4-2

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4-2 What Shapes an Ecosystem?
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Biotic and Abiotic Factors
Abiotic Biotic
Physical, non-living factors that shape ecosystems Examples temperature, climate, humidity, wind, nutrient availability, soil type, sunlight Biological (living) influences on organisms within an ecosystem Examples birds, trees, bacteria Predators, Competition, Prey

• Biotic and abiotic factors determine the survival
  and growth of an organism and the productivity of
  the ecosystem in which the organism lives.

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Habitat vs. Niche

• Habitat the area where an organism lives
  (includes both biotic and abiotic factors).
• Niche the way the organism uses a habitat and
  the role it plays within it

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• No 2 species can share the same niche in the same
  habitat.
• Different species can occupy niches that are very
  similar.

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Community Interactions Competition

• When organisms attempt to use an ecological
  resource in the same place at the same time.
• A resource is any necessity of life, such as
  water, nutrients, light, food, or space.
• Often results in a winner and loser (loser
  doesnt survive).

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Community Interactions Predation

• An interaction in which one organism captures and
  feeds on another organism is called predation.
• Predator the organism that does the killing and
  eating
• Prey the food organism

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Community Interactions Symbiosis

• Any relationship in which two species live
  closely together is called symbiosis.

Mutualism Commensalism Parasitism
both species benefit from the relationship one member of the association benefits and the other is neither helped nor harmed one organism (the parasite) lives on or inside another organism (the host) and harms it
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Ecological Succession

• Ecosystems are constantly changing in response to
  natural and human disturbances.
• Ecological succession the series of predictable
  changes that occurs in a community over time.

Primary
Secondary
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Primary Succession

• Succession that occurs on surfaces where no soil
  exists.
• Example after volcanic eruptions
• The first species to populate the area are called
  pioneer species (example lichen).

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1. In this example, a volcanic eruption has
destroyed the previous ecosystem.
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2. The first organisms to appear are lichens.
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3. Mosses soon appear, and grasses take root in
the thin layer of soil.
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4. Eventually, tree seedlings and shrubs sprout
among the plant community.
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Secondary Succession

• Succession that happens when there is still soil.
  
• Example natural events (ex fires) or by human
  disturbances (ex farming).
• Secondary Succession The regrowth of a community
  from these events.
• Pioneer Species small grasses

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• Climax Community when the community is restored
  to its full natural state.

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4-1 and 4-2 Vocab

• Abiotic
• Biotic
• Habitat
• Niche
• Competition
• Predation
• Predator
• Prey

• Symbiosis
• Mutualism
• Commensalism
• Parasitism
• Ecological Succession
• Primary Succession
• Secondary Succession
• Pioneer Species
• Climax Community

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