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Chapter 3
Communities, Biomes, and
Ecosystems
3.1
Community Ecology
I. Communities
• A. What is a community?
• B. Limiting factors: any biotic or abiotic
factor that restricts the numbers,
reproduction, or distribution of an
organism
Examples of
Abiotic Limiting Factors
• 1. Nutrients
• 2. Water
• 3. Space
4. Sunlight
5. Climate
6. Temperature
7. Soil Chemistry
8. Fire
Examples of Biotic Limiting
Factors
1.
2.
3.
4.
Food
Competition
Disease
Predation
C. Range of Tolerance
• 1. There is an upper and lower limit
for any environmental factor
• 2. Tolerance: ability of an organism
to survive when subjected to biotic
or abiotic factors
a. Example: oxygen level
b. Amount of sun
c. Amount of water
II. Succession: Change over time
• A. Ecological succession is the change in
an ecosystem that happens when one
community replaces another as a result
of changing abiotic and biotic factors.
– there are two types (primary and secondary)
1. Primary Succession
• a. The establishment of a community in
an area of exposed rock that does not
have any topsoil. (usually happens very
slowly at first)
b. examples
• (1) volcano making new land.
(2) Avalanche exposes rock.
c. Pioneer Species
• (1) First species to colonize an area.
(2) Example-Lichens
2. Secondary Succession
• a. The orderly and predictable change
that takes place after a community of
organisms has been removed but the soil
has remained.
• b. Pioneer species – mainly plants that
begin to grow in the disturbed area – are the
first species to start secondary succession
– Like these “baby pines”
B. Succession Occurs Because
of COMPETITION!
d. Climax Community
• (1) A stable mature community that
undergoes little or no change.
• (2)Can develop from bare rock.
3.2
Terrestrial Biomes
I. Terrestrial Biomes: Effects
of Latitude and Climate
• A. Ecosystems on land are grouped into
biomes based on the plant communities
within them.
• B. Biomes are a large group of ecosystems
that share the same type of climax
communities.
C. Two keys to understanding
terrestrial biomes include:
• 1. Latitude – from 0o at equator to 90o at
the poles (see page 65)
• 2. Climate – average weather conditions,
including temperature and precipitation
II. Major Land Biomes
A. Tundra
• Precipitation: 15-25 cm per year
• Temperature: -34oC to 12oC
• Plants: Treeless, grasses, shrubs (shallow
roots)
• Permafrost is present.
• Animals: birds, wolves, fish, polar bears,
caribou
B. Boreal forest (taiga)
•
•
•
•
Great northern coniferous forest
Precipitation: 38-51cm per year
Temperature: -68oC to 32oC
Plants: Spruce, fir and some deciduous trees;
small shrubs
• Animals: Birds, moose, deer, beavers,
wolverines, mountain lions
C. Temperate Forest (Deciduous)
• Precipitation: 75-150cm per year
• Temperature: -30oC to 30oC
• Plants: oak, maple, beech (deciduous trees
lose their leaves); shrubs; thick humus
• Animals: Squirrels, rabbits, skunks, birds,
deer, foxes and bears
D. Temperate Woodland/Shrubland
(Chaparral)
• Precipitation:
25-43cm per year
•Temperature: 10oC to 40oC
• Plants: evergreen shrubs, sagebrush
• Animals: fox, coyote, bobcat, jackrabbit
lizard, snakes, birds
E. Grassland (Temperate Grasslands)
•
•
•
•
Precipitation: 50-89cm per year
Temperature: -40oC to 38oC
Plants: Grasses and herbs
Animals: Horses, deer, mice, coyote, birds,
bison, snakes, and grasshoppers
F. Desert
• Precipitation: 15-26cm per year
• Temperature: high of 20oC to 49oC
low 2oC to 26oC
• Plants: Cacti, Joshua trees, succulent
• Animal: lizards, rats, tortoises, bobcats,
pygmies, antelope, toads
G. Tropical Savanna
•
•
•
•
Precipitation: 50-150cm per year
Temperature: 24oC to 49oC
Plants: Grasses and scattered trees
Animals: lions, hyenas, cheetahs, elephants,
zebra and giraffes)
H. Tropical Seasonal Forest
• Precipitation: 130-180cm per year
• Temperature: 20oC to 25oC
• Plants: Deciduous and evergreen trees;
orchids and cacti
• Animals: Monkeys, kangaroos, koalas,
rabbits, frogs, spiders
I. Tropical Rainforest (high
biodiversity – medicines!)
• Precipitation: 125-660cm per year!
• Temperature: 20oC to 34oC
• Plants: broadleaf evergreens, bamboo,
fig, and coconut trees
• Animals: elephants, orangutans, bats,
toucans, sloth, cobra
J. Mountains
• As altitude increases precipitation and
temperature change
• So, plant and animal life varies with
elevation
K. Polar regions
• Precipitation: snow and ice
• Temperature: average -30oC in winter
• Plants: some areas
grow vegetables in summer
• Animals: penguins in Antarctica,
whales & seals in water
3.3
Aquatic Ecosystems
I. Aquatic Ecosystems
• “How inappropriate to call this planet
Earth when it is quite clearly Ocean.” –
Sir Arthur C. Clarke
A. By the numbers…
• Earth is 71% water : 29% land
• Water is 97.5% Saltwater : 2.5% Fresh
– Of the 2.5% Fresh water
• 68.9% Frozen in glaciers
• 30.8% Groundwater
• 0.3% Lakes, Rivers, & Streams
B. Freshwater
• 1. Plants and animals adapted to low salt
content
• 2. Unable to survive in high salt
concentration
3. Rivers and Streams
• a. Water flows in one direction
• b. Headwater  mouth  into larger
body of water
• c. Sediment – material deposited by
water, wind, or glaciers
– Examples: silt, mud, and sand
4. Lakes and Ponds
• a. Oligotrophic lake: nutrient-poor; few
plant/animal species (good for game fish)
• b. Eutrophic lake: nutrient-rich;
abundant life
c. Lakes divided into three zones:
• (1) Littoral– closest
to shore
• (2) Limnetic – open
water area; sunlit
and full of plankton
• (3) Profundal –
deepest area; cold
and low in O2
C. Transitional Aquatic
Ecosystems
• 1. Wetlands – marshes, swamps, and bogs
– High levels of biodiversity
• 2. Estuaries – where fresh and salt mix
– **Among most diverse ecosystems, rivaled
only by rain forests and coral reefs!**
D. Marine Ecosystems–Saltwater
1. Intertidal Zone
• Ocean meets Land!
2. Open Ocean Ecosystem
• a. Photic zone – 0 to 200m; Sunlit
– Autotrophs – Phytoplankton and Zooplankton
• b. Aphotic zone – no sun; dark and cold
• c. Benthic zone – ocean floor
– Sand, silt, & dead organisms
• d. Abyssal zone – deepest region of ocean
Phytoplankton
• Found in the photic (euphotic) zone.
• Where light can penetrate.
Zooplankton
• Found in the aphotic zone and euphotic
(photic) zone.
• Aphotic-light does not penetrate.
• Benthic zone
3. Coastal Ocean
a. Most people live near the
coast
• 53% of us live within 200 km (124 mi) of
the ocean
• 67% of us live within 400 km (249 mi) of
the ocean
4. Coral Reef
• a. High biodiversity
• b. Provides natural barriers for continents
• c. Coral polyps – most have mutualistic
relationship with algae called zooxanthellae