

Sidmouth Arboretum
Caring for the trees of the Sid Valley

MORE TREES PLANTED
We have been able to continue planting trees.
We planted a disease resistant Elm in Long
Park. The tree was donated by the Tree Council in celebration of the
thirtieth anniversary of the Tree Warden Scheme. We have three Tree
Wardens, Diana East, Simon Pollentine and Ed Dolphin. Like all our team, they
volunteer to keep an eye on local trees, but the Wardens are also consulted by
the Town Council Planning Committee when they consider applications for work on
trees. There was going to be a planting ceremony, but Covid restrictions
limited us to Jon and Graham doing the planting.
We continued planting more of the Devon Whitebeams
from the East Devon AONB. The last of the thirty trees should be planted
by the end of February.
We received a generous gift from local resident
Anne Reece and this has paid for a Sweet Chestnut in Long Park. Along
with the Tree Council Elm, this will grow to fill some of the gap created by
the loss of 9 Ash trees which had to be felled because of Ash Dieback.
We have worked with the SVA and Devon Wildlife
Trust to plant more fruit trees in the Peasland Knapp community orchard and the
Knapp Pond area.
Lastly, we planted a Crab Apple at the Recreation
Ground to commemorate the late Sandy MacFadyen from Sidmouth
Rotary. As Rotary representative for the
environment, Sandy was able over many years to introduce Sidmouth college
students to the benefits of trees. In particular, he worked with
Sidmouth Arboretum and the students to plant hedges around the Salcombe Regis
Recreation Field, where we planted this crab apple tree. It
will enhance the entrance to the Scout House and be a fitting memorial to
Sandy’s great contribution. Later this
year, we hope to be working with Rotary and the College in a Tree for Life
project celebrating the departing year group.
DEVON WHITEBEAM
We have started planting the Devon Whitebeams paid for with a grant from East Devon AONB. The first three saplings were planted at the top of the Delderfield Nature Reserve on Peak Hill.FAMILY TREE
Sidmouth Arboretum has helped to replace a well-loved Family
Tree.
In 1993, EDDC joined with the UK Tree Council to celebrate
National Tree Week by planting Family Trees.
Local multi-generational families were given trees to plant. A Red Oak was planted in the grounds of the
council offices, Knowle. It was planted
by four generations of a local family, headed by Dorothy McGuigan.
Articles about Knowle trees on Facebook prompted Dorothy’s
granddaughter, Sharon MacKay, to contact Sidmouth Arboretum asking about their
tree. Arboretum volunteers did some
research and found that the tree had died.
It was replaced by a new tree planted in memory of a popular council
employee, Jane Cuthbe. The Arboretum agreed to replace the original
tree in a new site.
Family members came together to plant a new Red Oak in the
park of the Knowle last Sunday. Sadly,
Dorothy is no longer with us, and Megan MacKay, the youngest family member at
the original planting, is serving in the army and not able to get away. They were represented by Dorothy’s youngest
daughter, Teresa Cooper, and her husband Rob.
The family was assisted by councillor Kelvin Dent, Chair of
the Knowle Residents Association. KRA volunteers
hope to play an active part in caring for the park and gardens of Knowle when
they pass to the Town Council next year.
HEDGE SURVEY INTERIM REPORT
Hedges 2020 An
Interim Report, June 2020
In 2014 Sidmouth Arboretum undertook a survey of the
valley’s trees, now they are following up that work with a study of the
agricultural hedges.
The 2014 Survey* revealed that, apart from nearly half a
million trees, there are over 500Km (300 miles) of hedges currently enclosing
farmers’ fields in the Sid Valley, and they play an important role in the
valley’s appearance and ecosystems.
Using a computerised geographical information system,
Arboretum chairman Jon Ball made a random selection of 100 fields across the
valley, and then selected one side of each field to be surveyed.
Thank you to the volunteers who have been out estimating the
dimensions of the hedges, their state of maintenance, the presence of standard
trees and the maximum size of those trees, the variety of woody species in the
hedge, and the range of herbaceous plants associated with the hedges. In Devon, the term hedge often refers to a
bank planted with shrubs and trees and many of the hedges in our survey fit
that description, but some do not include the bank. If there is a bank, the height of the hedge
is recorded as the height of the growth, that is what is above the bank.
