1.2-a) Succession

Question 1

• Define ecological succession.

Answer 1

• Ecological succession:
  ➞ is described as the changes in the species structure (the different types of species) in a community over time.
• Succession is a process that is driven by the organisms involved, where the organisms change the habitat, making it less suitable for themselves and more suitable for other species.

Question 2

• Define the term ‘adaptation’.

Answer 2

• Adaptation:
  ➞ is any feature which makes an organism well suited to living in its environment.

Question 3

• Explain the 4 stages of succession.

Answer 3

1. As an organism colonises a habitat, they change the habitat conditions 🐛
2. As the conditions change, the organisms become less well adapted to their niche ✨
3. This allows another species to outcompete the original species for the niche 🆚
4. As the conditions change, the original organism makes the conditions less suitable for themselves and more suitabe for the next species on succession ➡️

➞ (The rate of succession can be influenced by either cliamtic, biotic or edaphic factors)
➞ (The climate of region is determined by its temperature, precipitation, altitude and latitude)

Question 4

• What is a climax community and can you describe the 4 key features of a climax community?

Answer 4

• Climax community:
  ➞ is the final stage of ecological succession. Here a community of plants and animals remains stable and exists in balance with each other and their environment.
• Key Features:
  1. Stable community ➡️
  2. High biodiversity 🐛
  3. Complex food webs 🕸️
  4. High biomass (big trees) 🌳

Question 5

• Explain primary succession.

Answer 5

• Primary succession:
  ➞ is the colonisation of a new site by communities of plants and animals after an event has removed all exisitng soil (i.e. glaciation or a lava flow)
• This type of succession must first wait for soil to develop sufficiently to support colonising species.

Question 6

• Explain pioneer species

Answer 6

• Primary colonisers (pioneer species) are adapted to growing on bare rock (i.e. lichen and algae).
• Pioneers form the first seral communtiy and will eventually form the first layer of soil.
  ➞ This results in them being outcompeted by vascular plants (i.e. grasses)

Question 7

• Define a seral community and their role in ecological succession.

Answer 7

• A seral community:
  ➞ is an intermediate stage found in ecological succession that advances towards its climax community, where depending on the foundations and climate of the area, a sere can be one of many types.

Question 8

• Define the 4 types of succession

Answer 8

1. LITHOSERE:
   ➞ succession that begins on bare rock. They are common in Scotland due to glaciation. (Lithosere can also be seen in islands formed as a result of volcanic eruptions) 🪨
2. PSAMMOSERE:
   ➞ succession that begins on newly exposed coastal sand (e.g. sand dunes) ⌛
3. HYDROSERE:
   ➞ succession that occurs in areas of fresh water (e.g. ox box lakes). The open freshwater will naturally dry out and become swamp marsh and finally, woodland 🌊
4. HALOSERE:
   ➞ succession that occurs in saline environments (e.g. salt marshes) 🧂

Question 9

• Explain the stages of LITHOSERE succession.

Answer 9

1. SERAL STAGE 1:
   ➞ The pioneer community (usually lichens and algae) start to form on newly exposed bare rock.
   ➞ They can absorb mositure from the atmosphere and break down the rock and minerals to release nutrients.
   ➞ As the pioneers die and decompose, small quantities of organic matter build up.
2. SERAL STAGE 2:
   ➞ Early colonisers (i.e. grasses and mosses) take advantage of the new niches created by the pioneer species.
   ➞ They are adapted to survive in these conditions, so can outcompete the pioneers. For example, larger leaf area for sugar production by photosynthesis which leads to rapid growth.
3. SERAL STAGE 3:
   ➞ As soil and organic matter continues to build up, late colonisers (i.e. gorses, heather, hawthorn and bramble) outcompete the early colonisers.
   ➞ They have larger, animal dispersed seeds and grow much faster and taller.
   ➞ Their roots penetrate more deeply in the rocky substratum which causes more weathering and soil formation.
4. CLIMAX COMMUNITY:
   ➞ Trees begin to grow among the shrubs and the forest climax community forms.
   ➞ It will eventually grow higher than the shrubs and shade them. These shrubs are outcompeted by shade-loving plants.
   ➞ Leaf litter and decaying roots weather the soil further and add humus to it.
   ➞ An equilibrium is reached between the environment and the biotic community. The type of climax community depends upon the climate.