Biology 12

Chapter 13 Ecological Principles • MHR 435

There is also a tremendous amount of variation
within each biome. For example, the taiga biome
(sometimes referred to as the northern coniferous
forest or the boreal forest) covers a major part of
central and northern Canada, Europe, and Asia. Taiga
also varies widely from north to south and from
east to west with respect to the density and type of
trees it contains. Thus, each biome may contain a
variety of different habitats, each with its own set
of organisms and abiotic conditions. A habitatis a
place or area with a particular set of characteristics,
both biotic and abiotic. Each type of organism is
found in the specific type of habitat in which its
physical, physiological, and behavioural adaptations
equip it to survive and reproduce optimally.
In some cases, all members of a certain species
live in the same general type of habitat. The habitat
may be spread over a single large area or be found
in a number of separate locations. In other cases,
species are divided into populations that prefer
different types of habitats. The caribou, for example,
is a species found in many parts of Canada. It is
divided into a number of populations that live in
different habitats, as shown in Figure 13.11. Some
caribou live in forests, while others prefer the
open tundra.

Figure 13.11The distribution of caribou (Rangifer tarandus)

in Canada. Why do you think caribou are found in these areas?

These different populations are sometimes

referred to as subspecies or ecotypes, and they vary

somewhat in behaviour and physical features. The

barren-ground caribou is smaller and lighter in

colour than many other types of caribou. Most

Grant’s caribou

woodland caribou

barren-ground caribou

Peary caribou

transitional zone for

Peary and barren-

ground caribou

polar ice

tundra

taiga

mountain zone

temperate deciduous forest

temperate rain forest

tropical deciduous forest

tropical seasonal forest

tropical rain forest

shrubland

temperate grassland

savanna

semi-desert

desert

Figure 13.10Distribution of Earth’s major biomes. What do you think are the two
most important factors determining the distribution of these vegetation zones?