from 2.5 to 1.5 and representing average increase in
girth (cm) per year (Mitchell (1974) A Field Guide to the
Trees of Britain and Northern Europe). By using 1.5 as
the dividing number, ages of the biggest trees in Hadley
Woods come in at between 160 and 220 years.
Wokingham (Berkshire) District Veteran Tree
Association’s tree sizing guide says most broadleaf
woodland trees with girths of around 250 cm will come
in at just over 200 years old. For much-faster-growing
common ash, a 330 cm girth tree comes within the same
age range. The much smaller maximum size for sycamore
(165 cm) fits in with the relatively recent invasion of
Hadley Woods by this naturalised and domiciled tree
species.
HORNBEAM – SEEDLING REGENERATION
Mature standard hornbeam casts a dense shade offering
little opportunity for regeneration of seedling trees,
whether hornbeam or other tree species. This was
certainly the situation under the unbroken hornbeam
canopy, where light levels reaching the woodland floor
were very low, with correspondingly poor tree seedling
regeneration. However, the area featured a number of
failed hornbeam trees, all of which were windblown.
The woodland canopy had been opened at various
points across the area and for varying periods of time,
from just a few months to 10 years or more. Regeneration
of the various tree species was well underway, with young
trees at different stages of growth and development,
and crucially of different heights, depending
on when the light-facilitating hornbeam
had failed, thus offering an opportunity
to gain an insight to species
succession.
Seedling tree regeneration
across the site was assessed
using 1 m square quadrats and
counting the number of seedling
and sapling trees according
to species. Each seedling/
sapling tree was assigned to a
specific height range category,
with the range of categories being
appropriate to the overall stage of
seedling/sapling growth within the
sampled area. A summary of the areas and
findings are as follows:
- Under a closed canopy with low light levels where
there was some seedling germination but no evidence of
sustained seedling regeneration: hornbeam and ash were
in the majority with a scattering of sycamore and holly.
Seedlings were small, sickly and not progressing beyond
this stage. - Around a recently windblown hornbeam tree which
had opened up the canopy just months before: Early stage
regeneration with all seedlings less than 10 cm in height.
Majority of the 98 seedlings were hornbeam, with 23 ash
and 19 sycamore seedlings. - Within several established open spaces created by
hornbeam trees windblown over the previous five years:
Fewer trees but a wider range of species with some ash
and sycamore tree seedlings exceeding 100 cm height.
Of the 139 trees counted in two quadrats, 58 were ash
followed closely by hornbeam on 55 and sycamore on 16.
Other species present but in very small numbers were
holly, hawthorn and elder.
54 AUGUST 2019 FORESTRYJOURNAL.CO.UK
- Inside well-established
open spaces created by trees
windblown at least 10 years
previously and where sycamore and
ash had completely taken over with
saplings of 2 m or more:
This snapshot of tree species succession
does indicate that when up against much
faster-growing and aggressive species like common
ash and sycamore, hornbeam may struggle to regenerate.
NO APPARENT OBSTACLES FOR HORNBEAM
Despite its long-standing reputation as an understorey
tree, hornbeam should be seriously considered for
planting and culture as a standard high-forest tree. There
are no identifiable potential disasters from insect pests
and pathogens waiting in the wings for hornbeam.
Its credentials for combatting climate change,
including warmer and drier growing conditions, appear
encouraging. Together with beech, hornbeam was one
of the last tree species to cross the land bridge which
once connected the British Isles with the rest of Europe.
As such, it should be in a better position than most to
withstand any future climate warming in the UK. This
calculation is supported by the natural distribution of
Carpinus betulus, which extends right across Europe,
through the Balkans and well into western Asia.Above left: Old standard
hornbeams in Hadley
Woods are surprisingly
straight.Above right: One of
the biggest hornbeams
found in Hadley Woods.
The tree came in with a
CBH of 230 cm and an
estimated age of 200
years.Left: Hornbeam was
traditionally grown and
cut as coppice (shown
here in Essex), hence its
long-standing reputation
as a ‘downstairs’ (under-
storey) woodland tree.Left inset: Hornbeam
trees in Hadley Woods
are prolific seed
producers, but the
species struggles to
regenerate alongside
faster-growing and more
aggressive common ash
and sycamore.TREE PLANTING