Unit 3 Flashcards
What is a climatic climax community (CCC)?
this is the stable ecological community which forms naturally under given climatic conditions
What is the CCC of the U.K?
Temperate Deciduous Woodland
What would the CCC of the U.K been 20,000 years ago?
Ice/ Polar
How has the retreat of ice sheets changed the U.K’s CCC?
a landscape of glacial till, dominated by sand, gravels and bare rock
to now a forest dominated by 45 - 50m oak and Beech trees
Occurred through the process of succession
What is the definition of ‘ecological succession’?
describes the process by which a sequence of ecological communities develop over time
What is each succession known as?
a sere or a seral stage
Which initial conditions can succession occur?
- Lithosphere = bare rock
- Hydrosphere = fresh water
- Psammosere = sand dunes
What is the definition of primary succession?
Occurs on newly formed / exposed land
e.g. when a glacier retreats, or after volcanic eruption
occurs on a sterile environment and created without any species to being with
What is the definition of secondary succession?
succession that occurs on land that has been previously vegetated.
e.g. land that has been cleared for farming
commonly seen in urban areas and derelict sites
What is the definition of a prisere?
the complete set of seral stages from bare ground to the climatic climax community
What is the first seral stage in the formation of a CCC, from the lithosphere?
LICKENS AND MOSS
these are the first pioneers
small, but wide spread over the area, will secrete acid and will form thin layers of soil overtime
What is the second seral stage in the formation of a CCC, from the lithosphere?
GRASSES AND HERBS
these species have a larger leaf area, so they can grow faster and OUTCOMPETE the lichens and moss
they have larger roots so add both organic and inorganic matter to the soil
What is the third seral stage in the formation of a CCC, from the lithosphere?
SHRUBS AND BUSHES
larger plants grow, now grow in thicker soil
outcompete the smaller herbs
What is the final seral stage in the formation of a CCC, from the lithosphere?
TREES - grow slowly and eventually outgrow and shade the shrubs
a complex layered community is now established with many trophic levels and interactions
= CCC
What is the definition of a pioneer species?
the first species to colonise new land
What does it mean when one species out competes another?
Each new species may change the environment meaning it becomes less suitable for the previous species.
Therefore, each existing species is outcompeted by another species that is colonising.
What is the case study for Primary Succession?
Volcanic Eruption of Krakatoa 1883
How deep was the layer of ash over the Earth after this eruption on the island?
50m deep
There was no biodiversity left, however, after 3 years how many new species were there?
26 species had reappeared
After 1933, how many species of plant and insects were recorded to be on the island?
271 plant species
720 insect species
What is a sub - climax and how does it occur?
this is when the succession is interrupted and halted by the natural physical factors other than climate. The seral stages do not continue to develop
What is a sub-sere stage?
a sub-climax consequently develops where succession is held
What are some of the factors that may cause a sub - climax to occur?
- grazing by animals
- spontaneous fire
- area of poor drainage
- area of high drainage
- frequent volcanic eruption depositing ash
What are three examples of sub climax communities?
- some temperate grasslands, due to grazing animals
- peatlands, due to waterlogged conditions
- limestone pavements, where chemical weathering occurs and surface water drains through limestone
What is a plagio-climax?
When human activity has changed many regions of the world resulting in a new stable ecological community
What are some examples of human activity that result in a plagio-climax?
- fire clearance
- agriculture
- grazing
How large is the West Midland area and how much of its natural climatic climax community is left in that area?
5000km sq
less than 5% of this area is temperate deciduous woodland
Explain how crop agriculture stops the succession process?
monoculture, dominates, pesticides are used which means that insects cannot establish themselves
Explain how livestock agriculture stop the succession process?
dominate the food chain, have protection from herbivores
What is the case study for a Plagioclimax, in the U.K?
Heather Moorlands and Heathlands
What are the Heather Moorlands and Heathlands, what type of biome?
Tundra, like conditions around the Scottish mountains creating sub climax
How are the Heather Moorlands managed to maintain the plagio-climax?
- grazing
- Heather Burning
How does grazing maintain the Heather Moorlands plagio-climax?
deer and sheep grazing, prevents young saplings growing into trees, providing nutrients for the sheep, deer and cattle
How does heather burning maintain the Heather Moorlands plagio-climax?
= periodic burning of heather helps create young nutritious growth for grazing animals
= the older taller heather creates an environment suitable for nesting birds and cover for birds
= burning creates an ecosystem that has a mix of different ages of heather
What are the four stages of growing heather?
pioneer, building, mature and degenerative
once the degenerative stage is reached the heather dies and new species will invade enabling the succession process to recommence
What is the definition of rewilding?
an increasing movement in regenerative agriculture, where human activities are reduced enabling succession to occur
What is an example of a place in the U.K where rewilding has occurred?
Knepp Estate in Sussex, where 3500 acre ex dairy farm is reverting ploughed and overgrazing fields to natural vegetation
What is a mosaic habitat?
mixed landscape with an array of ecosystems, Knepp
How will the rewilding of Knepp benefit biodiversity and outline the interdependence between vegetation and other species?
- pigs impact soil - routilling, pigs plow snouts into soil and help overturn soil
- cattle impact vegetation - stimulate different types of vegetation
- increase diversity, species keep level of vegetation that’s required for them
