1. Ecosystems and Communities
Chapter 4:
Ecosystems and Communities

2. 4-1 The Role of Climate Weather vs. Climate
Weather: day-to-day condition of Earth’s atmosphere at a particular time & place
Climate: the average, year-after-year conditions of temperature and precipitation in a particular region
Influenced by: atmosphere trapping heat, latitude, winds & ocean currents, precipitation, shape & elevation of land masses

3. Greenhouse Effect
Sunlight
Natural situation in which heat is retained in Earth’s atmosphere by carbon dioxide, methane, water vapor, and other gases
Necessary to keep temperatures suitable for life
Some heat
escapes
into space
Greenhouse
gases trap
some heat
Atmosphere
Earth’s surface

4. The Effect of Latitude on Climate
Distance north or south of the equator
Due to Earth’s tilt on its axis, solar radiation strikes different parts of the Earth’s surface at an angle that varies throughout the year.
Produces three main climate zones
Polar zones
Temperate zones (seasons)
Tropical zone

5. Different Latitudes Sunlight Most direct sunlight 90°N North Pole
90°S South Pole
Arctic circle
Tropic of Cancer
Equator
Tropic of Capricorn
Different Latitudes

6. Heat Transport in the Biosphere
Unequal heating of Earth’s surface drives winds & ocean currents
Winds form because warm air rises and cold air sinks
Landmasses can interfere with movement of air masses
Mountains cause moist air to rise
Air mass cools, moisture condenses, causes precipitation
Causes a rain shadow (dry climate) on the far side of the mountains

7. 4-2 What Shapes
An Ecosystem?

8. Ecosystems are influenced by a combination of biological and physical factors.
Biotic Factors
Abiotic Factors
Biological influences (living components)
Animals
Plants
Fungi
Protists
bacteria
Physical factors (nonliving components)
Temperature
Precipitation
Humidity
Wind
Nutrients
Soil
Sunlight

9. Abiotic Factors
Biotic Factors
ECOSYSTEM

10. Habitat vs. Niche Habitat (address) Niche (occupation)
The area where an organism lives
Includes both biotic and abiotic factors
Niche (occupation)
The full range of physical & biological conditions in which an organism lives and the way in which the organism uses those conditions
Eating & obtaining food, physical conditions needed for survival, when & how it reproduces, etc.
No two species can share the same niche in the same habitat

11. Bay-Breasted Warbler
Feeds in the middle
part of the tree
Yellow-Rumped Warbler
Feeds in the lower part of the tree and
at the bases of the middle branches
Cape May Warbler
Feeds at the tips of branches
near the top of the tree
Spruce tree

12. Describing a Niche Place in a food web Temperature range
Food (what it eats)
How it obtains food
What eats it
Physical conditions
When & how it reproduces
Any other important requirements, relationships, etc.

13. Community Interactions
Competition
Predation
Symbiosis
Mutualism
Commensalism
Parasitism

14. Competition
Organisms of the same or different species attempt to use an ecological resource in the same place at the same time.
Resource: any necessity of life (water, nutrients, light, food or space)
Competitive exclusion principle
No two species can occupy the same niche in the same habitat at the same time

15. Predation
Interaction in which one organism captures and feeds on another organism
Predator: organism that does the killing and eating
Prey: the food organism

16. Symbiosis Any relationship in which two species live closely together
Mutualism
Both species benefit from the relationship
Flowers & insects
Commensalism
One benefits and the other is neither helped nor harmed
Barnacles attached to whales
Parasitism
One organism (parasite) lives in or on another organism (host) and harms it
Parasites usually weaken, but don’t kill, their hosts
Tapeworms living in mammals, fleas on mammals

17. Ecological Succession
Series of predictable changes that occurs in a community over time
Can result from slow changes in the physical environment or sudden disturbances from human activities
Primary Succession
Occurs on surfaces where no soil exists
Ex: Volcanic eruptions building new islands, rock after glaciers melt
Pioneer species: 1st species to populate an area
Secondary Succession
Succession following a disturbance that destroys a community without destroying the soil
Ex: After wildfires or abandoned farmland

18. 4-3 Biomes

19. Biomes
Complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals
Not all kinds of organisms can live in every biome.
Adaptation: inherited characteristic that increases an organism’s ability to survive and reproduce
Tolerance: ability to survive and reproduce under conditions that differ from their optimal conditions
Microclimate: the climate in a small area that differs from the climate around it

