Runoff, Sediment Loss and the Attenuating Effectiveness of Vegetation Parameters in the Rainforest Zone of Southeastern Nigeria

Abstract

The research was conducted to assess the pace of sediment loss in deserted 3-, 5- and 10-year-fallow traditional farmlands, as well as cultivated farmlands, in a remote forested zone in southern Nigeria. During the 2012 rainy and cropping season, field measurements of sediment and runoff caused by rainfall were carried out. Pearson’s correlation revealed that crown cover positively and significantly correlated with runoff on the cultivated farmland (r = 0.652, p < 0.01). The results showed that the vegetation characteristics assessed on the different fallows explained 73.1%, 89.9%, 53.7% and 86.7% of the runoff variations. In addition, Pearson’s correlation demonstrated that girth explained sediment loss on the 5-year fallow (r = 0.807, p < 0.01), while a strong positive and significant association existed between sediment loss and crown cover on the farmland plot (r = 0.835, p < 0.01). The vegetation components were mutually responsible for 48.4%, 84.3%, 95.1% and 85.9% of the changes in sediment enrichment on the 5-year-, 10-year-, 3-year-fallow and cultivated farmland, respectively. The study found that mature/older fallows had a more substantial attenuating impact on soil erosion control than younger fallows.