Summary of Aims
The Hedge Survey has four main aims:
1)
Establish the hedgerow species diversity
2)
Establish the scale of standard trees in our
hedgerows
3)
Estimate the age of hedges
4)
Establish the floral diversity in our hedgerows.
With more than half the sample now surveyed, this is an
interim report on the findings. This
report, being interim, concludes with a brief look ahead and a summary of the
data. The final report will include a
list of action points that need to be addressed if future generations are going
to enjoy the same level of amenity provided by our wonderful hedgescape.
Woody Species Diversity
It is clear that, although this is a small, self-contained
valley, the diversity of form, structure and quality of our hedges is wide,
possibly more so than in areas of intensive farming such as parts of North West
Norfolk.
Some of our hedges are clearly very old, some have been
planted more recently, there will be a separate report, Hedges 2020 Historical
Changes to follow this report. The
differing geology, topography, and history across the valley support a wide
variety of species profiles in the hedges.
Many areas have a mix of Hawthorn and Blackthorn and a good variety of
other woody species. Two thirds of the hedges have more than five woody
species. Some of the hedges in the
larger fields are in distinct sections, perhaps a stretch of Field Maple and
then a stretch of Hawthorn or Blackthorn.
In some cases, this is linked to previous field patterns where the
different stretches used to be in separate fields that are now amalgamated. In other cases, a farmer might have
revitalised a neglected hedge with a new planting where the old hedge had
failed, but they have used a different species.
In some of the upland areas, particularly the areas on
Greensand, Beech predominates in hedges that were planted as the open heath was
enclosed in Victorian times. The fields
to the north of Sid Road from Fortescue to Sidford, although known to be at
least two hundred years old, appear to have been planted more recently and are
made up of Elm mainly. Two thirds of the
hedges surveyed so far are traditional Devon Hedges in that they are planted on
a bank, sometimes just earth, others supported by stone cladding. This includes some of the hedges that have
clearly been replanted comparatively recently.
Many of the hedges are maintained regularly, others have
been neglected for decades and have grown into lines of trees rather than a
hedge, these are known as relict hedges.
Some of the relict hedges were once maintained by the traditional
practice of hedge laying where upright growth is half cut through, laid down,
and branches are woven together to form a stock proof barrier. A small number of the well-maintained hedges
show evidence of having been laid comparatively recently, but the majority are
maintained by tractor mounted flail.
There is a negative correlation between a hedge being left
untended and relict and having a wide range of woody species. There is some
correlation between being sited next to a road and the hedge having multiple
species of woody plant. Whether or not a
hedge is banked does not appear to influence the number of woody species.
Standards
One of the main aims of the study was to establish the
condition of standard trees, trees allowed to grow to maturity spreading their
canopies above the hedge. Standard trees
are very important in the appearance of the valley and to wildlife. Our standards are part of a group known as Trees
Out Of Woods (TOWS). TOWS have ecologic
impacts far beyond the proportion of land they occupy, by increasing the
permeability and habitat value of the whole landscape. **
Of the valley’s estimated tree population of nearly half a
million trees, the survey suggests there are about 38,000 standard trees in our
hedgerows. Often, these standards are
pollards, trees cut off at the height reached by a man with an axe to keep the
new growth out of reach of browsing livestock.
This used to be common practice because the wide spreading crowns
provided shelter for livestock and repeated pollarding, like coppicing,
provided valuable timber for craft and woodfuel.
Modern maintenance by tractor mounted flail means that
maintaining standard trees happens less often now, and the majority of the
standards are the mature trees left by previous generations in the old hedges and
they are coming to the end of their lives, particularly the Ashes, but more on
that later.
Our valley’s hedges still have a good stock of mature
standards, but the tidy, maintained hedges, which make up half the survey
sample so far, have fewer standards per 100m than other hedges. The difference is even more marked when it
comes to young trees that could grow into mature standards in the future, tidy
flailed hedges have far fewer young trees per unit length. One possible action point is to work with
farmers to promote the idea of leaving more of the young trees in the regularly
maintained hedges to grow as standards.
