Biodiversity

Open any magazine or newspaper today and you'll soon see the word "biodiversity". What does it mean, you may ask? Why is there such a fuss about it? Here's why: biodiversity is the total variety of life on Earth - all genes, populations, species and ecosystems and ecological processes.

The value of biodiversity

Life on earth depends on ecological processes that, among other things, determine climate patterns, mediate the carbon cycle, protect river catchments, and create and stabilise soil. Animals, plants and micro-organisms provide foods, goods and medical cures that are essential for human survival.

Countless organisms have yet to be discovered or named, let alone tested for any pharmacological values, and these "unknown" elements of biodiversity are immensely valuable. Potential cures for cancer, HIV and other diseases may lie in the cells of a tiny plant growing on the slopes of Tanzania's Usambara Mountains or the highveld grasslands of South Africa.

Apart from its benefits, many of us find value in the simple fact that biodiversity exists. To sit on a headland and watch humpback whales cavorting offshore, or to listen to the dawn chorus of birds in a tropical rainforest is "soul food" for many people.

Natural events of any kind need all parts to be in working order. If you take a tiny part out of the back of your wristwatch, it will either malfunction or stop. It's the same in nature although, for humans, the signs are not always obvious.

Given its possibilities, it is hardly surprising that conservationists are making a strong effort to protect biodiversity.

Protection of biodiversity

To do this, one needs to first know how much of it there is and where it exists, no easy task. We have learned much about biodiversity in recent years, but our knowledge is still incomplete and biased towards larger species.

To date, about 1.7 million species of all forms of life have been named and described scientifically. This includes a high proportion of the actual number of the world's larger terrestrial plants and animals, particularly the so-called higher vertebrates (mammals, birds, reptiles and amphibians), but a far smaller percentage of other groups have been categorised, especially invertebrates, fungi and micro-organisms which together comprise the vast majority (over 90%) of living species. Estimates for the total number of species on Earth vary from 10-100 million.

Exploration and sampling shows that the greatest biodiversity exists in the tropical regions, and that forests are the most species-rich of all ecosystems. Endemic "hotspots" - places where a high number of unique life forms are confined to a geographic area - have been identified on all continents. In Africa, these include high altitude grasslands, "fynbos", heathland and afro-alpine communities.

Extinction of species is the best way of measuring loss of biodiversity. But extinction is also a natural phenomenon. The fossil record suggests that all species have a finite life span, with the number of extinct forms outnumbering living ones.

However, there is evidence that the rates of extinction brought about directly or indirectly by humans are much greater than "natural" rates of extinction, and they are accelerating. It seems that we are heading for an extinction spasm which, if unchecked, will be the greatest since the dinosaurs became extinct, an event that was probably triggered by an asteroid colliding with Earth 60 million years ago in the Mesozoic era.

In the face of such a crisis can anything be done?

Birds as biodiversity indicators

It is clearly impossible to save all of the species or ecosystems on Earth. We've simply left it too late. What we must aim for - at a local and global level - to save a representation of the different ecosystems, which are identifiable by vegetation structure and composition.

One strategy is to prioritise protection those areas which are considered to be the richest in terms of known species, as these are also likely to contain the most "unknown" species and are therefore of greatest "value" from a biodiversity perspective.

Since identifying and cataloguing invertebrates, fungi and micro-organisms is time consuming, it is necessary - given the rate at which natural habitats are being destroyed and the threat to recognisable species - to identify something which provides the best possible indication that an area is particularly rich in biodiversity, and that it is worth devoting time and resources to saving.

Because birds are conspicuous, comparatively easy to identify and popular as things to look for and watch, their distribution on the planet is much better known than any other group (including mammals, many of which are tiny and/or nocturnal). After decades of field work, study and interpretation, ornithologists have mapped those parts of the world with the greatest species diversity and with the highest number of threatened species.

Priority areas for conservation have now been established by BirdLife International on the basis of restricted-range (endemic) species. It has been demonstrated that overall biodiversity is very often linked to bird diversity, and that areas rich in birds invariably have lots of other life forms.

Conservationists across the world are now using the BirdLife International data to decide which areas to try and secure for posterity.

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For more information on birds and biodiversity visit the BirdLife International website - http://www.birdlife.net/
Copies of the superb book - "Endemic Bird Areas of the World" can be ordered from BirdLife.

Posted: Other by CC Africa, Date: 21 November 2006