Chapter 20
Terrestrial Biomes &
Aquatic Ecosystems
Section 1 Objectives:
Distinguish between abiotic factors and
biotic factors in biomes.
Identify seven land biomes on Earth.
LARGE ECOSYSTEMS
Human-classified divisions
Same types of climates = similar types of
vegetation
Similar vegetation = similar biome
≠ exact same flora, fauna, or physical abiotic
makeup
Terrestrial Ecosystems or Biomes
10 Types
Aquatic Ecosystems
3 types
TERRESTRIAL BIOMES
Terrestrial Biomes
Large area characterized by its climate and the
plants and animals that live in the area – contains
related ecosystems.
Tundra
Polar Ice
Taiga/Coniferous Forests
Mountainous regions
Temperate Deciduous Forest
Tropical Rainforest
Chaparral
Temperate Grassland
Savanna
Desert
Tundra
Tundra (Polar and Alpine)
Tundra = “treeless plain”
Flat terrain with low shrubs, grasses, sedge,
mosses, lichens; low biodiversity
One-fourth of Earth’s terrestrial surface
Present in northernmost latitudes (≥ 60° N)
Desert-like rainfall (30-50 cm or 12-20 in
per year) but bogs and marshes in summer
rainy season due to permafrost
Tundra (cont’d)
Permafrost – condition of permanent
frozen soil beginning ~ 1 meter (m) below
surface and extending down to 500 m
Water can not drain
Plants produce in short 50-day season
Year-round: Arctic lemmings, hares, foxes
Summer migratory animals seeking food
No reptiles or amphibians
Taiga
Taiga
Also known as the Boreal or northern forests –
covered with coniferous trees such as firs, pines,
spruces, and cedars (dominant vegetation) –
located south of tundra
Largest biome on Earth; low biodiversity
Winters: very cold and snowy
Summers: warm, rainy, and humid
Large mammals, fur-bearing animals
Very few reptiles and amphibians
Temperate
Deciduous Forest
Temperate Deciduous Forest
Majority of eastern US, as well as continental western
Europe and east Asia
Deciduous trees (with seasonal leaf loss) including
maples, beeches, oaks, and hickories, as well as
understory of woody shrubs and vines and
herbaceous plants
Much precipitation (75 to 200 cm /yr) (3-8x that of
tundra)
Milder winters, warm to hot summers
Great variety of animals, including reptiles and
amphibians
Temp. Deciduous Forest (cont’d)
Abundance of pines (evergreens) in the SE
US is only temporary
“Succession” – as ecosystem “ages,” new
flora species replace previous ones (e.g.,
grass to low shrubs and vines to evergreens
to hardwoods); as flora change so will fauna
Here, climax successional stage is
oak/hickory forest
Temperate Grassland
Temperate Grassland
Areas of predominantly tall, mixed, or short
grasses sandwiched between temperate
deciduous forests and deserts
Annual precipitation of 25-100 cm
Extremely fertile soil (US Midwest farms)
Natural grasslands destroyed for
agriculture; very little left in world
Short grass prairie – crops and cattle
Savanna
Subtype of grassland: tropical grassland in
Southern Hemisphere (Africa, South
America, and Australia)
Seasonal drought, warm climate, dotted
with stands of trees, and home to typical
large mammals (e.g. in Africa, elephants,
giraffes, zebras, lions, spring boks, cape
buffalo, etc.)
Desert
Desert: “Got Water?”
Desert – area receiving < 25 cm annual
precipitation; evaporation > precipitation
Deserts may be cold, temperate, or hot
Flora and fauna specialized to survive with little
water – collect and conserve
Soils poor because lack of water = very little
biomass, or net productivity, low organics =
inability to hold water
Concentration of inorganic salts high
Tropical Rainforest
Tropical Rainforest
Large warm equatorial areas, abundant
annual precipitation (200-450 cm and even
to 1000 cm for some) with high biomass
productivity and biodiversity
7% of Earth’s land mass under massive
destruction; can not be replaced
Poor, acidic soil: plants uptake quicklydecomposed organic nutrients
Polar Ice and Mountains
Polar Regions:
Cold, dry, devoid of terrestrial plant life
Animals capable of living in frigid conditions
and basis of survival on highly productive
marine ecosystem
Mountains:
Increase in altitude similar to northern latitudes
(cooler climate and conifers)
Rain shadow on lee side (desert area)
Chaparral
Not a grassland
Punctuated with lowgrowing evergreen
shrubs, pines, and scrub
oaks
Lands on Western coast
lines with Mediterranean
type climate (wet mild
winter/ hot dry summer,
ocean winds)
Biome Ecological Concerns
Tundra/Taiga– ore mining, oil drilling, ecosystem
fragmentation, global warming/species changes
Temperate Deciduous Forests – human destruction
for resources and population
Temperate Grasslands – very little remaining,
non-native grass species; agriculture
Deserts – In US, human encroachment
Tropical Rain Forests - human destruction for
resources and population; expansive loss of
species, biomass net productivity
Section 2 Objectives:
List three abiotic factors that shape marine
ecosystems.
Describe four major ocean zones.
