What is biodiversity?
3. Biological diversity, or biodiversity, refers
to: the variety of all species of plants and animals; the genetic
variety within each species; and to the variety of habitats that
support them. It is often thought that large losses or changes
in biodiversity reflect negative and normally man-made pressures.
Biodiversity can therefore be used as a measure of the health
of the natural environment.
4. Global assessments of biodiversity indicate that
many natural environments are under considerable pressure. The
UN Millennium Ecosystem Assessment found that the majority of
species are either declining in abundance or that their population
distributions are contracting. Although biodiversity will change
over time with evolutionary and other natural processes, humans
have accelerated the natural extinction rate by as much as 1000%.[4]
Globally some 12% of birds, 23% of mammals and 32% of amphibians
are threatened with extinction over the next 100 years.[5]
UN experts warn that a species is lost every 20 minutes, putting
the global extinction crisis on a par with the loss of the dinosaurs
some 65 million years ago.[6]
5. Biodiversity loss is often considered an emotive
or moral issue, particularly where large charismatic species are
involved. But biodiversity loss can have significant economic
impacts:
- the loss of genetic diversity
in crop species can increase the vulnerability of global food
production to new pests and diseases;
- the loss of species with known or unknown uses
reduces the material from which important new discoveries might
be made, such as in medicine; and
- biodiversity directly or indirectly supports
many of the natural processes from which we currently receive
substantial benefits.
6. A dramatic example of the critical importance
of biodiversity for humans occurred in the 1970s when a new rice
virus appeared, the grassy stunt virus. The virus destroyed a
significant proportion of the rice crop in Asia and had an impact
on billions of people. Scientists screened thousands of different
rice varieties but only a single wild rice strain was found to
have resistance to the virus. This wild rice strain came from
one known location and had been collected by scientists shortly
before the site had been destroyed by a hydroelectric dam. Without
this one strain of wild rice, production of one of the world's
most important food crops would have been seriously damaged. Other
food crops have faced similar problems.[7]
7. Closer to home, bees provide another example of
the importance of biodiversity. Without insect pollination at
least 39 UK crop species either fail to produce fruit or seeds
or produce a substandard crop. The economic value of this to the
UK is estimated to be around £120-200 million per annum,
but the true value is substantially greater given that many wild
plant species also require insect pollination.[8]
The loss of bee species and other pollinators could have major
economic impacts by damaging food production and causing unplanned
changes to natural ecosystems. It is therefore of considerable
concern that many bee species are declining or have become extinct
in the UK.[9]
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