Impacts of Vegetation Losses over Time on Land Surface Temperatures in Borgu Sector of Kainji Lake National Park, Nigeria

Abstract

The effects of vegetation-changes on land-surface temperature (LST) in Kainji-Lake National Park was evaluated. Hitherto, the possible interaction(s) between land-use/cover, vegetation-index (NDVI) and LST were unknown. This study utilized cloud-free Landsat images within five data-periods (i.e., 1986-1990-1999-2009-2020). The red and near-infrared bands of the images were processed using ArcGIS for NDVI (bands 4 and 3 of Landsat 5 and 7, and bands 5 and 4 of Landsat 8 OLI/TC). Emissivity and LST were determined using thermal-bands 6 for Landsat 5 and 7, and 10 for Landsat 8. Data were analyzed using descriptive statistics and Pearson-correlation. The results revealed that LST increased from 28.46±3.01°C (1986) to 34.13±2.07°C (2020). However, highest mean-temperature (41.35±1.16°C) was in 1999, with the lowest (28.46±3.01°C) in 1986. Area with highest temperature had NDVI of 0.120±0.071, while the NDVI of the area with lowest temperature was 0.436±0.062. Thus, there were inverse-correlations between NDVI and LST (r = -0.934, -0.931, -0.992, -0.942 and -0.972) for 1986, 1990, 1999, 2009 and 2020, respectively. With the decrease of NDVI (vegetation cover), the LST were found to increase. Therefore, there is need to discourage forest-conversions, as losses in vegetation-covers were consequent upon intense anthropogenic-activities such as overgrazing, illegal-logging, fuel-wood exploitation and mining.