Multi-temporal assessment of forest cover, stocking parameters and above-ground tree biomass dynamics in Miombo Woodlands of Tanzania

摘要

Miombo woodlands form the widespread ecosystem in Tanzania. The ecosystem of these woodlands serves as a carbon sink and source containing majority of the above-ground terrestrial organic carbon. The study assessed forest cover, stocking parameters and above-ground tree biomass dynamics in the Miombo woodlands of Bereku and Duru Haitemba in Tanzania. The data were obtained from conventional forest inventory and remote sensing and GIS techniques. Results show that forest cover has increased for the two consecutive assessment period of 1988 to 2000 and 2000 to 2009, mostly by higher canopy cover of 6.82 and 0.79%, respectively. Stocking parameters: stand density (N) stand volume (V) and stand basal area (G) were found to be 1909.5 ± 9.4 stem/ha, 12.3 ± 0.6 m2ha-1 and 71.0 ± 6.8 m3ha-1, respectively. Vegetation indices (NDVI, ARVI and ND54) were then combined with forest inventory data for computation of average above ground biomass which was found to increase from 64 ± 6.53, 67.8 ± 5.42 to 79.218 ± 2.75 t/ha for 1988, 2000 and 2009, respectively. The results suggest that, the Miombo woodland resources have been consistently improving over the years of assessment. This could be attributed to reduction in negative anthropogenic factors that are known to be the major cause of resources degradation in Miombo woodlands. However, this improvement may be partial as plot level information revealed higher exploitation of the dbh class of 4 to 5 cm. Increase of management effectiveness through involvement of local people under participatory forest management, strengthened bylaws and provision of other incentives might have contributed greatly to the improvement of the forest resources.