Biology 17.3 Major Biological Communities
Major Biological Communities:
Biomes
Climate’s effect on where species live


If we were to drive across
the country we would notice
that the plants and animals,
the variety of species,
changes as we move from
zone to zone, climate to
climate. Plants and animals
from one climate will not live
in another climate zone.
Climate refers to the
prevailing weather conditions
in any given area.
Climate map of North America
Showing plant hardiness zones
Temperature and Moisture



The two most important elements of a
climate are temperature and moisture.
Temperature : Most organisms are
adapted to live within a particular
range of temperatures and will not
thrive if temperatures are colder or
warmer. Every living organism has a
range of temperatures it can live
within.
Moisture: All organisms require water.
On land, water is sometimes scarce, so
patterns of rainfall often determine
an areas life forms. The moistureholding ability of air increases when it
is warmed and decreases when it is
cooled.
Biological Communities: Biomes




If we look at all the world’s
biological communities we
notice a trend. Similar
communities exist in different
world areas that have similar
climates and geographies.
A major biological community
that occurs over a large area
is called a biome.
The Earth is a biosphere and is
broken up into biomes.
A biome’s structure and
appearance are the similar no
matter where in the world it is
geographically located. All
desert biomes are similar for
example.
World biome map
Biomes of the world

While there are different ways of
classifying biomes, the classification
system we will examine uses 7 of the
most widely distributed biomes.
 Tropical rain forests
 Savanna
 Taiga
 Tundra
 Desert
 Temperate grassland
 Temperate forest
Biomes of the World




Many factors such as soil type
or wind play important roles in
where biomes occur.
The two most important
factors that determine a
biome are temperature and
precipitation.
The chart at right shows the
relationships between coldwarm and wet-dry locations
and the biomes that they
produce.
The 11 biomes shown are in
response to the climate
combinations of temperature
and precipitation (rain)
available.
Terrestrial Biomes: tropical rain forests
Tropical Rain Forests



Tropical rain forests receive an
average of as much as 450 cm (180
inches) of rain per year, with little
difference in amount of rain from
season to season.
The richest biome in terms of the
number of species is the tropical
rainforest.
Tropical rainforest may contain half
the world’s species, more than 2
million.
Terrestrial Biomes: tropical rain forests
Tropical Rain Forests


Tropical rainforest have a high
productivity even though they
often exist on infertile soil.
Most of the nutrients in a
rainforest are held within the
plants, not the soil.
Terrestrial Biomes: Savannas
Savannas



The world’s great dry grasslands,
savannas, are found in the tropical
areas that have relatively low
precipitation (little rain) or
prolonged annual dry seasons.
Annual rainfall is generally 90 to
150 cm (35 to 60 inches) in
savannas.
There is a wider range of
temperatures throughout the year
than in a tropical rain forest, and
there is a seasonal drought where
little or no rain falls.
Terrestrial Biomes: Savannas
Savannas


These factors have led to an open
landscape with widely spaced trees.
Many of the animals are active only
during the rainy season. Huge herds
of grazing animals are found on the
savannas of East Africa.
Terrestrial Biomes: Taiga
Taiga:


Cold wet climates promote the growth
of coniferous trees and forests. A
great ring of coniferous trees,
primarily spruce and fir, extends
across vast areas of Eurasia and
North America.
This biome, one of the largest on
Earth, is called by it’s Russian name,
taiga.
Terrestrial Biomes: Taiga
Taiga:


Winters in the taiga are long and cold,
and most of the precipitation falls
during the summer.
Many large mammals, including
herbivores such as elk, moose and
deer and carnivores such as bears,
lynx, and wolverine live in the taiga.
Biomes: Tundra
Tundra:





Between the taiga and the
permanent ice cap that surrounds
the North Pole, lies the open boggy
biome we call the tundra.
Tundra biome covers approximately
one fifth of the entire Earth’s
surface.
Annual precipitation in the tundra is
very low, usually less than 25 cm (10
inches) and water is unavailable most
of the year as it is frozen.
The permafrost, or permanent ice,
usually exists within 1 meter of the
surface.
Foxes, owls, lemmings and caribou
are among the inhabitants.
Biomes: Deserts
Deserts:



In deserts, less than 25 cm (10
inches) or precipitation falls annually.
The scarcity of water is the
overriding factor influencing most
biological processes within a desert
biome.
In desert regions, vegetation is very
sparse.
Biomes: Deserts
Deserts:



Deserts are most extensive in the
interiors of continents.
Less than 5 % of North America is
open desert.
The amount of water that can fall in a
particular place in a desert can vary
greatly, both during a given year and
during successive years.
Biomes: Temperate Grasslands
Temperate grasslands:



Moderate climates half-way between
the equator and the poles promote
the growth of rich temperate
grasslands called prairies.
Temperate grasslands once covered
much of the interior of North
America.
Such grasslands are often highly
productive when converted to
agricultural use.
Buffalo on a prairie
Biomes: Temperate Grasslands
Temperate grasslands:



The roots of prairie grasses
characteristically penetrate far into
the soil, which tends to be deep and
fertile.
Herds of grazing animals often
populate grasslands.
North America was once covered with
huge herds of buffalo that covered
the plains.
Buffalo on a prairie
Biomes: Temperate Deciduous Forests
Temperate Deciduous Forests:


Relatively mild climates and plentiful
rain promote the growth of temperate
deciduous forests.
Temperate deciduous forests
(deciduous trees shed their leaves in
the fall) grow in areas with relatively
warm summers, cold winters and
annual precipitation of from 75 to 250
cm (30 to 100 inches) of rain each
year.
Biomes: Temperate Deciduous Forests
Temperate Deciduous Forests:


Temperate deciduous forests cover
much of the eastern United States
and are home to deer, beavers,
raccoons, and other familiar animals.
The trees in these forests include
hardwoods such as oak, hickory and
beech.
Biomes: temperate evergreen forests
Temperate evergreen forests
 In other temperate areas, drier
weather and different soil conditions
favor the growth of evergreen
forests.

Large portions of the southeastern
and southwest United States have
temperate evergreen forests;
extensive areas where pine forests
are predominant over deciduous
forests.
Biomes: chaparral

Where conditions are even
drier, temperate forests
give way to areas of dry
shrubs such as in the
chaparral areas of coastal
California and in the
Mediterranean.
The chaparral is a shrub association
dominated by buckbrush and white-leaf
manzanita. Patches of chaparral occur as the
dominant vegetation, or as an understory
beneath the savanna or woodland. Plants
found in this habitat must be able to live in
hot, dry conditions on shallow soils. You will
see mostly bushes or shrubs with woody,
round, waxy leaves that prevent loss of water.
This area supports large bird populations by
providing good food sources and many great
places to live.