Download The Amazon Rainforest should be conserved to protect the

The Amazon Rainforest should be conserved to protect the
biodiversity of the planet. This is essential for the well-being of
mankind.
‘O, wonder! How many goodly creatures are there here! The day has passed delightfully. Delight itself,
however, is a weak term to express the feelings of a naturalist who, for the first time, has wandered by
himself in a Brazilian forest. The elegance of the grasses, the novelty of the parasitic plants, the beauty of
the flowers, the glossy green of the foliage but above all the general luxuriance of the vegetation, filled me
with admiration.’ (Charles Darwin, Journal of Researches, 2nd edition 1845)
Anyone who travels from Europe to the Amazon is immediately struck by the richness of the
vegetation and the many different forms which life takes. This is a superficial impression: the Amazon
basin is one of the most species-rich areas in the world. It is also under serious threat from increasing
human development, along with most other areas of the planet. Ninety percent of the land area of the
earth has been disturbed already and five percent is burned annually. Tropical rainforests, which are
widely believed to contain a majority of the species on earth, are being destroyed at the rate of 1.8 per
cent per year, twice that of a decade ago. Because of these threats, the study of biological diversity,
biodiversity, has taken on a new importance.
Biodiversity is: ‘The sum total of all the plants, animals, fungi and micro-organisms in the world, or a
particular area; all of their individual variation; and all of the interactions between them.’ (P H Raven,
Defining Biodiversity, Nature Conservancy 1994)
About 1.4 million species are currently identified but it is estimated that there are about ten million species
on the planet–some say up to 100 million. About 90 per cent of the named species occur on land, mostly
in the temperate regions of North America, Russia, Europe and Australia. All species, including humans,
are dependent on others. Some eat or are eaten by others; some are used for the nesting material of
others; some are necessary for the reproduction of others. The web of life which these species together
make up, known by ecologists as an ecosystem, is the means by which life captures and uses the energy
of the sun, which drives all life on the planet.
Within an ecosystem, different species play different roles, with the most important being played by a
keystone species. The loss of a keystone species is catastrophic for an ecosystem. This is well illustrated
by the sea otters of the Pacific coast of North America. The sea otters feed on sea urchins, which in turn
feed on giant kelp. The giant kelp, whose fronds can grow by six inches a day, provides a habitat for
numerous species of fish. In this case, the fish are not essential to the ecosystem’s survival. The fish are
not the keystone species, the sea otters are. The sea otters were hunted by fur trappers to near extinction
over much of their range by the end of the 19th century and as a consequence the kelp forests were
decimated by sea urchins and fish catches in the area plummeted. As a consequence of conservation
measures, sea otters are returning but still there are areas of coastline which are physically similar but
with completely different ecology, depending on whether there are sea otters present.
What is causing loss of biodiversity?
There are four main human reasons for loss of biodiversity. These are, in roughly historical order, overkill,
introduction of alien species and diseases, habitat destruction and global warming.
Overkill refers to the killing of a species at a greater rate than its potential to reproduce and is
something at which pre-historic man excelled. In Africa, large animals had evolved along with man for
millions of years and so could look after themselves. In other parts of the world, large animals
disappeared soon after men arrived. In the Americas, after the retreat of the last glaciers, people moved
into the continent from Europe and soon 80 per cent of the great Pleistocene mammals, such as the
mammoth and giant ground sloth, became extinct.
The voyages of discovery around the world introduced alien species to other lands. Rats travelled in
boats and swam ashore at any port of call, while other animals were introduced deliberately, such as
rabbits in Australia for food. Introduced species might either directly attack the indigenous species, for
example by eating the eggs or young, or simply out-compete them for scarce food resources. For
example, the invasion of rats onto the Galapagos islands threatens the survival of the giant tortoise.
Habitat destruction is the biggest threat to species diversity. If a species only exists in a very small
area, destruction of that area by, for example logging, will wipe out the species. More subtlety,
fragmentation of forests will eliminate species which require a large area for their habitat, such as birds of
prey. We can estimate the rate of species loss from a species area curve (Wilson and MacArthur, 1967),
which relates the number of species to the area. From this theory of island biodiversity, if a habitat is
reduced in area by 90 per cent, 50 per cent of its species will be lost. The deforestation of the rainforests
world-wide is estimated to be causing the extinction of some 50,000 species every year, many of these in
Amazonia, assuming that there are 10 million species.
