Flashcards in F215:03:04 Succession Deck (23):
What is succession?
a directional change of a community of organisms over a time
Give a recent example of succession
The island of Surtsey in Iceland was created by a volcano eruption in the 1960's.
Began as bare ground but is now home to a community of plants
What is primary succession?
The transformation from bare ground to a community of plants.
Describe the pioneering community
When algae and linchens begin to live on bare rock
How is soil formed from bare rock?
Rock erosion and the build up of dead and rotting organisms producing enough soil for plants like mosses and ferns to grow, which succeed the algae and linchens
What is a climax community?
The stage at which larger plants have succeeded smaller pnes and the final, stable community is reached
What does succeed mean?
Does succession always start from bare ground?
No, secondary succession takes place of previously colonised, but disturbed or damaged habitats.
Give an example of a good environemnt that displays all the stages of succession in the same place at the same time and show why
As the sea deposits sand on the beach, so the sand just above the high water mark is the start of the succession process, and sand much further away hosts its climax community.
Outline the stages of succession
1. Pioneer plants colonise bare ground/sand that can tolerate the harsh conditions
2. Plants colonise that stabalise the sand with their roots
3. The stability and nutrients accumulate, so more plants grow e.g. marram grass which traps sand
4. Nitrogen-fixing plants begin to colonise, increase nutrients in the sand, creates a habitat copable for more plants
Give an example of pioneering plants on a sea bed
sea rocket (Cakile maritima) and prickly sandwort (Salsola kali)
What kind of conditions to pioneering plants have to be able to withstand on sand
salt water spray
lack of fresh water
How do mini-sand dunes form? (stage 2 of succession)
Windblown sands build up around the bases of pioneering plants
Give an example of plants that begin to colonise once sand dunes begin to accumulate nutrients
sea sandwort (Honkenya peploides) and sea couch grass (Agropyron junceiforme)
then sea spurge (Euphorbia paralias) and marram grass (Ammophila arenaria)
How does sea couch grass help to stabalise sand?
As it has underground stems
What is special about marram grass, and helps succession along?
its shoots trap wind-blown sand and as the sand accumulates the shoots grow taller to stay above the growing dune.
Give examples of plants that begin to colonise once the marram grass has made enough of a sand dune
hare's foot clover (Trifolium arvense) and bird-foots trefoil (Lotus corniculatus)
(Members of the bean family (legumes))
How do legume plants aid the succession of sand dunes?
The bacteria in the root nodules convert nitrogen into nitrates, and then when more nitrates are available
Explain the meaning of primary succession
a directional change in a community of organisms over time, beginning from bare ground
Explain the meaning of pioneer community
The living organisms which first start to colonise on bare ground
Explain the meaning of climax community
The stable community that emerges at the end of a process of succession
Compare and contrast the process of succession on bare rock and on a sand dune
Pioneering community: BR- lichens/algae SD- higher plants
Climax community: both woodland
BR- no windblown sand SD- dfg