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OAK/HAZEL WOODLANDS ON THE ISLE OF MAN
Part One: The Natural History of Manx Oak/Hazel Woodlands
Wildflowers of Mann Project 2011
Oak/Hazel Woodlands of
the Isle of Man
Part One: The Natural History of Manx Oak/Hazel
Woodlands
Andree Dubbeldam
Wildflowers of Mann Project Manager Manx Wildlife Trust 7-8 Market Place
Peel Isle of Man
IM51AB
Wildflowers of Mann
A Government partnership project funded by Department of Environment, Food and Agriculture (DEFA), Department of
Infrastructure (DOI), and Department of Economic Development (DED).
Manx Wildlife Trust 2011
The Isle of Man has little remaining woodland. David Allen writing on ‘The Vanished Forests’ in 1956
is particularly tough on our forefathers who harvested timber for house-building, agriculture, fuel,
boats, furniture and implements but ‘never thought to replant a tree’. By the 16th century essentially
all forests had gone from the Manx landscape.
We therefore need to conserve what we have left of our woodland heritage. To that end the first
step is a description of the natural history and an inventory of what we have with detailed
descriptions of site history, maps and surveys of the wildlife contained: for example birds, plants
fungi, and invertebrates.
This is what Andree Dubbeldam of the Wildflowers of Mann Project, supported by the Manx Wildlife
Trust, has done for oak/hazel woodland in this excellent and beautifully illustrated monograph.
Some of these sites are fragments, the largest in Glen Roy covers more than 20ha.
Once we know what remains and the condition and special features of the individual sites, then
conservation efforts can be soundly based - with regular repeat surveys following appropriate
conservation action and education and publicity to underlie and explain the importance of this
heritage to our citizens.
This publication is the first step in rescuing the remaining oak/hazel woodland on the Isle of Man -
a conservation project that will take considerable time and commitment in order that future
generations will enjoy it as we do: as William Morris declared in 1880: ‘We are only custodians for
those that come after us’.
Dr Stephen Jeffcoate, Chairman, Manx Wildlife Trust. 2011
FOREWORD
Page
FOREWORD iii
CONTENTS iv
SUMMARY 1
1 INTRODUCTION 2
2 THE NATURAL HISTORY OF OAK/HAZEL WOODLAND 3
2.1 Why Oak/Hazel woodlands? 3
2.2 Areas Omitted 4
2.2.1 Woodlands without oak and hazel 4
2.2.1.1 The River Neb at St Johns/Tynwald Mills 4
2.2.1.2 Upper Sulby River 4
2.2.2 Alder carr woodland 4
2.2.2.1 Parts of the Central Valley Curragh 4
2.2.2.2 Fragments of alder carr at Cornaa and Port Soderick 4 2.2.3 Planted native woodlands 4 2.3 Which Oak? 4 2.4 Associate/Indicator Species 5 2.4.1 Oak 5 2.4.2 Hazel 5 2.4.3 Hay-scented Buckler-fern 6 2.4.4 Hard Shield-fern 6 2.4.5 Beech Fern 6 2.4.6 Wood Horsetail 6 2.4.7 Wood Vetch 6 2.4.8 Bitter Vetchling 6 2.4.9 Wild Strawberry 6 2.4.10 Spindle 6 2.4.11 Aspen 6 2.4.12 Goat Willow 7 2.4.13 Woodruff 7 2.4.14 Wood Speedwell 7 2.4.15 Common Cow-wheat 7 2.4.16 Marsh Hawksbeard 7 2.4.17 Hawkweeds 7 2.4.18 Sanicle 7 2.4.19 Hairy Woodrush 8 2.4.20 Remote Sedge 8 2.4.21 Wood Sedge 8 2.4.22 Smooth Stalked Sedge 8 2.4.23 Pale Sedge 8 2.4.24 Wood Melick 8 2.4.25 Wood Fescue 8 2.4.26 Wood Meadow-grass 8 2.4.27 Extinct Species 8 2.5 Flavour Species 8 2.6 Invasive Non-natives 9 2.6.1 Beech 9 2.6.2 Japanese Knotweed 9 2.6.3 Cherry Laurel 9 2.6.4 Rhododendron 9 2.6.5 Fuchsia 10 2.6.6 Salmonberry 10 2.6.7 Himalayan Balsam 10 2.6.8 Pyrenean Valarian 10 2.6.9 Hybrid Bluebell 10 2.8 Veteran Trees 10 2.9 Wych Elm 11 2.10 Natural Processes 11 2.11 Geography 12 3 THE SURVEY 13
CONTENTS
3 THE SURVEY 13 3.1 The Preliminary Survey 13
3.2 The New Flora of The Isle of Man 13 3.3 The Vascular Plant Survey 13 3.4 The Mollusc Survey 14 3.5 Historic Maps 14 3.5.1 Elfin Glen in a 1869 Historic Context 16 3.4.2 Glen Maye in a 1869 Historic Context 17 4 DISCUSSION 18 4.1 The Survey 18 4.2 The Sites 18 4.2.1 Tier 1 Sites 18 4.2.2 Tier 2 Sites 19 4.2.3 Tier 3 Sites 19 4.3 Further Research 20 4.4 The Future of Oak/Hazel Woodlands 20 5 CONCLUSIONS 21 6 ACKNOWLEDGEMENTS 22 7 REFERENCES 23
Appendix I National Vegetation Class Woodland Types in Oak/Hazel Woodlands 24
W i l d f l o w e r s o f M a n n P r o j e c t
Page 1
Oak/hazel woodlands are the Island’s ancient woodland resource. They are the irreplaceable natural capital
that contains the most important woodland biodiversity on the Isle of Man.