Global warming, finally, causes a species to need to move its range. If the change is very rapid, many
species, such as trees, may not be able to move their range fast enough and so will become extinct. In
addition, if the range is limited in some way, for example by a city or the edge of a continent there will be
nowhere to go. This could cause big problems for national parks. These have been set up in areas of
relatively high biodiversity but if the climate changes, the park may not be able to move with it. This is not
yet a problem.
Why is biodiversity important?
Humans have been dependent upon other species since the beginning of our existence. Our
development is largely based upon the way in which we use wild species. The genetic diversity of major
crops, such as cotton or potatoes, is of obvious importance, while other plants may have other uses as
yet unknown. There are literally hundreds of human needs which could be met by the huge and yet
largely untapped gene pool which exists in areas such as the Amazon. In particular cures for many
serious illnesses such as cancer and even AIDS may exist in forest flora or fauna. Seven thousand
species of plant have been collected for food but, of these, 20 species provide 90 percent of the world’s
food and just three–wheat, maize and rice–supply more than half. Chemical prospecting– the survey of
wild species for new medicines and other useful chemical products–is of increasing importance but is
impossible when species become extinct.
Preserving biodiversity is also important in protecting the climate. Slash and burn land use in the
tropics pumps out about 23 per cent of the total greenhouse gas produced by human activity world-wide.
Burning also releases soot, nitrogen oxides and non-methane hydrocarbons among other harmful
compounds. These have deleterious effects upon global climate change, human health and ozone
depletion. You only have to look at the destruction now happening from fires in Borneo– which have cast
a pall of smoke for thousands of miles around the region–to see the fate which may await Amazonia.
We need to preserve certain aspects of the environment which enrich our lives. It has been argued
that humans have an intrinsic need for nature, a “biophilia” (E O Wilson, The Diversity of Life 1992) and
should preserve nature for our own self-preservation. Indeed, the preservation of tropical forests is
instinctively felt to be important by most people who visit them. Finally it can be argued that any animals
which can suffer pain should have rights and that we should draw the line “somewhere between a shrimp
and an oyster” (Peter Singer, Animal Liberation 1975).
Protecting Biodiversity
If we want to preserve a few large, glamorous species like tigers, which are threatened particularly by
hunting, zoos can be important. The only practical way to conserve the majority of species is to conserve
them on the spot, by protecting their ecosystems. The first priority is to protect those species which are
most threatened– those which are endemic to a particular area (that is, occur nowhere else).
Conservation effort is now concentrated on identifying “hot spots” which contain a high level of endemic
species and protecting these. For example,
The importance of biodiversity has to be put into perspective.
Biodiversity is one human need amongst many. The instrumental use
of biodiversity in the Amazon has to be balanced against other
development needs of the Brazilian people.
Amazonia is generally seen as a kind of paradise, unchanged throughout thousands of years, which has
allowed the high level of biodiversity to develop. Contact with humans is perceived as modern and
negative, automatically putting the forests under pressure. There are at least three reasons for doubting
these views.
First, a key principle of evolutionary theory is that the rivers and other natural barriers which limit
contact between animal populations are what allow them to develop along separate evolutionary paths.
The very diversity of life in the rainforests suggests massive disturbance in the past. While there is
disagreement among scientists about whether this is most likely to have been due to forest shrinkage
during the last ice age, forest fires during drought, the division of the forest by the formation of the Andes
range, human intervention, or to some other cause, or combination of causes, some sort of disruption
seems to have been likely.
Second, people moved into the Americas from Europe a long time ago, perhaps as long as 20-30,000
years ago (Gore, The Most Ancient Americans, National Geographic October 1997). There is
archaeological evidence that people moved into the Amazon at least 10,000 years ago, using slash and
burn farming methods, based mostly on root crops. This created a rich texture of primary (untouched)
forest, interlaced with secondary re-growth. Before contact with Europeans, it is estimated that between
one and six million people and possibly more, lived in Amazonia, similar to today. When the Europeans
arrived in Central America, they brought with them diseases such as smallpox and influenza, which
spread down from Central America before the Europeans arrived in South America and caused a
population crash. This contributed to the myth of an untouched virgin forest, with a few savages within
and around it, rather than the developed region which had existed just a short time previously.