Describe five marine ecosystems.
Aquatic Ecosystems
Marine
Intertidal Areas
Coral Reefs
Estuaries – fresh water from
streams and rivers spills into
oceans
Sargasso Sea (middle of Atlantic
Ocean – floating rafts of algae
called sargassum)
Polar Ice – Arctic Ocean and
ocean around Antarctica
Freshwater
Stream and River; Pond and Lake
Wetland
Marshes and Swamps
Marine Ecosystems
Saltwater
oceans cover
¾ of Earth’s
surface.
Photic zone = surface to
100 m down;
photosynthesis occurs
Marine Ecosystems, cont.
• Intertidal Zone: the place where the ocean meets the
land; area is exposed to the air for part of the day; sea
grasses, periwinkle snails, and herons are common in
intertidal mudflat; sea stars and anemones live on rocky
shores; clams, crabs, snails, and conchs are common on
sandy beaches
•Neritic Zone: Ocean floor starts to slope downward as you
move away from shore; water is warm and receives a lot of
sunlight; plankton and seaweeds common; sea turtles,
dolphins, corals, sponges, and colorful fishes dominate –
CORAL REEFS!
Marine Ecosystems, cont.
•Oceanic Zone: Sea floor drops sharply; contains deep
water of open ocean; many unusual animals are adapted to
this zone, such as whales, squids, fishes that glow, sharks,
etc.
•Benthic Zone: Ocean floor; deepest parts do not get any
sunlight and are very cold; animals, such as fishes, worms,
sea urchins, and crabs, have special adaptations to the deep,
dark water
Marine Ecosystem
ESTUARY Coastal point of contact between freshwater and
saltwater; mix = “brackish” water
Constant mixing stirs up nutrients for
photosynthesizers; animal life abundant
As productive as tropical rainforests and coral
reefs
Concerns:
Although protected, human pollution and encroachment
threaten health of estuaries
Marine cont’d
Abundance of life is generally greater:
Nearer coast (intertidal zone) due to stirring
action of waves and nearer surface from light
In polar regions rather than tropical regions
(abundant food – plankton - for large
organisms)
In tropical coral reefs along shallow coastlines
Marine cont’d
Ecological Concerns:
Overfishing and industrial fishing techniques
that destroy deep water habitats
Human pollution of the coastal waters (sewage,
construction erosion, chemical use, etc.)
Human physical destruction of sensitive
ecosystems such as coral reefs, tidal pools
Section 3 Objectives:
Describe one abiotic factor that affects
freshwater ecosystems.
Describe the three zones of a lake.
Describe two wetland ecosystems.
Explain how a lake becomes a forest.
Freshwater Ecosystems
Inland freshwater
streams, ponds, and
lakes cover 2.1% of
Earth’s surface.
Freshwater Ecosystems
Littoral Zone - area of water closest to edge of lake or
pond; cattails, rushes, algae, water lilies; small animals,
snails, insects, clams, worms, frogs, salamanders,
turtles, fish, and snakes
Open-Water Zone – the zone of a pond or lake that
extends from the littoral zone and that is only as deep
as light can reach – bass, lake trout, and other fishes
Deep-Water Zone – the zone of a lake or pond below
the open-water zone, where no light reaches – carp,
catfish, worms, crustaceans, fungi, and bacteria
Freshwater cont’d
Natural lake nutrient concentrations
(phosphorus often is limiting factor)
Shallow, nutrient rich = eutrophic
• Abundant aquatic photosynthesis and animals
(cloudy, murky water)
• Occurs naturally over long periods of time
Deeper, nutrient poor = oligotrophic
• Few nutrients to aid photosynthesis, little animal life
(clear water)
Freshwater Concerns
Artificial eutrophication of lakes: nutrient rich
sewage, fertilizers, construction erosion, etc. feed
algae
Algal bloom leads to accumulation of dead algae;
decomposition by oxygen-using bacteria; fish kills
Clean Water Act has helped, but battle not over
(Pollutants regulated under the CWA include "priority"
pollutants, including various toxic pollutants;
"conventional" pollutants, such as biochemical oxygen
demand (BOD), total suspended solids (TSS), fecal
coliform, oil and grease, and pH; and "non-conventional"
pollutants, including any pollutant not identified as either
conventional or priority. The CWA regulates both direct
and indirect discharges. )
Wetland
Land remaining wet for at least part of the year
(bog, marsh, swamp, tidal marshes) and very
productive
Most are inland, freshwater
Soils and plants can capture pollutants, act as
wastewater system and clean up
Play important role in flood control
Concerns:
Federal protection requires restoration, but
many destroyed
Loss of migratory bird habitat
Marshes and Swamps
Marshes
Treeless wetland ecosystem where plants grow; found
in shallow areas along shores of lakes, ponds, rivers,
and streams; grasses, reeds, bulrushes, wild rice,
muskrats, turtles, frogs, and birds dominate
Swamps
Wetland ecosystem in which trees and vines grow;
found in low-lying areas and beside slow-moving
rivers; flooded part of the year; willows, bald cypresses,
oaks, poison ivy, water lilies, orchids, fish, snakes, and
birds dominate