learning objectives understand ecological successions success criteria describe and explain the...
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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