Third, most people in Amazonia nowadays live in cities. Prior to contact with Europeans far more
people were involved in farming and lived in rural areas. These people would have raised crops, rather
than cattle, so a higher rural population could be supported. The overall cleared area of forest in 1500
was probably close to that in 1990, although the individual areas cleared would have been smaller. If you
could have flown over Amazonia in 1500 after the rainy season you would have seen innumerable small
fires dotting the forest. The common idea that the Amazon is being destroyed by land-hungry colonists
must be put into context with this long history of human inhabitation of the land. Amazonia should be
considered as an anthropogenic forest–one which has been produced in its present form by man. People
in Amazonia have altered the distribution of animals and plants for thousands of years, along with
triggering increased soil erosion and altering smaller rivers and streams. In fact, it is not unreasonable to
consider humans as a keystone species in much of the area and continued human intervention to be vital
to its health.
Amazonia, far from being an untouched paradise has been the site of massive disruption, both natural
and human, over thousands of years. At the same time, it has managed to support a much larger rural
population than today, without triggering massive environmental collapse.
How much biodiversity is being lost ?
It is argued that there is a massive loss of biodiversity, mainly caused by habitat destruction, of perhaps
50,000 species a year. The evidence for this is slender. Scientists use two ways to estimate extinction.
The first is straightforward: count them. The second is by extrapolating loss of species by measuring the
loss of different kinds of habitat.
A species is said to have become extinct if it has not been seen in the wild for over fifty years. On this
basis, the International Union for the Conservation of Nature and Natural Resources (IUCN) has reported
593 extinct animal species (IUCN Red list of Threatened Animals 1994). Another study (in 1992) listed
384 vascular plants which have become extinct. This approach will miss many species–potentially
thousands– which have never been described by science. In addition, this approach does not mean that a
species is lost–for example the small wild cat (the guigna) weighing just five pounds, was recently trapped
on an island off Chile for the first time in seventy years. (National Geographic October 1997).
Documented extinction of animals peaked in the 1930’s and since then has been running at around
ten per decade. About 75 per cent of recorded extinction has occurred on islands, including almost all bird
and mollusc extinction. Island species are far more vulnerable because they have a small, confined range
and may not have evolved to deal with predators. They may also be better studied by scientists and are
more likely to be missed. Very few extinctions have been recorded in continental tropical forest habitat,
where mass extinctions are predicted to be occurring, although this may be partly due to the difficulty of
demonstrating extinction.
The extrapolation method is based originally on measurements on islands, which related numbers of
species to the size of island. These showed that, if one island is ten times the size of another, you would
expect to find twice as many species. The converse also holds: if you reduce the size of a habitat to ten
per cent of the original, 50 per cent of the species will remain. It is these mathematical models which are
used to make the predictions of enormous loss of biodiversity.
How useful are these predictions? The simple answer is that we do not really know and more work is
needed. The equations predict the number of species which will be found in an area of forest, not whether
the species only exists there. In addition, forests are not uniform but contain areas of different levels of
diversity. Vernon Heywood and Simon Stuart, who head the IUCN’s Plant and Species Conservation
Program, recently noted that “there is currently little evidence of extinction at the rates predicted by some
theoretical models”. This does not, of course, mean that there is no cause for concern but that the figures
which are commonly presented should be treated with caution. If biodiversity hot-spots are protected, it
may be that most of the biodiversity will be too.
Why is biodiversity important?
It is important for us to work out what value biodiversity has to us. In arguing for the preservation of
biodiversity many writers say that nature has an intrinsic value beyond any potential uses it may hold for
humanity. They believe that the human species should be equated with other species on an equal plane
and that we should not be so arrogant as to think that we are at the top of a natural hierarchy. Others put
forward an instrumentalists case. They argue that biodiversity should be preserved because it could have
potential benefits for humanity in the form of as yet undiscovered drugs or foodstuffs. There are serious
problems with both arguments.
