A plant-based system for evaluating the health of wetlands in Mathioya watershed, Murang’a county, Kenya

Abstract

Wetlands in Mathioya watershed have been undergoing degradation over the past decades. This can be attributed to human activities such as farming within the wetlands, washing of cars in wetlands, and harvesting/clearing of wetland vegetation. Such activities are likely to impact on the health of the wetlands, which could lead to an overall loss of wetland function and ecosystem services. The aim of this study was to assess the health status of wetlands in Mathioya watershed, Murang’a County. Plant metrics and water quality parameters were used to develop the Plant Index of Biotic Integrity (PIBI). The PIBI was then used to evaluate the health of the wetlands in response to anthropogenic disturbance. The plant metrics selected to be included in the final PIBI include: number of tolerant species, sensitive species, exotic species and shrub species. A trisect interquartile method was then used to assign values to the core metrics. Scores from the selected four metrics were summed to come up with the final PIBI. The metric scores ranged between 4 and 20, with 4 being very poor health and 20 very good health. From the results, only two wetlands were of moderate health, six were of poor health, and one wetland was of very poor health. The average score shows that wetlands in Mathioya watershed are generally of poor health. This study concludes that the majority of the wetlands (6 out of 9) were of poor health, wetlands in areas with relatively low human activities were of better health. Therefore, a restoration project should be initiated to restore the ecological integrity of the wetlands.