ASSESSMENT OF VEGETATION COVER DYNAMICS IN THE KPASHIMI FOREST RESERVE, NIGER STATE, NIGERIA.

Jibrin, A.

Changes in the vegetation cover of the Kpashimi Forest Reserve, was assessed over 20 years period (1987-2007). The study made use of satellite imageries TM, SPOT, ETM+, and NIGERIASAT-1 of 1987, 1994, 2001 and 2007 respectively. Arc GIS 9.2 and ERDAS Imagine 8.3 softwares were used for image processing and quantification of landscape transformation processes. Four land cover maps were produced for the four dates-1987, 1994, 2001 and 2007. Ground truth was conducted against the 2007 classified map and based on the derived confusion matrix, the Kappa coefficient is 0.73 while the overall accuracy is 0.77. The findings revealed a significant shrinking in the Savanna woodland and Riparian forest, with a corresponding expansion in Degraded forest, Bare surface and Scrubland classes. The Average annual rate of change of Bare surface is +2.0%; Scrubland is +2.6%; Degraded Forest is +2.4%; Savannah woodland is -2.8%; Riparian Forest is -2.1% while Grassland recorded +10.3%. The observed spatio-temporal variation of the respective vegetation communities over the period of study was found to be statistically significant with chi-square value of 43.75 at P<0.01. The study indicates that the landscape structure of the forest reserve has undergone significant change over the 21 years period of study and the resulting landscape mosaic vary in shape, size, arrangement and structure. Based on the findings of this study, it is recommended that Kpashimi forest reserve requires more effective conservation measures in order to mitigate the far reaching ecological consequences of vegetation changes.

Key words: Remote Sensing, Deforestation, Degradation, Vegetation dynamics.