20. The Major Biomes Tropical rain forest Tropical dry forest
Tropical savanna
Desert
Temperate grassland
Temperate woodland and shrubland
Temperate forest
Northwestern coniferous forest
Boreal forest
Tundra

21. 4-4 Aquatic Ecosystems

22. Aquatic Ecosystems
Determined primarily by the depth, flow, temperature, and chemistry of the overlying water
Grouped according to the abiotic factors that affect them (not geographically)

23. Freshwater Ecosystems
Only 3% of Earth’s surface water is fresh water
Flowing-Water Ecosystems
Standing-Water Ecosystems
Freshwater Wetlands

24. Flowing-Water Ecosystems
Rivers, streams, creeks, brooks
Organisms adapted to rate of flow
Ways to attach to plants or rocks
Streamlined bodies
Usually originate in mountains from underground water source
Plenty of dissolved oxygen & little plant life at source
Sediments build up as water flows down hill & plants establish themselves
As it slows downstream, may find turtles, beavers, river otters

25. Standing-Water Ecosystems
Lakes and ponds
Water circulates within (not just flowing in and out)
Helps distribute heat, oxygen & nutrients throughout the ecosystem
Plankton
Tiny, free-floating, weakly swimming organisms
Phytoplankton: single-celled algae; base of aquatic food webs
Zooplankton: feed on phytoplankton

26. Freshwater Pond Ecosystem
Section 4-4
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.
The roots of water lilies
cling to the pond bottom,
while their leaves, on long
flexible stems, float on the
surface.
The bottom of the pond is
inhabited by decomposers and
other organisms that feed on
particles drifting down from the
Fish share the pond
with turtles and other
animals. Many of
them feed on insects
at the water’s edge.
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.
Duck
Water
lilies
Frog
Dragonfly
Mosquito
larvae
Duckweed
Phytoplankton
Snail
Pickerel
Diving
beetle
Trout
Hydra
Crayfish
Snail
Benthic
crustaceans

27. Freshwater Wetlands wetland
Ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year
May be flowing or standing
Fresh, salty or brackish (mixture of fresh & salt)
Very productive ecosystems
Bogs, marshes, swamps

28. Estuaries Wetlands formed where rivers meet the sea
Mixture of fresh water & salt water
Affected by rise & fall of ocean tides
Most primary production is not consumed by herbivores
Instead enters the food web as detritus (particles of organic material that provide food for organisms at the base of the estuary’s food web)
Support an astonishing amount of biomass
Spawning & nursery grounds for commercially important fishes and for shellfish
Salt marshes, mangrove swamps

29. Marine Ecosystems Oceans Photic zone Aphotic zone
Well-lit upper layer of the oceans
Aphotic zone
Permanently dark layer of the oceans below the photic zone
Only producers here are chemosynthetic autotrophs

30. Intertidal Zone Organisms exposed to regular & extreme changes
Submerged in water then exposed to air, sunlight & temperature changes
Competition leads to zonation
Prominent horizontal banding of organisms that live in a particular habitat

31. Coastal Ocean
Extends from the low-tide mark to the outer edge of the continental shelf
Often rich in plankton & other organisms
Kelp forests
Named for their dominant organism: a giant brown alga that can grow as much as 50 cm a day

32. Coral Reefs
Diverse and productive environments named for the coral animals that make up their primary structure
Found in warm, shallow water of tropical coastal oceans
Among the most diverse & productive environments on Earth

33. Open Ocean Oceanic zone
Begins at the edge of the continental shelf and extends outward
Largest marine zone
More than 90% of the surface area of the world’s oceans
Low levels of nutrients, only the smallest producers, low productivity
Swordfish, octopus, dolphins, whales

34. Benthic Zone Ocean floor Benthos
Organisms that live attached to or near the ocean floor
Often depend on food from organisms that grow in the photic zone
Most feed on detritus (dead organic material)

35. Figure 4-17 Zones of a Marine Ecosystem
Section 4-4
land
Photic zone
200m
Coastal
ocean
1000m
Open
ocean
4000m
Aphotic zone
6000m
Ocean
trench
10,000m
Continental
shelf
Continental slope and
continental rise
Abyssal
plain