Coppicing is an ancient form of woodland management in which selected trees are periodically cut down right at
the base and then allowed to sprout from the stump and cut again in a few years time. For example, ash is a tree
that grows back readily from stumps by putting out new shoots and may be coppiced every 12 years, starting
when the tree is 12 years old. The persistent stump becomes a
stool from which the tree continually regrows.
This occurs because the dominant terminal shoot (main stem) is removed and the tip of this shoot was producing
plant-hormones (phytohormones) such as indoleacetic acid (IAA) which pass down back along the shoot to
suppress the growth of other buds, which remain dormant. Removing the dominant shoot tip then removes these
growth-suppressiing  hormones and the dormant shoots become active, producing a mass of new shoots. This is
an adaptive response, if a tree loses its main stem, either because of storm damage or because of grazing
herbivores (in the case of a sapling) then it responds by producing more smaller shoots, investing in numbers, in
case one or more of these also gets damaged. (The downside is that it may lose some competitiveness in other
respects since trees tend to produce single stems when competing for light; whilst shade-tolerant shrubs often
produce multiple stems in the first instance).

If we look more closely at this hollow Ash tree, then what can we see? King Alfred's Cakes!

King Alfred's Cakes

These are sporing bodies of the fungus Daldinia concentrica, better knows as King Alfred's Cakes after the legend of King Alfred hiding whilst on the run from the Vikings and asked by an old woman to keep an eye on her cakes baking by the fire, but distracted by his problems he accidentally let the cakes burn! Initially covered by a red dust of spores, but appearing blacker once the spores have washed off, the internal structure of these sporing bodies consist of visible concentric layers (hence the Latin name). This fungus prefers to grow on Ash but can also be found on other deciduous trees. It is an ascomycete (see Fungi).

King Alfred's Cakes

King Alfred's Cakes

Ash stool

Below, a tree which is coppiced, or otherwise cut-back to the base will regenerate by growing a series of stems.

Coppiced trees tend to live longer (producing a single main stem eventually produces growth problems as only
the outermost layers of wood in a tree conduct water up the stem and so a new layer of wood needs to be added
each year and eventually the trunk becomes too wide for the tree to accomplish this). Ash stools over one
thousand years old are known and the limit of the lifespan of such a stool is unknown.

Not all trees can be coppiced. Most conifers, such as pine trees, and many other trees, die when cut back to the
base. Ash and oak respond well and usually grow new shoots, called spring shoots. Elm does not produce a
stool but will grow back by means of
suckers. Suckers are underground roots which grow up to the surface and
emerge as new shoots. Many plants produce suckers naturally as a means of
asexual reproduction. This
produces groups of genetically identical trees (identical apart from mutations and the like) called a
clone. In
Britain, the modern climate did not particularly favour elm and the tree rarely reproduces by seed, but
reproduces by
suckering (producing suckers). This is likely one reason why the tree succumbed so readily to
Dutch Elm disease (a fungal disease spread by the larvae of wood-boring beetles) as most of the trees were
genetically identical and so if one was susceptible, most would be. Indeed, typically each locality was dominated
by one or a few clones. (This may also have resulted from regeneration of the population from fewer individuals,
perhaps after felling, something which actually favours asexual reproduction). Nevertheless, prior to outbreak of
Dutch Elm's disease, the English Elm dominated the English countryside, but does so no more. Trees may hang
on for many centuries when climates become unfavourable, perhaps long enough for the climate to become
favourable once more. Elms still survive as young trees regenerating from the suckers of old infected trees, but
once the stems become mature enough they succumb to beetle attack and fungal disease again. However, it is
thought that the trees are becoming more resistant and the fungus less virulent. Often pathogens are at their
most deadly when they spread to a new population that has no acquired resistance, but killing off too many of
one's host does not benefit parasites in the long run, so there is pressure on them to become less virulent
(though there are exceptions, but that is another story).

Coppicing was done to provide lots of spring shoots of a convenient size for use as fuel and for weaving. Wood
obtained from coppicing is called
underwood. A coppiced woodland is also called a copse (a word which may
be used to refer to any small woodland or group of trees these days).

Pollarding is a similar practice, but involved cutting the tree back only to 2-3 metres (6 - 10 feet) above the
ground, leaving a base stem from which the tree could regenerate. This is harder to do, and was only done in
areas where grazing, such as by sheep, would destroy the new shoots growing back from a stool at ground level.
Pollarding put the new shoots out of the reach of most grazers. Pollards are similarly long-lived and the oldest
oaks may well be pollards (although oak naturally has a very long lifespan anyway). The pollard respomnds
much like the coppice - putting out many new shoots, that if left (such as when pollarding ceases) can become
quite aesthetic tangles of 'serpentine' branches (with an eerie look about them). More seriously, if these many
shoots are allowed to grow too large, then they may exceed the mechanical limits of the trunk and cause the
trunk to rupture and whole sections of the stem may topple - the tree can become unstable.

Trees left unpollarded and uncoppiced are called
maiden trees. If left alone on so as to produce large straight
trunks to provide building wood called timber (timber is from large trunks) they are called
standards. 'Wood', in a
commercial sense, refers to both timber and underwood.

Woodland management

Although used traditionally to supply important wood, without destroying woodland, coppicing and pollarding are
still carried out today, and are in fact making a comeback. Periodically cutting back trees in this way, in some kind
of rotation, allows more light to reach the woodland floor and encourages woodland flowers, such as bluebells,
and the insect, bird, mammal and reptile populations that prefer such undergrowth. This practice is known as
thinning. Many people complain that such management is unnatural and so ought to be unnecessary, however,
woodland is much more fragmentary than in its natural state. In a large forest there will be natural openings due
to tree fall, but to maintain biodiversity in small clumps of woods requires artificial efforts to recreate the many
different habitats that would occur in equilibrium in a large forest. Wood produced by coppice can also help pay
for the maintenance of woods.

Coppicing and Pollarding