A LevelGeographyAQARevision Notes6. Ecosystems Under Stress6.6 Local Ecosystems6.6.2 Factors Affecting Development

Factors Affecting Development (AQA A Level Geography)

Revision Note

Jacque Cartwright

Expertise

Geography Content Creator

Wasteland Climate

  • There are a number of climate factors that influence which plants can colonise a wasteland:
  • Buildings and debris create subtle variations in microclimates that encourage different types of colonisation
  • If the area too shady, only shade tolerant plants will be able to colonise easily
  • Sheltered sun traps attracts buddleia and attract butterflies
  • Mosses and ferns prefer damp areas
  • Spiders thrive in drier areas

Wasteland Soil & Soil Moisture

  • Soil
    • Absent - soil will be mostly absent, thin and/or infertile, perfect for pioneer species such as mosses and lichens
    • Slope - debris accumulates on horizontal surfaces and slopes, helping to develop soil
    • Porosity - the more porous the surface, the easier it is colonised
    • Surface - the surface needs to be rough enough for plants to grip onto; cracks and hollows provide a depth of soil that allows deeper-rooted plants and trees to flourish 
    • Pollution levels - previous land use depends on whether there are chemicals which may be toxic to colonisation
  • Soil water budget 
    • Wastelands low levels of soil, results in poor moisture retention
    • Potential evaporation exceeds precipitation
    • Therefore, a negative soil water budget results
    • Plants adapt through shallow root systems, allowing quick absorption of any precipitation
    • In areas where precipitation exceeds runoff, water loving plants succeed such as ferns, ragwort and brambles
    • Slower drainage areas allows for greater diversity of flora and fauna

Plant & Animal Adaptations

  • Stage 1: Pioneers
    • Mosses and lichens develop first on bare, exposed or sheltered surfaces
    • They obtaining nutrients by photosynthesis and from the bare concrete beneath them
    • The concrete is slowly weathered by the production of acids in the roots
    • As the plants die, they provide a thin mat of organic matter which, mixed with the weathered mineral matter produces a form of soil that other plant species can start to root into
  • .Stage 2: Oxford ragwort
    • Cracks in the surface provide sheltered places for seeds to germinate
    • The cracks also retain moisture and dust, that help with plant rooting
    • Wind blown seeds like the Oxford Ragwort arrive, and due to its long flowering season (May-November) it produces millions of seeds
    • Many plants like willow herb, annual meadow-grass and dandelion can tolerate waste ground rubbish and debris
    • Plant succession is usually rapid at this stage
  • Stage 3: Tall herbs
    • As stage 2 plants die off, they produce a thicker and more nutrient-rich soil
    • Taller plants can become established
    • The most common is rosebay willow herb, which spreads initially by seeds and then rhizomes which can extend up to 1m a year
    • Other common plants include fennel and daisies
    • These plants shade out smaller plants, preventing them from photosynthesising 
  • Stage 4: Grassland
    • As soil depth and nutrients continues to increase, the amount of grass vegetation increases
    • The smaller grasses are replaced by taller species
    • At this stage the area takes on the appearance of grassland containing scattered clumps of tall herbaceous plants
    • Invasive species can begin to colonise due to improved soil conditions and smother out most species beneath them
  • Stage 5: Scrub woodland
    • Eventually, the taller herbaceous plants are replaced by shrubs and eventually trees
    • The early woody plant are grey willow and birch and have light, windborne seeds
    • However, as the herbaceous vegetation thickens, it becomes difficult for these, small-seeded plants to establish unless there is further disturbance, such as fire
    • Later trees have larger seeds that can enter denser vegetation
    • These include the sycamore, laburnum, rowan and hawthorn
    • Denser thickets of bramble and other scrubby plants develop in the deeper crevices in the brickwork or concrete
  • As each stage, plant succession allows the development of fauna, such as as earthworms, as the soil improves
  • There is also an increase in the number and diversity of insects and mammals
  • Due to sub-stratum (soil) variations, there can be a number of different successions, all in the same area
  • This is results in variations in the type of surface being colonised for example, the differences between the colonisation of an alkaline surface compared to an acidic one

You've read 0 of your 0 free revision notes

Get unlimited access

to absolutely everything:

  • Downloadable PDFs
  • Unlimited Revision Notes
  • Topic Questions
  • Past Papers
  • Model Answers
  • Videos (Maths and Science)

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

    Next topic

    Did this page help you?

    Jacque Cartwright

    Author: Jacque Cartwright

    Jacque graduated from the Open University with a BSc in Environmental Science and Geography before doing her PGCE with the University of St David’s, Swansea. Teaching is her passion and has taught across a wide range of specifications – GCSE/IGCSE and IB but particularly loves teaching the A-level Geography. For the last 5 years Jacque has been teaching online for international schools, and she knows what is needed to pass those pesky geography exams.