GIS-Supported Survey and Biodiversity Assessment in a Derived Savannah Ecosystem

摘要

Assessment of relics of natural vegetation of a derived-savannah ecosystem within the campus of the Federal University of Agriculture, Abeokuta Nigeria was conducted by combining ground surveys with Geospatial technologies. The study aimed at investigating conservation capacity and wildlife of the remaining habitats within the University land. 1x1km grid cells were laid on the Landsat TM image of the campus acquired for year 2014.Supervised classification of the Landsat image was conducted using 5% maximum likelihood. Training sets were created from field notes from reconnaissance survey. 25% of the cells that fell on the densely vegetated areas were selected for inventory. Twenty-five 1 km transects were created in all; using cattle trails, human footpaths and vehicle tracks. Fauna inventory were conducted at 250 m intervals along all transects.Results image analysis revealed that many of the vegetation-cover are fragmentized into patches by human activities such as farming, logging and buildings. Total area of natural vegetation is only 5.14 km2; 5 percent of the reserve area within the University land. In the survey, 121 animals were recorded including 79 birds, 29 mammals and 11 reptile species.The observability and abundance index rated Bush buck and grass cutter highest with 8.14 and 7.75, respectively; and sighting frequencies of 21 and 20, respectively. Warthogs, hare, civet cats and forest genets are evidently threatened. The vegetation around a sacred grove within the campus and portion of the conservation reserved area were identified for protection. To reduce further human impacts creation of a zone of influence around critically important areas was suggested.