Unit 3 Notes Flashcards
What is the Climatic Climax community?
The stable ecological community which forms naturally under given climatic conditions.
What is the UK’s climatic climax community?
Temperate Deciduous forest.
What was the CCC of England 20,000 years ago?
Tundra.
What is Succession?
The change in the ecological community over time.
What would most areas in Britain have had 20,000 years ago?
A landscape of glacial till, dominated by sands and gravels, with no vegetation.
What is a Seral stage?
Each stage of succession.
What are the Initial conditions on which succession can occur?
Bare rock - Lithosere. Fresh Water - Hydrosere. Sand Dunes - Psammosere.
What are the processes of Lithosere succession?
Primary succession, secondary succession.
What is Primary Succession?
Succession operating on newly formed or exposed land. Occurs when a glacier retreats, creating a till of outwash plain.
What is Secondary Succession?
Succession that develops on land that has previously been vegetated.
What is the first seral stage of the lithosere?
Lichens and mosses.
What are Lichens?
Organisms which are part algae and part fungi. Algae photosynthesises to produce energy. Fungi has high water retention properties.
What is the Second seral stage of the Lithosere?
Grasses and Herbs.
What forms in the Second Lithosere seral stage?
A basic soil by mosses and lichens now enables grasses and herbs to colonise the area, and outcompete mosses and lichens for sunlight, as they grow taller.
How is Dead organic matter added into the soil in the Second seral stage?
Grasses seasonally dying back.
What is Stage 3 of the Lithosere seral stage?
Shrubs such as Bramble.
Why does soil become deeper?
Because of the growth of grass, absorbing more moisture, and more dead organic matter being added when grasses die back.
What is stage 4 of the Lithosere seral stages?
Woodland such as oak.
What happens to soil in the fourth seral stage?
Soil deepens until the species can colonise the area. When the trees reach maturity, the climatic climax community is reached.
What is a pioneer species?
The first species to colonise new land.
What is an example of a Lithosere?
Krakatoa.
What happened to Krakatoa in 1883?
Volcanic eruptions, reducing Krakatoa to 1/3 of its’ original size, 50m of ash, where no vegetation was left on the island.
What happened within 3 years?
26 species had reappeared. 1933 - 271 plant, 720 insect species had been recorded.
What are the physical factors, causing a sub climax?
Grazing by animals, spontaneous fire, areas of poor drainage, areas of high drainage, frequent volcanic eruption.
What are the examples of physical factors?
Temperate grasslands are sub climaxes, as if grazing animals were removed, the process of succession would continue. Peatlands where waterlogged conditions exist, such as raised bogs.
What are the locations where repeated volcanic activity would interrupt the process of succession?
Iceland and Hawaii.
What are the human activities, causing a plagio climax?
Fire clearance, grazing, agriculture.
What % of the West Midlands is covered by the natural climatic climatic community?
Less than 5%.
Why does Agriculture stop the succession process?
Because harvested crops don’t have time to grow, before being harvested again. Pesticides and fertilisers may delay and prolong the process.
Why does livestock stop the succession process?
Because animals eat plants, trample them, as well as grazing stopping larger plants from developing.
What is an example of an extensive form of Plagioclimax?
Heather Moorlands, as the majority are caused by human factors, leading to a plagioclimax.
What are the 4 stages of heather growth?
Pioneer phase, Building phase, mature phase, degenerate phase.
What is the Pioneer phase?
Small shoots among dead heather stems, other plants present such as mosses and lichens.
What is the Building phase?
Dense dome shaped plant, flowers large, little light penetrates to ground, heather is dominant.
What is the Mature phase?
Reduction in vigour, stems tough, some light penetrates to ground.
What is the Degenerate phase?
Large gaps, not many shoots, mosses, lichens, grasses and hedges present.
What is Rewilding?
Human activities are reduced, enabling succession to recommence.
What is the Knepp Estate?
3500 acre ex-dairy farm is reverting ploughed and overgrazed fields to natural vegetation.
What is a Mosaic Habitat?
The landscape experiencing secondary succession, with different areas at different stages of the succession process.
What does the effect of wild, roaming, grazing animals create?
Sub-climaxes in some areas.
Why do Mosaic Habitats benefit biodiversity?
Because they no longer use pesticides and herbicides. Instead, natural vegetation and invertebrate species are increasing. These provide the basis of food chains.
What are the ecosystems services which link to water and carbon cycles?
Surface 1 - runoff decreases, reducing flood risk. More interception, more infiltration. No machinery - reduction in carbon emissions. Increases soil’s organic matter storage.
What does the biomass store act as?
A carbon sink, as the biomass store increases, leading to more soil storage.
What is the succession pathway for a bare sterile surface?
Natural factors interrupt succession, normal environmental conditions resume. Climatic climax community reached. Human activity interrupts succession. Human activity stops.
What is the Succession pathway for an uninterrupted prisere?
Climatic climax community reached, natural factors interrupt succession, normal environmental conditions resume. Human activity interrupts succession. Human activity stops secondary succession.
