon removed were found to be 0.6 ± 0.18 tC ha−1 year−1 and 0.21 ± 0.05 tC ha−1 year −1 respectively. Since the estimated annual volume removals exceed estimated mean annual increment of 1.6 ± 0.2 m3 ha−1 year−1 in Miombo woodlands, the removals indicate unsustainability that would end up into forest degradation. The results also show that removals are more prominent in the following categories: shifting cultivation, production forest, grazing land, general land, village land, and Eastern and Southern zones. This paper calls for increased appropriate management strategies to ensure sustainability in these land categories and in the entire Miombo woodlands of Mainland Tanzania.