1.5 Introducing another variable: humans

For some considerable time humans have had a major impact on ecosystems on the Earth’s surface and that impact is increasing. The impact can be small, such as using insecticide on an ants’ nest (though that is certainly not a small event for the ant colony), or so large as to completely destroy ecosystems. Using an insecticide on an ants’ nest is a deliberate attempt to destroy an ecosystem, but other actions may work to save an ecosystem.

Humans have not always had the degree of control over ecosystems that they have today.

Humans were originally very much an integral part of the ecosystem: they lived in caves, gathered roots and berries and hunted wild animals during the day. Humans themselves were hunted by those wild animals.

Fire became an important tool for humans. It provided warmth and protection. Australia’s first inhabitants used fire to modify the environment for their own use. Fire was used to remove undergrowth and encourage the growth of new shoots, which would attract animals. It has only recently been recognised that there was often a pattern to the burning. This pattern left a mosaic of sections of undergrowth at different stages of development. Some of this undergrowth provided protection for the animals the people hunted. The important thing was that catastrophic bushfires were prevented, as different parts of the land were in different stages of recovery from deliberate fires.

In time, humans learned which plants could be grown in certain areas and which animals could be brought under control.

This knowledge resulted in the domestication of plants and animals and is the basis of agriculture in the modern world.

Over time humans have become established at the top of the ecosystem. Humans can save, protect, destroy or modify an ecosystem. The sequence should probably be:

In reality, the sequence in many places has probably been:

The Tasmanian tiger

The thylacine, better known as the Tasmanian tiger, was native to Australia and primarily found in Tasmania and some regions of Victoria. It was the country’s largest carnivorous marsupial and had existed for over 4 million years.

The introduction of humans and dogs to the environment brought disease and predators to the ecosystem of the thylacine, and numbers declined drastically. Thylacines were kept in zoos, but suffered in captivity. They were also hunted by farmers who assumed the thylacine had been killing their sheep.

The last thylacine died in captivity in 1936, and although sightings have been reported and extensive searches carried out, there is no conclusive evidence of the creature being still in existence.

Currently, scientists are making attempts to clone thylacines from preserved specimens.

Humans have been altering ecosystems for thousands of years. Increasing populations required more food than could be provided by hunting and gathering. Providing more food required clearing land of its vegetation cover. In many parts of the world the flow of water had to be altered to provide water for larger and larger areas of crops and for the increasing number of livestock being raised. The flow of water also had to be altered to provide for increasing numbers of people living in settlements. The Industrial Revolution placed even more pressure on ecosystems as trees were cut and burned, and later coal and oil were extracted from the ground. Cities were built and spread across the countryside and communication networks of road and rail were constructed to connect them.

In the desire for this kind of progress, ecosystems for a long time took second place in humans’ thinking. In parts of the world where development is still seen as the primary goal, or in places where disputes cannot be settled without conflict, ecosystems still take second place.

Fortunately, in other places the need to save and protect ecosystems is regarded as important.

As a result, an international network of botanical gardens and zoos seek to protect and enhance the future of plant and animal species that are under threat. There is also a network of reserves, state forests and, more importantly, national parks – both on land and on the water – which seek to preserve ecosystems. There are no guarantees that the efforts will be successful, but the efforts must be made.

The world’s first national park – Yellowstone, in the United States – was opened on 1 March 1872.

Australia’s first national park was the National Park, south of Sydney. It was opened on 26 April 1879. It was the world’s second national park. It was renamed the Royal National Park after a visit by Queen Elizabeth II in 1955.

In 1972, the United Nations recognised that parts of the world needed to be set aside as having special cultural or physical significance. By 2012, 962 sites had been recognised by the UN Educational, Scientific, and Cultural Organization (UNESCO) as World Heritage listed sites.

While world governments realise that parts of the Earth’s surface need to be protected, it is not always easy, or possible, to do so. The fight to save the Cooloola area of Queensland was a classic example of the will of the people clashing with the government of the day and a mining company.

Many clashes like this have occurred in the past 50 years, and many are under way around the world today.