changes in ecosystems: ecological succession eq: how do communities change over time?

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  • Changes in Ecosystems: Ecological SuccessionEQ: How do communities change over time?

  • Succession isa series of predictable changes in types of species that occurs in a community over timeTwo types: primary and secondary

  • Primary SuccessionOccurs on surfaces where no soil existsEvents which expose bare rock: volcanoesfloodingglaciersBegins with arrival of organisms such as lichens that do not need soilLichen are the pioneer species (first organisms to arrive in an area)

  • Primary Succession Soil starts to form as lichens, weathering, and erosion break down rocks into smaller piecesWhen lichens die, they decompose, adding small amounts of organic matter to the rock to make soil Over time, the soil layer thickens, and grasses, wildflowers, and other plants begin to take over

  • Primary SuccessionIn time insects, birds, and mammals move inWhat was once bare rock now supports a variety of life, including trees

  • Secondary SuccessionOccurs in an area with soil that contains seeds, spores, roots, or other plant partsEvents that destroys most of an ecosystem forest fireharvesting HurricaneHappens faster and weeds are a typical pioneer species in secondary succession

  • Succession

  • Climax CommunityMature community made up of plants and animalsDoes not always mean big treestall grasses in prairiescacti in desertsSpecies can continue to change in response to climate and other factors

  • Succession: starting overPrimaryNo soil is available and must be created by pioneer speciesLichens are usually the pioneer speciesUsually the result of a volcano or glacierSecondarySoil is still available and pioneer species can take rootWeeds/plants are usually the pioneer speciesUsually the result of a forest fire or hurricane


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