Ecosystems & Biomes
A biome is defined as the similar ecosystems of a large geographic area with species adapted
to that environment. Biomes are described in terms of abiotic factors like climate and soil type,
and biotic factors like plant and animal life.
Ecologists classify Earth’s terrestrial ecosystems into at least ten different groups of regional
climate communities called biomes. Biomes are described in terms of abiotic factors like
climate and soil type, and biotic factors like plant and animal life. Major biomes include
tropical rain forest, tropical dry forest, tropical grassland/savanna/shrubland, desert,
temperate grassland, temperate woodland and shrubland, temperate forest, northwestern
coniferous forest, boreal forest, and tundra.
Organisms within each biome can be characterized by adaptations that enable them to live
and reproduce successfully in the environment. However, even within a defined biome, there
is often considerable variation among plant and animal communities. These variations can be
caused by differences in exposure, elevation, or local soil conditions. Local conditions also can
change over time because of human activity or because of community interactions.
Biomes can be classified as terrestrial (land biomes) and aquatic (water biomes). Latitude is
the measure of the distance from the earth’s equator. The higher the latitude, the farther from
the equator and closer to either pole. Tundra is the coldest biome having a permanent layer of
frost beneath the soild (permafrost), surrounds the North Pole. Taiga (the boreal forest) is
found just south of the Tundra. Altitude is a measure of a location’s distance above sea leavel.
Biomes found at higher altitudes are farther from sea level and usually have colder
temperatures. Mountain ranges make up the high-altitude alpine biome.
The biomes of the earth can be divided into three categories according to temperatures:
cold, temperate & tropical.
Cold Terrestrial Biomes
Biome
Conditions
Soil
Plant life
Animal Life
Summers: short
& cool
Thin, nutrient-poor, Grasses & small
Permafrost
shrubs
Caribou, Polar
Bears, Wolves
Acidic, thin &
nutrient-poor
Foxes, bears,
moose,
chipmunks
Arctic Tundra
Winters: long &
cold
Taiga
(Boreal forest)
Little
precipitation
Summers: short,
warm & wet
Winters: long,
cold & dry
Summers: short
& cool
Alpine Tundra
Rocky & nutrientpoor
Evergreen trees
Have many
conifers,
evergreen trees
with needlelike
leaves
Small shrubs
Sheep &
mountain goats
Winters: long &
cold
Little
precipitation
Ex. Rocky
Mountains
Temperate Terrestrial Biomes
Biome
Conditions
Soil
Plant Life
Animal Life
Temperate Forest
Summers: warm
& wet
Thick & nutrientrich
Deciduous trees
Deer, rabbits,
bears & squirrels
Shrubs & grasses
Winters: cool
Thick & nutrientrich
Prairie dogs, mice
& coyotes
Some rain
Summers: hot &
dry
Thin & nutrientpoor
Some deciduous
trees, shrubs
Rabbits, foxes,
coyotes
Grassland
Chaparral
Winters: cool &
wet
Summers: hot
Winters: mild &
rainy
The Chaparral Ex. Found in the west coast of the United States & areas of the Mediterranean
Tropical Terrestrial Biomes
Biome
Conditions
Summers: long,
hot & dry
Desert
Shorter, dry
winters
Very little
precipitation
Warm all year
Tropical Rain
Forest
Soil
Plant Life
Animal Life
Sandy or coarsegrained &
nutrient-poor
Cacti & shrubs
Lizards & small
rodents
Acidic, thick &
nutrient-poor
Tall trees with
wide leaves &
vines
Butterflies,
snakes &
chimpanzees
Long wet season
& short dry
season
Hot & fairly dry
Savanna
Thin & relatively
nutrient-poor
Shrubs & grasses
Alternating wet &
dry seasons
Pennsylvania is located in the temperate deciduous forest biome.
**Has the
greatest species
diversity of any
terrestrial
biome**
Lions &
wildebeests
Besides the important terrestrial biomes the earth is home to many aquatic or water biomes as
well. There are two important factors that affect aquatic biomes: sunlight & salinity.
Sunlight is an important factor because the sun only penetrates to a certain depth & that
depends upon how clear the water is. The variety of organisms found in the zones of the earth
are determined by this factor, Salinity refers to the concentration of salt found in the water.
Ocean biomes also called marine biomes are characterized by the salt water. A biome that is
partly salty is referred to as brackish.
Nonmarine Aquatic Biomes
Biome
Fresh-water lake
River
Estuary
Wetland
Location
Conditions
Ranges from a
small to a large
body of water
surrounded by
land
Great variety in
the amount of
dissolved O2 &
nutrients & the
organisms this
biome can
support
Moving fresh
water
This biome varies
in the amount of
dissolved
settlement,
temperature &
turbulence.
Salty water from
mixing with
seawater
Transition zone
located between
the mouth of a
river and a marine
biome
Shallow basins, in
river flood zones,
along the coasts
of oceans
Salinity changes
with the tides
Can be freshwater
or saltwater
Plant life
Aquatic plants
Rooted plants
Aquatic grasses &
algae
Animal Life
Invertebrates:
phytoplankton &
zooplankton
Vertebrates: fish
in areas where
there is enough
oxygen
Phytoplankton,
fish &
invertebrates
Invertebrates,
food species
(crabs & oysters)
Invertebrates,
shore birds, and
other predators
Can be dry part of
the year
Invertebrates are organisms that do not have backbones. These include shrimp, lobster,
oysters, clams and snails. Marine invertebrates also include jellyfish, octopus, and squid.
Marine Biomes
Biome
Intertidal Zone
Location
Area between low
& high tide lines
Conditions
Plant life
Changes
periodically in
exposure to air,
temperature &
salinity
Large algae
Animal life
Small fish,
invertebrates (sea
stars, worms,
clams, mollusks,
crustaceans)
Pounding force of
ocean weaves
Pelagic
Organisms may
bury in sand or
mud
Light shines in the
upper layer
Vast waters of the allowing
open ocean
photosynthesis
Phytoplankton,
zooplankton, fish,
marine mammals,
turtles, squid &
other
invertebrates
Most organisms
exist in the upper
layer
Ocean floor
Benthic & Abyssal
Deepest
regions—abyssal
zone
*greatest rate of
photosynthesis
occurs here
No sunlight,
except on the
sloping ocean
floor along the
coast
Invertebrates such
as worms & crabs,
fish
Some organisms
are adapted to
complete
darkness
At lowest
depths—high
pressure & cold
temperatures
Coral Reef
Upper layers of
the tropical
pelagic
Organic matter
drops from
pelagic biome
Built up of coral
skeletons over
long periods of
time
Corals
Fish &
invertebrates
High species
diversity