freshwater will not support rooted, submerged plants because there is not enough light for
photosynthesis in the depths.
There will be
micro-organisms and plankton floating in the water.
time, sediments will be transported into the lake (or pond) by streams or rainwater
draining into it from the land. Large amounts of sediment can be deposited in this way.
The water depth will gradually decrease, allowing rooted,
submerged plants, such as starwort and pondweed to grow. Waterlilies, which are rooted,
but with floating leaves may also become established.
Floating plants, such as duckweed, may also be
With the added plant life will also have come a
great variety of invertebrates and fish. The large numbers of different species present
give rise to complex foodwebs.
The vegetation traps and holds more and more of the
incoming sediment, so that the water becomes shallower.
Decomposing dead plant and animal matter provides
food for detritivores and increases the nutrients in the water. This promotes plant
this stage, the water may be too shallow to support fully submerged plants. Instead,
emergent plants,such as Yellow Iris, Branched Bur-reed and reedmace, grow partly in and
partly out of the water.
These plants tend to have tall, flexible
spear-shaped leaves. This allows the plants to cope with large fluctuations in
water level, always retaining some portion of the leaves above the water for effective
The water in swamp areas teems with invertebrate
life. It also provides an ideal place for frogs to spawn.
The leaf bases of the swamp plants are extremely
effective at retaining incoming silt, particularly in the winter when the leaves have died
back (below). Rotting plant material progressively builds up, which also raises the ground
plants which are adapted to grow in partially submerged conditions, will gradually die out
as the marsh floor progressively rises above the water level.
Some plants such as Yellow Iris, which grow equally well in swamp or marsh
conditions, will continue to grow, while marsh plants such as Water Mint, scent the air
with minty aromas when crushed.
These damp areas provide a wonderful transition
habitat for young amphibians such as frogs and toads newly emerged from the water. At this
point they are very small and extremely vulnerable to drying out. The lush wet vegetation
provides an ideal hiding place.
However, their presence will also attract predators
such as Grass Snakes. A Marsh is a good place to spy Grass Snakes (which are not
poisonous!) basking in the sun.
Tree seedlings, such as willow,
which favour wet soil conditions, will become well-established and begin to grow up.
Willow has a very high transpiration rate,
transferring large quantities of water from the sediment into the atmosphere. Together
with the silt-trapping effect of the marsh plants, this greatly increases the rate at
which the marsh dries out.
soil is still wet, but no longer completely waterlogged and anaerobic.
By now, the willow has grown up and dominates the ground.
Willows will support a diverse range of invertebrates (more than 450 different species).
This means that there is plenty of food for insectivorous birds such as Marsh Tits.
(For a list and information on birds surveyed in a
wet woodland area, click here)
Alder, another tree which flourishes in wet conditions
may also be present. Many of the marsh plants will have been shaded out by the trees.
They are replaced by a variety of woodland floor
plants including sedges, rushes, ferns and small flowering herbs which are adapted to low
light levels and which flourish in wet conditions.
A variety of fungi which grow well in wet soils will
also become established. In the more boggy patches of the woodland, the bright orange
fruiting bodies of the fungus, Mitrula
palludosa might be spotted protruding from
the soil like miniature lollipops.
Fruiting Bodies of
In drier areas, increasingly aerobic decomposition
will accelerate nutrient recycling, elevating the humus and nutrient content of the soil.
Tree transpiration will continue to dry out the soil
to the point where climax tree species such as Oak, Beech or Ash can become established.
tree species include Oak, Ash and Beech. They are slow-growing, but because they are also
tall and long-lived, in time, they will come to dominate an area.
The particular climax tree species which eventually dominates
the woodland will depend on soil type and other environmental conditions. In many parts of
Britain, the climax community is likely to be a mixed Oak wood.
The number of species making up the woodland
community is very dependent on the structure of the wood and on how much light gets
through to the woodland floor.
Where the ground is not too heavily shaded, herbs
such as Wood Anemone and Wild Garlic will flourish.
A ground cover of flowering plants and grasses will
ensure that a variety of woodland butterflies are present.
A different range of fungi will inhabit the climax
woodland. Rotting wood provides microhabitats for many different fungi and invertebrates.
The living trees are also hosts for a variety of mycorrhizal
fungi, such as the Fly Agaric, which is associated with birch.
Many mammals will inhabit the woodland from Dormice
(in southern counties of Britain) to squirrel, fox and badger.
The number of different species present in a climax
oak woodland community will run to many thousands.
Continue to Primary Succession
Find out about plant zonation
in wetlands here.
Explore plant adaptations to
life in and out of water here
Wetland Ecological Survey
Find out about woodlands and
their management here.