Biodiversity

Biodiversity?

Biodiversity deals with biological units such as genes, species, ecosystems up to biogeographic regions. There are many different definitions of biodiversity among which the one used under the Convention on Biological Diversity (CBD) is one of the most frequently cited:

"Biological diversity means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems."

How many species are there? Estimates differ from 2 to 10 million different species. The table below (derived from the Global Biodiversity Assessment, UNEP, 1995) shows that only a small portion of the species has been described.

Importance of Biodiversity

The Global Environmental Outlook 3 (UNEP, 2002)describes the importance of biodiversity as follows.

'Living organisms contribute to a wide variety of environmental services, such as regulation of the gaseous composition of the atmosphere, protection of coastal zones, regulation of the hydrological cycle and climate, generation and conservation of fertile soils, dispersal and breakdown of wastes, pollination of many crops, and absorption of pollutants (UNEP 1995). Many of these services are neither widely recognized nor properly valued in economic terms; however, the combined economic value of 17 ecosystem services has recently been estimated in the range of US$ 16-54 trillion per year (Costanza and others 1997).
Human health and well-being are directly dependent on biodiversity. For example, 10 of the world's top-selling drugs in 1997 were derived from natural sources. The global market value of pharmaceuticals derived from genetic resources is estimated at US$ 75 -150 billion annually. Some 75 per cent of the world's population relies for health care on traditional medicines, which are derived directly from natural sources (UNDP, UNEP, World Bank and WRI 2000).
Biodiversity also provides genetic resources for food and agriculture, and therefore constitutes the biological basis for world food security and support for human livelihoods. A number of wild crop relatives are of great importance to national and global economies. For example. Ethiopian varieties have provided protection from vital pathogens to California's barley crop, worth US$ 160 million per year. Genetic resistance to disease obtained from wild wheat varieties in Turkey has been valued at US$ 50 million per year (UNEP 1995).'

Forest biodiversity

Forests are critically important for maintaining biological diversity. Estimated to contain half of the world's biological diversity, natural forests have the highest species diversity and endemism of any ecosystem type.Tropical forests ecosystems contain more plant and animal species than any other terrestrial habitat in the world. Rain forests are among the oldest ecosystems on earth and as a result, boast millions of different species, many of which occur in very restricted areas and nowhere else (endemism).

Threats

The most important causes of the loss of biodiversity are land conversion, climate change, pollution, unsustainable harvesting of natural resources and the introduction of exotic species. The ultimate causes of biodiversity loss are human population growth together with unsustainable patterns of consumption, increasing production of waste and pollutants, urban development, international conflict, and continuing inequities in the distribution of wealth and resources. In forests fragmentation exacerbates the impacts on biodiversity of overall deforestation and forest degradation by blocking migration routes and making access easier for further exploitation by humans and entry by invasive species.

Conservation

Three approaches to biodiversity conservation can be distinguished.

• in-situ conservation refers to setting aside natural and semi-natural areas for protection purposes (national parks and other protected areas) under legally defined management regimes, limiting human expansion into undisturbed areas and regulating human activities on the basis of conservation objectives;
• ex-situ conservation refers to preserving organisms, tissues and genetic material in special facilities outside their natural habitat (zoos, botanic gardens, seed and gene banks);
• on-farm conservation refers to conserving the (genetic) diversity in cultivated species in appropriate farm conditions. This biodiversity in a man-made environment is also referred to as agro-biodiversity.

WRI´s Biodiversity Conservation Guidelines provide a number of helpful overviews for policy development on the use and preservation of biodiversity. Biodiversity is most likely to be maintained if local values are fully captured and local costs of conservation are minimised. The Convention on Biological Diversity has created a new framework that requires the negotiation of formal agreements with a range of stakeholders. This is a way to share more equally the profits from the forest resources with indigenous and local communities, recognizing their roles as both contributors to and custodians of forest biological diversity.

TBI sources

Further reading: