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 best interest of the mining company to reduce costs. A

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)