Ecosystems- Ecosystems in the British Isles over time Flashcards
What is succession?
The change in a plant community over time
Plants will invade an area when the conditions are suitable and then die off when the succession leads to unfavourable conditions. This means there is a change in the dominant plant species over time
What is a climatic climax?
When the plant species live in perfect balance with their current environmental conditions
Succession continued undisturbed—-> Climatic climax
Name the two basic types of succession
Primary and Secondary
What is primary succession?
Occurs on surfaces that have had no previous vegetation. There are 2 main types of primary successes which are xeroseres and hydroseres.
Xeroseres- formed on dry land
Hydroseres- formed in water
What is secondary succession?
Follows the destruction or modification of an existing plant community
Can occur naturally or through human activity
Explain the development of a succession
- When plants first invade bare group, groups of species become established. These pioneer species are extremely hardy plants
- Pioneers compete for available space, light, water, nutrients and as they die, they help to modifying the habitat, adding organic matter to the developing soil
- As the ground is improved by the creation of an immature soil, other plants are able to colonise
- Each stage of the colonisation provides better conditions for plant growth than the previous one so an increasing number of species is found
- Taller plants also provide shelter from the sun and wind which allows other plants to be established
What is a sere?
A community of plants that forms a stage in the development of vegetation over time
What is a lithosphere ?
A succession that begins life on a newly exposed rock surface
What is a raised beach?
An example of a lithosphere created by either falling sea levels or by the isostatic uplift of land from the sea
Explain a lithosphere plant succession
- Bare rock surface is initially colonised by bacteria and algae. This is because bacteria and algae can survive where there are few nutrients, little moisture and no soil
- Colonisation: the pioneers begin to colonise starting with lichens. Here lichens can survive in the dry windy soil free conditions. As the lichens die, they add dead organic matter to the weathered rock, creating a simple soil
- Establishment: Species diversity increases. As the soil develops, it allows grasses to grow. Again, these plants die back and this increases the soil fertility
- Competition: Larger plans such as gorse establish and thee plants use up a lot of the available water
- Stabilisation: large fast growing trees establish such as birth
- Seralclimax: Slower growing species begin to develop. These trees are able to grow because by this stage, the soil is deep allowing the roots to spread out in addition to the nutrients required
Name the key stages in a lithosphere succession
- Colonisation
- Establishment
- Competition
- Stabilisation
- Seral climax
What is a biome?
A global scale ecosystem
Describe the location of temperate deciduous woodland
- Found between 40 and 60 degrees north and south of the equator
- Northern hemisphere- includes western and central areas of the USA, Western Europe (including UK) and central Eastern Asia
- Southern hemisphere- includes SE Australia and New Zealand
Describe the climate of temperate deciduous woodland
Average winter temps 2- 7 degrees
Average summer temps 13 -17degrees
Total precipitation 500-2000mm per year
Low pressure systems dominate
Describe the vegetation of temperate deciduous woodland
Autumn leaf fall
Broadleaved deciduous trees such as oak
Describe the Gernmehl diagram of temperate deciduous woodland
Small litter store- leaf falls in autumn decays slowly due to low temperatures
Large amounts of nutrients in biomass store= lots of plant and tree growth. This is because there is a long growing season
Relatively large soil store= organic matter decomposes which releases nutrients in the soil
Describe Brown Earth Soil
Deep and well drained
Fertile soil
Lead litter accumulates during autumn and can be quickly decomposed in spring and summer
Soil is well mixed by earthworms so layers aren’t clear
Leaching
Slightly acidic
What is a plagioclimax?
When a plant community is stood from reaching climatic climax
Human activity such as agriculture and deforestation will lead to a plagioclimax community such as heather moorland
Describe the heather moorland plagioclimax
- Many of the upland ares in Britain were once covered by a climx vegetation of deciduous woodland, particularly oak forest
- Removing forests for reasons such as providing space for grazing. This had a damaging effect as it caused the soils to deteriorate and less rainfall was intercepted and so more leaching of nutrients. Therefore, hardy plants such as heather began to dominate this land
- Humans allowed sheep grazing to occur as it became the amor for of agriculture- prevented trees from growing
- Managed burning in order to encourage new heather shoots to grow. Burning heather occurs on average every 15 years
Describe the key features of the tropical savanna
- Temperatures above 20 degrees throughout the year
- Total precipitation can range from 600 to 2000mm
- prolongued drought of at least 5 months
- 90% of annual rainfall falls during the wet season
Tropical savanna vegetation
- There are many types of vegetation in the savanna, including grasses and trees
- Trees dominate over grasses where the wet lesson is longer, closer to the equator
Tropical savanna- adaptations to drought (xerophytic)
Deep tap roots so it can reach down to the water table
E.g acacia trees
The trunk and bark can absorb and store water so it can survive dry season
partial or total loss of leaves to reduce transpiration
Tropical savanna- adaptations to fire (phyrophytic)
Very hick barks that resis fire and prevents water loss
-The bulk of the biomass being below ground
