Download Sand Dune Vegetation Succession Methodology

Sand Dune Vegetation Succession Methodology
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Ask students to sit on fore dune.
Show the students the adaptations of sand couch – a pioneer species adapted to arid, wind swept
conditions with few nutrients:
 Can keep pace with sand accumulation
 Sends down deep roots to extract fresh water from salt water
 Curls its leaf around the stomata to prevent moisture loss
 Waxy surface to leaf to prevent water loss
 Spreads by sending out rhizomes
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Ask students to find another pioneer species. Ask them to explain its adaptations.
Explain that the pioneer species are essential for the formation of sand dunes. Without the plants,
the sand would be blown inland and lost. Dunes form an important barrier, protecting the land
from erosion. But the pioneer species sow the seeds of their own destruction. They change the
conditions, (providing more shelter, organic matter and moisture) which allow new species
better adapted to the changing conditions to grow and eventually shade out the pioneer species,
killing it. In fact, sand couch can only grow well in windy locations: it requires a constant
accumulation of sand on top of it to generate growth. Without growth, it becomes moribund and
dies. The dunes are also moving inland, so the inland dunes are older. These changes create a
series of changing vegetation zones across the dunes called SERES.
Ask the students to place 10 poles at the 10 different zones or seres that have been identified
within the dunes. Make sure the chosen transect is away from any path across the dunes.
5.
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Sere 1 (Fore Dune): Sea Medick (low purple rosette), Sand Couch, Sea Bindweed,
Echinophora spinosa
Sere 2 (Dune top): Echinophora spinosa, Sea Holly
Sere 3 (Lee of dune): Echinophora spinosa, Sea Holly, Sea Medick, Maritime
Crosswort, Thymelaea Hirsuta
Sere 4 (between lee and slack): Sea Medick, Maritime Crosswort, Thymelaea Hirsuta,
Sun Spurge
Sere 5 (dune slack): Sea Plantain, Hare’s Tail
Sere 6 (between slack and path): Thymelaea Hirsuta
Sere 7 (close to path): Thymelaea Hirsuta
Sere 8 (bushes): Stone Pine
Sere 9 (gully behind bushes): Asperula cynanchica, Furze, Tamarisk, Sage-leaved
Cistus.
6. Check the location of the poles is correct. Ask the students to justify the location of the poles.
Readjust pole positions as necessary.
7.
All students now use the optimum quadrat size and random numbers method to sample for
vegetation density, vegetation variety, names of dominant and secondary species and % bare
sand at each sere or zone. Explain and demonstrate the method. The random numbers should be
used as the distance in metres to be paced parallel to the pole location. Walk one way or the
other from the pole but be consistent. Students record results on their worksheets.
8.
Other work (divide up):
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2 students: Dune profile using abney level. Record changes in height or the angle in
degrees every 3 metres across the dunes and woodland
2 students: Collecting soil samples (plastic bags) and tube cores (tubes). Make sure all
samples are VERY CLEARLY labelled.
2 students: Wind speed and infiltration rates. Explain the infiltration rates method
clearly. Demonstrate it to the students.
Stone Pine woodland. Measure the girth at chest height of every tree along a transect
through this woodland. Include all trees along the transect or within 3 metres of the
transect line.
