Learning Objectives

Understand ecological

successions

Success Criteria

• Describe and explain the meaning and the

succession of a PSAMMOSERE

1

Plant succession

Plant succession is the development of

plants. This can take place in many

areas such as

• Fresh water (hydosere)

• Bare rock (lithosere)

• Sand dunes (psammoseres)

Ecological succession

During succession the ecosystem

goes through a series of stages.

Each stage is called a seral stage and

the complete series of plant

communities resulting from the

process of succession is called a SERE!

Psammosere

A psammosere is a plant succession on a

sand dune.

It consists of a series of dry sandy ridges

interspaced with wet hollows called

slacks.

Sand dunes become stable when plant life

develops

Three main stages

Pioneer stageSeeds are blown in by the wind or

washed in by the sea. Rooting conditions are poor due to drought, strong winds and salty sea waster immersion and alkali conditions created by seashells

Three main stages

Building stagePlants trap sand and grown with in binding together the sand with their roots. The humus created by decaying pioneer plants creates more fertile conditions.

Three main stages

Climax stageTaller plants (like trees) and more complex species can now grow, Plants from earlier stages die out due to competition for light and water.

Climax Vegetation

• Final stage of plant succession• Relatively stable and self sustaining• Does not change• High highest biomass/ variety of species• Vegetation in harmony/ equilibrium with

environment• Scottish examples – Oak, Pine, Birch

woodlands

Questions

1. What is a pioneer community?2. Why are these plants able to grow on

bare rock?3. How does a thin layer of soil form on

bare rock?4. What happens when smaller plants die?5. What is the name given to this event?6. What is climax vegetation?7. What does equilibrium mean?

Learning Objectives

Understand ecological

successions

Success Criteria

•Describe and explain the formation of a

dune system

2

Growing a Sand Dune system• A plentiful supply of sand

• Strong winds to transport sand particles

through saltation (bouncing and hopping of

sand on surface)

• An obstacle to trap the sand, usually it’s a

plant or a piece of seaweed that’s located on

the tide or strand line

An aerial view of a sand dune system

youngest dunes

oldest dunes

A transect across a sand dune system...

X Y

Reveals variations in relief and vegetation ………..

X Y

A transect across a sand dune system

Embryo and Fore Dunes: the environment

on-shore winds

high water mark

seaweed

deposits

humus

sand builds up against

pioneer plants

transient dunes

poor water

retention

Yellow Dunes: the environment

above the level of

high tides

reduced wind

speeds

Surface continually blown away

and replenished with fresh

sand

‘Soil’ slightly less alkaline and more water retentive

Some humus forming

Grey Dunes: the environment

sheltered by higher, seaward

dunes

lower pH

higher humus content

little mobile sand

sand no longer

accumulating

a more closed vegetation community in which marram grass

is no longer able to compete

Dune Slacks: the environment

relief intersects the water

table

water table high –

especially in winter

soil acidic

occur in low lying hollows between

dune ridges

Dune Heath/Woodland: the environment

well sheltered

from winds

acidic soil

nutrient rich

soil has high organic matter

content

Past paper handout 2008

Learning Objectives

Understand ecological

successions

Success Criteria

• Describe how plants have adapted in

dune systems

3

VocabXerophytic – plants which are water

resistant

Hydrophytic – plants which are water tolerant

Halophitic – Salt resistant

Rhizomes – long roots/ stems

Factors influencing dune stability

People

Soil

Climate

Slope

Other vegetation

People:People walk on dunes and trample plants

Soil:It is tidal so is never 100 % dry or 100% wet

Lack of organic content so less nutrientsAlkaline soils– sea shellsSaline soils – salty water

Drainage is too good – can be a lack of water

Climate:Windy – blows sad at plants

Exposed – no shade or shelter

Slope:Sand is mobile

Some plants may get buried

Other vegetation:Competition

Not enough humus to support/ create different vegetation types

Marram Grass• Xerophytic (drought resistant)• Long and sharp to prevent animals eating it

