The Ecosystem

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The Ecosystem

• 2.6 Changes

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Assessment Statements

• 2.6.1 Explain the concepts of limiting factors
  and carrying capacity in the context of
  population growth.
• 2.6.2 Describe and explain S- and J- population
  curves.
• 2.6.3 Describe the role of density-dependent and
  density-independent factors, and internal and
  external factors, in the regulation of
  populations.
• 2.6.4 Describe the principles associated with
  survivorship curves including, K- and
  r-strategists.

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Assessment Statements Cont.

• 2.6.5 Describe the concept and processes of
  succession in a named habitat.
• 2.6.6 Explain the changes in energy flow, gross
  and net productivity, diversity, and mineral
  cycling in different stages of succession.
• 2.6.7 Describe factors affecting the nature of
  climax communities.

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2.6.1 Explain the concepts of limiting factors
and carrying capacity in the context of
population growth.

• Limiting Factors Factors that limit the
  distribution or numbers of a particular
  population. They are environmental factors that
  slow down population growth. Usually involve an
  optimal range, with upper and lower tolerances.
• Temperature
• Water
• Nutrient Availability

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2.6.1 Explain the concepts of limiting factors
and carrying capacity in the context of
population growth.

• Carrying capacity the number of organisms or
  size of population that an area or ecosystem can
  support sustainably over a long period of time.

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2.6.2 Describe and explain S- and J- population
curves.

• S-population curve Three Stages
• Exponential growth stage population grows at
  increasingly rapid rate
• Transitional phase continues to grow, but slows
  considerably
• Plateau or stationary phase number of
  individuals stabilizes and population growth
  stabilizes

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2.6.2 Describe and explain S- and J- population
curves.

• J-population curve Only has the exponential
  growth stage. Growth is initially slow and
  becomes increasingly rapid. It does not slow
  down.

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2.6.3 Describe the role of density-dependent and
density-independent factors, and internal and
external factors, in the regulation of
populations.

• Density-dependent factors that lower the birth
  rate or raise the death rate as a population
  grows in size. Operate as negative feedback
  mechanisms.
• Examples resources, space, disease, parasitism,
  and predation

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2.6.3 Describe the role of density-dependent and
density-independent factors, and internal and
external factors, in the regulation of
populations.

• Density-independent factors that lower the
  birth rate or raise the death rate irrespective
  of population density.
• Examples Natural disasters, and long term
  climate change.

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2.6.3 Describe the role of density-dependent and
density-independent factors, and internal and
external factors, in the regulation of
populations.

• Internal factors include density-dependent
  fertility or size of breeding territory.
• External factors include predation or disease.
• Physical environmental factors water and
  nutrient availability, and temperature
• Biological environmental factors Predation, and
  competition.

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2.6.4 Describe the principles associated with
survivorship curves including, K- and
r-strategists.

• K-strategists species
• Grow and mature slowly
• Produce few large offspring
• Stable environments
• r-strategists species
• Grow and mature quickly
• Produce many small offspring
• Disturbed or new environments
• Those that lie between are called C-strategists

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2.6.4 Describe the principles associated with
survivorship curves including, K- and
r-strategists.

• K-strategists survivorship curve
• Almost all survive potential lifespan, and then
  die almost simultaneously
• Salmon and humans
• r-strategists survivorship curve
• Most die at a very young age, but those that
  survive are likely to live a very long time
• Turtles and oysters

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2.6.5 Describe the concept and processes of
succession in a named habitat.

• Succession Orderly process of change over time
  in a community divided into stages called serals
• Zonation The arrangement or patterning of plant
  communities or ecosystems into bands in response
  to change, over a distance, in some environmental
  factor.

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2.6.5 Describe the concept and processes of
succession in a named habitat.

• Primary Succession Succession on previously
  uncolonized substrate
• Secondary Succession Succession where a
  previous community has been disturbed

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2.6.6 Explain the changes in energy flow, gross
and net productivity, diversity, and mineral
cycling in different stages of succession.

• Pioneer community Earliest seral stage
• Early Stages of Succession
• Gross Productivity low
• Respiration loss low
• Net Productivity high
• System Growing
• Biomass Accumulating

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2.6.6 Explain the changes in energy flow, gross
and net productivity, diversity, and mineral
cycling in different stages of succession.

• Climax community Final seral stage
• Final Stages of Succession
• Gross Productivity high
• Respiration loss high
• Net Productivity near 0
• Production/Respiration Ratio Near 1

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2.6.7 Describe factors affecting the nature of
climax communities.

• Climax community features
• Greater biomass
• Higher levels of diversity
• Favorable soil conditions
• Lower pH
• Taller and longer-living plant species
• More K-strategists or fewer r-strategists
• Greater community complexity and stability
• Greater habitat diversity
• Steady-state equilibrium
• Plagioclimax interrupted succession