Forest Biodiversity Degradation: Assessment of Deforestation in Ohaji Egbema Forest Reserve, Imo State, Nigeria Using GIS Approach

Abstract

This research is focused on a spatial analysis of a reserved forest deforestation over a period of time using a GIS approach in Ohaji Egbema Local Government Area Imo state, Nigeria. It aimed at assessing and analyze deforestation in Ohaji Egbema forest reserve and examined the possible effects of deforestation on the forest environment. The assessment concentrated on when and where have forestlands changed in the reserved forest programmed within the period of 1984 - 2040 forecast. The key objectives were to assess the impact of land use and land cover changes on forest cover for the past 36 years, while sub objectives were dedicated to achieve in mapping out different land cover in Ohaji Egbema forest reserve, to assess land cover changes in the forest reserve susceptible to long term degradation from 1984 to 2020 of about 20 years. To evaluate forest loss in the area for the past 36years, and to predict the state of the land cover (forest) for the next 20 years (2040). Primary and secondary data employed using (200 ground truth points) were systematically collected from four different LULC classes in the study area using geographical positioning system (GPS), the secondary data (Satellite Landsat Imageries of 1984, 2002 and 2020) of the study area was acquired. The imageries were processed, enhanced and classified into four LULC classes using supervised classification in Idrisi and ArcGis software Ground truth points were utilized to assess the accuracy of the classifications. The data collected was analyzed in tables and figures and represented with a bar chart and pie chart graphs. Results showed that forest land, built up, grassland and water body were the four LULC classified in the study area. Kappa coefficient values of 91%, 85% and 92% for 1984, 2002 and 2020 respectively shows the accuracy of the classifications. Classifying the land uses into built-up and forest lands revealed that the built-up lands constantly rose while the forest lands kept dropping. The built-up lands increased by 49.30% between 1984 and 2000, 50.00% between 2002 and 2020 and 28.40% between 2020 and 2040 at the expense of the forest portion of the area which fell by 33.88% between 1984 and 2000,46.45% between 2002 and 2020, and 49.22% between 2020 and 2040. Increase in population, per capita income, and land use activities and by extension urban expansion were found to be the major factors causing deforestation in the forest reserve, it is likely that in the nearest future the remaining forest lands would be gradually wiped out and consequently the environmental crisis would be aggravated. Based on the findings of the study, there is need to urgently limit and control the high rate of deforestation going on in Ohaji Egbema forest reserve and embark on tree replanting campaigns without delay. There is need and recommended that a higher quality satellite imagery that offers up to 4m resolution should be used and a forest relic analysis should be conducted.