EFFECT OF FOREST DEGRADATION ON THE SOIL QUALITY IN THE KWARI-KWASA FOREST RESERVE OF KEBBI STATE, NIGERIA

Abstract

The Kwari-Kwasa forest reserve is reportedly degraded as a result of anthropogenic influences. How much of changes it has undergone and the effect on the soil quality remain unknown. This study therefore used Lansat ETM of 1986 and ETM+ of 2013 to assess the changes in the forest reserve and the effect of such changes on the soil quality. With standard algorithms within the Idrisi Taiga Environment, the data were rectified radiometrically and geometrically and eventually classified into Land Use-Land Cover (LUC) types using Maximum Likelihood Classifier. To determine the effect of forest degradation on the soil, eight plots were randomly sampled from each LUC, each plot measuring 30mx30m. Within each plot, four sub- plots were also randomly sampled, and soil samples were taken at 10 cm, 10-30 cm and 30 - 60 cm soil depths. Replicates within a plot and same depth were bulked and homogenised, part of which was taken to the laboratory for analysis following standard procedures. Results showed increase in farmland, reduction in scrubland, dense shrubland and grassland which were the Land Use/Land Cover (LUC) classes obtained. Based on Chi-Square value derived from the Cross Map Tabulation (CMT), the forest reserve experienced significant change (P<0.05) between both dates. Soil texture is predominantly sandy (84.18%), while pH values are acidic. The CEC and organic matter content of the soils were low and ranged from 4.98 to 5.43 cmol kg-1 and 1.78 to 2.02% respectively. Total nitrogen and available phosphorus values ranged from 0.78 to 0.89% and 0.78 to 0.88 mg kg-1 respectively. It was concluded that the forest reserve got seriously degraded with serious effect on the soil quality.