Figure 25.29: Herds of bison also made up part of the tallgrass prairie community. ( 14 )Other causes of habitat destruction include poor fire management, invasion of pest and
non-native species, overfishing, mining, pollution, and storm damage.
Why Habitat Destruction Threatens Species
Agriculture, forestry, mining, and urbanization have disturbed over half of the earth’s land.
Inevitably, species disappear and biodiversity decreases. Habitat destruction is currently
ranked as the most important cause of extinction of species worldwide.
The destruction of a species’ habitat may alter the landscape to such an extent that the
species is no longer able to survive and becomes extinct. This may occur directly, such
as the environment becoming toxic, or indirectly by limiting a species’ ability to compete
effectively for diminished resources or with a new species.
Habitat destruction through pollution can kill off a species very rapidly, by killing all living
members by contamination or sterilization. It can also occur over longer periods at lower
toxicity levels, by affecting life span, reproductive capability, or competitiveness.
Habitat destruction can also occur physically by elimination of certain niches in a habitat.
For example, elimination of dense tropical rainforest and replacement with open pastureland
can affect certain species. Thus, a fern that depends on dense shade for protection from
direct sunlight can no longer survive without trees to shelter it. Another example of this is
the destruction of ocean floors by bottom trawling.
Fewer resources or introduction of new competitor species often accompany habitat destruc-
tion. Global warming has allowed some species to expand their ranges, sometimes into those
of species that previously occupied that area. If these new competitors are predators, they