9. Collect in and check all equipment.
10. Return to hotel and again check in all equipment.
Equipment with numbers in brackets
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0.25m² quadrats (4)
Ranging Poles (12)
Calibrated pole (1)
Abney level (2)
Anenometer (2)
Measuring tapes (3)
Buckets (2)
Measuring cylinders (2)
Tubes (10)
Plastic bags
Rubber bands
Marker pens
Vegetation identification packs
Paper to mark the poles 1-10
Kit bags (4)
VOCABULARY:
abscission: the dropping or shedding of a leaf
anthocyanin: a water-soluble red to blue plant pigment
carotene: orange-yellow pigment located in the chloroplasts
chlorophyll: green pigment in green plants
chloroplasts: specialized cellular body where photosynthesis occurs
conifer: cone bearing plants
cuticle: waxy covering or layer on outsides of leaves
deciduous: broadleaved woody plants that that drop their leaves in the autumn
epidermis: outer layer of cells of leaves, roots, stems
grana: the stacks of plate-like structures in the chloroplasts
mesophyll: the layer of cells between the upper and lower epidermis
mitochondria: minute cellular bodies where cellular respiration occurs
palisade cells: mesophyll cells directly under upper epidermis
petiole: the stem of the leaf blade
photosynthesis: the plant process by which plants take water and carbon dioxide and form carbohydrates
and oxygen
pigment: any substance that absorbs light, the colour of the pigment coming from the the wavelengths of
light reflected
respiration: the plant process by which plants oxidize carbohydrates for the release of energy
stomata: the pores in the leaf and stem epidermis through which carbon dioxide enters the leaf and water
vapour is lost
xanthophyll: a yellow to colourless photosynthetic plant pigment
Building a Leaf
Let’s look at the structure of a leaf. The epidermis is the “skin” or outer protective layer of cells on a leaf.
The epidermis is covered with a waxy coating. It’s called the cutin or the cuticle. The cuticle may also
contain “hairs” as part of the cuticle. The cuticle keeps the leaf tissues from drying out and protects them
from insects and disease. In many of our shade trees the layer of cutin thickens gradually as the weather
warms in the spring and summer.
Considering that sunlight comes from overhead, where would you expect to find the cells containing the
greatest amounts of chloroplasts in the leaf? You’re right... they’re in a layer of cells just under the top
surface of the leaves. You’ll find the most chloroplasts in the palisade layer of cells just below the upper
epidermis.
Between the layers of epidermis coated with cuticle, is the mesophyll generally composed of two
different types of cells. The layer of cells just beneath the upper epidermis is composed of tightly packed,
elongated palisade cells that contain chloroplasts. It is in the palisade cells that most of the photosynthesis
occurs. Beneath the palisade layer or layers of cells is a loose arrangement of more irregular cells with
space between them. These are part of the spongy mesophyll. Some photosynthesis may occur here too,
but it is also a place where gases are exchanged. Remember that formula for photosynthesis. The palisade
layer and the spongy mesophyll make up the mesophyll.
If there is a place for gas exchange to occur in the spongy mesophyll there must be a place for air to get
into the leaf. Remember that carbon dioxide is required for photosynthesis and oxygen is a product of this
process. The openings in a leaf are called stomata (stoma, singular). They open or close depending on
environmental conditions The opening and closing of the stomata is regulated by the guard cells. Stomata
are closed during hot temperatures, dry weather, and darkness. Water vapor is also lost through the
stomate openings.
Most stomata are on the undersides of leaves. Why do you think that might be? Probably to protect from
excess loss of moisture through leaves, to keep stomata from becoming plugged with dust, and to prevent
easy entry by fungal spores.
Veins running in the mesophyll are part of the tree’s plumbing system. They carry water and nutrients to
the leaves and transport away the photosynthates or the products of photosynthesis. Keep in mind that
these are the tree’s food or chemical energy stored in the form of carbohydrates
Getting Energy from the Food Factories
How does a plant get its stored energy to use for plant processes and the building of other plant
compounds, such as vitamins, fats, and proteins? It’s able to obtain energy by the means of process of
respiration by which a plant uses oxygen to convert the carbohydrate energy into energy and carbon
dioxide and water.
The chemical process of respiration:
Carbohydrates
Oxygen
=
Energy
Carbon Dioxide
Water
stored form of
energy
taken in by
the leaves
=
used for plant
processes
given off by the
leaves
given off by
the leaves
Photosynthetic energy is stored in cells in the form of carbohydrates, starch, fats, and proteins. The is
energy becomes available through the respiration process within the cells. The site of respiration is in the
mitochondria. The released energy is used for other plant processes and the synthesis of plant compounds
needed for growth.