What is it?

Biodiversity (a shortened version of biological diversity) is a measure of the variety of the Earth's animal, plant and microbial species. It is a new phrase which has been coined in 1992 when an international convention for the preservation of biodiversity was signed by over 100 world leaders at the Earth Summit in Rio de Janeiro, Brazil. Much research has been done in this area and it has been found that the biodiversity of the Earth is far greater than previously thought. For instance, it is now thought that approximately only 1-10% of the world's species of bacterial are known at present. It is important to monitor to ensure that species do not die out unnecessarily. A large biodiversity ensures ecological stability and is a resource for research into new drugs and crops. 

What is the problem? 

Of all the world's species, humans have the greatest effect on the environment. In the 20th century the world's human population has been increasing at an alarming rate. This has meant that more land has had to excavated to house them and supply enough food for them to have a healthy existence. The problem with this is that the land destroyed is home to many species that can only survive in certain conditions. Once their habitat is destroyed the animal will also die out. So, although this century has provided us with many great people and discoveries the number of animals lost forever is phenomenal. It is not only the destruction of habitats that threaten the Earth's biodiversity, the balance of nature is upset by other activities such as, overfishing, over hunting, cutting down of too many trees as well as by pollution of land, air, oceans and rivers.

Habitat Destruction

In many areas it is the habitat's destruction that is wiping out many species, for instance, forests are a haven for creatures and these are being rapidly depleted by the intervention of humans. Another example is the destruction of the rain forests in South America. These are home to many species, many of which are unknown to man, so it is crucial that these are not destroyed.

To conserve the biodiversity of some of the most important area for wildlife, large areas of tropical grassland in Africa and India have been declared 'National Parks'. The Serengeti Plain in Tanzania, Africa, is one of the best known. It experiences spectacular migrations of wild animals, notable up to 1.2 million wild beast each year. These parks need to be preserved so that animals are able to live without risk of their habitats being destroyed.

Desertification

Desertification is the process by which areas of a desert are created by the destruction of natural forests or by the activities of man. An example of such action is in Africa, south of the Sahara Desert. The Savanna Grasslands form part of the Sahel, a zone that is prone to drastic climatic fluctuations with prolonged droughts. Since the late 1960s the situation has worsened and droughts and famine have affected much of sub-saharan Africa. Around 80 million people now subsist on severely degraded land.

The problem is mainly due to increasing populations around the world. Much of the land surrounding the Sahara desert has been cleared for crop farming so many of the scrub trees, vital in preventing complete desertification, have been destroyed. The wood has been used for firewood and the land has been overgrazed by the domestic animals. This has altered the microclimate which has allowed the desert to encroach southwards into areas of former Savanna. The removal of natural vegetation cover has also led to an increase in soil erosion by both wind and the infrequent falls of rain. The result is that over many areas of Ethiopia and Sudan people have migrated from the worst hit areas, i.e. where sand dunes have encroached on villages and farmland at the desert's margins. People are then overcrowded in small areas where the land is fertile. This land is, in turn, over used and the people move elsewhere. This unsustainable management of the land has been the 'trigger' for short-term human misery and disaster.

Another problem with increasing deserts is the amount of soil erosion that can take place. For instance if there are no obstacles to stop the wind, it can pick up speeds and blow much of the useful topsoil away. This further prevents any vegetation from growing. The situation is not lessening, in some areas of the south Sahara the advancement of the desert is up to 10 km/year. Once an area has been taken over by the ever expanding desert it is not necessarily the end. They can be turned back through appropriate tree-planting schemes and better agricultural and land management techniques.

(Source: 'Save The Earth' by J. Porrit)