British ecosystems Flashcards
What is succession?
The succession of vegetation as it adapts to environmental changes.
What is climatic climax?
This is achieved when the largest, most dominant species that the environment will allow are established and the vegetation is in a state of equilibrium with its environment.
What is a sere?
A sere is a stage in this sequence of colonisation by which the vegetation develops over a period of time.
What is a prisere?
A prisere is the complete sequence of events beginning with the first plants to occupy the area and finishing with the climatic climax vegetation.
What is plagioclimax?
If human interference takes place, such as allowing cattle to graze or the planting of specific trees, then the climatic climax will not be reached and a plagioclimax is created instead.
Define primary succession.
Primary succession occurs in lifeless areas where conditions are extreme and barely capable of sustaining vegetation.
Define secondary succession.
Secondary succession occurs in areas where the existing ecosystem has been removed but soil and nutrients remain and succession can being once more (e.g rainforest clearance, burning of heathland vegetation on dunes).
Name the case study for psammosere succession.
Kenfig Dune System, Margam, South Wales
What does the development of a psammosere system require?
- A plentiful supply of sand
- Strong winds to transport sand particles through saltation
- An obstacle to trap the sand e.g. a plant, seaweed or driftwood.
- Plants are therefore central to the formation, growth and character of sand dunes
Name factors which contribute to the harsh environment for embryo and fore dunes.
- Poor water retention
- High water mark
- Low, hummocky dunes
- On-shore winds
What is needed for embryo dunes to be created?
- A plentiful supply of sand
- Strong winds to transport sand particles through saltation
- An obstacle to trap the sand e.g. a plant, seaweed or driftwood.
- Plants are therefore central to the formation, growth and character of sand dunes
Describe the environment for yellow dunes.
- Pioneer plants helped to make the environment more hospitable
- The ‘Soil’ slightly less alkaline and more water retentive
- Reduced wind speeds
- Some humus forming
- The surface continually blown away and replenished with fresh sand
What plants are present in yellow dune?
Marram grass is the dominant species. Other plants such as Ragwort, Red fescue and Sand sedge begin to appear
How do yellow dunes develop into grey dunes?
- First plants trap sand and grow with it
- Humus is created by decaying plants, creating more fertile soil.
- Soil becomes less fertile as pioneer plants grow and trap water.
- Less hardy plants then develop.
- As the humus develops and the dune becomes less sandy they become grey dunes.
Describe the environment for grey dunes.
- Sheltered by higher, seaward dunes
- Little mobile sand – sand is stable
- Nutrient supply and water retention of the soil is greatly improved
- A more closed vegetation community in which marram grass is no longer able to compete
- Lower pH
- Sand no longer accumulating
