Fragmentation of wetlands in the south eastern coastal savanna of Ghana

Abstract

Temporal changes in a wetland were studied over a period of 25 years (i.e. 1990–2015) through the use of satellite images to assess the extent of environmental degradation in the Songor Ramsar Site, with special emphasis on fragmentation in the wetland. The study sought to analyse the wetland fragmentation and loss at the site. The specific objectives of the study were to assess the changes in the wetland classes, analyse the landscape configuration of the wetland classes and finally examine the composition of the wetland landscape. The wetland classes were categorised by employing the Ramsar classification system for wetland types. The validation results were established to be satisfactory after employing standardised accuracy assessment measures and comparison with ground truth data. Eight (8) landscape metrics were selected based on the literature and the potential of each metric to best describe wetland fragmentation. Interview surveys were used to complement data produced by Geographic Information System (GIS) application. During the 25-year period, lagoon/lake and inter-tidal forested wetland experienced a positive change while seasonal/intermittent and permanent marshes experienced a negative change. Further analysis using landscape metrics revealed that the configuration of the wetland types, especially inter-tidal forested wetland, has been fragmented and their ecosystem composition has reduced considerably.