In this study thirty sites have been identified as probably native oak and or hazel woodland from tiny
fragments of less than 0.1ha at Ohio plantation to Glen Roy which covers over 20ha. The total resource is over
127ha. Sites are found around much of the Island, but are concentrated on the north and eastern edge of the
Northern Hills, where they generally form narrow ravine woodlands between 50 and 150m in altitude.
The sites are in various
conditions from the pristine
semi-natural woodland in
Narradale through to heavily
replanted sites such as
Groudle and Glen Maye, which
while somewhat diminished,
still contain significant
conservation value. Many rare
and protected species, such
as beech fern and wood
fescue, are found wholly or
mostly within these sites. The
study looked primarily at the
flora of the woodlands to
make assessments of their
relative importance, but Dr
Keith Alexander, an
entomological consultant was
contracted to look at
woodland slug and snail fauna
to corroborate findings from
the floral surveys.
This is the first part of a two
part study. The second part is
an inventory of the sites studied.
SUMMARY
Downy birch at Glen Killey
W i l d f l o w e r s o f M a n n P r o j e c t
Page 2
Relic oak stands have long been known to occur on the Island
with ecologists such as Larch Garrad (1972) and David E Allen
(1984) associating these relic woodlands with species such as
sanicle. In a British context the association of relic ‘ancient
semi-natural woodland’ with rich biodiversity has been
academically established since the 1970’s by noted ecologists
such as Oliver Rackham (1976) and George Peterken (1981)
and since then the study of ancient woodlands has taken off
with gusto. Now ‘ancient’ is the popular benchmark for an
ecologically interesting woodland, with the term recognised in
British planning law and in many aspects of countryside policy.
On the Isle of Man, ancient woodlands have until now avoided
an in depth study, probably due to the perception that the
resource is not extensive enough to warrant closer inspection,
though interest in native woodlands, particularly planting new
ones has been strong for some time, championed by
individuals such as Andrew Millichap and the ‘Native Oak
Group’.
Interest from the Wildflowers of Mann Project began in
earnest in 2008 with surveys for the Project’s ‘Rare Species
Action Plans’, which aimed to identify the most rare species
under threat from Island extinction and put in place action
plans to ensure their survival. As many of these species
occurred in woodlands a thorough survey was required to
establish their status on the Island.
It soon became apparent that the current level of woodland
natural history knowledge did not reflect the biodiversity on
the ground, with even the 2006 ‘The Evolution of the Natural
Landscape’, designed to be the standard text on the Island’s
geology and natural history, giving ancient woodland hardly a
mention. While some woodlands such as Narradale, Dhoon,
Glen Maye and Santon Gorge have been repeatedly
highlighted as of interest, other sites of equal interest such as
Groudle, Glen Roy, Brookdale and the Ramsey Glens had not
been identified as of importance. A limited study as part of a
PhD project by Rob Bohan, published in 1998, led to
interesting conclusions based upon historic maps, but was only
supplemented by limited field work. Never the less, the
conclusions reached about the antiquity of sites such as Glen
Roy and Santon Gorge are largely confirmed by this study.
The state of woodlands on the Isle of Man today is extremely
interesting, as semi-natural woodland are continuing a
century-long trend towards rapid natural expansion up
riversides, into marshes and along steep upland fringe areas.
The area of semi-natural woodland is greater now than for
probably a millennium, and yet the flora of ancient woodland
relics is showing a reversal of fortune and would appear to be
in decline, with species such as field rose, hairy brome and
three-nerved sandwort probably now extinct on the Island, the
last two disappearing in the last decade.
