Forestry Journal – August 2019

TREE PLANTING

Native hornbeam

overlooked as an

‘upstairs’ forest tree

As the debate continues over which tree species should be planted

to provide sustainable forests for the future, Dr Terry Mabbett makes

the case for the all-too-often omitted hornbeam.

52 AUGUST 2019 FORESTRYJOURNAL.CO.UK

T

HE all-consuming conundrum is what tree

species to plant to secure resilient forests for the

future – but resilient to what? Climate change

is quoted as the biggest longer-term threat, but

insect pests and pathogens are more immediate

and faster-acting agents that undermine the integrity of

native tree species and semi-natural woodland. Nativity

of trees has generally been paramount in UK broadleaf

tree planting policy and plans, but insect pests

and pathogens, predominantly alien in origin, have

drastically reduced the options for planting native trees

to secure climax stands in future forest and woodland.

Common ash (Fraxinus excelsior) has completely

succumbed to chalara ash dieback in little more than

five years, with the fungal pathogen (Hymenoscyphus

fraxineus) now infecting and killing common ash in all

parts of the country.

English oak (Quercus robur and Quercus petraea) does

not face such an acute, survival-threatening problem

despite the advance of acute oak decline (AOD), caused

by several plant pathogenic bacteria in association

with the oak jewel beetle (Agrilus biguttatus). Oak

processionary moth (OPM) already breeds in every

London borough and all adjoining home counties but has

not yet proved fatal to oak trees in its own right. However,

who is to say what will happen to oak trees weakened

by AOD when OPM spreads into the predominantly oak

woodlands of southern England? While grey squirrels

continue to run amok, landowners will always think twice

about planting common beech (Fagus sylvatica).

Overlooked in all of this is hornbeam (Carpinus

betulus), a member of the birch family (Betulaceae). Not

because of any intrinsic deficit but simply because the

tree has traditionally been cut mostly as coppice. As such,

hornbeam has grown up and evolved into a ‘downstairs’

(understorey) tree or, at best, a ‘mid-storey’ component on

the less-frequent occasions when trees were pollarded.

However, look hard enough and you will find hornbeam

as an ‘upstairs’ woodland tree, uncut, untouched and

growing for several hundred years, striking for light at the

top of the woodland canopy alongside classical climax

trees like oak, ash and beech.

Hertfordshire is hornbeam country. Trees were

traditionally cultivated as coppice and historically

harvested for the hard, dense wood with a calorific value

approaching anthracite. Living in south Hertfordshire, I

don’t have to look far to find ‘upstairs’ hornbeam of an

exceptional age and vintage.

Monken Hadley Common was described by the late

Oliver Rackham as the last authentic two per cent of

Enfield Chase. This unique remnant covers 70 ha on

the northern fringes of the London boroughs of Barnet

and Enfield, close to where they coalesce with the

county of Hertfordshire. 53 ha is classed as semi-natural,

mixed deciduous woodland with open glades, while the

remainder is open grassland planted with native trees.

Enfield Chase was finally enclosed in the late 18th

century. Most of the land was allocated to local parish

councils but the Enfield Chase Act of 1777 ordered

control of Hadley Common to be passed to the trustees

of Monken Hadley Common, who would hold the land in

trust for the ‘commoners’.

However, it appears the commoners were not allowed

into the woodland to cut and coppice hornbeam

for firewood or to allow their livestock to forage on

hornbeam’s succulent spring foliage. Indeed the many

hundreds of Hadley’s hornbeams are standards to the

last tree. Hadley Woods provides a rare opportunity to

Above: The Hadley

hornbeams are

standard to a tree.