This will involve the farmers in extra work and a good cost benefit
analysis would have to be made.
Dating Hedges
It is true generally
that older hedges have a wider range of woody species in their length. In the 1960s, ecologist and historian Max
Hooper used a wealth of observations and archive evidence to propose a method
of dating hedges which became known as Hooper’s Rule. Dating a hedge is not a precise science and,
with modern farming trends, it is becoming less reliable, but Hooper’s Rule is
still a useful guide. The rule states
that the number of woody species in a 30 yards length of hedge multiplied by
110 gives you the age of the hedge site in centuries. The explanation is that, although hedges are
usually planted as a single species, a Hawthorn or a Field Maple hedge for
example, other species are introduced by natural processes of seed dispersal as
time passes. Saying that a hedge is 500
years old does not mean that is the age of the trees and shrubs currently
making up the hedge, although this might be true for the occasional ancient Oak
standard. It means there has been a
field boundary on this site for that length of time with a succession of trees
and shrubs. Hedge 611N in our survey has
13 woody species in its length. If you
took any 30 yard section, it contains at least 9 of these and so, x110, the
rule suggests there has been a hedge on that site for about 1,000 years, but
the oldest tree in the hedge is an oak that is about 200 years old.
Modern hedge planting often includes multiple species as a
deliberate choice. Sidmouth Arboretum
has planted three hedges in the last year each of which were a mixture of five
species. If a researcher surveyed the
hedge five years from now without knowing the history, and simply applied
Hooper’s Rule, they would conclude the hedge had been in place for 550
years. In the case of 611N, there is
other evidence that backs up the conclusion about the age of the hedge, but
that will be covered in the separate Historical Changes report.
Hooper’s Rule may have some problems, but it is certainly
true that ancient hedge sites, as with ancient forests, tend to have more woody
species than younger hedge sites and this diversity is considered a good thing
from an environmental point of view.
Herbaceous Diversity
There is a strong correlation between the hedges in the
valley with many woody species and a diverse herbaceous storey underneath.
Where hedges are associated with a rich variety of
herbaceous species this provides a good base for a food chain that will support
many types of invertebrates, and small vertebrates, particularly birds and
small mammals. See above for a list of
herbaceous plants recorded so far. Some
names are generic and cover a number of species, for example more than one type
of Buttercup was found, but the list was a secondary purpose of the survey and
received less attention during recording.
Also, the visible species change during the year, some of the sites were
surveyed before summer plants emerged and others were surveyed after early
spring plants had died back. It is
beyond the scope of this study to record the myriad species of invertebrates
that live in the hedges.
Nineteen of the 59 hedges surveyed so far were rated as
having a good range of herbaceous species, 24 were medium, and 16 were poor. The distribution of good and poor diversity
was not even across all hedge conformations.
Possibly contrary to some expectations, the hedges kept
under control with the flail had slightly better diversity in their herbaceous storey
overall, 50% of the hedges surveyed are flailed but they represent 64% of the
hedges rated as good for herbaceous diversity and only 25% of the poor hedges.
However, this is not a straightforward picture because there
is an interaction between management method, structure, and location. Half of the flailed hedges are on a roadside
where they have to be kept under control for road safety reasons, and more than
half are banked. Roadside hedges and
banked hedges are more likely to have a very long history and, as might be
expected, they do have a disproportionate share of the good herbaceous
diversity. The widest diversity is found
with the banked hedges on old, quiet lanes such as Harcombe Lane and Milltown
Lane, one of which is flailed and one not.
If you move away from the roadside to the hedges between
fields, 18% of the flailed hedges have good herbaceous diversity compared to
25% of the unflailed hedges. However,
18% of the flailed hedges have poor diversity compared to 40% of the unflailed
hedges. These results are skewed by the
relict banks on the high ground which have grown out as lines of Beech, the
canopy of Beech trees is dense and shades out the herbaceous layer almost
completely. Other flailed hedges are in
arable fields where cultivation, including some spraying, is taken right up to
the hedge. The numbers are too small to
draw firm conclusions, but the overall impression is that flailed hedges can
support a rich and diverse herbaceous storey.
