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3. Food Supply: Humans

and Agriculture

OBJECTIVES
> To understand why agriculture is a threat to conservation
> To understand how careful management can help to conserve biodiversity

The human population is increasing and may use of pesticides to eliminate competitors for
reach 9 billion (9000 000 000) by the end of the crop species has caused the reduction in
century. More people means a demand for more population of many native wildflowers and
food. This food is mainly provided by agriculture - some non-target insects and birds by direct
the management of land for food production. toxicity or, more often, by removal of their food
Around the world, agriculture presents a serious sources. Pesticides include insecticides to
threat to conservation of existing habitats. improve the quality and yield of crops by killing
Although 75% of England is designated as insects, and herbicides which reduce
farmland, only 2% of the UK population is competition with weeds
involved in farming. In 1850, one farm worker the tendency towards monoculture

produced enough food for about 4 people; now in selective breeding of both crops and
advanced agricultural countries the same worker livestock.
produces enough for 60 people. The enormous All of these can have negative effects on the
rise in productivity of land is due to many factors. environment.
These include:
increased and more efficient use of It all boils down to monoculture!
machinery has resulted in increased field Farms used to be small and mixed, supplying
sizes and the removal of hedges enough food for just a few families throughout the
increased use of inorganic fertilisers year, but now tend to be large and specialised.
affects plant diversity dramatically and can Growing a single crop in this way is called
result in excessive nitrate levels in rivers, monoculture and, as ever, there are pluses and
leading to eutrophication. minuses.

Learning Module Organisms and Their Environment | Class 11 6