Laterite Exploitation and its Impact on Vegetation Cover in Calabar Metropolis, Nigeria

Abstract

The impact of environmental degradation caused by mining activities is not bourne by the construction companies but rather by the inhabitants of the area.  The effects of laterite quarrying are degradation of arable land, ecological instability, reduction in fauna and floral population density, contamination of water and air, landslide and landscape alteration.  The study was carried out to ascertain the level of impact of laterite exploitation on floral population density in Calabar metropolis. Direct field measurement was utilized for the study and a quadrant of 50 x 50m was used to demarcate the sample area into plots for easy identification of tree, shrub, herb, and grass species of plants lost during the extraction process.  The Shannon weaver’s index was then used to calculate the diversity index of each species. Aerial photographs and metric tape were used to measure the lateral extent of degraded land and the Magellan meridian GPS was used to obtained the co-ordinates of laterites site. Questionnaires was used to obtained information on socio-economic impacts of laterite extraction. The study revealed that the total area of vegetation cover destroyed was 8,520 hectares. Elaeis guineensis was the only plant specie with the diversity index of 1.5 and the mean diversity index for the twenty species of plant identified was 0.5.  The major socio-economic impact felt by the inhabitants of the area as obtained from the respondents was the destruction of vegetation cover with 37.5 percent.  The R² value obtained from multiple regression analysis was 0.856 that means 85.6 percent of the impact of laterite exploitation on vegetation cover was explained by the model.  It was then recommended that a proper environmental impact assessment study be carried out before sitting a quarry, to minimize the damage on the environment.

Keywords: Environment, exploitation, laterite flora, and degradation.