10
Biological
Diversity
1.C4T1 2.C4T2 3.C4T3
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4. Lichens, composed of an alga and a fungus.
They are indicators of a pollution-free environment.
© Amélie Dupuy

What is biological diversity?

During the United Nations Conference on Environment and Development, commonly known as the ‘Earth Summit’ (Rio, June 1992), the international community elaborated the Convention of Biological Diversity. Biological diversity or biodiversity refers to the variety and variability of plants, animals and micro-organisms living on Earth. It is a recent concept used to describe the different expressions of life forms and includes multiple biological, ecological and economical considerations. Biodiversity includes genetic, species and ecosystem or habitat diversity.

The importance of biodiversity

Biodiversity contributes ecological goods that are indispensable to life on Earth such as oxygen production, water and nutrient cycling, waste assimilation, water and air cleansing and climate regulation. Furthermore, biodiversity provides a formidable stock of raw materials necessary for the development of food, medicine, science and technology. Thus it is of utmost importance to conserve biodiversity for both present and future generations. Human intervention has resulted in the loss of biodiversity, species extinction and the decline of genetic capital. These pressures are linked to human population growth, industrial development and the over-exploitation of natural resources that all contribute in accelerating environmental turmoil on a global scale.

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5. South Africa: Aloe dichtoma. The variety of shapes
and colours found in the wild are the result of millions of
years of evolution, contributing to biodiversity richness.
© Jean-Michel Battin

The role of biodiversity in the drylands

The biodiversity we see today is the fruit of billions of years of evolution, shaped by natural processes and increasingly by the influence of humans. It forms the very web of life of which we are an integral part and upon which we so fully depend. More than anywhere else, societies in the drylands depend on the use of biodiversity for their daily needs and their economic and spiritual development. The greater the variety of resources at their disposal, the greater their capacity to survive climatic difficulties and the uncertainties of the environment.

Desertification threatens biological diversity

Land degradation transforms fertile soils into deserts that are no longer fit for cultivation. Organisms that cannot adapt to such hostile conditions do not survive, even though it is important to conserve a large diversity of species to guarantee a stable arid ecosystem. Survival adaptations of animals and plants in the drylands are determined by genetic characteristics that have evolved over the centuries. However, the rapidity of the desertification process means that organisms cannot adapt quickly enough to these sudden changes and therefore risk disappearing from these regions.
The co-existence of plants and animals, which are adapted to their environment, is at the heart of a balanced ecosystem, providing the life-supporting conditions in the drylands. Local populations use and depend on these essential resources to live.

Biodiversity, cultural richness and identity

Many wild species participate in the cultural life of local dryland populations, for instance, by providing elements used for jewellery or corporal decoration. Biodiversity also includes the numerous medicinal plants and other natural resources whose virtues are passed on from one generation to another. On a spiritual level, certain species play an important role as totems or mythical tribal ancestors. The fact that Tuaregs employ one hundred words to describe dromedaries (according to its age, sex, colour, physical form, origin etc) attests to their importance.

What is endemism?

A species is said to be endemic when it is found only in one place or specific region. The rate of endemism indicates that certain world regions are unique for their fauna and flora and represent particularly valuable conservation areas. However, due to the complexity of these ecosystems, these centres of endemism are often under threat from foreign species that risk spreading dangerously and threaten the local equilibrium. The rate of endemism varies between 10% to 25% in the drylands while islands tend to have a higher rate of endemism due to their isolation. In Madagascar, 70% of plants are endemic and in Australia, more than 90% are endemic plants. Lemurs, small primates found only in Madagascar, are endemic to Madagascar. The addax antelope is endemic to Sahara.

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6. Bouaké market in Côte d’Ivoire : by conserving biodiversity, populations assure the necessary resources for a balanced and healthy diet.
© Amélie Dupuy
7. In the drylands, trees and shrubs represent up to 50 % of cattle fodder during the dry season, but only 5 % during the humid season.
© UNESCO-MAB

activities

pencil

Compile a list of all the animals you know that are found in your region.

pencil

Make a sculpture in papier mâché of your favourite animal of the drylands.

smile

Which animal is linked to your daily life and/or the wealth of your culture?

Why is it important?

smile

Is there a plant or animal in your country that is associated with a local legend or myth?

Ask the older members of your community.

smile

Is it possible for your teacher/school to organize an excursion close to your school so that you can observe local animals closely?

Is it easy to identify an endemic plant or animal in your region?

smile

Identify a plant or animal that is protected by law in your country.

smile

Underline the following correct phrases:

• lemurs are endemic
to Madagascar.
• cameleons are endemic
to Chad.
• addax antelope are endemic
to Central Europe.
• kangaroos are endemic
to Australia.
• pineapple is endemic
to Latin America.


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