Plant Species Dynamics and Recovery from Sites Routinely Maintained by Application of Herbicides in the Ile-Ife Municipality, Osun State, Nigeria

Abstract

This study investigated the effect of indiscriminate application of herbicides on weed recovery in urban environment in Ile-Ife, Osun State, Nigeria. A survey was carried out to identify sites maintained by the application of herbicides (test plots) and those without herbicide history (control plots). Comprehensive enumeration and identification of plant population to species level were carried out during recovery on four different experimental plots. Sorenson's index of similarity was used to determine the relationship in plant species composition between plots treated with herbicides and the untreated plots and the relationship in plant species composition between plots treated with herbicides and the soil seed bank. A reduction in weed species density was achieved after each successive herbicide application. Although the vegetation was not allowed to restore to an earlier state due to the incessant application of herbicides, the trend of increasing plant species was observed in all the treated plots with a change in weed species composition. A low similarity index was observed between the composition of the vegetation in the treated plots and the control vegetation at all visits. A low similarity was also observed between the aboveground vegetation and the seed bank in all the plots. The result of this study has shown that the population dynamics of weeds in the herbicide-treated plots have practical implications in the use of herbicides for general weed control because it provides an opportunity to monitor the response of weeds to extreme dosages, extreme combinations of herbicides and persistent applications.