Ecosystems In The British Isles Over Time

Question 1

What is succession

Answer 1

The process by which an ecosystem changes over time (change in plant community). The biotic conditions change as as abiotic conditions change

Question 2

What is primary succession

Answer 2

Occurs on land that’s been newly formed or exposed eg where a volcano erupts and forms new rock surface.
Abiotic conditions harsh eg no soil, seeds spores blown by wind

Question 3

What is secondary succession

Answer 3

Happens on land that’s been cleared of all plants but soil remains eg after forest fire

Question 4

What happens during each stage of a succession

Answer 4

Different plants and animals are better adapted for improved conditions move in and outcompete plants and animals already there to become dominant species. Ecosystem becomes more complex over time, species diversity increases

Question 5

Describe primary succession

Answer 5

On land that’s newly formed or exposed.abiotic conditions harsh. First species to colonise are pioneer species they adapted to harsh conditions. They change abiotic conditions, die and decompose to form a soil so conditions less hostile eg soil retain water, new organisms grow, die and decompose soil is deeper and richer so larger plants can grow

Question 6

What are the stages in a succession called?

Answer 6

Sere -a community of plants that forms a stage in the development of vegetation over time.

Question 7

Example of a succession

Answer 7

Lithosere (raised beach) created by falling sea level or by isostatic uplift of land from sea

Question 8

Raised beach succession stages

Answer 8

Seral stage 1- colonisation 
Seral stage 2- establishment 
Seral stage 3 - competition 
Seral stage 4 - stabilization 
Seral climax

Question 9

During raised beach succession what happens at stage 1 - colonisation

Answer 9

Pioneers begin to colonise eg lichen, are adapted to severe(dry,windy,soil free) conditions. They die and add dead organic matter to weathered rock - simple soil, water retention improved Mosses grow. More soil so more advanced plants begin to grow

Question 10

During raised beach succession what happens during stage 2 - establishment

Answer 10

Soil develops furthur, ferns, small herbaceous plants and grasses begin to grow. Species diversity increases. Humus created and improves soil fertility. Soil holds more water.

Question 11

During a raised beach succession what happens during stage 3 - competition

Answer 11

Larger plants establish themselves eg shrubs (gorse) and small trees, use up water and shade ground. Some of earlier colonisers unable to compete and die out

Question 12

During a raised beach succession what happens during stage 4 - stabilization

Answer 12

Fewer new species colonise, larger pioneer trees dominate such as willow, birch, and Rowan

Question 13

During a raised beach succession what happens during the seral climax stage ( final stage)

Answer 13

Slower growing tree ps develop eg ash, oak. They are dominant soft climatic climax community -temperate deciduous woodland

Question 14

Where is temperate deciduous woodland biome found ?

Answer 14

In mid latitudes where there’s adequate moisture

Question 15

Climate of temperate deciduous woodland 
-Ave winter and summer temps
-Total precipitation 
-winds 
Which weather system dominates?

Answer 15

• Winter temp 2-7c Summer - 13-17c
• Total precipitation 500-2000mm per yr
• On shore westerly wind predominate - moderates temperature, bring moist air
• low pressure weather systems dominate

Question 16

Vegetation In temperate deciduous woodland

Answer 16

• Characterised by Seasonal colour change
• Broadleaved deciduous tree set oak,ask beech ,birch shed leaves in Autumn before Cold temp
• Soil temp fall so growth retarded - can’t absorb much water
• Heat loss reduces transpiration and demand for water during cooler months.

Question 17

Soil of temperate deciduous woodland

Answer 17

• Brown earth, fertile, 1.5m deep , well drained
• Leaf litter accumulates during autumn and is quickly decomposed the following year
• Soil well mixed by earthworms so layers unclear
• Mild leaching occurs so soil slightly acidic ideal for plant growth

Question 18

Oak woodland characterised by 4 layers

Answer 18

• Tall tree canopy - Oak, beech, sycamore, ash. Loose leaves I winter reduce transpiration, light limited? Reduce species
• Shrub layer - small trees eg hazel, hawthorn , rowan
• Field layer- woodland flowers eg bluebell,primrose
• Ground layer - mosses,tree seedlings. Fallen and decaying wood and leaf litter important for fungi

Question 19

What are interfering or arresting factors

Answer 19

Those that stop a plant community from reaching climatic climax

Question 20

What is a plagioclimax

Answer 20

The plant community that exists when human interference prevents the climatic climax vegetation being reached

Question 21

Examples of types of human activity that stop succession or redirect it towards a different climax

Answer 21

Deforestation - reduces soil quality fewer plants can grow
Animal grazing- small plants/ saplings eaten or trampled
Clearance by fire - all plants destroyed ,fastest growing types recolonise
Afforestation - trees cleared to make way for new saplings, only one species planted and managed (monoculture)

Question 22

Example of a plagioclimax in the uk

Answer 22

Heather moorland

Question 23

Describe Heather moorland plagioclimax

Answer 23

Upland of Britain was covered in deciduous woodland (oak forest) Heather in small amounts. Forests gradually removed + soil deteriorated + hardy plants (Heather dominate ). Sheep grazing prevented regeneration of climax woodland as destroyed young saplings. Managed burning used to control uplands to encourage new Heather shoots , less fire resistant species eliminated Heather shoots dominate.

Question 24

How often is Heather burnt In Heather moorland

Answer 24

On average every 15 years if left longer there’s too much woody tissue and nutrients lost in smoke