Application of ecosystem function analysis (EFA) in assessing mine tailings rehabilitation: an example from the Mhangura Copper Mine tailings, Zimbabwe
GM Dowo, S Kativu, DJ Tongway
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 longterm
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.
Keywords: ecosystem function analysis, EFA, mine tailings, rehabilitation,
monitoring, Mhangura Copper Mine, ecosystem function.