Transcript Sand_dunes JS

Learning Objectives
1
Understand ecological
successions
Success Criteria
• Describe and explain the meaning and the
succession of a PSAMMOSERE
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 stage
Seeds 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 stage
Plants 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 stage
Taller 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
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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
2.
3.
4.
5.
6.
7.
1. What is a pioneer community?
Why are these plants able to grow on
bare rock?
How does a thin layer of soil form on bare
rock?
What happens when smaller plants die?
What is the name given to this event?
What is climax vegetation?
What does equilibrium mean?
Learning Objectives
2
Understand ecological
successions
Success Criteria
•Describe and explain the formation of a dune
system
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
Reveals variations in relief and vegetation ………..
Y
A transect across a sand dune
system
X
Y
Embryo and Fore Dunes: the environment
high
water
mark
poor water
retention
sand builds up
against pioneer
plants
on-shore
winds
seaweed
deposits
humus
transient
dunes
Yellow Dunes: the environment
above the
level of high
tides
reduced wind
speeds
‘Soil’ slightly
less alkaline
and more
water
retentive
Some
humus
forming
Surface
continually blown
away and
replenished with
fresh sand
Grey Dunes: the environment
sheltered by higher,
seaward dunes
lower pH
little mobile
sand
sand no longer
accumulating
higher humus
content
a more closed vegetation
community in which marram
grass is no longer able to
compete
Dune Slacks: the environment
occur in low lying hollows
between dune ridges
soil acidic
water table high –
especially in
winter
relief
intersects
the water
table
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
3
Understand ecological
successions
Success Criteria
• Describe how plants have adapted in dune
systems
Vocab
Xerophytic – plants which are water
resistant
Hydrophytic – plants which are water
tolerant
Halophitic – Salt resistant
Rhizomes – long roots/ stems
Factors influencing dune
stability
People
Soil
Slope:
Sand is mobile
Some plantsClimate:
may get buried
Windy – blows sad at plants
People:
Exposed – no shade or shelter
People walk on dunes and trample plants
Climate
Soil:
Other vegetation:
It is tidal so is never 100 % dry or 100% wet
Competition
of organic content so less nutrients
Slope Lack Not
enough humus to support/
Alkaline soils– sea shells
create different
Saline soils – salty water
vegetation types
OtherDrainage
vegetation
is too good – can be a lack of water
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
1.
2.
3.
4.
5.
6.
7.
8.
True or False
Humus content decreases as you go inland
Ph declines as you move inland
Plants are well sheltered on the Embryo dunes
Marran grass is found on the Yellow dunes
Dandelions are found on the Fore dunes
Sandwort can be found on the Embryo dunes
Salt content increases inland
Yellow dunes, Grey dunes and Mature dunes are
all fixed dunes
9. 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
Saltwort
Sandwort
Sea couch
Sea rocket
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
Marran Grass
Ragwort
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
• higher species diversity
• mainly perennials
• marram becomes more
sparse
• surface lichens give ‘grey’
appearance
Older grey dunes may have extensive covering of
lichens and heather
Dune Slacks: the plants
The community which develops here comprises moisture-loving plants
commonly found in many fresh water wetland areas e.g.
Flag iris
rushes
Reeds
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
Scots Pine
Heather
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”?.
4 marks
•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
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