Environmental Engineering Reference
In-Depth Information
Figure 23.11
The eighteen hot spots of the world - areas of
exceptional ecological diversity.
Source: After Wilson (1992).
particularly rich in plant species and which would safeguard a high proportion of the
world's flora if they were to be protected. In contrast to 'hot spots', though, CPDs are not
classed on the basis of threat of extinction.
Part of the awakened interest in global biodiversity is undoubtedly economic as much
as ethical in nature. The world's food supplies depend upon about 200 plants which have
been domesticated, of which perhaps twenty are of major economic importance. The
development of high-yielding varieties depends upon wild plants to donate genetic
material to the cultivars for needed improvements, e.g. to improve resistance to pests and
diseases (see p. 462). Future breeding programmes will depend upon the availability of
wild plants. Similarly, there is enormous potential among the plants of the world for
medicinal use and the extraction of new drugs. The World Health Organization (WHO)
lists 20,000 plants with medicinal uses, of which only 25 per cent have been studied as a
source of new drugs. However, anthropologists and ethnobotanists estimate that among
the world's indigenous peoples perhaps 50,000 to 70,000 plant species are used for
medicines; again, only a few have been studied in detail and there is an urgent need to
investigate them before they become lost for ever through extinction. Given the
importance of biodiversity, it is not surprising that it has been the subject of several
important conservation programmes. The
World Conservation Strategy
published by the
IUCN in 1980 brought the issue to centre-stage. It proposed that countries should develop
national conservation strategies, with biodiversity as one of several goals. More recently
in 1992 in Rio de Janeiro the United Nations Conference on Environment and
Development (UNCED) proposed a Biodiversity Convention which amounted to a global
strategy for maintaining biodiversity. In November 1995, at a conference in Jakarta,
