Journal of the Southern African Institute of Mining and Metallurgy
versão On-line ISSN 2411-9717
versão impressa ISSN 0038-223X
DOWO, G.M.; KATIVU, S. e TONGWAY, D.J.. Application of ecosystem function analysis (EFA) in assessing mine tailings rehabilitation: an example from the Mhangura Copper Mine tailings, Zimbabwe. J. S. Afr. Inst. Min. Metall. [online]. 2013, vol.113, n.12, pp.923-930. ISSN 2411-9717.
The widespread environmental damage caused by slimes dam construction requires rehabilitation as one of the key management strategies towards land restoration. From the time when Mhangura Copper Mine in Zimbabwe was shut down in 2000 due to viability problems, no follow-up studies were carried out on the slimes dams to assess their development with respect to ecosystem function and long-term recovery. The ecosystem function analysis (EFA) method was thus employed to achieve this end. EFA is a monitoring procedure that establishes how well an ecosystem functions as a biophysical system through the use of rapidly assessed field indicators. The field procedure makes use of simple visual indicators that are related to various soil surface processes. Conventional sampling methods are used to collect the vegetation data. The data was first analysed using landscape function analysis (LFA) software packages and then with various multivariate statistical techniques. In total 27 species were recorded from 14 families; 21 of them occurring in the acacia woodland and only 8 on the slimes dams. Hyparrhenia sp. was the dominant grass on Dam 5 and Imperata cylindrica dominated Dam 6. Acacia saligna was the most abundant tree species on the dams. The tree layer on the slimes dams was not as developed as the grass layer. The rehabilitated slimes dams converged with the natural woodland for the LFA indices of stability, nutrient cycling, and infiltration, which suggested a high level of functionality. The main factors affecting the sustainability of the rehabilitation are postulated to be fire, grazing, and tree harvesting. The study contributed to the importance of, and methods used for, assessing ecosystem function on rehabilitated slimes dams in Zimbabwe, which are often ignored as most efforts focus on the establishment of vegetation on the dams.
Palavras-chave : ecosystem function analysis; EFA; mine tailings; rehabilitation; monitoring; Mhangura Copper Mine; ecosystem function.