Evaluation of forest-cover dynamics and its drivers in Okeluse Forest Reserve, Ondo State, Nigeria

Abstract

This study x-rays the prevailing situation in the Okeluse Forest Reserve (OFR) for necessary interventions. The study assessed the effects of anthropogenic activities on land-use changes in OFR between 1984 and 2020 using Landsat TM, ETM+ and OLI images of 1984, 1990, 2001, 2010 and 2020. The images were acquired from USGS Earth Resources Observation and Science Center (EROS), processed, and classified using ArcGIS. Ground-truthing was achieved using GPS receiver. The images were pre-processed and classified using unsupervised iso-cluster classification method. The classified iso-cluster images were re-classified into forest, agricultural land, shrubland, built-up areas and water bodies. Normalized difference vegetation index (NDVI) was used for assessing vegetated areas and non-vegetated land within the reserve. The rates of changes and forest-cover losses within the 36-year-period were then analyzed. The result revealed losses in forest areas and water bodies within the period. Area coverage of forest reduced from 11,422 ha in 1984 to 5,706.2 ha in 2020, water bodies also contrasted by 80.8%, from 1,425.9 ha in 1984 to 273.6 ha in 2020. Consequently, agricultural land increased by 832.4% from 702.7 ha in 1984 to 5,849.6 ha in 2020. Shrubland, a resultant effect of deforestation and eventual degradation, increased from 647.8 ha in 1984 to 2,196.1 ha (339%) in 2020. Built-up areas increased from 225.2 ha in 1984 to 398.1 ha in 2020 due to increases in farm settlements and other infrastructure. The results further showed that the reserve was far more vegetated in 1984 (NDVI = 0.67), and less vegetated in subsequent years. The major drivers of changes in the forest reserves were unsustainable timber exploitation, and unpermitted land clearing for agricultural activities. It is projected that there would be a substantial increase in agricultural land, shrubland, and built-up areas, if deforestation persists at the current pace. However, there would be continued contractions in forest areas and water bodies.