Transcript CHAPTER 3: COMMUNITIES + BIOMES

CHAPTER 3:
COMMUNITIES + BIOMES
3-1: COMMUNITIES
P.65-69
Life in a Community
• Types of things found in your lawn:
– Weeds
– Insects
– Earthworms
– Grubs
– Soil
– Fungi
– Bacteria
Life in a Community
• How do all these things survive?
– The various combination of biotic + abiotic
factors
Limiting Factors
• Any biotic or abiotic factor that restricts the
existence, numbers, reproduction, or
distribution of organisms
• Such as:
– Availability of food + water
– Predators
– Temperature
Common Limiting Factors
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Sunlight
Climate
Temperature
Water
Nutrients/Food
Fire
Soil Chemistry
Space
Other Organisms
Limiting Factors
• Factors that limit one population in a
community may also have an indirect
effect on another population
• Example:
– Lack of water
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Affects growth of grass
Affects # seeds produced
Affects # mice
Affects # hawks
Ranges of Tolerance
• Tolerance
– The ability of an organism to withstand
fluctuations in biotic + abiotic environmental
factors (“EXTREMES”)
– Represented by a GRAPH
Succession: Changes over Time
• Succession
– The orderly, natural changes and species
replacements that take place in the
communities of an ecosystem
– Occurs in STAGES
– Difficult to observe because it can take
decades or centuries for communities to
succeed
Primary Succession
• The colonization of barren land by
communities of organisms
– Takes place on land where there are no
LIVING ORGANISMS
– Example:
• Volcano
Primary Succession
• Pioneer species
– First species to appear on new, barren land
– Example:
• Lichen – group of small organisms
Primary Succession – the
process…
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Pioneer species dies….
Provides 1st stage of soil….
New soil develops……
Small weedy plants develop…
New organisms move in…
Area grows in size….
Primary Succession
• After some time, primary succession slows
down and becomes stable
• Climax community
– Mature, stable community with little or no
change
– Change is dynamic – balances out
– May last for hundreds of years
Primary Succession Stages
Secondary Succession
• Sequence of changes that takes place
after an existing community is severely
disrupted in some way
– i.e. A natural disaster
• Community of organisms inhabiting an
area gradually changes
• Occurs in areas that previously contained
LIFE + land still contains soil
Secondary Succession
• May take less time to reach climax
community
• Example:
– Yellowstone National Park (1988)
Secondary Succession Stages