Chapter #6
Major Ecosystems/Biomes of the World
Overview of Chapter 6
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Earth’s Major Biomes
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Aquatic Ecosystems
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Tundra, Boreal Forests, Temperate Rainforest,
Temperate Deciduous Forests, Grasslands, Chaparral,
Deserts, Savanna, & Tropical Rainforests
Vertical Zonation
Freshwater ecosystems
Estuaries
Marine Ecosystems
Interaction of Life Zones and Humans
Earth’s Major Biomes
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Biome
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Location of each biome is primarily
determined by:
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A large, relatively distinct terrestrial region with a similar climate
soil, plants, and animals, regardless of where it occurs in the world
Nine major biomes
Temperature (varies with both latitude and elevation)
Precipitation
Biomes can also be defined by
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Winds, rapid temperature changes, fires, floods, etc.
Vertical Zonation
Increasing in
elevation has
similar effect on
ecosystem as
traveling to
higher latitudes
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Tundra
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Treeless biome in the far north with harsh, cold
winters and extremely short summers
Precipitation
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10-25 cm/yr
Temperature
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Short growing season
50-160 days
Tundra
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Nutrient poor soils with little organic material
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Low species richness
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Permafrost present
Veg is mostly grasses and
sedges
Very simple food web
Low primary
productivity
Boreal Forests
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A region of coniferous forests in the northern
hemisphere
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Covers 11% of earth’s
land
Growing Season
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Just south of tundra
A little longer than
tundra
Precipitation
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~ 50 cm/yr
Boreal Forests
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Soils are acidic and mineral poor
Vegetation comprised of drought resistant conifers
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White spruce
Balsam fir
Eastern larch
Mostly small animals and
migrating birds
Some large animals are
present
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Wolves, bear, moose
Temperate Rainforest
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Coniferous biome with cool weather, dense fog and
high precipitation
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Precipitation
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Ex: Northwest US
> 127 cm/yr
Heaviest in winter
Temperature
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Winters are mild
Summers are cool
Temperate Rainforest
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Soils are nutrient-poor, but high in organic material (dropped
needles)
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Dominant Vegetation
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Cool temperatures slow decomposition
Large evergreen trees
Old-growth forest
Variety of cool
climate animal life
Very high species
richness
Heavily logged
Temperature Deciduous
Forests
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Forest biome that occurs in
temperate areas with a moderate
amount of precipitation
Precipitation
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75-150 cm/yr
Temperature
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Seasonality
Hot summers and cold winters
Temperate Deciduous Forest
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Topsoil is rich in organic material and underlain by
clay
Vegetation is primarily deciduous
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Animals
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Oak, maple, beech
Deer, bear and small animals
Most of this biome land area has
been regenerated after farming &
timber harvest
Grassland
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Grasslands with hot summers, cold
winters and too little precipitation
to support trees
Precipitation
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25-75 cm/yr
Tall grass prairies
Short grass prairies
90% of this biome has been lost to
farmland
Grassland
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Soil has thick, organic material
rich organic horizon.
Periodic fires keep the dominant vegetation
grasses
Animals
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Once covered with
bison- no longer true
Smaller animals are
still present (ex:
prairie dogs)
Chaparral
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Also called a Mediterranean
Climate
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Temperature
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Ex: Southern California
Ex: Greece
Mild, moist winters
Hot, dry summers
Frequent fires
Chaparral
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Soil is thin and often not
fertile
Vegetation
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Dense growth of evergreen
shrubs
Lush during the growing
season
Animals
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Mule deer, chipmunks, many
species of birds
Deserts
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Biome where lack of
precipitation limits plant
growth
Temperature
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Can very greatly in 24-hr
period, as well as yearly
(based on location)
Precipitation
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< 25 cm/yr
Deserts
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Soils low in nutrients, high in salts
Vegetation sparse
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cactus and sagebrush
Animals are very small to regulate temperature
Sonoran Desert
Savanna
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Tropical grassland with
widely scattered trees
Temperature
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Varies little throughout the
year
Precipitation
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Seasons regulated by
precipitation, not temperature
76-150 cm/yr
Savanna
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Soil low in nutrients due to leaching
Vegetation
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Wide expanses of grass
Occasional Acacia trees
Have fire adaptive
characteristics
Animals
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Herds of hoofed
animals
Large predators- lions,
hyenas, etc.
