Habitat refers to the range of resources that a species needs to
maintain a viable population including sufficient territory, necessary
food and water, and required physical features such as tree cover,
rocky hills or deep pools, as well as the organisms and ecosystem
disturbances that must be present for it to complete its life cycle.
The major current cause of biodiversity loss in Africa is habitat loss
and that is likely to remain true for the first third of the 21st
century.
Habitat is lost when land cover (or its aquatic
equivalent) is changed, usually as a result of changing use by humans.
Common examples are the conversion of near-natural vegetation to
temporary or permanent croplands; the replacement of forest by
pastures; the expansion of human settlements; and the alteration of
river habitats by dams, pollution and removal of water for human use.
Forests and woodland cover is declining at a rate more or less
equivalent to the increase in cropland. The terrestrial ecosystem type
where the greatest degree of habitat loss has occurred is grasslands,
which have been converted to cereal agriculture.
Habitat
fragmentation – the division of continuous patches into smaller pieces
which are partly or fully disconnected from one another by
infrastructure, agricultural fields or human settlements – can have
similar outcomes for biodiversity as outright habitat losses. First,
the “edge effect” disrupts biodiversity for a considerable distance
into the remnant patches. Second, the number of species that can be
supported in the long term depends on habitat size.
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