Communities & Biomes
Chapter 03
Abiotic Influences
• Communities are groups of
populations of different species.
• & the environment plays a big role
in how big a community will be.
Abiotic Influences
• Food, water, temperature, and
others can all limit a community’s
ability to survive.
• Therefore these are called
Limiting Factors
• If there is a lot a food in an area,
but no water what will happen
to the community?
1. Limiting Factors
• Any biotic or abiotic factor that
restricts the existence, numbers,
reproduction, or distribution of
organisms
Examples
• Sunlight, Climate, Temperature,
Water, Nutrients/Food, Fire, Soil
Chemistry, Space,
Other organisms
2. Tolerance
• the lower and upper limits that an
organism can survive in.
• (i.e. saltwater, temperature,
oxygen levels, and any other
limiting factors…)
– A “range of tolerance”
3. Succession
• Overtime communities change.
• Natural changes and species
replacements in a community
are called SUCCESSION.
• Two Types
A. Primary Succession
• Colonization of new land by
communities of pioneer species
(first organisms in an area).
• Example:
• After a volcanic lava flow.
http://www.countrysideinfo.co.uk/successn/primary.htm
B. Secondary Succession
• Colonization after a natural
disaster.
• Example:
• after a fire, flood, or mudslide
http://www.countrysideinfo.co.uk/successn/second.htm
Which type of success is which?
How do you know?
C. Climax Community
Mature, stable community;
Equilibrium has been reached.
If a community is allowed to grow to
the point where it is fairly stable,
there is now, little or no change in
species.
Examples:
sonoran desert, taiga, rainforest
II. Biomes
• Biomes are large groups of
ecosystems that share
the same type of
climax community.
• They are the Earth’s
major life zones.
Earth’s Biomes
1. Aquatic Biomes
• freshwater biome
• marine/saltwater/ocean biome
a. Freshwater Biome
--- low salt concentration
— usually less than 1%
Examples:
Ponds and lakes
Streams and rivers
Wetlands
b. Marine Biome
o
o
o
covers about ¾ of the Earth's surface
algae supply most of our oxygen and
absorb tons of carbon dioxide.
Evaporation of the seawater provides
rainwater for the land
Examples:
Oceans ,Coral reefs
Estuaries
2. Desert Biome
o
o
o
o
covers about 1/3 of the Earth's surface
rainfall is less than 50 cm/year
low and high altitudes
specialized plants and animals
Examples
Hot and dry
Semiarid
Coastal
Cold
3. Forest Biomes
Tropical
Temperate
Taiga (Boreal)
a. Tropical forest
o
o
o
o
greatest species diversity
only rainy and dry seasons
12 hours daylight
always 20o-25oC
b. Temperate forest
o Well-defined seasons
o with a distinct winter
o Moderate climate
o loose leaves annually,
oExamples: oak, elm, maple
o -30° C to 30° C
c. Taiga forest (Boreal)
o largest terrestrial biome
o short, moist, warm summers
& long, cold, and dry winters.
o mostly conifers with needle-like
leaves;
o Examples: fir, spruce, and pine
o precipitation is mostly snow
4. Grassland Biome
o Mostly grasses rather than large shrubs
or trees.
o
AKA – prairies or savannas
o
ideal for growing foods
o
rain in late spring and early summer
o
large temperature range/variation
o
Most have been converted
into farms and grazing lands.
5. Tundra Biome
o
o
o
o
o
o
coldest of all the biomes
extremely low temperatures
little precipitation
very short growing seasons
Low biotic diversity (little variety in life)
Simple small plants/vegetation.
Examples:
Arctic tundra - polar – high latitude
Alpine tundra –high altitude -Mtns.