IMPACT OF FARMING ON RIPARIAN VEGETATION ALONG ONA AND OROGUN RIVER, IBADAN, OYO STATE, NIGERIA

Abstract

Agriculture has been known to dominate the riparian zone because of its high fertility which supports and allows the high yield of crops. In this study, an attempt was made to establish the impact of farming on species structure, species floristic composition and patterns of diversity of species on the riparian vegetation. A total of 20 plots were sampled, 10 plots from the cultivated riparian forest and the other from the uncultivated forest. A quadrant of size 20m by 20m was delimited in each plot for vegetation sampling. Multivariate ordination technique of factor analysis showed the strength of the differences in tree density between cultivated and uncultivated riparian savanna. The correlation between tree species density in the cultivated and the uncultivated plots using t-tailed test showed that landuse type correlated positively with tree density at P?0.05. A comparison of the two levels of landuse showed a significant difference in the structure as well as the floristic composition of the vegetation, suggesting an effect of farming on riparian vegetation of the derived savanna. The calculated diversity using the Simpsons diversity index revealed that the highest diversities where found within the uncultivated plots (0.102) on the riparian zone and the least diversities were found within the cultivated (0.600) plots of the riparian zone. The research results concludes that the impact of farming on riparian ecosystem leads to the depletion of tree species diversity and ultimately on vegetation.