Chapter 20
The Earth’s Ecosystems
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Section 1 Land Biomes
Section 2 Marine Ecosystems
Section 3 Freshwater Ecosystems
Concept Mapping
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Chapter 20
Section 1 Land Biomes
Bellringer
Write the answers to the following questions in your
science journal:
• What is a biome?
• List seven land biomes.
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Chapter 20
Section 1 Land Biomes
Objectives
• Distinguish between abiotic factors and biotic
factors in biomes.
• Identify seven land biomes on Earth.
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Chapter 20
Section 1 Land Biomes
The Earth’s Land Biomes
• Abiotic Factors Abiotic factors are the nonliving
parts of an environment.
• Biotic Factors Biotic factors are the living parts of
an environment.
• Biomes A biome is a large area characterized by
its climate and the plants and animals that live in
the area.
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Chapter 20
Section 1 Land Biomes
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Chapter 20
Section 1 Land Biomes
Forests
• Temperate Deciduous Forests In a temperate
deciduous forest, mammals, birds, and reptiles
thrive on the many leaves, seeds, nuts, and
insects.
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Chapter 20
Section 1 Land Biomes
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Chapter 20
Section 1 Land Biomes
Forests, continued
• Coniferous Forests Coniferous forest has
evergreen trees and many animals must
hibernate through the cold winters.
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Chapter 20
Section 1 Land Biomes
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Chapter 20
Section 1 Land Biomes
Forests, continued
• Tropical Rain Forests Tropical rain forests
have a greater variety of organisms than any
other biome.
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Chapter 20
Section 1 Land Biomes
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Chapter 20
Section 1 Land Biomes
Grasslands
• Temperate Grasslands
Temperate grasslands
have few trees, and many
different kinds of seed and
grass-eating animals.
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Chapter 20
Section 1 Land Biomes
Grasslands, continued
• Savannas A grassland that has scattered
clumps of trees and seasonal rains is called a
savanna.
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Chapter 20
Section 1 Land Biomes
Deserts
• Dry and Hot Biomes that are very dry and
often very hot are called deserts.
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Chapter 20
Section 1 Land Biomes
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Chapter 20
Section 1 Land Biomes
Tundra
• Polar Tundra In polar tundra, the layer of soil
beneath the surface soil stays frozen all of the
time. This layer is called permafrost.
• Alpine Tundra Alpine tundra also has
permafrost. But alpine tundra is found at the
top of tall mountains.
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Chapter 20
Section 1 Land Biomes
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Chapter 20
Section 2 Marine Ecosystems
Bellringer
Write the answer to the following question in your
science journal: What are abiotic factors in marine
ecosystems?
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Chapter 20
Section 2 Marine Ecosystems
Objectives
• List three abiotic factors that shape marine
ecosystems.
• Describe four major ocean zones.
• Describe five marine ecosystems.
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Chapter 20
Section 2 Marine Ecosystems
Life in the Ocean
• Abiotic Factors Marine ecosystems are shaped
by abiotic factors including water temperature,
water depth, and the amount of sunlight that
passes into the water.
• Plankton Trillions of plankton live in the ocean.
Plankton are tiny organisms that float near the
surface of the water.
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Chapter 20
Section 2 Marine Ecosystems
Temperature
• Depth and Temperature The temperature of
ocean water decreases as the depth of the water
increases.
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Chapter 20
Section 2 Marine Ecosystems
Depth and Sunlight
• The Intertidal Zone The intertidal zone is the
place where the ocean meets the land.
• The Neritic Zone As you move farther away from
shore, into the neritic zone, the water becomes
deeper.
• The Oceanic Zone In the oceanic zone, the sea
floor drops sharply
• The Benthic Zone The benthic zone is the ocean
floor. The deepest part does not get any sunlight.
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Chapter 20
Section 2 Marine Ecosystems
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Chapter 20
Section 2 Marine Ecosystems
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Chapter 20
Section 2 Marine Ecosystems
A Closer Look
• Intertidal Areas Intertidal areas are found near
the shore. These areas include mudflats, sandy
beaches, and rocky shores.
• Coral Reefs Coral reefs are found in warm,
shallow areas of the neritic zone. Reefs provide
homes for many marine animals and plants.
• Estuaries An area where fresh water from rivers
spills into the ocean is called an estuary. Plants
and animals living in estuaries must be able to
survive in a changing concentration of salt.
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Chapter 20
Section 2 Marine Ecosystems
A Closer Look, continued
• The Sargasso Sea An ecosystem called the
Sargasso Sea is found in the middle of the
Atlantic Ocean. The ecosystem contains floating
rafts of algae.
• Polar Ice The Arctic Ocean and the ocean around
Antarctica have icy waters, which are rich in
nutrients. Many fishes, birds, and mammals live in
this ecosystem.
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Chapter 20
Section 3 Freshwater Ecosystems
Bellringer
Write the answer to the following question in your
science journal: What are four freshwater ecosystems?
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Chapter 20
Section 3 Freshwater Ecosystems
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.
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Chapter 20
Section 3 Freshwater Ecosystems
Stream and River Ecosystems
• Water in Streams and Rivers The water in
brooks, streams, and rivers may flow from melting
ice or snow. Or the water may come from a
spring.
• Tributaries Each stream of water that joins a
larger stream is called a tributary.
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Chapter 20
Section 3 Freshwater Ecosystems
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Chapter 20
Section 3 Freshwater Ecosystems
Tributary, River System, and
Drainage Basin
Click below to watch the Visual Concept.
Visual Concept
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Chapter 20
Section 3 Freshwater Ecosystems
Pond and Lake Ecosystems
• Life near Shore The are of water closest to the
edge of a lake or pond is called the littoral zone.
The plants in the littoral zone are homes to small
animals.
• Life Away from Shore The area of a lake or pond
that extends from the littoral zone across the top
of the water called the open-water zone. Beneath
the open-water zone is the deep-water zone,
where no sunlight reaches.
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Chapter 20
Section 3 Freshwater Ecosystems
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Chapter 20
Section 3 Freshwater Ecosystems
Wetland Ecosystems
• Marshes A treeless wetland ecosystem where
plants, such as grasses, grow is called a marsh.
Muskrats, turtles, frogs, and birds live in marshes.
• Swamps A wetland ecosystem in which trees and
vines grow is called a swamp. Water lilies and
other plants grow in standing water. Many fishes,
snakes, and birds also live in swamps.
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Chapter 20
Section 3 Freshwater Ecosystems
From a Lake to a Forest
• Build Up of Sediments Water entering a
standing body of water usually carries nutrients
and sediments. These materials build up on the
bottom of the lake or pond.
• Formation of a Wetland Over time, the pond or
lake is filled with sediments. Plants grow in the
new soil and the pond or lake starts becoming a
wetland. The wetland then may develop into a
forest.
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Chapter 20
The Earth’s Ecosystems
Concept Mapping
Use the terms below to complete the Concept Mapping
on the next slide.
land biomes
biotic factors
tundra
biomes
marine
freshwater
abiotic factors
grasslands
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Chapter 20
The Earth’s Ecosystems
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Chapter 20
The Earth’s Ecosystems
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