Transcript Ch. 4: Ecosystem and Communties

Ch. 4:
Ecosystem
and
Communties
Ch. 4 Outline
• 4-1: The Role of Climate
– What is Climate?
– The Greenhouse Effect
– The Effect of Latitude on Climate
• 4-2: What Shapes an Ecosystem
–
–
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Biotic and Abiotic Factors
The Niche
Community Interactions
Ecological Succession
Ch. 4 Outline
• 4-3: Biomes
– The Major Biomes
– Other Land Area
• 4-4: Aquatic Ecosystem
– Freshwater Ecosystems
– Estuaries
– Marine Ecosystems
What is Climate?
• Weather: the day-to-day condition of
the Earth’s atmosphere at a particular
time and place
• Climate: the average, year-after-year
conditions and temperature and
precipitation in a particular region
– Caused by many factors including latitude,
wind currents, ocean currents, etc.
• The energy of incoming sunlight drives
Earth’s weather and helps determine
climate.
The Greenhouse Effect
• Temperature on Earth remain in a
suitable range for life because of
the atmosphere.
– Carbon dioxide, methane, water
vapor and a few other atmospheric
gases trap heat energy and maintain
the Earth’s temperature range.
Greenhouse Effect
• Greenhouse effect: the natural
situation in which heat is retained
by the layer of gases around Earth
– Gases in the atmosphere allow solar
energy in but do not allow it to pass
out as easily (after it bounces off the
Earth and heads in the other
direction). This is how heat is trapped
inside the Earth’s Atmosphere.
Greenhouse Effect
Greenhouse Effect
Sunlight
Some heat
escapes
into space
Greenhouse
gases trap
some heat
Atmosphere
Earth’s surface
The Effect of Latitude on Climate
• Earth is tilted on its axis. As a result,
sunlight hits the Earth at different
angles.
– Ex. In the tropics (around the
equator), sunlight hits directly year
round.
• Because of this, earth has three
different climate zones: polar,
temperate, and tropical.
The Effect of Latitude on Climate
• Polar zone: cold areas where the sun’s
rays strike the Earth at a low angle.
– Around North and South Poles
• Temperate zones: located between
polar zone and tropics
– Climates ranges in these zones depending
on the season
• Tropical zone: near the equator
– Receive direct sunlight year around.
The Effect of Latitude on Climate
Different Latitudes
90°N North Pole
Sunlight
Arctic circle
Sunlight
Most direct sunlight
66.5°N
Tropic of Cancer
Equator
23.5°N
0°
Tropic of Capricorn 23.5°S
Sunlight
Arctic circle
Sunlight
66.5°S
90°S South Pole
Heat Transport in the Biosphere
• The unequal heating of Earth’s surfaces
drives wind and ocean currents
• Warm air tends to rise and cool air sinks.
Warm air above the equator rises and
cool air from the poles sinks. As a result,
air currents (winds) form.
– A similar pattern occurs in the oceans
• Winds and Ocean currents transport
heat
Biotic and Abiotic Factors
• Ecosystems are influenced by a
combination of biological (living)
and physical (nonliving) factors.
• Biotic Factors: biological influences
on an ecosystem
• Abiotic Factors: physical or nonliving factors
– Ex. Temperature, humidity, wind, soil,
etc…
Biotic and Abiotic Factors
• These types of factors together
determine the survival and growth
of an organism and the
productivity of the ecosystem
• Habitat: the area in which an
organism lives
– Includes both abiotic and biotic
factors
Biotic and Abiotic Factors
Abiotic Factors
Biotic Factors
ECOSYSTEM
Community Interaction
• When organisms live together in a
community, they constantly
interact. These interactions (such
as predation, competition, and
symbiosis) greatly affect an
ecosystem.
Community Interactions
• Competition:
– Occurs when organisms try to use the same
resources at the same time and place
– Resource: any necessity of life (ex. Food)
– Competitive exclusion principle: no two
organism can occupy the same niche in
the same habitat
• One will always have a reproductive advantage
over the other (even if very small) and will “win”
over the other  survive and pass on their
genes!!!
