Geospatial Analysis of Vegetation Health Response to Urbanisation and Land Use/Land Cover Changes in Lokoja, Nigeria Using NDVI

Abstract

Urbanization-driven changes in Land use/Land Cover (LULC) represent humanity’s most pervasive alteration of terrestrial ecosystems. These changes have a direct influence on vegetation health, a critical determinant of ecological resilience. The city of Lokoja has seen tremendous population expansion because of its strategic situation at the confluence of Rivers Niger and Benue, its historical significance and its economic potential. Using geospatial techniques and NDVI, this study investigates the how vegetation responds to urbanization and changes in Land Use/ Land Cover. This study also assessed the relationship between urban growth and vegetation cover in Lokoja, Nigeria between 1990 and 2019. The mapping of LULC changes was done by analyzing Landsat (5 TM, 7 ETM+   and Landsat 8 OLI) images of 1990, 1999, 2009 and 2019. LULC was divided into 5: built-up areas, bare surfaces, forest, water and scrub/shrublands. This study’s findings revealed that while built up areas grew by 505.5% during the study period, forest cover decreased by 75.99%. A highly significant negative correlation (R² = 0.9562) between built-up areas and forest cover was found at 0.05 level of significance indicating that there is a decrease in vegetation as the city grows. On the contrary, there is a significant positive linear correlation between the built-up areas and low NDVI values (R2 = 0.8991, p > 0.05). In conclusion, this study revealed that there was great decrease in vegetation cover (forests and scrublands), while built-up areas increased in multiple folds, during the study periods. Recommendations include integration of green infrastructure and land use zoning, reforestation and afforestation programs, strengthening environmental regulations and enforcement, and public awareness and community engagement.