Changes in ecosystems/succession Flashcards
1
Q
What is primary succession
A
- changes that happen in an ecosystem overtime, when the starting point was nothing
2
Q
How do the early colonisers change abiotic conditions to enable more and more species to thrive
A
- pioneer or colonise species are the first species
- early colonisers go through cycle of life, death and decay
- they make habitat suitable for more species to thrive
3
Q
Explain the stages of a lithosphere
A
- weathering of exposed rocks
- growth of lichen
- moss outcompetes lichen
- grasses, fern and small herbs colonise
- small shrubs such as bramble colonise on the surface
- pioneer trees outcompete shrubs
- legumes make nitrogen which increases soil fertility
- larger trees colonise
- creates a climax community
4
Q
Explain the stages of a hydrosphere
A
- sediments build up and the water gets shallower
- emergent species grow partly in the water
- submerged plants establish on the surface
- a swamp forms
- death and decay of plants lead to rising nutrient levels
- species adapted to wet conditions die out
- transpiration of plants dries the soil meaning rushes and ferns thrive
- small flowering herbs are adapted to wet soils
- shrubs form
- climax community forms
5
Q
Explain the stages of a psammosere
A
- mobile dunes in an upper beach accumulate sand
- hardy species tolerant of salt, wind such as marram grass colonise the area
- vegetation mat develops and the dune system stabilises
- accumulating humus changes the soil to allow wild thyme to accumulate
- moisture loving plants such as willow colonise followed by woodland
6
Q
What is meant by the term secondary succession
A
- occurs when there is a disturbance to the natural process of succession
7
Q
What is the main difference between primary and secondary succession
A
- primary has nothing and secondary has soil
- secondary happens much quicker as soil is present
8
Q
During the succession process, what increases over time
A
- biodiversity
- soil depth
- more decay
9
Q
Define plagioclimax
A
- deflected or halted succession
10
Q
Where is surtsey and hoe and when was it created
A
- its a volcanic island
- in november 1963-1967 surtsey was formed in a volcanic eruption
11
Q
What happened and what organisms appeared on surtsey
A
- stage 1 - soil has poor levels of nitrogen and oxygen
- stage 2 - few new colonisers
- stage 3 - arrival of gull colony and vegetation enhancement
- stage 4 - appearance of first bushy plant
