Optical remotely sensed data for mapping variations in cashew plantation distribution and associated land uses in Ogbomoso, Nigeria Southwest

The study examined spatial variation in the extent of land used for cashew plantation cultivation and associated land uses as notable agroecosystem in the guinea savanna region of Ogbomoso, Southwestern Nigeria. Data used for the study include point data recorded with GPS through purposive sampling and satellite imageries of 1987, 1997, 2002 and 2018 were acquired from Landsat-5 TM, Landsat-7 ETM + and Landsat-8 OLI/TIRS. The satellite imageries were processed and classified using supervised classification. The imageries were classified into five themes of water, plantation, savanna and farmland, built-up area and bare land. Results revealed that cashew plantation occupied 12.4% of the total area in 1987, 16.2% in 1997, 23.1% in 2002 and 20.7% in 2018. This reflects 8.3% increase in the area of land covered by cashew plantation between 1987 and 2018 being notable agricultural tree/cash crop in the vegetation zone. Cashew plantations showed strong correlation with advances in years with correlation coefficient value r = 0.74. Image classification accuracy assessment conducted returned overall accuracy level ranges from 87.6% in 2002 to 93.2% in 1987. The study concludes that there is gradual increased in the area of land use for cashew cultivation but this is however recently threatened by rapid urbanization process.