Assessment of the Status of Mangrove Vegetation and their Degradation in Rufiji Delta in Tanzania

Abstract

Mangroves are among the most degraded ecosystems in the World. This study focused on assessment of the status of mangroves and their degradation in Rufiji Delta. It was guided by the following objectives: to determine the types of use of mangrove resources in Rufiji Delta, estimate the extent of mangroves cover degradation, identify the factors causing mangrove resources degradation and investigate coping strategies of local communities for management of mangrove resources in the study area. Remote sensing was used for land cover change detection, and Landsat images data of 2000 and 2011 were analysed. Findings indicated that the bareland increased by 7412.8 ha (2.62%), Rhizophora dominant improved by 3076.47 ha (1.09%), Sonneratia almost pure stands enhanced by 1998 ha (0.71%), Sonneratia dominant amplifies by 129.06 ha (0.05%), Heritiera almost pure stands increased by 900.45 ha (0.32%), and Heritiera dominant added 3872.1 ha (1.37%) between 2000 and 2011. Whereas, Avicennia dominant decreased by - 1962.9 ha (-0.69%), Avicennia almost pure stands reduced by -1681.83 ha (-0.59%), mixture of Avicennia and Ceriops degraded by -15222.8 ha (-5.38%), and Ceriops dominant dropped by -2302.56 ha (-0.81%) within this period of time. Pressures on mangroves in the Rufiji Delta are mostly human-induced , and it was inferred that direct causes of mangrove resources degradation include tree felling for firewood and building materials(poles and timber), clearance of mangrove areas for agriculture (rice farming), solar salt works, and human settlement (population increase). Other causes include reduction in fresh water flow (both surface and groundwater), flooding, storms, and heavy or increased sedimentation. To reduce mangrove resources loss in the Rufiji Delta, it is important to focus not only on the management aspect but also to provide more economic alternatives and opportunities to the local communities that will discourage them from over-utilisation of these resources. In addition, stakeholders (NGOs) should organise more programmes on awareness-raising for the people of Rufiji Delta with respect to sustainable use of mangrove vegetation. Further training programmes for various stakeholders especially the local community to address on sustainable mangrove vegetation use and the current widespread mangrove degradation should be implemented.