Transcript Plant Succession and Climax Vegetation

Plant Succession and Climax
Vegetation
Case Study
Sand Dune Succession
Aims
• You should be able to explain the term
ecosystem and the processes which
produce ecosystems.
• You should be able to explain what is meant
by climax vegetation.
• Describe and explain the process known as
plant succession with specific reference to
a sand dune transect.
Ecosystems
• A system in which plants, animals,
insects and miro organisims (Biotic)
interact with the natural environment
which includes climate, rocks, and soil
(Abiotic).
• Small area of land in a garden.
• Whole zones of rainforest.
An Oaktree EcoSystem
• First there is the roots, soil and
leaf-litter zone beneath the
tree. Here decomposers such as
bacteria, woodlice, and
earthworms feed off last year's
leaves and acorns, and fungi grow
on its roots
• Next is the trunk layer, which
provides shelter or food to
insects, caterpillars and larvae.
• Finally comes the branches,
leaves and canopy. In this zone
bees gather pollen and nectar,
fungi grow on the leaves, gall
wasps and moths lay their eggs,
and squirrels gather acorns. Small
birds such as bluetits hunt the
moth larvae; and sparrowhawks
hunt the small birds
An Ecosystem depends on two main processes.
• Flow of energy,
the main source of
which is the sun.
• Solar energy
absorbed by plants.
• This energy passes
through the
ecosystem in food
chains.
• Recycling of
nutrients.
• Plants absorb
nutrients from the
soil and these are
passed on to
animals which die,
decompose and
return to the soil.
Plant succession
• The process of plant succession involves a
series of stages during which the species
of plant life changes.
• From the pioneer stage to the…..climax
vegetation.
• Read page 162 an example of plant
succession on a scree slope.
An example of plant succession
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The first of these stages is referred to as the __________ stage. At
this stage the first plants that __________ are completely new,
perhaps a bare site such as a beach or sand dune are
called__________.
The pioneer plants through their______ ______, begin to bind the soil
together preventing its removal by wind or rain. Gradually the soil is
___________ and this assists in the process of plant succession.
The pioneer plants add __________ matter to the soil that holds water
and nutrients. This is turn changes the conditions of the site
sufficiently so as to allow other less _____________ plants to become
established.
__________ and ____________which were present in the pioneer
stage may be replaced by __________ which in turn may eventually give
way to _________ and __________. This would be known as the
_________ vegetation which is the final stage in the process and these
plants would be in a state of ___________.
Root action, Equilibrium, Pioneer, Grasses, Mosses,
Lichens, Protected, Pioneers, Shrubs, Colonise, Woodland,
Organic, Resilient, Climax.
• The first of these stages is referred to as the pioneer
stage. At this stage the first plants that colonise are
completely new, perhaps a bare site such as a beach or sand
dune are called pioneers.
• The pioneer plants through their root action, begin to bind
the soil together preventing its removal by wind or rain.
Gradually the soil is protected and this assists in the
process of plant succession.
• The pioneer plants add organic matter to the soil that holds
water and nutrients. This is turn changes the conditions of
the site sufficiently so as to allow other less resilient plants
to become established.
• Lichens and mosses which were present in the pioneer stage
may be replaced by grasses which in turn may eventually give
way to shrubs and woodland. This would be known as the
climax vegetation which is the final stage in the process and
these plants would be in a state of equilibrium.
Sand Dune Succession
• Sand dune succession can be split into four zones
reflecting the development of sand dunes, plant
communities and their effect on each other.
• The zones can be seen below;
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Zone 1:
Zone 2:
Zone 3:
Zone 4:
Strandline to Fore Dunes (Pioneer stage)
Yellow Dunes (Building Stage)
Grey (Fixed) Dunes (Building Stage)
Dune Heath/Grass (Climax Stage)
Important trends in sand dune succession
are;
• Important trends in sand dune succession are;
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Sea Shore
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pH declines
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Salinity declines
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Age of dunes increases
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Available nutrients increase
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Available water increases
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Humus content increases
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Shelter increases
Inland
Sand Dune Transect
Zone 1: Strandline to Fore Dunes
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Pioneer plants such as Saltwort, Sea Rocket, Sea Lyme.
Plants that can survive in very salty conditions.
For short periods of time they can survive under salt water.
Some have waxy frosting on surface to resist salt spray.
Fresh water from rain so roots go deep underground and close
to surface of sand looking for moist sand.
Sea Rocket/Sea
Couch
Sea Lyme
Zone 2: Yellow Dunes
• Building stage (early) plants such as Marram Grass.
• Salt and alkalinity content starting to decrease ·
• Marram Grass starting to dominate, it cannot tolerate salt
water so is more common in this zone (2) than zone (1).
• In general though a slightly greater variety of species, as
humus starting to develop, demise of pioneers such as
Saltwort, aiding humification.
Yellow Dunes
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Plants may include sand sedge, mosses,
lichens, sea holly.
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Marram has very long roots
so can tap into underground
supplies and also tolerant of
drought conditions.
Plants are starting to stabilise
dunes through their root
systems.
Marram grass grows apace
with dunes at about 1m/annum
so taller dunes developing 510m high providing shelter.
Youngish dunes, which are still
developing.
Name derives from the rapid
growth of the dunes from
newly wind blown sand, which
is yellow.
Sea Holly
Zone 3: Grey Fixed Dunes
Plants in later part of building stages such as Clover &
Chickweed.
Some areas of slack water, where the water table reaches to
or close to the surface resulting in water logging and plants
such as reeds & rushes.
Further reduction of alkalinity now about 7.5pH and also salt
reduced, both as a result of distance from sea shore.
Now starting to see a deeper humus develop as more plant
species colonizing and more neutral pH allows improved
humification so more nutrients in soil.
Closer to water table so easier access to fresher water,
Humus gives the characteristic grey look to the dunes.
Mature Dune
• The most mature dunes
are found several hundred
metres from the shore.
Left undisturbed these
dunes develop a soil which
can support shrubs and
trees including hawthorn,
ash and birch. Humans may,
as in the picture on the
right, plant fast-growing
conifers which flourish in
the sandy soil. Eventually
an oak climax vegetation
may develop.
Zone 4 Mature Dune
More or less the climax stage with plants such as heaths,
gorse and possibly some trees such as birch.
T The widest variety of plants as the dunes are more stable
and unlikely to move from wind action.
Dunes several hundred metres from the shore.
The deepest humus layer with the greatest nutrients and
slightly acidic pH and lowest alkalinity.
In the UK the true final stage of dune succession is rarely
seen whereby mixed woodlands develop including trees such
as Pine, Birch and Oak are common,
Transect Of Sand Dune Progression
seaweed
marram
grass
lyme
grass,
sea
couch
grass,
marram,
sea
rocket
saltwort
ragworts
creeping
fescue,
sand sedge,
mosses,
lichens, sea
holly and
sea spurge.
Red fescue,
sand sedge,
sea spurge
brambles,
gorse,
buckthorn
rushes,
sedges,
cotton
grass and
creeping
willow
hawthor
n, ash
and
birch
pH  8,
rapid
drainage,
high salt
spray &
high wind
Dunes
up to 5m
high,
mararm
grass
roots
long
bind
sand
pH  7.5,
more
shelter &
less salt
spray, 5 10m dunes
Vegetation
100% in
places,
shelter
humus, 10m
+ dunes &
wide, more
acid soil
water
table
reaches
the
surface,
wet
(waterlog
ged) &
sheltered,
peaty soil
Several
100m’s
from
shore,
soil for
shrub
trees,
humus