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Conference Report - 2009 - BSBI Spring Conference on alien trees and shrubs, Berwick 59
CONFERENCE REPORT
BSBI Spring Conference on alien trees and shrubs, Berwick-upon­
Tweed, 9 th - 11th May
Rarely has a BSBI meeting been held in such
a grand setting. With chandeliers glittering
overhead in the Guild Hall the President,
Michael Braithwaite, welcomed 86 members
and guests from several local societies and
remarked on the excellent turnout. After a
brief commentary on George Johnston, a
former Mayor of Berwick and founder of the
Berwick Naturalists' Club in 1831, he handed
over to Jane Croft, BSBI Vice-president and
chair of the morning session.
She introduced the first speaker, Jeremy
Ison, who confessed that, although a member
for over 30 years, this was the first time he had
assisted the BSBI on a specific project - a
BSBI report on The status of some alien trees
and shrubs in Britain. The uneven treatment
of alien taxa in the New atlas had prompted the
sending of a questionnaire over the winter
period to all vice-county recorders asking for
such information as: which alien trees and
shrubs were becoming naturalised (not just
planted), what habitats were being colonised
by naturalising species, and for any changes in
patterns of planting.
Results were received from 48 vice-counties
and ofthe 148 taxa included in the survey, 112
were reported to be naturalised somewhere,
and all had regenerated somewhere to some
extent whether vegetatively or by seed.
Amongst the problems, it was noted that
Picea sitchensis (Sitka Spruce) was widely
recorded as having a 'weedy' tendency,
frequently colonising moorland habitats.
Pinus contorta (Lodgepole Pine) regenerated
well in wetter vice-counties. Quercus cerris
(Turkey Oak) and Q. ilex (Holm Oak) were
both reported to be spreading into lowland
heaths in south-west England. Pseudotsuga
menziesii (Douglas Fir) was regenerating well
and becoming naturalised in many southern
vice-counties.
GWYNN ELLlS & MICHAEL BRAITHW AITE
Biomass plantings were not well recorded,
due to the difficulties in visiting sites and in
determining which taxa are involved in the
Salix hybrid plantations.
The species most widely reported as regenerating
were similar to those most widely
reported as naturalised, with the addition of
three of the species that spread vegetatively to
form large patches: Fallopia japonica
(Japanese Knotweed), F. sachalinensis
(Sachalin Knotweed) and Spiraea agg.
One of the main aims of the survey was to
stimulate the study of regeneration of alien
trees and shrubs and it is hoped that this is
indeed the case.
The next speaker was Maggie Magee,
formerly of FW AG, but newly self-employed
as a consultant, who gave a fascinating talk on
species selection and sourcing for farm
woodlands. Farmers have long relied on
native woodlands as a source of timber for
fencing and buildings, but only where grazing
pressure has been greatest have they needed to
look at re-planting woodland - Elm, Ash and
Holly are all readily eaten by sheep.
In the nineteenth century new species of tree
were introduced from foreign parts and many
of these were planted by owners of great
estates and became the mainstay of planted
trees in woodland. We now have semi-natural
woodlands and plantations. Some of the trees
planted were at the whim of the forester in
charge at the time. Blocks of conifers were
planted as shelter-belts, often monocultures of
Sitka Spruce or larches, with (occasionally)
some broad-leaved trees at the margins.
Today, species choice is important, but so is
proper management - woodland needs to be
thinned if an economic timber crop is to be the
end product. A woodland of native species
needs to be planted at random, with Birch,
Hazel and Blackthorn, for example, with no