Land Use Mapping and Change Detection of Abayomi Forest Estate Ikoyi, Osun State, Nigeria

Abstract

Incessant encroachment of log poachers, bush burning, conversion of forest for agricultural purposes and other land use contribute largely to deforestation in Nigeria. However, adequate information about the changes in most of our forest ecosystem is scarce. Therefore, this study examined the use of Geographic Information System (GIS) and Remote Sensing (RS) in mapping Land Use Land Cover (LULC) dynamics in Abayomi Forest Estate, Ikoyi, Osun State between 2006 and 2016 with a view to providing information for relevant stakeholders in forestry for sustainable management. Satellite imagery and sketch map of Abayomi Forest Estate were obtained. Coordinates of some benchmark places that could be identified on satellite imagery, sketch map and on ground were obtained. Historical imageries for 2006, 2011 and 2016 of the study area were also obtained. The coordinates of the benchmark places were used to georeference the sketch map. The georeferenced sketch map was used to develop shapefile for the study area. This was superimposed on the satellite imagery to delineate various land use through vectorisation. After vectorisation, the historical imageries of 2006, 2011 and 2016 were analysed using open layer plugin geoalgorithm of quantum GIS to determine the changes in various land use within the forest ecosystem. Geometry algorithm was used to determine the various land use size of each year. It was observed that eight land use land cover; forest (73.16 ha), oil palm plantation (29.96 ha), bareland (0.18 ha), pineapple plantation (0.16), built up area (0.13 ha), forest road, footpaths and water bodies were delineated from a total of 103.59 ha of the study area. Forest recorded absolute change of -0.37 and 0.00 between 2006 and 2011 and between 2011 and 2016 respectively. The Oil palm Plantation recorded absolute change of -0.06 and 0.00 between 2006 and 2011 and between 2011 and 2016 respectively. Bareland and built-up area recorded 0.16 and 0.11 between 2006 and 2011 while between 2011 and 2016, both recorded zero absolute change. The forest estate was maintained in a sustainable manner between 2006 and 2011 and under strict conservation without any iota of deforestation.