The deciduous woodland around the bog
included hazel and birch, like now, but then it would
have been very different because large oaks and some
elm trees overshadowed these relatively small trees.
The sheltered woodland environment provided ideal
conditions for ferns like polypody, which often grows
on trees such as oak. This woodland didn’t form
a continuous dense cover because there were also
small numbers of trees which need light to grow, like
rowan, bird cherry and ash.
The fern polypody (Polypodium)
growing on an oak tree © SNH
Hunting and gathering the
woodland produce>
Then around5590 years ago (226cm) elm
disappeared. This happened all over Britain and in
parts of Europe around the same time but we
don’t really understand why. Climate
change, people and disease have been blamed, but
often happens, there may have been more than one
cause. There is no evidence for a change in climate
that could have caused just one tree to disappear
from such a big area, especially when trees that need
warmer and drier conditions carried on growing. This
is why a more selective cause has been suggested:
people and disease could both have targeted elm or
one could have helped the other. For example, people
may have damaged the trees by removing trees or
branches, letting the beetle get through the bark and
into the living wood more easily.
Dutch elm disease killed many elms in
the last century and we know that the beetle which
carries this disease lived in Europe around 5700
years ago, but we don’t know if the fungus that
lives on the beetle and actually causes the disease
was also around.
Elm trees killed by
Dutch Elm Disease © SNH
The elm decline also coincides with the
start of farming in northern Europe– the Neolithic
or new stone age, before metals had been discovered.
We know from archaeological sites that people used to
cut elm leaves to feed their animals over the winter.
But at Greenhead Moss there is no sign
of farming until later, around 5520 years ago (220
cm), so maybe the elm trees around the bog died
from disease. Beneath the skeletons of the dead elm
trees, more hazel trees grew, benefiting from the
increase in light.
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