Community Interaction
•
Predation
–
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Predation: an interaction in which one organism
captures and feeds on another organism
Predator vs. Prey
Symbiosis:
–
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Symbiosis: any relationship in which two species live
closely together
3 main classes of symbiotic relationships:
1. Mutualism: Both Species benefit
•
Ex. Mycorrhizae
2. Commensalism: One benefits, the other is neither
helped nor harmed
3. Parasitism: one benefits, the other is harmed
•
Ex. Tapeworms in mammal intestine.
Ecological Succession
• Ecosystems are always changing.
They change in response to natural
and human disturbances. Older
inhabitants gradually die out and
new organisms move in, causing
even further change.
• Ecological succession: a series of
predictable changes that occurs
in a community over time.
Ecological Succession
• Two types of succession:
1. Primary succession: Succession that
occurs where no soil exists
– Ex. After a volcano Erupts
– Pioneer species – first species to
populate the area (often lichens)
2. Secondary Succession: occurs
when changes happen without
removing the soil.
–
Ex. When a forest is cleared for farming.
Biomes
• Biome: a complex of terrestrial
communities that covers a large area
and is characterized by certain soil and
climate conditions and particular
groups of plants and animals
• Plants and animals have specific
adaptations to help them survive in a
particular biome.
– Ex. Leaves of cacti are small to prevent
water loss.
The Major Biomes
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Tropical Rain Forest
Tropical Dry Forest
Tropical Savanna
Desert
Temperate Grassland
Temperate Woodland and Shrubland
Temperate Forest
Coniferous Forest
Boreal Forest
Tundra
All of these biomes are characterized by a unique set of
abiotic factors (mostly climate) and groups of plants
and animals.
The Major Biomes
Ten Major Biomes
Biome
Precipitation
Temperature
Soil
Diversity
Trees
Grasses
Tropical Rain Forest
high
hot
poor
high
dense
sparse
Tropical Dry Forest
variable
mild
rich
moderate
medium
medium
Tropical Savanna
variable
mild
clay
moderate
sparse
dense
Desert
low
variable
poor
moderate
sparse
sparse
Temperate
Grassland
Temperate
woodland and
Shrubland
Temperate Forest
moderate
summer hot
rich
moderate
absent
dense
summer low,
winter
moderate
moderate
summer hot
poor
low
medium
medium
rich
high
dense
sparse
Northwestern
Coniferous Forest
high
summer
moderate, winter
cold
summer mild,
winter cold
rocky, acidic
low
dense
sparse
Boreal Forest
moderate
summer mild,
winter cool
poor, acidic
moderate
dense
sparse
Tundra
low
summer mild,
winter cold
poor
low
absent
medium
World’s Major Biomes
Tropical rain forest
Temperate grassland
Temperate forest
Tundra
Tropical dry forest
Desert
Mountains and
ice caps
Tropical savanna
Temperate woodland
and shrubland
Northwestern
coniferous forest
Boreal forest
(Taiga)
Other Land Areas
• Some areas of Earth do not fall neatly
into a major biome category
– Ex. Mountain Ranges and Polar Ice Caps
• Mountain ranges:
– On mountains, abiotic and biotic conditions
vary with elevation
• Polar Ice Caps:
– Cold and Icy all year round
– Dominant life includes penguins and other
marine mammals (in Antarctica) and polar
bears and insects (North Pole)
Aquatic Ecosystems
• Almost ¾ of the Earth is covered in
Water. Aquatic ecosystems are
determined primarily by the depth,
flow, temperature, and chemistry
of the overlying water.
• Aquatic biomes are mostly
grouped by the abiotic factors
that affect them, rather then
geography.
Freshwater Ecosystems
• Only 3% of the surface water on
Earth is Fresh water.
