Amazon (Rondonia)
1975 - 1986
What is the relationship between the landcover change that we have found
within Australia over the last twenty years, and global trends?
To answer that question it is necessary to step far back in time. For at
least the last 10 000 years humans have cleared forests to create either
grasslands, croplands or, most commonly, a mixture of both. It is important
to realise that the croplands and pastures that are the basis of subsistence
for the developed countries of the northern hemisphere are the consequence
of the deforestation of temperate woodlands in Europe, or of ploughing the
native grasslands, such as the Great Plains in the USA and Canada.
Thus the great human civilisations of the first world are based on deforestation.
There is debate about whether it was the development of agriculture that
permitted a dramatic expansion of sedentary human populations or that sedentary
agriculture arose in response to the burgeoning needs of growing human populations.
Whether cause or consequence, growing human populations have been and are
still associated with the expansion of, and latterly, with the intensification
of, agriculture.
Two examples from other continents are included in this Chapter to reinforce
the idea that the landcover consequences of agricultural landuse are similar,
and reflect common underlying processes.
Use your browser to open each image
in a new window to compare them.
The landcover change between the two dates, 1975-1986, for an area in
Brazil. The landcover is being changed from tropical rainforest to cropland
or pastures. This particular landcover conversion, more commonly called
tropical deforestation, has generated a great deal of international criticism
that is based on very uncritical thinking. I do not condone this activity.
However, I predict that if you, the reader, are under the age of 25 years,
you will witness the clearing of all tropical rainforests in your lifetime.
The first pair of images are readily recognised because they
have been prominent in public debate and media reporting for the last few
years.
From the pair of images, the landcover change between the two dates, 1975-1986,
is easily interpreted. The location of these changes is in Rondonia, Brazil.
The landcover is being changed from tropical rainforest to cropland or pastures.
This landcover conversion - more commonly called tropical deforestation
- has become the focus of attention amongst environmental and political
leaders and the target of much (valid) criticism. However, the fundamental
driver of this deforestation has been ignored in the exhortations to the
Brazilian government to stop it.
The Brazilians are burning and clearing the rainforest not because they
are ecological vandals, but because they wish to grow food.
Increasing human populations drive an increasing demand for foodstuffs.
This demand has been met in Rondonia by increasing the amount of land used
for agriculture. Agricultural landuse drives the landcover conversion of
tropical rainforest to grasslands or croplands.
With this causal connection, the ultimate tradeoff is between people and
rainforests. As the human population increases in tropical areas, (which
have the highest rates of increase), so the area of tropical rainforest
will decrease. Rainforests are apparently being cleared with dramatic speed
throughout the tropics.
I want to add a note about this particular Brazilian example. In spite of
it being targeted by the developed world, there is one significant way in
which this deforestation activity is both atypical and soluble.
This epoch of deforestation was government subsidised; principally by the
construction of the road that catalysed the spread of forest clearing. It
was the Brazilian government's intention to encourage agricultural expansion
in Rondonia and thereby solve a rapidly growing urban population problem.
The slogan was - 'for the people without land, here is land without people'.
Unfortunately, the land was not without people, and large numbers of the
Amerindians have been displaced or murdered. A similar claim, Terra Nullus,
was made about Australia by the European settlers with similar results.
Now, with the application of very intense and diverse international pressure,
the Brazilian government has withdrawn the subsidy and the rate of deforestation
has significantly declined. Agricultural experts suggest that the pastoral
and agricultural systems installed in the middle of this rainforest cannot
be sustained, either ecologically or economically.
