|Woodlands are habitats where trees
are the dominant plant form. The individual tree canopies often overlap and
interlink to form a more or less continuous canopy, shading the ground to varying degrees.
However, woods are not just trees! They usually also contain
a great variety of other plants depending on the amount of light available under the tree
Look closely within a woodland and you will find that it is
seething with enormous biodiversity (variety of life). The species present are all
interacting in relationships which are often staggeringly complex.
||The plants in a woodland will
all host a variety of animal life. Oak trees alone, will support an amazing 400+ different
invertebrate species, although not of course, necessarily all on one tree!
A tree's value for animal life does not end with the death of the tree. Even such a
seemingly mundane habitat as rotting wood, hosts about 1,700 different kinds of
invertebrates in Britain.
bacteria are an often overlooked component of woodlands. They are vital for recycling dead
material into reusable nutrients to fuel new plant growth.
What is a
|There are many different types of woodland.
||Coniferous woods are made up of trees often
having needle- shaped leaves, such as the well-known Christmas tree. Conifers also have
their seeds in
||Broadleaf woodlands are composed of trees with
flat leaves, such as Oak and Beech.
Within these broad categories there are many
different kinds of woodland, depending on the dominant tree species making up the wood.
Woodlands also vary depending on how long they have been
established. In Britain, 'Ancient' woodlands
are designated as those which have been continuously wooded since at least 1600 AD.
Ancient woodlands may contain substantially different species
and greater biodiversity than newer woods. This is because old
trees tend to have greater biodiversity value than young ones. Continuity of wooded
cover also favours species which are slow to colonize, or poorly dispersed.
The presence of certain species can indicate ancient woodland
|The plant species in a woodland tend to
grow at various different heights within the wood. This will depend on their growth form
(tree, shrub or herb) and degree of tolerance to shading.
This often leads to the development of several distinct
layers of vegetation within a wood. The dominant trees form the tallest layer. Under this,
there may be shorter, shade tolerant trees and shrubs making up an understorey layer.
Where herbs and grasses grow, they form a field layer. There may also be a ground layer of
plants such as mosses and lichens.
Trees in a wood provide food and microhabitats
for a variety of different invertebrates. The other plants are no less important. The
caterpillars of many of the woodland butterflies feed on the grasses and herbs on the
woodland floor rather than on the trees themselves. If there is insufficient light for
this field layer to develop, the butterflies will be eliminated.
A wide range of plants within a woodland
will provide a seasonal variety of flowers, fruits and seeds to feed animals such
as insects and mammals.
Value of Tree
Species for Invertebrates
Woodlands are actively managed
for a number of reasons. These include maximizing the yield of economically important
products such as timber and game, as well as for conservation and biodiversity. Recreational
access is also becoming increasingly important.
A woodland may be managed for one or more of
these reasons. Where woodlands are multipurpose, conflicting management options can often
|Coniferous woods will almost always have
been planted for timber production. This is because conifers grow much faster than
broadleaf trees and can yield crops of timber up to six times faster. Most are made up of
non-native species introduced to improve yields.
Coniferous woodlands have wildlife value as well as timber value. In general
however, their biodiversity will be less than that of broadleaf woodlands such as Oak.
This is because coniferous woods are mostly composed of non-native
tree species and are usually being managed to maximise timber production. However, the
species making up the biodiversity of a coniferous forest are often different to those of
a broadleaf forest.
Woodlands for Biodiversity
Animal diversity is to a great degree controlled
by plant diversity. This is because the plants generally provide the architecture and
structure of a habitat, as well as being the basis of food chains.
Plant diversity in woodlands can be encouraged
by making sure there are a variety of light levels within a woodland from deep shade to
open glades. Planting a variety of native trees will also enhance animal diversity because
native trees support many more invertebrate species.
Different plants also provide structural diversity, offering multitudes of different
microhabitats for other organisms.
Native woodlands in Britain were traditionally managed to
provide a continuous source of wood for firewood and structural materials, such as those
used for hurdle making. This was done by coppicing trees within a woodland in rotation.
Coppicing makes use of the natural
self-regenerating power of trees. The tree is cut close to ground level for its timber,
with the remaining base (stool) left to regenerate naturally. Regeneration takes the form
of multiple shoots, so that coppiced trees have a distinct growth form with several
similar sized trunks.
Where animals such as deer have access to a woodland, they
may eat the regenerating shoots. To prevent this, trees may be pollarded instead of
coppiced - that is cut off at between 2 - 5m above the ground, leaving a permanent trunk
or 'bolling'. This sprouts in the same way as a coppiced 'stool' but out of reach of
Traditionally, only a few of the trees would be cut at any
one time. Cutting would be rotated through the wood. As a result, there would always be
variation in tree age, from mature, through various stages of regeneration.
This rotational cutting had the effect of letting light into
the wood. It also created glades where a diversity of plants could flourish. Along with
the diversity of plants also came a great diversity of associated animals. Traditionally
managed woods are therefore good places to find high biodiversity.
Do you have a woodland to
manage or would like to plant one?