Biodiversity threatened

Destruction of habitats, changing ecosystems, exploitation of living resources... Human activities have disastrous consequences on our planet's biological heritage.

Natural habitats: Man is the worst enemy

No natural landscape is safe from the hands of mankind. While urban and suburban environments and intensive agriculture zones are starting to look like biological deserts, the progressive destruction of ecosystems is the principal threat to animal and plant diversity.

The decline of forest areas is one of the most striking examples of the human degradation of natural habitats. Tropical rain forests are biodiversity reserves: they harbour 60% to 75% of the world's species on just 2% of the earth's surface ⁽¹⁾. Heat, humidity and the lack of seasons are ideal for the development of life. However, history has demonstrated our ability to shrink forests: in Europe, between 900 and 1900, forest surfaces declined from 90% to 20% of its territory, primarily due to the development of farming. In addition, the remaining forests are altered: they are split up, and plant diversity is reduced, particularly in the case of replanted forests. History repeats itself, but this time in the south: 14 million hectares of tropical forest disappear each year ⁽²⁾, an area equivalent to three times the size of Switzerland. The cause of this is the extraction of precious wood such as teak and mahogany (15% of the deforestation ⁽¹⁾), breeding (in Central America, pasture land has tripled in order to meet the needs of North American markets ⁽²⁾), and, of course, agriculture, which expands at the expense of forests. But deforestation is primarily a socio-economic problem: 500 million poor people living near forests primary employ slash-and-burn agricultural techniques in order to survive, causing two thirds of annual forest losses ⁽¹⁾. Rich nations are largely to blame for this. As the original looters of precious wood, they also overwhelm poor countries with the weight of debt: in the ten countries that are most affected by deforestation, debt has risen from 26% to 60% of their GNP in the last 20 years ⁽³⁾.

Coral reefs are considered to be the marine equivalent of tropical forests due to their biological wealth. Although the abundance of life present in the high seas has not been examined much, coastal areas are more familiar to us. Coral reefs, in particular, harbour over 450,000 species. However, these areas are victims of looting (dynamite fishing...), diseases which are partially linked to pollution and warming oceans. The consequence: coral bleaching, which already affects 80% of Caribbean corals ⁽¹⁾. Yet only 2% of coral reefs are now located in protected areas ⁽⁴⁾.

Freshwater ecosystems are also contaminated by pollutants, even though they contain 40% of known fish species (in just 0.01% of the world's water volume) ⁽¹⁾. Wetlands are suffering from dryness and pollution. They purify fresh water and limit flooding, but they are also necessary for many bird species (50% of species in France ⁽⁴⁾). Semi-arid ecosystems are threatened by desertification. Even polar regions are affected by industrial fishing, atmospheric pollution and global warming. How many more years are left before polar bears have drowned forever?

Other threats to biodiversity

The introduction of invasive species is the second factor which contributes to biological extinctions ⁽⁵⁾. When a species is moved to another ecosystem (holds of ships, intentional introductions...), one species out of a thousand has an impact on native biodiversity ⁽⁶⁾ (one third of threatened bird species ⁽¹⁾). The consequences can be severe. In the second half of the 19^th century, the Australia's rabbit population rose from 24 to 600 million, accelerating the desertification of the country and causing agricultural and ecological crises. Other examples: the Nile perch, which colonised Lake Victoria, and the water hyacinth, which disrupts aquatic ecosystems.

Some species are threatened by direct pressure from humans. The hunting of animals for food is devastating, particularly in Africa ("bush meat"), as are natural medicines which end up killing tigers and rhinos. Each year, commerce puts 350 million endangered animals and plants on the market ⁽¹⁾. Lastly, in addition to the disappearance of fish stocks, the indirect damage caused by fishing is disastrous: nets scrape the seabed, capturing 25% of fish that are too small, and they have become the leading cause of mortality for many species (50% of seals...). Several bird species (albatrosses, petrels...) are threatened by floating line hooks ⁽¹⁾.

Thousands of endangered species

The International Union for Conservation of Nature (IUCN) is the world's leading authority on the monitoring of species. Each year, it publishes a list of endangered species. In 2010 ⁽⁷⁾, 18,000 species are officially endangered. However, barely more than 40,000 species have been subject to an evaluation (0.2% of our planet's living beings ⁽¹⁾).

Among the categories that have been evaluated, 21% of mammals are threatened, as well as 12% of birds and 30% of amphibians. At the current rate, two thirds of all plant species will be endangered at the end of the century ⁽⁸⁾. This would have dramatic consequences on all other living entities, including invertebrates, which represent 95% of terrestrial biomass ⁽¹⁾. The dangers that humans face are real: extinction of pollinating insects…

Threatened species include the gray whale, the Siberian tiger, the Atlantic salmon and the white shark, which is disappearing quite rapidly. One species out of every thousand disappears each year, a pace a thousand times higher than the natural extinction rate ⁽⁹⁾. Will Homo sapiens also join the dodo bird and the Tasmanian tiger on the list of extinct animal species, which are victims of our current lifestyle?

What about human biodiversity?

Globalisation, cosmopolitan cities... The mixing of human populations has never been stronger. The genetic biodiversity of our species is therefore doing very well. But over the centuries, many societies have disappeared, victims of extermination and of diseases carried in by settlers. Today, they still suffer from evictions and poisonings due to the exploitation of natural resources by foreigners. By losing these races, which can be considered as being human endemisms, from a biological and cultural point of view, we also miss out on culture and ancestral knowledge. However, all of mankind could benefit from such knowledge, particularly in the areas of both botany and pharmacy ⁽¹⁰⁾. Is the standardisation of humanity really a synonym of progress?

Written by Florent Planas for "One year for the Planet" (translated by Anyword).

Find out more…

1. Yves Sciama, Petit atlas des espèces menacées (Larousse, 2008)
2. FAO (Food and Agriculture Organization)
3. The World Bank
4. Michel Barnier, Atlas pour un monde durable (Acropole, 2007)
5. Millenium Ecosystem Assessment (2005)
6. M. Williamson, Biological invasions (Chapman & Hall, 1996)
7. International Union for Conservation of Nature (IUCN), Red list of threatened species (2010)
8. 16^th International Botanical Congress (1999)
9. WWF (World Wildlife Fund)
10. For example, the Kayapo people (Brazil) worked for 20 years with American anthropologist Darrel Posey in order to share its knowledge, especially regarding its use of plants.