Long rhizomes (underground stems) stabilise the dune/ bind sand together

• Rhizomes also reach underground for water to deep water table

• Curled up shape of grass reduces evapotranspiration

• Grows on bare soils with little competition• Fast growing 1m per year

Learning Objectives

Understand ecological

successions

Success Criteria

•Identify plant species along a psammosere

transect

•Describe how plants have adapted along a

psammosere transect

True or False1. Humus content decreases as you go inland2. Ph declines as you move inland3. Plants are well sheltered on the Embryo

dunes4. Marran grass is found on the Yellow dunes5. Dandelions are found on the Fore dunes6. Sandwort can be found on the Embryo dunes7. Salt content increases inland8. Yellow dunes, Grey dunes and Mature dunes

are all fixed dunes9. At the climax stage plants are stable and

relatively unchanging

Zone 1: Embryo and Fore dunes

•Sand is poor in nutrients and is very dry

•They are resistant to occasional immersion in

water and are able to withstand high winds.

• Plants that grow here have lateral roots and

underground stems

•Low lying to avoid strong winds

•High salt tolerance

•Waxy leaves to retain moisture and withstand

winds

•Alkaline with no humus

Embryo and Fore Dunes: the plants

Sea rocket

Saltwort

Sea couch

Sandwort

Zone 2: Yellow Dunes

•Marram grass becomes the dominant plant

•Its RHYZOMES (long creeping underground

stems) help to bind deposited sand and reach

water table

•Leaves curl up in order to retain moisture

•Marram can align itself with prevailing wind to

reduce moisture loss

•Marram grows quickly (~1 metre/ year) to keep

above the sand.

•Salt tolerant

Yellow Dunes: the plants

Ragwort

Marran Grass

Zone 3: Gey Dunes and Slacks

•Increased shelter + damper soil = higher species

diversity

•Shelter restricts supply of sand

•Increased humus content

•Vegetation cover now complete

• Marram becomes more sparse

•On Slacks, water table is near surface

encouraging plants which prefer damp conditions

Grey Dunes: the plants

Older grey dunes may have extensive covering of lichens and heather

• marram becomes more sparse

• mainly perennials

• higher species diversity

• surface lichens give ‘grey’ appearance

Dune Slacks: the plantsThe community which develops here comprises moisture-loving plants commonly found in many fresh water wetland areas e.g.

Reeds

Flag iris rushes

Bog cotton

Zone 4: woodland/ grassland

•Taller species indicate a deeper and wetter soil.

Dune Heath / Woodland: the plants

Human interference means that true mixed woodland climax vegetation is rarely seen on dune systems in the UK

Heather

Scots Pine

Heather

Learning Objectives

Understand ecological

successions

Success Criteria

•Explain fully what is meant by climax

vegetation

•Explain the plant succession in a sand

dune

Explain what is meant by the term “Climax

vegetation”?.

•What is the question asking you to do?

•Structure

•What is important

•Key words

•Plant types

4 marks

Explain what is meant by the term “Climax

vegetation”?.

•Final stage/ stage of maturity = ecosystem is relatively

unchanging and biomass is at a maximum

•Dynamic equilibrium -maintains overall stability

despite continuous small changes.

•Progression – pioneers are displaced as conditions

change

•Plants compete for water, nutrients and space

•Species such as scots pine and oak become dominant

4 marks

In your teams ………

With the aid of a diagram describe AND explain

the plant succession in a sand dune habitat.

You may wish to think about……

• Succession

• Plant type

• Conditions

• Adaptations

You have 20 minutes

Using the Core Higher Textbook....

1. Read pages 152-155

2.Answer the following questions on page 173-

174

• 2(b)

• 2(d)

• 2(g)

Describe and Explain the changes in

vegetation as you move inland from the

coast.

What is the question asking you to do????

Give the name of a type of vegetation in the

pioneer stage and say how it has adapted to that

environment and do the same for each stage.

What do you need to mention ………

•Each stage – from strandline to Woodland

•Conditions

• Humus content

• Salt content

• Ph

• Shelter

•Plant type

•Adaptations