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8. Humans can have a

positive effect on the environment:

Conservation of Species

OBJECTIVES
> To understand that humans may have a beneficial effect on the environment
> To realise that conservation often involves compromise To understand a conservation strategy
> To know some examples of successful conservation

Humans do not always damage the environment - The reasons for this are not always understood,
growing numbers of conservationists try to but the following may be to blame:
balance the human demands on the environment Pest control - the term pest includes any
with the need to maintain wildlife habitat. They will species that causes inconvenience to humans.
try to assess the likely effects of any human Many species have been hunted ruthlessly,
activity by producing an Environmental Impact such as red deer (which damage trees), and
Statement. also predators such as cheetahs, and

Forest management scavengers such as vultures.
Humans have been responsible for deforestation Commercial exploitation - species of value to
of much of the Earth's surface. Humans have also humans have been exploited, such as the tiger
set up schemes for the large-scale planting of which has been hunted and trapped for fur and
trees - in areas that have been cleared medicinal compounds.
(reforestation) or in a new site (afforestation). Loss of habitat - more land is being used for
There are a number of reasons for planting trees: agriculture, including previously unusable land
as a cash crop, providing timber for building that has been drained. This removes habitats

(coniferous plantations in the UK) or for fuel for many species, such as wading birds and
(fast-growing eucalyptus trees are widely amphibians.
planted in central Africa) Climate change - loss of ice from the Arctic
to reverse soil erosion, particularly valuable in reduces hunting sites for polar bears.
areas that have become deserts Pollution - ponds and rivers may be polluted
to provide valuable wildlife habitats - for by fertilisers and sewage. Many oxygen-
example, Scots pine plantations are important requiring species can be lost.
habitats for red squirrels Introduced species - predators such as
as recreational areas, providing leisure stoats and weasels introduced to offshore
activities such as camping and mountain- islands can eliminate ground-nesting birds.
biking. Conservationists work to slow down or stop the
A well-managed forest can combine all of these decline in biodiversity (the number of different
functions and maintain this valuable resource. species), and also to raise public awareness of the
Endangered species need to maintain species and their habitats. The
number of different species in a community of
Competition between humans and other living
living organisms can be described by a formula
organisms means that many species have
called the Species Diversity Index.
disappeared or declined in number.

29 Learning Module Organisms and Their Environment | Class 11