• Types of Freshwater ecosystems:
– Flowing-water Ecosystems
• Rivers, Streams, creeks
• Organisms there have adapted to the
rate of flow
– Ex. Anchoring Structures
Freshwater Ecosystem
• Standing Water Ecosystems
– Lakes and ponds
– Water circulates within them to
distribute nutrients
– Provide habitats for plankton: tiny,
free-floating organisms
• Ex. Phytoplankton – type of algae
• Ex. Zooplankton – animals that feed on
phytoplankton
Freshwater Ecosystems
• Freshwater Wetlands
– Wetland: Ecosystem in which water
covers the soil (or at least near the
surface of soil) for part of the year.
– Water may be standing or flowing
– Freshwater or saltwater (brackish)
– Common breeding ground for many
animals
– Three types: bogs, marshes, swamps
Freshwater Ecosystem
Spoonbill
Frogs lay eggs in the shallow
water near shore.The eggs
hatch in the water as tadpoles
and move to the land as adults.
The shore is lined with grasses
that provide shelter and nesting
places for birds and other
organisms.
Duck
Water
Frog lilies Mosquito
Duckweed
larvae
Dragonfly
Snail
The roots of water lilies
cling to the pond bottom,
Pickerel
Diving
beetle Fish share the pond
while their leaves, on long
flexible stems, float on the
with turtles and other
surface.
animals. Many of
them feed on insects
at the water’s edge.
Trout
The bottom of the pond is
inhabited by decomposers and
Hydra
other organisms that feed on
particles drifting down from the
Snail Crayfish
surface.
Phytoplankton
Plankton and the organisms that
feed on them live near the surface
where there is enough sunlight for
photosynthesis. Microscopic algae
are among the most important
producers.
Benthic
crustaceans
Estuaries
• Estuaries: Wetlands formed where
rivers meet the sea
• They contain a mixture of fresh and
salt water. Most are shallow so
sunlight reaches the bottom
(photosynthesis can happen
there!)
Estuaries
• Primary producers there: Plants, algae,
bacteria
• Most organic matter is not consumed by
herbivores, but enters the food web as detritus
– Detritus: tiny pieces of organic material
• Clams, worms, and sponges all feed on
detritus.
• Estuaries support a large amount of biomass.
Many fish are born there. Other animals feed
and grow in estuaries, where they head out to
sea to mature but return to reproduce.
Estuaries
• Salt Marshes: Temperate-zone estuaries
dominated by salt-tolerant grasses and
seagrasses underwater.
– Found on East Coast of North America.
• Mangrove swamps: found in tropical
regions, have salt-tolerant trees called
mangroves
– Ex. Florida’s Everglades National Park
Marine Ecosystems
• Photic zone: Upper layer of water where
photosynthesis can occur
• Aphotic zone: no light penetrates the water
• In addition to the division between the photic
and aphotic zone, scientists divide the ocean
into zones based on the depth and distance
from shore
– Intertidal zone
– Coastal Ocean
– Open Ocean
• Benthic zone: covers ocean floor
Zones of the Marine Ecosystem
land
Coastal
ocean
Open
ocean
200m
1000m
Photic zone
4000m
Aphotic zone
6000m
Ocean
trench 10,000m
Continental
shelf
Continental slope and
continental rise
Abyssal
plain
Marine Ecosystem
• Intertidal Zone
– Organisms that live here are exposed
to many changes in their
surroundings. Competition often
leads to zonation.
• Zonation: the horizontal banding of
organisms that live in a particular habitat
Marine Ecosystem
• Coastal Ocean
– Extends from the low-tide mark to the
outer edge of the continental shelf
(the shallow border that surrounds the
continents).
– Most of the coastal oceans fall in the
photic zone so it is rich in many
organisms
– In tropical coastal oceans, coral reefs
exist
Marine Ecosystem
• Open Ocean
– Begins at the edge of the continental
shelf and extends outward. It covers
more than 90% of the surface area of
the world’s oceans.
– Productivity here is low because
there are low levels of nutrients deep
in the ocean. Fish dominate the
open ocean.
Benthic Zone
• The Ocean Floor
• Benthos: Organisms that live
attached to or near the ocean
floor
– Ex. Sea Stars
• Depends on food from organisms
that grow in the photic zone.
• Detritus that rains down to the
floor.