18. Biodiversit y of Canadian Forests
357
Cetacea (Whales) . In contrast, British Columbia Environment (1991)
estimates 163 species excluding both Cetacea and Pinnepedia (seals);
while Environment Canada (1991) gives 193 as the total number of
species including these two groups. For breeding birds, Bunnell and
Williams (1980) report 288 species for British Columbia, compared with
295 reported by British ColumbiaEnvironment (1991).
The number of mammalian species in Canada tend to increase from
around 30 at the treeline, to about 60 at the Canada-US border, with up
to 80 in southern British Columbia (Simpson, 1969). Bunnell and Williams
(1980) report 112 species of land mammals for British Columbia, which
amounts to 74% of all Canadian species. Range maps given in Banfield
(1974) indicate that a little over 50% of all Canadian species are found in
the forests of the west coast. Of Canadian breeding bird species, 70%
breed in British Columbia (Bunnell & Williams, 1980; British Columbia
Environment, 1991). The comparative .species diversity of amphibians
and reptiles is not quite so impressive. Fifteen species of reptile are found
in British Columbia, representing 37% of the Canadian total of 41 species,
while there are 18 species of amphibian , 44% of the Canadian total
(Orchard, 1980; British Columbia Environment, 1991; Orchard, 1992;
Environment Canada, 1991).
Not only is species diversity highest in British Columbia, but the number
of species found exclusively in the province are much higher than for
other provinces. For breeding birds, 35 species are exclusive to British
Columbia , representing 55% of all species exclusive to one of Canada 's
political jurisdictions, and for mammals 24 species are exclusive, 73%
of the Canadian total (Bunnell & Williams, 1980; British Columbia
Environment, 1991). The environmental gradients of precipitation and
temperature caused by mountainous terrain account for this high species
diversity. Banfield (1974) also notes that during the last glaciation, refugia
in the Queen Charlotte Islands would have allowed some species to
persist, and would have served as centres for post-glacial migration .
Beta species diversity is related to both ecosystem diversity, discussed
below, and topographical diversity. Clearly, beta diversity is greater
in landscapes having steep environmental gradients, such as British
Columbia, than in landscapes having more subtle gradients , such as
northern Ontario.
Rare and Endangered Species
The Committee on the Status of Endangered Wildlife in Canada
(COSEWIC) lists 195 species of animals and plants as being vulnerable ,
threatened, endangered, or extirpated in Canada in 1990 (Canadian
Wildlife Service, 1990). Endangered species are those that are in imminent
danger of becoming extinct or extirpated in Canada. Threatened species
are those which are likely to become endangered in the near future if
357
Cetacea (Whales) . In contrast, British Columbia Environment (1991)
estimates 163 species excluding both Cetacea and Pinnepedia (seals);
while Environment Canada (1991) gives 193 as the total number of
species including these two groups. For breeding birds, Bunnell and
Williams (1980) report 288 species for British Columbia, compared with
295 reported by British ColumbiaEnvironment (1991).
The number of mammalian species in Canada tend to increase from
around 30 at the treeline, to about 60 at the Canada-US border, with up
to 80 in southern British Columbia (Simpson, 1969). Bunnell and Williams
(1980) report 112 species of land mammals for British Columbia, which
amounts to 74% of all Canadian species. Range maps given in Banfield
(1974) indicate that a little over 50% of all Canadian species are found in
the forests of the west coast. Of Canadian breeding bird species, 70%
breed in British Columbia (Bunnell & Williams, 1980; British Columbia
Environment, 1991). The comparative .species diversity of amphibians
and reptiles is not quite so impressive. Fifteen species of reptile are found
in British Columbia, representing 37% of the Canadian total of 41 species,
while there are 18 species of amphibian , 44% of the Canadian total
(Orchard, 1980; British Columbia Environment, 1991; Orchard, 1992;
Environment Canada, 1991).
Not only is species diversity highest in British Columbia, but the number
of species found exclusively in the province are much higher than for
other provinces. For breeding birds, 35 species are exclusive to British
Columbia , representing 55% of all species exclusive to one of Canada 's
political jurisdictions, and for mammals 24 species are exclusive, 73%
of the Canadian total (Bunnell & Williams, 1980; British Columbia
Environment, 1991). The environmental gradients of precipitation and
temperature caused by mountainous terrain account for this high species
diversity. Banfield (1974) also notes that during the last glaciation, refugia
in the Queen Charlotte Islands would have allowed some species to
persist, and would have served as centres for post-glacial migration .
Beta species diversity is related to both ecosystem diversity, discussed
below, and topographical diversity. Clearly, beta diversity is greater
in landscapes having steep environmental gradients, such as British
Columbia, than in landscapes having more subtle gradients , such as
northern Ontario.
Rare and Endangered Species
The Committee on the Status of Endangered Wildlife in Canada
(COSEWIC) lists 195 species of animals and plants as being vulnerable ,
threatened, endangered, or extirpated in Canada in 1990 (Canadian
Wildlife Service, 1990). Endangered species are those that are in imminent
danger of becoming extinct or extirpated in Canada. Threatened species
are those which are likely to become endangered in the near future if