Changes in Ecosystems (succession) Flashcards
Primary Succession
the changes in an ecosystem over time when the starting point was nothing
e.g. volcanic islands
How do the early colonisers change abiotic conditions to enable more species to thrive?
mosses and lichens attach to hard substrate
grass starts to grow
flowering plants and shrubs
tree (climax community)
plants go through life cycle, start to decay and form soil, allows more complex species to thrive
What are colonisers also known as?
pioneer species
What does lithosere mean?
succession on rock
Stages of a lithosere
1) weathering of exposed rock
2) growth of lichen
3) moss outcompetes lichen
4) grasses and small herbs colonise
5) small shrubs colonise the surface
6) pioneer trees outcompete shrubs
7) legumes make nitrogen - increasing soil fertility
8) larger trees colonise, casting shade and killing off smaller species
9) climax community forms - deciduous woodlamd
What does hydrosere mean?
succession when the starting point is water
Stages of a hydrosere
1) rooted plants can’t survive in water
2) sediment builds up - water gets shallower
3) emergent species grow partly in the water
4) submerged plants (pondweed) establish on the surface
5) a swamp forms
6) death and decay of plants increases sediment
7) species adapted to very wet conditions die out
8) transpiration of plants dries the soil - ferns thrive
9) small flowering plants are established
10) decay and aerobic decomposition adds nutrients to soil
11) oak and ash develop with flora
12) climax community reach (deciduous woodland)
What does psammosere mean?
succession on sand
Stages of a psammosere
1) mobile dunes accumulate sand
2) hardy species (marram grass) colonise the area
3) vegetation develops and dunes are stabilised
4) wild thyme, plantains and buckthorn accumulate
5) moisture loving plants colonise - followed by heath and woodland
6) climax community reached - deciduous woodland
What is meant by the term secondary succession?
occurs when succession/climax community is impacted by a disturbance (natural or human)
may take succession back to earlier stages
Primary vs Secondary Succession
primary = starting point is nothing
secondary = soil is present and happens much faster
During succession, what increase over time?
biodiversity
soil depth/richness
complexity of plants
size of plants
shade on forest floor
amount of niches
What does plagioclimax mean?
an area or habitat that has been prevented form carrying on natural succession
deflected or halted succession
Examples of plagioclimaxes in the UK and how they’re managed
Lowland heathland and upland moorland = grazing and controlled burning
chalk grassland and water meadows = grazing
hay meadows = harvesting
coppiced woodland = coppicing
garden lawn = mowing/weeding
Case Study: Surtsey
Volcanic island in Iceland
formed by volcanic eruptions, 1963-1967
provides the world with a natural laboratory
1965 = first vascular plants
89 species of bird and 355 species on invertebrates
