Forest Cover Change Assessment of Tangaza Forest Reserve, North-West of Sokoto State, Nigeria

Abstract

Tangaza forest reserve is one of the forest reserves in the northern Nigeria aimed at checking desertification. However, it is reportedly undergoing rapid degradation due to encroachment of human activities. The assessment of forest landscape change is a necessity for improved forest management, desertification prevention planning and decision-making. The study therefore aimed at assessing and predicting the dynamics of the forest reserve. Remote sensing technique was used in this study where 1986 and 2005 Landsat and 2007 SPOT data were processed and analyzed within the Idrisi Andes and ArcGIS environments. With maximum likelihood supervised classification method preceded by unsupervised classification and ground truthing, five classes namely bare surface, shrub-grass, tree-shrub, forest and cultivated land were derived at 88% degree of classification accuracy. Descriptive statistical tools were used to assess changes between both dates. Also Marcov-Chain was used to predict 2020 land covers. Results showed that between 1986 and 2005, bare-surface expanded by 1,033% and will further expand by 15% in 2020. The shrub-grass expanded by 55% and will expand by 17.2% in 2020. Tree-shrub reduced by 42% between 1986 and 2005 and will further reduce by 13.3% in 2020. Cultivation expanded by 271% between 1986 and 2005 and will marginally expand by 0.01% in 2020. The forest cover reduced by 66% between 1986 and 2005 and will further shrink by 48% of its size in 2005 by the year 2020. Also, between 1986 and 2005, 23.5% of the forest got converted into bare surface, 18.8% into tree-shrub, 11.8% into shrubgrass
and 10.5% into cultivation. The study concluded that the area will continue to undergo forest degradation in the face of perpetual human activities without corresponding forest management. Public enlightenment, tree planting, establishment of cattle ranches, improved farming practices, reduction in kerosene price to reduce the pressure on the existing but fragile forests and employment of more forest guards for improved forest management were recommended.