Biodiversity management on the MCR iron ore mine
The Morraria de Santa Cruz lies approximately 30km south of Corumbá in the State of Mato Grosso do Sul (Brazil). Mineração Corumbaense Reunida, a subsidiary of Rio Tinto, currently operates an open-cast iron ore mine on the mountain. The Morraria, the main body of which covers about 30 square kilometres and reaches approximately 1060m above sea level, is one of a series of inselbergs lying on the edge of the Pantanal wetlands. It is clothed in a mixture of grassy savannas, cerrado (tree savanna) and semi-deciduous/ deciduous forests.
In 2005 The MCR mine was entering a period of expansion during which its production is predicted to increase tenfold. This expansion was to be supported by the development of a new steel plant at the foot of the mountain.
The full implications for the environment and biodiversity of the Morraria de Santa Cruz remain unclear, as mine expansion plans and ownership have changed. However, it is evident that continued mining on the site will have a significant impact on a range of vegetation types.
Preliminary vegetation survey
The survey (2005) was designed to provide essential baseline information on the vegetation of the area, including data on rare species and sensitive habitats. Vegetation was surveyed using a combination of remote sensing (satellite imagery), ground-truthing, and quantitative survey techniques, whilst training was provided for the local students.
The primary objective of the initial survey, jointly funded by Rio Tinto and MCR, was to undertake rapid characterisation and mapping of the vegetation on the mountain. The results are now being used:
Kew continued to support these processes through the following activities:
Vegetation on the mountain: a brief summary
The zonation of the vegetation is closely related to topography. The central part of the mountain is defined by a curved ridge forming roughly three sides of a square (N, E & W). The outside of the ridge is characterised by a steep scarp slope with intermittent cliffs. On the inside the ground slopes more gently, descending via a series of secondary ridges and gulleys towards the central area and thence to the south. The bases of these gulleys, though apparently associated with drainage, were dry when visited and showed no sign of watercourses.
The upper parts of the ridges are clothed in grassy savanna with scattered shrubs, classified as campo sujo vegetation. The shrubs generally become more abundant with decreasing altitude. Descending towards the centre of the massif, vegetation typically passes through cerrado and cerradão to tall semi-deciduous forest. Tthere is a clear association between these changes and altitude, but also other factors such as slope, soils and hydrology.
Although this is the general trend, the vegetation does not always follow the sequence described. In some areas, for example, there is direct transition from campo sujo to cerradão. In these locations the vegetation at the forest edge generally includes a scattering of tall shrubs and trees typical of cerrado vegetation, together with species more typical of forest margins, but there is no actual cerrado band. Similarly, in places where campo sujo makes a fairly abrupt transition to tall semi-deciduous forest (e.g. in the upper reaches of some of the valleys), there is little separating them except a narrow band of marginal vegetation with scattered cerrado and cerradão elements.
Within the forested areas the transition between cerradão and tall semi-deciduous forest is gradual, and cannot be defined very precisely. These forest types are similar in floristic composition, the principal difference being the presence of typical cerrado/cerradão species in the former. For the purposes of mapping, these were defined by crown size of the trees (visibly greater in the taller semi-deciduous forest). Although in general this forest type is confined to the lower parts of the mountain slopes, it can ascend to greater altitudes in the bottoms of the valleys between secondary ridges.
On the steep scarp slopes around the edge of the mountain, the vegetation is generally composed of a mixture of campo sujo (over from the tops of the ridges), cerrado (dominating much of the the slopes) and cliff vegetation (a mixture of campo sujo, cerrado and epiphytic/lithophytic species). At the base of the scarp there is a fairly rapid transition to tall semi-deciduous forest.
Secondary vegetation on the mountain occurs in a range of locations including abandoned mines (generally covered in grasses and scattered herbaceous and shrubby species), road and clearing margins (with a typical mixture of introduced weeds and pioneer species) and cleared areas that have not been mined. These areas support either scrubby vegetation dominated by cerrado species or, more extensively, dense secondary forest dominated by pioneer forest species. This type of vegetation covers a large area to the north of the main access road to the mine.