Landcare Revegetation Essay, Research Paper
Rehabilitation is the process of reclaiming land for economical or
conservation purposes. This process usually involves
re-vegetation. The main aim in rehabilitation is to either return the
land to a self-sustaining ecosystem or prepare the land for human
use, i.e. crops, pastures and plantations. Rehabilitation should take
place at a rate that is significantly higher than natural succession.
Several principles are implemented for successful rehabilitation. Of
these principles includes the need for preventing disasters and
anticipating problems before they arise, if this is taken to
consideration then rehabilitation will be less costly and trouble
free. When rehabilitating a site, all the components making up the
ecosystem need to be looked at individually. They include soil,
climate, vegetation, time and animals. These components need to
interact at certain rates in order for the desired effect to be
achieved and so might need to be altered. There are other
principles of rehabilitation, which will be discussed, in greater
detail.
There are many methods and strategies involved in rehabilitation
which, are specific to a site. In this case, surface mine reclamation
and farmland will be looked at. A step by step illustration of the
processes involved will be covered. When rehabilitating mine land,
it is important to first prepare a plan before mining takes place.
Researching and obtaining data on the floral and faunal elements
of the ecosystem by conducting surveys of the upper, mid and
under-story species present. If the aim is to restore the land to its
original ecological balance and to conserve the species present,
then further studies should be conducted on the ecology of the
native species, i.e. seed biology of all species. Propagation
techniques and the order of re-establishing species should be
studied. When rehabilitation work was conducted on the bauxite
mines in the southwest of W.A., special research was conducted
on the germination requirements of sown seed.
The aim in this case was to re-establish a self-sustaining forest,
which maintains water, timber and all the valued qualities of forest.
The timing component was carefully considered when removing
topsoil in summer to ensure maximum seed store this was achieved
when the forest was cleared after seed set took place. Hand
seeding was done soon after ripping in order to ensured that the
seeds other propagules were well established before germination.
When conducting mining operations it is generally desirable that
rehabilitation work takes place at the same rate as mining occurs.
The soil component in this case needs to be removed in layers
(topsoil and overburden) and stock piled during the mining
process. The topsoil is very important because is contains most of
the seed, propagules and micro-organisms which are needed for
successful revegetation. Topsoil is often treated with fertiliser after
being reapplied as it is already nutrient poor and would not be able
to support new plant growth. A major purpose for rehabilitation is
to reduce of soil erosion. This also a problem that occurs during
the early stage of revegetation. Young seedlings cannot provide
enough protection for the soil as wind and rain move soil particles.
It would also be unwise to plant too many small shrubs, i.e.
legumes to help combat the problem as they will compete with
other seedlings. Before replacing soil it is important to ensure that
the land is reshaped so to resemble the original landscape.
Adequate drainage is necessary and can be achieved by deep
ripping the soil. This also ensures that the soil is not compacted,
well aerated and root penetration is better achieved. Before
returning soil to a site, it should be thoroughly tested for toxicity.
It is extremely important to treat affected soil overburden before it
is returned. When the aim of a rehabilitation project is to return the
land to a self-sustaining ecosystem, then a sound understanding
of the nutrient cycle is required.
The least abundant and most limiting nutrients in Australian soils
are phosphorus and nitrogen. Nitrogen is mostly present in
organic matter and is accumulated in the roots of nitrogen fixing
plants i.e. legumes. Most phosphorus can be added as fertiliser.
This will aid the initial growth of vegetation but will not sustain the
ecosystem?s needs. The addition of mycorrhizal fungi in this case
would be most appropriate.
Mine site rehabilitation is probably the most involved of all the
types. Before any rehabilitation or research is conducted, it is
necessary that the post-mined land use be agreed upon. It would
be at the
significant cost reduction strategy is rehabilitating an area in a way
that it would require minimum post-mining management. This
means that the area will have to be self-sustaining environment.
Management can be time consuming and very expensive if feral
animals, invading stock of harmful human activity takes place.
Pastures and farmland are less affected by such activity and tend
to recover quickly as opposed to forests and arid ecosystems.
Maintenance after rehabilitation is always necessary, this would
include replanting dead seedlings, pest and weed control, fire
management, fertiliser application, water during dry periods and
the control of soil pH.
So far only mine-site rehabilitation work has been looked at.
Farmland rehabilitation or reclaiming devastated land for farming
use is considerably different to mine-rehabilitation in that the end
result will not be a self-sustaining ecosystem but will require
human input for stability to occur. Similar principles apply but are
only used when appropriate. The most common sources of
farmland degradation include are:
Salinity
Water erosion
Wind erosion
Waterlogging
Acidification
Eutrophication
Decline in overall soil condition
Most of these factors are interrelated and do not occur exclusively.
Water related problems can be solved by increasing water use and
introducing good water disposal systems. The presence of
perennial vegetation i.e. remnant vegetation, agroforestry and
perennial crops will significantly increase water use because they
transpire all year round. Waterlogging, salinity and water erosion
can too be controlled by drainage strategies i.e. graded contour
banks and reverse interceptor banks (on hills and slopes).
Wind erosion is a common factor in farmland degradation and
occurs in three different ways.
The most major form of wind erosion is saltation which, transports
about 50-80% of soil. Suspension and surface creep account for
the remainder of the erosion process. Wind erosion can be avoided
by planting trees at regular intervals which, will act as wind breaks.
Having some crop or pasture stubble as well as decreasing field
size (decreasing saltation) are sound methods of reducing wind
erosion. Tilling the land at right angles to erosive winds will also
decrease saltation impact. If the farmed land cannot resist
degradation effects and preventative methods are ineffective, then
it would wiser to rehabilitate the land so that is self-sustaining.
Rehabilitation and reclamation is essential for the conservation of
heritage and economically significant land. Land is a precious
resource, which is non-renewable. If rehabilitation does not take
place in a disturbed piece of land, that land might continue to
erode and never return to its normal functioning capacity.
Rehabilitation can be an accelerated form of succession. This
process returns the land to its normal stability at a higher rate than
if it was left alone. Rehabilitation is an ever-evolving area of study,
which involves the manipulation of certain factors to suit
unchangeable factors such as climate and topography.
Revegetation is perhaps the most common and most effective
practice in mine rehabilitation. It has been proven to stabilise soil,
return nutrients to non arable land and increase the aesthetic and
economic value of land. Over time rehabilitation has improved and
scientists are becoming more accurate in predicting outcomes. The
general public too is becoming more aware of the importance of
rehabilitation. Community involvement is increasing and
rehabilitation laws are being well defined and enforced. It would be
unrealistic to assume that in all cases rehabilitation will restore land
to its original condition as human impact leaves is permanent mark
on the environment. However if rehabilitated land is carefully
monitored and managed, the results will almost always be
agreeable. More effort is being invested in rehabilitation and
research in rehabilitation as we resources dwindle and
conservation is becoming more valued.
References
AMIC.
Mine Rehabilitation Handbook.
Australian Mining Industry Council 113, (1990).
Russell J. Hutnik, Grant Davis.
Ecology and Reclamation of Devastated Land.
Gordon and Breach, New York. (1973)
E.S. Lyle, Jr.
Surface Mine Recalmation Manual.
Elsevier Science Publishers, New York 1987.
Ward, S.
Rehabilitation and Revegetation. In: Best Practice Environmental
Management in Mining.
Environmental Protection Agency, Canberra (1995)