chapter 3: communities + biomes 3-1: communities p.65-69
TRANSCRIPT
CHAPTER 3: CHAPTER 3: COMMUNITIES + BIOMESCOMMUNITIES + BIOMES
3-1: COMMUNITIES3-1: COMMUNITIES
P.65-69P.65-69
Life in a CommunityLife in a Community• Types of things found in your lawn:
– Weeds– Insects– Earthworms– Grubs– Soil– Fungi– Bacteria
Life in a CommunityLife in a Community• How do all these things survive?
– The various combination of biotic + abiotic factors
Limiting FactorsLimiting 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 FactorsCommon Limiting Factors
• Sunlight• Climate• Temperature• Water• Nutrients/Food• Fire• Soil Chemistry• Space• Other Organisms
Limiting FactorsLimiting Factors• Factors that limit one population in a
community may also have an indirectindirect effect on another population
• Example:– Lack of water
• Affects growth of grass• Affects # seeds produced• Affects # mice• Affects # hawks
Ranges of ToleranceRanges of Tolerance• Tolerance
– The ability of an organism to withstand fluctuations in biotic + abiotic environmental factors (“EXTREMES”)
– Represented by a GRAPH
Succession: Changes over TimeSuccession: Changes over Time
• SuccessionSuccession– 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 SuccessionPrimary Succession• The colonization of barren land by
communities of organisms– Takes place on land where there are no
LIVING ORGANISMS– Example:
• Volcano
Primary SuccessionPrimary Succession• Pioneer speciesPioneer species
– First species to appear on new, barren land– Example:
• Lichen – group of small organisms
Primary Succession – the Primary Succession – the process…process…
• Pioneer species dies….
• Provides 1st stage of soil….
• New soil develops……
• Small weedy plants develop…
• New organisms move in…
• Area grows in size….
Primary SuccessionPrimary 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 StagesPrimary Succession Stages
Secondary SuccessionSecondary 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 SuccessionSecondary Succession• May take less time to reach climax
community
• Example:– Yellowstone National Park (1988)
Secondary Succession StagesSecondary Succession Stages