This study shows the assessment of the mangrove ecosystem of Gazi Bay, Kenya with the use of remote sensing and Geographic Information Systems (GIS) techniques. It aims to analyse impacts of environmental variations and anthropogenic disturbances on landscape structure. Remote sensing data available indicate change in vegetation structure between 1965 and 1992. Environmental data and tree characteristics data were collected from 6 carefully selected sites, 3 chosen from where changes in vegetation structure occurred and the other 3, from areas that remained unchanged. The choice was based on observations made from change-detection map of Gazi Bay (1965-1992) (De Cauwer, 1996). Information from scientific studies carried out in the past was also integrated into GIS using ArcView software, creating thematic maps. Some parts of Gazi area have been subjected to heavy exploitation of the mangroves due to human activities with Makongeni and Kinondo being the most extensively affected. The species that was preferred most for harvesting was Rhizophora mucronata (58%). Documented information on past scientific studies carried out in Gazi indicates a bias in sampling locations being found towards the western and northwestern areas (Figs. 22, 23, and 24). Ground-truthing information obtained confirms R. mucronata species occupied the indicated areas shown in the satellite images (De Cauwer, 1996). |