Tropical Rainforest
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Lush, species-rich biome
that occurs where climate is
warm and moist
throughout the year
Precipitation
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200-450 cm/yr
Very productive biome
Most species-rich biome
Tropical Rainforest
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Ancient, weathered, nutrientpoor soil
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Vegetation
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Nutrients tied up in
vegetation, not soil
3 distinct canopy layers
Animals
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Most abundant insect, reptiles
and amphibians on earth
Aquatic Ecosystem
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Fundamental Division
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Aquatic Ecosystems also affected by
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Freshwater
Saltwater
Dissolved oxygen level, light penetration, pH,
presence/absence of currents
Three main ecological categories of organisms
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Plankton- free floating
Nekton- strong swimming
Benthos- bottom dwelling
Freshwater Ecosystems
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Includes:
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Rivers and streams
Lakes and ponds
Marshes and swamps
Represent 2% of earth’s surface
Assist in recycling water back to the oceans
(Biogeochemical Cycling)
Rivers and Streams
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Changes greatly from
headwater to mouth
Headwaters
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Shallow, cool, swiftly
flowing, high oxygenated
Mouth
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Not as cool, slower
flowing, less oxygen in
water
Lakes and Ponds
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Body of freshwater that does not flow
Three zones
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Littoral
Limnetic
Profundal
Experience thermal stratification (depending on
depth)
Lakes and Ponds
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Littoral Zone - shallow water area along the shore
Limnetic Zone - open water beyond the littoral
zone
Profundal Zone - beneath the limnetic zone of
deep lakes
Thermal Stratification
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Temperature changes
sharply with depth
Thermocline
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Temperature transition
between warmer
surface water and
colder water at depth
Only present in warm
months
Fall Turnover
Marshes and Swamps
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Lands that shallow, fresh water covers for at least part
of the year
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Characteristic soil- water logged and anaerobic for periods
of time
Water tolerant vegetation
Were once regularly filled
in
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More recently their
ecosystem services have
been better recognized
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Flood protection, water
filtering, etc.
Estuaries
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Where freshwater and saltwater mix
Highly variable environment
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Temperature, salinity, depth of light penetration
Highly productive
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Nutrients transported from land
Tidal action promotes rapid
circulation of nutrients
High level of light penetrates
shallow water
Many plants provide
photosynthetic carpet
Estuaries
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Marine Ecosystems
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Subdivided into
life zones
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Intertidal zone
Benthic zone
Pelagic
environment
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Neritic Province
Oceanic Province
Intertidal Zone
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Area of shoreline between low and high tides
Habitat
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Sandy or rocky
Muscles
Crabs
Algae
Oysters
Barnacles
Animals must
adapts to
changing
conditions
Benthic Zone
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Ocean floor, extending from tidal zone to deep sea
trenches
Sediment is mostly mud
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Burrowing worms and clams
Three zone
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Bathyal: 200m - 4000m deep
Abyssal: 4000m -6000m deep
Hadal: 6000m – bottom of deep sea trenches
Productive Benthic Communities
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Seagrass Beds
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Kelp Forest
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Present to depth of 10 m
Provide food and habitat to
ecosystem
60-m long brown algae found off rocky shores
Diversity of life supported by kelp rivals coral reefs
Coral Reefs
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Built from accumulated layers of CaCO3
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Colonies of millions of tiny coral animals
Found in shallow warm water
Most diverse of all marine environments
Productive Benthic Communities
Left: Seagrass Bed
Right: Kelp Forest
Coral Reef
Environments
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Three types of coral
reefs
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Fringing reef- directly
attach to continent- no
lagoon
Atoll- circular reef in a
lagoon
Barrier reef- separates
lagoon from ocean
Human Disturbance
Human Impact on Coral Reefs
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Sedimentation
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From clear-cutting
upstream
Overfishing
Coral bleaching
Mining of corals as
building materials
Runoff pollution
www.marinebiology.org
Pelagic Environment
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All the open ocean water
Two main divisions
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Neritic Province
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Water that overlies the continental shelf (to depth of 200 m)
Organisms are all floaters or swimmers
Oceanic Province
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Water that overlies depths greater than 200 m
75% of world’s ocean
Most organisms are dependent on marine snow
Organisms are filter feeders, scavengers and predators
Human Impacts on the Ocean