Plant Succession

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Plant Succession

  • Refers to process of change over time in plants in an ecosystem
  • Beings with colonisation- plants invade and grow on bare rock or soil- primary succession, initial colonising plants are pioneer species
  • After colonisation, plants replace one another as they go through seral stages
  • Climatic climax vegetation is reached- final stage when vegetation reaches a balance with its environment
  • Secondary succession occurs on previously vegetated surfaces that have lost their vegetation through natural fires or landslides
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Soil Changes

Depth increases- More organic matter and weathering of bedrock

Humus increases- More organic matter added via nutrient cycling

Moisture increases- Humus aids moisture retention and shade from plants reduces evapotranspiration from soil

Stability increases- Increasing root network binds soil together

pH decreases- Soil becomes less alkaline due to addition of humic acids

Colour darkens- More organic matter is added to the soil via nutrient cycling

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Plant and Microclimate Changes

Biomass and Plant Longevity increases- Deeper and richer soils cam support more long-lived plants eg trees, plant abundance increases and land not covered by plants decreases

Species Diversity increases- Improving soil and microclimate conditions can support a wider variety of plant types, not just those adapted to harsh conditions of colonisation

Stratification- Wider variety of plant types increases stratification

Wind Speed drops- Increased plant cover provides shelter and acts as a windbreak

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Plagioclimax

Plagioclimax- A vegetation community that is found when humans interfere with natural sequence of succession and prevent it from reaching its climatic climax

Activities that cause a Plagioclimax:

  • Deforestation
  • Burning
  • Draining
  • Grazing
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Case Study: Plant Succession at Murlough Bay

  • Plant Succession at Murlough Bay is in the form of a psammosere (sand dune)

Embryo Dunes: Waves and onshore winds carry material above tide which gets trapped. Very low in nutrients, saline soils so pioneer species is sea couch grass

Fore Dunes: Root system of species allows more sand to be trapped allowing marram grass to grown surviving lots of sand and growing a deep root network binding the dune in place

Ridge Dunes: Created parallel to the shoreline allowing ragwort dandelion to grown here

Dune Slack: Wet and dry conditions that are sheltered allowing sea buckthorn and red fescue grass to grown

Climatic Climax Vegetation: Beech and birch tree however it is burned by the National Trust resulting in a plagioclimax

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