Geospatial Assessment for Sustainable Management of Mangroves in Kilifi Creek, Kenya

摘要

Mangroves are salt-tolerable trees that grow on zones parallel to the coastline along the creeks. They follow the mud flat accretions which are unvegetated areas consisting of sand or gravel that are either exposed or flooded by tides. They provide 70% of the wood requirement along the Kenyan Coast. Currently, there are no harvest plans of the mangroves and there is selective removal of suitable poles and most of the quality poles have been wiped out. This not only leaves the inferior species unsuitable for the market but also affects the quality of the forest. Moreover, areas that are suitable for mangroves growth have been occupied by human settlement and infrastructure, hence, there is a need of sustainable use of the mangroves so as to protect them from degradating and eventually extinction. To achieve this, geospatial techniques need to be employed in order to determine the spatial extent of the vegetation and devise methods and plans of managing them. The Kilifi Mangrove Forest creek is home to major six species: Avicennia marina, Ceriops tagal, Sonneratia alba J., Rhizophora mucronata, Lumnitzera racemosa and Bruguiera gymnorrhiza. This study showed that the most dominant species in the forest is Avicenna Marina which had a percentage stand of 25.6%. The less dominant species Lumnitzera racemosa and Heritiera littoralis had a stand of 0.10% which were restricted for harvesting in the analysis, they need to be protected so as to prevent its extinction in the forest which will affect the biodiversity and richness of the forest. Density and heights of the mangroves were considered so as to decide on which areas to do reforestation in order to protect the forest and help in preventing soil erosion. The final suitable area for harvesting after carrying out conditional and majority filter was 394 acres which are 9% of the total forest area. The total area most suitable for reforestation is 1151 acres which are 27% of the total Kilifi Mangrove Forest. A recommendation for proper harvesting plans should be made by identifying suitable sites for harvesting and areas which showed low mangrove stand density should be identified and necessary measures should be taken to restore them.