First, the case that nature has an intrinsic value above and beyond meeting human needs. Nature has
no intrinsic value. One can agree that there is no hierarchy in nature in evolutionary terms as all animals
are on the same plane. But humans are unique in their ability to create society and have a right to be
arrogant about their position from that perspective relative to other species. There are many reasons for
this uniqueness, the most important is that we are the one species, that through creating society, has
separated itself from nature. Humanity as a social entity is completely divorced from nature. The natural
world in and of itself does not have any social capabilities. Unlike animals we do not just live in nature and
respond to its dictates, we manipulate it. Although we are not alchemists–we cannot defy nature and
conjure something out of nothing–our unique social development has been achieved through
manipulating nature for our own particular needs. In so doing we have been able to transcend nature’s
meagre gifts to us. Our manipulation of biodiversity is one aspect of this process. Only human beings are
able to endow species with value, so biodiversity should be brought down from its pedestal and
considered as one human need among many.
We may feel that we want to preserve certain aspects of the environment which enrich our lives. The
preservation of tropical forests is felt to be important by most people who visit them. Certain species are
important for aesthetic reasons. Other species may be of less immediate interest but their existence is of
scientific and intellectual importance. We must be prepared to make distinctions and say that the tiger is
more important to us than some species of tree slug, identical to another species except to an expert.
Once we have gained knowledge about a chemical derived from a species, which can be used to
make a drug, we can synthesise the chemical artificially much more cheaply than we could extract it from
the plant. From that point on, the plant loses a lot of value. Even a keystone species is only of value if the
ecosystem which it supports is important to us.
The argument that biodiversity should be preserved because of its potential benefits for humanity is
more complicated but equally problematic. Humanity is unique and indeed superior to nature as the only
species capable of consciously intervening in nature and utilising it to serve its own needs and thereby
allocating it value. It is therefore entirely rational to preserve biodiversity as a pool of resources which
could be of potential benefit or value to humanity. The problem is that advocates of such an approach
refuse to put the argument for potential benefits into the broader context of human needs. They focus
almost entirely on the future potential benefits of biodiversity preservation and ignore the immediate
needs of humanity in the here and now. In fact, attempts to preserve biodiversity in the Brazilian Amazon
have often undermined the ability of humanity to meet its immediate needs.
Environmentalists’ demands for biosphere reserves, sustainable development programmes and
nature parks and the general impact of the preservationist approach have prevented many industrial,
mining and energy development programmes from being completed in the Brazilian Amazon. Potential
benefits are just that–a potential–of unknown benefit to some known or even unknown need. Today we
have plenty of real and immediate needs. There exist pressing social problems such as poverty which we
know that we can solve with resources that we know exist and which we have at our immediate disposal.
Brazil has a foreign debt of about US$150 billion and this is a major contributory factor to the misery
experienced by its 43 million citizens who live below the poverty line. Brazil also has the Amazon, a
source of fantastic wealth which could help end this misery. It is estimated that its timber supply is alone
worth US$5 trillion. To this can be added the value of its huge stocks of minerals and its massive
hydroelectric potential.
The question is how should the Amazon be utilised to serve the needs of the country which
possesses its wealth? By focusing almost exclusively on a preservationist approach the resolution of such
huge problems would be delayed and indeed may never arrive. The rational answer is a trade-off
between the actual and the potential. A trade-off between known solutions to immediate problems and the
future benefits of an unknown potential. If a mineral resource which could generate billions of dollars of
foreign exchange to pay off the debt, is discovered in an area of potential biological wealth then the mine
must be built. If a dam is planned for an area which is known to have genetic material to cure cancer or
malaria and there are alternative sites for the dam, build it elsewhere. The immediate needs of first
Brazilians and then humanity generally, should come before any potential benefits.
Many scientists calling for the preservation of biodiversity are not driven by rational calculations over
the instrumental use of biodiversity. Much of their scare-mongering about the extent of loss of biodiversity
and the problems of population pressure does not rely on a scientific and rational consideration of the
benefits to Brazilians or humanity generally but on sentiment. Such sentiment will not only impede
science but human development as a whole. Arguments about conservation, including those about loss of
biodiversity, reflect a sentiment that says we no longer have much faith in the progress of human
development. That lack of faith is reflected in the current idea that humans have already gone too far in
developing the world and its resources. Most people are today concerned with putting the brakes on.
Rather than looking for paths to make further developments in human progress the arguments for
conservation now have the upper hand. The irrational, one-sided preservationist approach to the
utilisation of biodiversity fits into this conservative, conservationist mood. We should reject it if we want
human society to go forward and attempt to solve the real problems we are still confronted with in
Amazonia and elsewhere.