Mine Closure - Mining and the Environment: From Ore to Metal - page 820

FIGURE 21.3
Nurseries are Surprisingly Small, Even
for Large Mines

Legumes and Grasses

Legumes are commonly used in rehabilitation; some as discussed above make good cover
crops. Others can be used to make hedges, or as individual shrubs or trees. Most vegeta-
tion communities benei t from inclusion of one or more legume species because of their
nitrogen i xing properties. Grasses are also used as components of many rehabilitation
vegetation communities. Most grasses have good soil binding properties while their seed
provides food for a variety of insects, birds and small mammals. Clearly, if local grasses are
available, these should receive preference. However, there may be difi culties in establish-
ing local grasses in the short-term, in which case consideration may be given to temporary
use of carefully selected exotic grasses. Hybrid grasses which are sterile, are obvious candi-
dates for consideration. A readily available example is Regreen, a sterile wheat/wheatgrass
hybrid.

If local grasses are available, these
should receive preference.

Vetiver Grass

Vetiver grass ( Vetiveria zizanoides ) is another widely used species in mine land rehabilita-
tion, which has proved to be both highly effective and non-invasive (World Bank 1993).
This densely tufted grass has been used for erosion control in many tropical and semi-
tropical situations, particularly on moderate to steep slopes where it is planted along the
contours to form dense hedges ( Figure 21.4 ) which interrupt overland l ow and trap sus-
pended sediment. The species is extremely versatile, being tolerant of extended l ooding as
well as drought conditions.
This is not a short-term solution to erosion control as it commonly requires two or three
years to establish dense, continuous hedges. However, as this is a perennial grass which is
sterile outside its natural swampy habitat, it is suitable for retention as part of the long-term
vegetation community in both agricultural and natural vegetation applications. In a hand-
book entitled 'Vetiver Grass - The Hedge Against Erosion', The World Bank (1993) com-
pares the use of Vetiver Grass hedges to constructed Earth bunds or banks. A particular

Vetiver grass ( Vetiveria zizanoides )
is widely used species in mine
land rehabilitation, which has
proved to be both highly
effective and non-invasive.