Threats to Biodiversity

Biodiversity is under threar in many aquatic and terrestrial ecosystems as the human population continues to increase and we take more resources from the environment and produce increasing quantities of waste. Ecosystems and species are being lost at an alrming rate, not just by the direct action of humans, but also indirectly as a result of climate change.

There are five major threats to biodiversity:

• habitat loss and the degradation of the environment
• climate chabge
• excessive use of fertilisers and industrial and dometic forms of pollution
• the overexploitation and unsustainable use of resources
• the effects of invasive alien species on native species, especially endemics

The destruction of the natural environment leads to habitat loss

Clearing of land for agriculture, housing leisure facilities and industry removes vegetation

Consequently, many species of plant and animal either lose their habitats completely or their habitats become divided into small areas; this is known as habitat fragmentation

Most at risk of extinction are endemic species on small islands

Deforestration has had a devastating effect on the biodiversity of some countries

Deforestration can lead tosevere land degradation as a result of soil erosion once the vegetation is removed

Although agriculture provides most of our food, we still rely on taking wild fish from its environment

It's very difficult to know whether fish stocks are sustainable, but the history of the fishing indusry suggests that many species have been driven to near extinction by over fishing

The response to the steep decrease in large, predatory species is to fish further down the food chain taking smaller fish that other animals, such as marine mammals and seabirds, depend on

Fishing is just one example of the overexploitation of resources

Another example is the removal by logging companies of valuable trees, suchas teak and mahogany, at a rate faster than they can regenerate

The loss of a single species can have devastating effects on the rest pf its community

• organisms that play a central role in an ecosystem are known as keystone species

The African bush elephant, Loxodonta africana, is a keystone species of the savannah grasslands of East and Southern Africa. Bush elephants are very destructive of vegetation as they push over and eat many tree species. This extreme form of grazing helps to maintain this ecosystem, which is renowned for its diversity of large mammals as well as many other species. Elephant dung provides a very rich habitat – in fact almost an ecosystem in itself – for many organisms including fungi and dung beetles. Elephants were once hunted widely for their ivory and their populations decreased considerably.…