Our Environment - Mining and the Environment: From Ore to Metal - page 322

FIGURE 7.5
Commonness, Rarity, and
Vulnerability to Extinction

MOST COMMON SPECIES

Species such as these show
no aspect of rarity; they are
among the most common in
the biosphere.

Extensive geographic range
Broad habitat tolerance
Large local population

House Sparrow
Passer Domesticus

Species can be subdivided
according to:
(1) geographic range (extensive
versus restricted),
(2) habitat tolerance (broad
versus narrow), and
(3) local population (large
versus small).
By combining these three cat-
egories, one class of common
species and seven classes of
rarity emerge.
Source:
Molles 2005

Restricted geographic range
Broad habitat tolerance
Large local population

Galapagos Medium
Ground Finch

Each of these species show
one aspect of rarity, which
gives them some vulnerability
to extinction.

Extensive geographic range
Narrow habitat tolerance
Large local population

California
Grey Whale

Each of these species show
one aspect of rarity, which
gives them some vulnerability
to extinction.

Each of these species show
one aspect of rarity, which
gives them some vulnerability
to extinction.

Extensive geographic range
Broad habitat tolerance
Small local population

Tiger

With two aspects of rarity,
these species are even more
vulnerable to extinction.

Restricted geographic range
Narrow habitat tolerance
Large local population

Fish Crow

Restricted geographic range
Broad habitat tolerance
Small local population

Tasmanian Devil With two aspects of rarity,

these species are even more
vulnerable to extinction.

Northern
Spotted Owl

With two aspects of rarity,
these species are even more
vulnerable to extinction.

Extensive geographic range
Narrow habitat tolerance
Small local population

Restricted geographic range
Narrow habitat tolerance
Small local population

Mountain Gorilla Species such as these are

the rarest in the biosphere
and are the most vulnerable
to extinction.

text on white highlights
aspect of rarity

RAREST

species. Peripheral populations are at the edge of the species geographical range, and a
declining species is one which was previously abundant but now with declining popula-
tions. The orangutan which has only a few remaining populations, is an example of a
declining species.
Threat or vulnerability is often used as a criterion for environmental protection
(Margules and Usher 1981; Smith and Theberge 1986). If a specific area or environmental
component is especially prone to negative project-induced changes or activities, it deserves
special attention with respect to environmental protection. Vulnerability is not a meas-
ure of the value of a site (Erikstad 1991), but understanding threat and vulnerability is
important when designing protection measures. This makes vulnerability a useful concept
in environmental impact assessment, in which vulnerability can be analyzed with respect
to specific project-induced impacts. Not all project activities are necessarily detrimental to
the natural area in which the activity is performed. A given nature type can have different

Vulnerability is not a measure
of the value of a site, but
understanding threat and
vulnerability is important when
designing protection measures.