Geoscience Reference
In-Depth Information
Plate 22.5
Caribou herds in North America are the largest concentrations of mammals on Earth. Although the herds are
vulnerable to wolf predation and hunting, population size ensures that the herd numbers recover quickly and are therefore
resilient.
Photo: Canadian Wildlife Service
Scotch broom, represented by the white node near the
centre. Each node represents the relationship of a species
of insect to the plant and to other insects. The decreasing
order of connectance is from red to green to blue . If one
of the red or green species were to disappear, this would
affect many other species in blue (Montoya 2007).
The 'keystone species model' is one model which
describes the relationship between ecosystem functioning
and species richness. Another biodiversity-stability model
proposed for species-rich communities in temperate and
tropical regions is the
redundancy model
, in which there
is a greater probability that 'spare' species within the
ecosystem will be able to substitute for any species lost,
and be able to take on its functional role. The more species
that are present in an ecosystem, therefore, the greater the
community's 'insurance' against stochastic or determin-
istic disturbances.
text for key.
Source: After Montoya (2007)
