Geospatial assessment of 32-year changes in vegetation cover of some mangal-rainforest ecotone in parts of Asarama, Andoni, Rivers State.

Abstract

The use of geospatial technologies, especially the GIS, has been helpful in monitoring and detecting changing patterns in various vegetation zones. The present study on Asarama study location site was on the basis that land use ecology of anthropogenic and natural influences have constantly led to changes in the vegetation ecotypes with attendant depletion and destruction in the study area. The study was aimed at evaluating the feasibility and use of geospatial tools in assessing these changes within the varying vegetation ecotypes (mangrove, ecotone and rainforest) spanning over 32 years at 16 -year intervals. Results of the 1986 Landsat imagery revealed maximum vegetal trend condition across the vegetation ecotypes that were impacted by anthropogenic activities (farming, logging, deforestation, road/bridge construction and urbanisation) with consequent vegetal cover change, loss and depletion as depicted in 2002 and 2018 Landsat imagery, exemplified in the normalised difference of vegetation index (NDVI) and normalised difference of build-up index (NDBE). The greener parts in the NDVI reflecting a higher value showing a healthy vegetal cover and the blue parts of NDBI with high reflectance values revealed areas of anthropogenic influence alterations. This, by implication, signifies the measure of the vegetation health condition and anthropogenic alteration, respectively.