Do Coastal Forests of Tanzania have the Potential to Undergo Natural Vegetation Restoration?

Abstract

Aim: To determine soil seed bank as a basis for forest restoration through natural regeneration in the Zaraninge and Mbwebwe coastal forests in Bagamoyo District Tanzania. Study Design: Temporary concentric sample plots of size 0.07 ha established systematically along transect lines that run parallel to each other was used. The sampling intensity was 0.02%. The distance between plots was 100 m and between transect lines was 200 m. Place of the Study: Soil samples were collected at Zaraninge and Mbwebwe coastal forests in Bagamoyo District Tanzania. Methodology: Eighteen sample plots of size 0.07 were established systematically along transect lines on each of the two forests to cover as much variations as possible. Soil samples were collected within each plot at 0-10 cm, 10-20 cm and 20-30 cm depths. Soil sample were analyzed for frequency of germination and seed density of different plant species at the different depths. Results: The seed bank density for vascular plants was 2,782 seeds m-2 and 1,170 seeds m-2 for Zaraninge and Mbwebwe forest respectively. A total of 71 seedlings belonging to 17 species and 10 families emerged from all samples of the two forests, most of them being herbs and grasses. The number of germinants decreased with increasing soil depth in both forests as most seeds germinating from the 0-10 cm soil depth and least 10 germinants in 20-30 cm stratum. Conclusion: Forest restoration through natural soil seed bank may greatly depend on the seed bank at the surface soil horizons.