Assessing The Ecological Status Of Woody Plant Species At Eroded Sites Of Abia And Imo States, Nigeria

Abstract

Woody plant species up to 0.10 m and above in height growing in and within 0.5 m from the edges of ten gully erosion areas of Abia and Imo states of Nigeria were enumerated in January and July 2000 through July 2003. Questionnaires were served to find the causal factors of each gully. The plants were enumerated and classified into their life form. The index of similarity according to Sorensen was used to determine the similarity of the sites. It was observed that a combination of factors contributed to form a gully. The gullies were caused by discharge from road culverts, 80%; run off from building, 70%; footpath, 60%; deforestation, 30% and flood 10%. A total of 49 plant families comprising 100 species were identified at the sites. The families Cyperaceae and Euphorbiaceae had the highest representation of species. The Phanerophytes, Therophytes and Chamaephytes were represented by 57.5%, 23.8% and 13.7%, respectively. A combination of grasses such as Acroceras zizanioides, Cynodon dactylon and Perotis indica and some tree species such as Antiaris toxicaria, Entandrophragma utile, Gossweilerodendron balsamiferum, Khaya ivorensis, Nauclea diderrichii and Terminalia superba were recommended for planting in and near gullies at a espacement of 1.0 x 1.0 m. The slope angle ranged from 55 to 122 degrees. The sites were similar. Variations in the species composition were not recorded within the studied period. The study revealed that some previous attempts to control gully erosion with Gmelina arborea failed because many of the trees were carried into the gullies by flood. It was concluded that the use of monoculture plant species in erosion control project should be minimized.

KEY WORDS: Woody plant, erosion, gullies and enumeration.

Global Journal of Environmental Sciences Vol.4(1) 2005: 77-85