The effect on animal diversity is beyond the scope of this study. Of the two laid hedges, one was rated with
good diversity, the other poor.
The Future
There are clouds on the future horizon that threaten our
trees and hedges. The long-term threat
to the hedges themselves from climate change is unquantified, but there are
serious concerns about the impact of climate change on our standard trees. Standard trees are a key part of the visual
and wildlife value of the hedges. Away
from the upland areas, Ash and Oak standards are the two main species. Many of the standards are succumbing to age
and there is a potential threat to the Oaks from a disease called Sudden Oak
Death, but that threat to our valley’s appearance and biodiversity is much
lower than Ash Die Back.
The 2014 Tree Survey revealed that Ash is the dominant
deciduous tree in the valley. Ash trees
are 10.7% of the tree population and provide 18% of the total leaf area. Their importance is even more significant
because they support much more of our local biodiversity than the larch and
Douglas Fir which are the most numerous trees.
To lose our Ash trees will be as devastating to the landscape and
ecology of the valley as Dutch Elm Disease was several decades ago across
southern England.
Ash Die Back is a fungal disease that spread from Asia where
the native Ash species have evolved resistance to its effects, our trees do not
enjoy that resistance. The fungus
invades and blocks the water transport xylem of the tree and eventually the
tree dies. As was said, Ash is the
dominant broadleaf tree in the valley and, as a native tree, it supports a wide
range of other species. The loss of most
of our mature Ash trees and the loss of young trees to succeed the old trees
will not only affect the landscape, but the valley’s invertebrate biodiversity
with a knock-on effect on vertebrates, particularly birds.
The stark numbers are that of the 59 sites surveyed, 50 have
Ash present either as a tree or shrub or both.
Of the sites with Ash present, 30 have signs of Ash Die Back, 14 of them
have evidence of significant infection. It
is not possible to stop Ash Die Back; you cannot inoculate nearly eight
thousand trees, forty thousand if you include the trees in woodland, even if
there was a tree antibiotic. It is
possible that some trees will show resistance and survive to breed new stock,
but that will be a long-term process that I will not see. The outlook for the next few years is not
promising.
To conclude, the overall picture is that our hedges are in a
fairly good state, with the exception of the younger but now relict ones on the
high ground. There is good diversity in
hedge type and the natural biodiversity they support. Things could be improved further with the
help of farmers committed to our aims. Action
needs to be taken to allow standard trees to be replaced if we want the
appearance of the valley to be maintained, but the replacements will have to
take account of climate change and tree pathogens.
We await the data from the remaining hedges to be surveyed
which may or may not cause major changes to these observations. The data
present a springboard into other investigations to explore particular aspects
of our wonderful network of hedges. A full
report will be published when we have all the data.
Ed Dolphin, with thanks to all the volunteer surveyors, and
to Jon Ball and Diana East for their help with editing this report.
*2014 Survey http://sidmoutharboretum.org.uk/documents/tree_survey_report_v6.pdf
** Trees Outside Woods https://www.woodlandtrust.org.uk/media/1821/trees-outside-woods-ecological-value.pdf
Further reading about Hedges and Hedges
Hedgelink UK http://www.hedgelink.org.uk/index.php?page=16
Devon Hedge Group http://www.devon.gov.uk/devon_hedges
Blackdown Hills Hedge Association http://bhha.info/
Natural England http://www.cfeonline.org.uk/hedge-trees/
FREE TREES SUCCESS
A big thank you to The Woodland Trust and Devon Wildlife Trust who supplied the 300 free trees for today's event. Also we are very grateful to the staff at King's Garden Centre for allowing us to use their premises, and for organising the car parking as so many people turned up. The biggest thank you has to go to you, members of the public of Sidmouth who have taken on the trees to grow in your gardens, the valley will be a better place because of your efforts. We are sorry that demand out-stripped supply, if you missed out, DWT are running several more events around Devon, the next one is at Seaton Jurassic next Tuesday, details are on their website https://www.devonwildlifetrust.org/what-we-do/our-projects/saving-devons-treescapes
Contact Sidmouth Arboretum at:
infoAATTsidmoutharboretumDDOOTTorgDDOOTTuk
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