Life on Earth comes in a vast variety of forms. No environment excludes
it. From the lichen clinging to the bare rocks of the Arctic
to the colony of insects breaking down the dead trunk of a tree, each
plant and creature plays a role in the great ecosystem that is the Earth.
This biodiversity is now seriously threatened by human beings. By creating
farms, cities, mines and factories, humans are destroying many natural
habitats, poisoning plants and animals, and exterminating species by overexploiting
them. They are also overwhelming environments by introducing exotic species
into them, whether accidentally or intentionally. Since the arrival of
the first European settlers in northern North America,
10 animal species and 1 caribou population are known to have become extinct,
and at least 17 other species or populations are no longer found in this
country, mainly as a result of human activity. Some have become forever
extinct, such as the great auk, which was formerly widespread in the North
Atlantic Ocean but fell victim to relentless hunting. Of this
great bird that was once so abundant on the islands in the Gulf
of St. Lawrence, there remain only a few stuffed specimens.
Fortunately, other species that have disappeared in Canada
still exist elsewhere and might be successfully reintroduced. As of 2001,
the Committee on the Status of Endangered Wildlife in Canada (COSEWIC)
has listed 212 species, subspecies, or populations of wild plants and
animals as threatened or endangered, and an additional 146 were listed
as a special concern.
Species diversity implies diversity of habitats. In this regard, Canada
is very well endowed, since a great variety of environments rub shoulders
on its vast territory. In particular, it contains nearly a quarter of
the planet's wetlands, most of them located in Ontario,
the Northwest Territories,
Nunavut and Manitoba.
These environments play a crucial ecological role: they harbour an extremely
rich variety of flora and fauna, including the migratory and water birds
that fly there to reproduce; also, because of their dense vegetation,
these wetlands cleanse the environment by retaining a large quantity of
carbon dioxide and by purifying the water. However, farming and urban
growth have spelled the end of most of the wetlands in southern Canada.
The proportion of wetlands that have been drained is estimated at 65%
in the Atlantic provinces,
70% in southern Ontario,
71% on the Prairies, and 80% in the Fraser River delta. Approximately
60% of the species designated by COSEWIC as at risk of extinction are
associated with wetlands, and about 80% are threatened by habitat problems.
It is also important to ensure that genetic diversity is protected. The
more varied its gene pool, the better a species can cope with the pressures
of the environment. This applies to both the plant and the animal species
that nourish the human population. But in plant breeding, modern agriculture
tends to make use of a small number of plant species, selected for their
high yield; as a result, the survival of most human beings now depends
on fewer than 20 species.
