The secret to understanding the ancient woodland cover in northern
Europe and America is to appreciate the relationship between meat on the
hoof, and deciduous woodland. Shortly after the last ice age, enormous
herds of steak rampaged their way across the countryside, ripping,
munching and felling the vegetation in the countryside.
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Vinney Ridge. A large beech tree in New Forest woodland
dominated by beech |
Although European rainfall is higher, as they do in
modern Africa, the northern equivalent of elephants, woolly mammoths,
would have torn down trees, and brought down branches for food. All this
dynamic activity would have had a profound effect on the ecology of
those days. Native Americans saw the importance of this balance, and did
not treat the huge herds of bison that roamed as an unlimited resource
that would continue without some sort of management. Not so the stone
age human equivalent in Europe. Here, bison and grazing animals were
brought to the verge of extinction in prehistoric times through
uncontrolled hunting and lack of management.
It was Franz Vera who, in his ground breaking book
Grazing Ecology and Forest History,
brought to the attention of ecologists the importance of the balance
between grazing and woodland in the northern hemisphere. An
understanding and appreciation of the finest, most natural non man
managed woodland moved from forests in Poland to the British New Forest.
The New Forest consists of a mosaic of habitats which have been created
by herds of grazing animals. These animals create areas of grassland
known locally as lawns. The ancient New Forest woodland contains little
regeneration, a more open shrub layer and a particularly impoverished
ground flora. The tradition in medieval Britain for deer hunting by the
king and his nobles created the New Forest, and the English medieval
deer parks. Since William the Conqueror, the New Forest has been
managed, one way and another primarily as a food resource for grazing
animals.
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South Ocknell Wood
Open canopy oak woodland |
In order to understand the primeval woodland that
dominated northern Europe and America between ice ages, and at the start
of the most recent interglacial period, it is just so important to find
out how it worked as a dynamic entity. It was the late, and great,
woodland ecologist Francis Rose who, in the New Forest studied its
dynamism, and I had the enormous privilege of being associated with him
at that time. With all the grazing, the chances of a tree seedling
surviving either beneath woodland canopy or out in the open was minimal.
Oak was the dominant tree, and had a special relationship with jays. In
the autumn, jays would hunt for acorns, and bury them in safe areas
beneath thorny bushes and scrub. Jays overdid their food resource, and
many of the acorns were never used. These would germinated beneath the
thorny protective layer, and in their early stages, because of the
starch stored in the acorn, they could develop in the low light levels
beneath the thorns. After a few years, the developing sapling would poke
its leaves above the thorny bushes, and further development would occur
in full sunshine. In order to develop new, high canopy woodland, the
level of successful regeneration only needed to be extremely low. Anyone
living beneath a mature oak tree will appreciate the incredible
efficiency of the oak in regeneration. Lawns soon become carpeted with
young seedlings.
Gradually over the years, the few
surviving oak trees develop with the bark of their young trunks
protected from the ring barking of deer by thorny bushes, and eventually
new oak woodland pushes its way into areas of lawn. At this stage, the
thorn bushes degenerate, and a ground flora in the wood having minimal
regeneration and shrub layer beneath a fairly open canopy becomes the
stable vegetation cover for several centuries. The unenclosed, ancient
and ornamental woodland of the New Forest must closely resemble the
primeval woodland before the ascent of man.
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East End Wood. New Forest Oak Woodland.
Note the thorny scrub around the base of the
trees where acorns can germinate |
By and by, the trees become over mature, and
senescent, but not all at once. The canopy becomes more open, grazing
animals remove most, if not all regeneration and the land reverts to
lawn or heathland. In the New Forest where beech has been a native
component of the forest, a beech dominated woodland develops under the
opening canopy of senescent oak. Beech can germinate and develop under
far lower light levels than oak, and its leaves are too acid for the
taste of most earthworms. This results in the development of an acid
soil, giving rise to open heath. Gradually the heathland plants improve
the soil, and the cycle starting with thorny scrub, jays and acorns
starts all over again.
The above can easily be
criticised as over simplistic. Of course it is. Other factors such as
drainage, water levels, slope gradient, the presence of rocks and
cliffs, and the nature of local geology, all would have had a profound
effect on primeval woodland.
One of the great
criticisms of the high levels of grazing in the New Forest has been that
the shrub and herb layers of New Forest woodlands do not develop. It is
well known that woodland inclosed against grazing animals develops
bramble and other important shrubs. The open rides in this inclosed
woodland provides habitat for insects, and especially butterflies that
is impoverished in the open forest. As a result of well grazed, open
woodland, the purple emperor is not a New Forest feature and the high
brown fritillary has been extinct for several decades.
Since
this post is about woodland, I have not mentioned that other vital, and
scarce habitat for which the New Forest is internationally renowned,
namely valley bogs. The New Forest is an assemblage of habitat variety
that has taken centuries to develop. In the New Forest, the balanced
management of grazing animals has resulted in its unique biodiversity.
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Ebernoe Common
An area of low grazing where holly has become dominant |
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Trodd’s Copse, Hampshire
Recent woodland where regeneration is
rampant reducing light levels and biodiversity |
In most of the rest of Britain, woodland consists of
coppice with oak standards, woodland managed for shooting and abandoned
wood pasture. Because in the eighteenth century it became more
profitable to graze animals in enriched, and artificially seeded
pasture, grazing in woodland all but ceased. This has resulted in the
development of woodland with very low light levels, a dense understorey
of regeneration, often by non native species such as sycamore and an
impenetrable thicket of holly, bramble and hawthorn. Flowering plants
and insects survive in woodland rides, but beneath the dense canopy
biodiversity is low. Even more alarming is the fact, pointed out by
Franz Vera that, due to these low light levels, over the next few
hundred years oak will be threatened with extinction as a woodland
component. This is because it cannot develop beyond an early seedling
stage without reasonable light levels. In this dense woodland, the only
grazing animals present are deer. These have the irritating tendency of
ring barking trees, and they are strictly persona non grata to many
conservationists. As a result, much woodland is now fenced against the
only available grazing, and this has produced a fossilised habitat with
low biodiversity and of little use for recreation.
In
the absence of a healthy grazing regime in woodland, an alternative
that could be considered is human recreation. Camping, hide and seek and
dog walking are all activities that should keep regeneration and the
shrub layer in check. Paint ball games, an activity that is perhaps not
considered as politically correct in the countryside as it might be,
could also be considered
as a possibly positive conservation activity.
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