Chapter 3 Communities, Biomes and Ecosystems

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Chapter 3 Communities, Biomes and Ecosystems

• 3.1 Community Ecology

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Communities

• All the interacting populations in an ecosystem
• A biological community is a group of interacting
  populations that occupy the same area at the same
  time.
• Abiotic and biotic factors interact and result in
  condition that are suitable for life for some
  organisms and unsuitable for other organisms

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Limiting Factors

• Environmental factors (abiotic or biotic) that
  restricts existence, numbers, reproduction or
  distribution of organisms
• Food, predators, temperature, light

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Limiting Factors

• Factors that limit one organism may indirectly
  limit others

What happens when the number of grasshoppers is
reduced?
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Tolerance

• Ability of an organism to withstand fluctuation
  in biotic and abiotic factors

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Range of Tolerance
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Ecological Succession

• Orderly, natural changes and species replacement
  that take place in the communities of an ecosystem

• Primary Succession
• After volcano or avalanche
• Start with rock (no soil)
• Secondary Succession
• After forest fire or abandoned farmland
• Start with soil

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Primary Succession
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Primary Succession

• Pioneer Species first species on bare land/rock
  is lichen or moss
• Breakdown of rock and decay of moss will build up
  the soil so other plants can survive

• Overtime additional habitats develop

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Primary Succession

• Producers are always present before consumer
• Ends with climax community
• Stable, mature community which undergoes little
  or no change in species
• Can take hundreds of years to develop a climax
  community starting with rock

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Secondary Succession
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Secondary Succession

• Sequence of community changes that take place
  after a community is disrupted by natural
  disasters or human actions
• Occurs in places that previously contained life
• On land that contains soil, so takes less time
  than primary succession to reach climax community

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Primary or Secondary Succession?
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Chapter 3 Communities, Biomes and Ecosystems

• 3.2 Terrestrial Biomes

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Effects of Latitude and Climate

• Weather is the condition of the atmosphere at a
  specific place and time.
• One of the keys to understanding these
  communities is to be aware of latitude and
  climatic conditions.

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Effects of Latitude and Climate

• The distance of any point on the surface of Earth
  north or south from the equator is latitude.

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Effects of Latitude and Climate

• The average weather conditions in an area,
  including temperature and precipitation, describe
  the areas climate.
• The graph shows how temperature and precipitation
  influence the communities.

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Effects of Latitude and Climate

• Biomes are classified by their plants,
  temperature, and precipitation.

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Biomes

• Large group of ecosystems that share the same
  type of climax community
• Identified by climax community of plants rather
  than animals because plants dont migrate.
• Plants are a better indicator of long term
  characteristics of a biome

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Major Biomes of the World
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Terrestrial Biomes

• From the North Pole
• Tundra
• Taiga
• Temperate Forest
• Grassland
• Desert
• Tropical Rain Forest

• Each have characteristic abiotic and biotic
  factors

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Aquatic Ecosystems

• Temperature and precipitation reflect its
  associated terrestrial biome

• Freshwater biomes
• Lakes, streams, rivers, ponds
• Marine Biomes
• Oceans and seas
• Study by amount of sunlight
• Specialty biomes estuary and intertidal zone

Intertidal zone
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Freshwater Ecosystems

• Only about 2.5 percent of the water on Earth is
  freshwater.

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Freshwater Ecosystems

• The characteristics of rivers and streams change
  during the journey from the source to the mouth.

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Freshwater Ecosystems

• Fast-moving rivers and streams prevent much
  accumulation of organic materials and sediment.
• Usually, there are fewer species living in the
  rapid waters.
• In slow-moving water, insect larvae are the
  primary food source for many fish, including
  American eel, brown bullhead catfish, and trout.

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Freshwater Ecosystems

• The temperature of lakes and ponds varies
  depending on the season.

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Transitional Aquatic Ecosystems

• Areas of land such as marshes, swamps, and bogs
  that are saturated with water and that support
  aquatic plants are called wetlands

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Marine Ecosystems

• The intertidal zone is a narrow band where the
  ocean meets land.
• Communities are constantly changing in this
  environment as a result of disturbance.

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Open Ocean Systems

• The photic zone is shallow enough that sunlight
  is able to penetrate.
• Below the photic zone lies the aphotic zonean
  area where sunlight is unable to penetrate.
• The benthic zone is an area along the ocean floor
  that consists of sand, silt, and dead organisms.