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, 20 per cent of all bird species are confined to just two per cent of the land. In this respect, it is necessary to have a series of nature reserves which span different habitats. Other areas which do not contain endemic species are of lesser importance for conservation. In Brazil, the most important areas are felt to be the eastern slopes of the Andes and the coastal lowland areas (ICBP, Putting Biodiversity on the Map 1992) rather than Amazonia. This is because while there are endemic species in Amazonia, they tend to range over a fairly large area and so are more resistant to loss of habitat.
While the first priority must be to protect biodiversity hot-spots, the largest loss of biodiversity is happening due to clearance of the tropical forests and action must be taken to prevent this. One way is to encourage sustainable harvesting of the forests. A survey of a one hectare plot of land in Peru identified fruits, vegetables, wild chocolate and latex that could be sold on the Peruvian markets, with an annual net profit of $422. This is just based on what is presently known about the biological riches there. This sustainable use of known natural resources and biodiversity conservation through the creation of biodiversity reserves must be promoted by international institutions and national governments of developing countries. We can not afford to waste the precious natural wealth upon which all human development depends.