Effect of land use / land cover change on the vegetation of Attah watershed in Obanliku Local Government Area of Cross River State

Abstract

The removal, destruction or impairment of natural ecosystems are among the greatest causes of critical impacts on the sustainability of our natural environment. The magnitude of the impacts will vary according to the setting’s conditions with a wide range of possible landscape changes. Changes that can occur to landscapes include: forest clearance, crop- or grazing lands replacing grasslands or other natural terrestrial ecosystems, urbanization (leading to changes in infiltration and runoff patterns as well as pollution), wetlands removal or reduction, new roadwork for transportation, and mining in quarries or large-scale open pits. For Data Acquisition and Pre-Processing Procedure, the change in the forest landscape across the study area was performed using satellite remote sensing data for three epochs (1987, 2000 and 2021). For this study, two scenes of Landsat 5Thematic Mapper (TM), one scene of Landsat 7 Enhanced Thematic Mapper (ETM+) and one scene of Landsat 8 (OLI) were used for the three epoch. Image Classification and Accuracy Assessment During image classification, revealed that Landsat 5, Landsat 7 bands with same spectral ranges as well as the Landsat 8 image were selected for input. A total of three broad classes were used in the study. The three broad classes were forestland, Agricultural land and settlements/bare earth. The process of image classification and accuracy assessment was performed using independent training and testing data. The result revealed that in 1987, the dominating area in Attah was the forest land. About twenty five percent (25.33%) of the forest land was lost to farming (16.76%) and settlement (8.57%).This loss of vegetation increased in the year 2000 where 37.86% of the total forest land was lost to farming (24.42%) and settlement (13.44%), while 46.28% of the forest land was lost to farming (30.34) and settlement (15.94) in 2021.This was as a result of the increase in population which made the settlement to increase while the farming portion also increased because of the peoples’ survival. all land use/land cover classes for the three epochs 1987, 2000 and 2021 shows that water bodies were affected by this land cover change as evident in the reduction in stream depth, width and water quality. The study concluded that the dominating area of the vegetation in the study area was the forested area which gradually reduces as the farming area increases because of the population growth which also caused an increase in the settlement area of the map and this trend continued throughout the study period with the forested area gradually reducing while the farming and settlement area increased.