This study aims to quantify the resource, by surveying,
mapping and producing an inventory to look at its significance,
through vascular plant and invertebrate surveys to compare
sites against each other and put them in a British context. The
survey will aim to bring to attention the importance of our relic
woodlands as part of the Island’s natural capital. With
recognition should come action to manage these sites with the
protection of biodiversity the priority.
It is hoped that this report will be of interest to professional
ecologists, foresters, decision makers and to lay readers
improving their local knowledge of the Island’s natural history.
With this wide audience in mind the use of Latin names and
technical jargon has been avoided wherever possible. The
classification of woodland types into National Vegetation
classification codes such as W7 or W17 (a standard shorthand
to describe different plant communities) is unavoidable in the
document for reasons of space, but a full explanation of the
codes is given in Appendix I. Readers not familiar with
National Vegetation Classification are advised to read this
appendix prior to reading the remainder of this document.
NB where latin names are used they are in italics and the
names used are taken from Stace 3rd edition
1 INTRODUCTION
W i l d f l o w e r s o f M a n n P r o j e c t
Page 3
2.1 Why Oak/Hazel woodlands?
This study started as a study of ancient woodlands on the
Island using the presence of oak and hazel as the prime
indicators for their presence. This was a good premise for
such a study as preliminary surveys soon revealed; where
good stands of oak and hazel grow together a suite of other
‘indicators’ are sure to be present such as sanicle and hairy
woodrush. It was soon apparent however that an ‘ancient’ tag
was not academically defensible due to the lack of historical
map evidence. Early 19th Century maps recorded oak and
plantations rather well, but large stands of hazel were often
conspicuously absent. This was either because hazel coppice
was not treated as woodland or that these trees were planted,
which was rather unlikely given the number of woodland
species present in these woodlands now.
The nature of the woodlands is also quite different to much of
lowland Great Britain with dynamic boundaries that contract
and expand over time, thus parts may be ancient and others
rather more recent. In most ravine sites where soils have
never been modified, old semi-natural secondary woodland is
indistinguishable from an ancient one, especially if indicator
species such as sanicle and remote sedge have colonised.
Oak/hazel woodlands should therefore encompass the sites
that would be classed as ‘ancient woodlands’ as well as the
bio-diverse areas adjacent to these sites. As the primary
purpose of an ancient woodland classification is to indicate
areas of native biodiversity, a local ‘oak/hazel’ classification
serves the same purpose.
Oak/hazel woodlands are not necessarily those that are
dominated by these two species, but those woodlands where
they are present, (sometimes just oak or hazel on their own).
In some cases such as Brookdale, oak and hazel are present in
90% of the site, whereas in Glen Helen, the proportion is
probably little more that 10%. The survey attempted to
differentiate those woodlands where oak and hazel are clearly
planted and those where these species are semi-natural. This
is not always easy, especially with oak which was planted
commonly in the 19th Century. As many of these plantings
were then cut down in the First World War, they subsequently
re-sprouted from the cut stumps and now look like overgrown
ancient coppice woodlands, unfortunately they are impossible
to tell apart from true ancient coppice. Sites such as Glen
Tramman and Glen Killey may well be predominantly of
planted origin. Ballaglass Glen contains a rare example of an
early 19th Century oak stand that was not felled in the 20th
Century. In this case it is adjacent to hazel and oak that would
appear to be of ancient origin thus much of the site is now
treated as oak/hazel woodland.
20th Century plantings of oak and hazel such as those in the
western part of Glen Auldyn (SC422929) still grow with a
conifer nurse and so are definitively of plantation origin and
not included.
2 THE NATURAL HISTORY OF OAK/HAZEL WOODLANDS
Mature hazel at Brookdale
Planted Beech at Glen Helen
W i l d f l o w e r s o f M a n n P r o j e c t
Page 4
2.2 Areas Omitted
Sites were identified during the initial recce survey by a
mixture of local knowledge and speculative pedestrian
investigations of ravine sites. Thirty sites were identified
across the Island with some of the less likely sites only found
due to gratefully received tip-offs. There are bound to be
some small sites in private ownership that have not been
identified.
2.2.1 Woodlands Without Oak and Hazel. With the scope
of the survey being restricted to oak/hazel woodlands there
may also be relic sites of ash and elm that are not picked up
and unless they come with accompanying indicator species will
probably never be identified. Two likely sites are;
2.2.1.1 The River Neb at St Johns/Tynwald Mills,
where a cluster of interesting species such as sanicle, bitter
vetchling, goat willow, wild strawberry and smooth-stalked
sedge grow with a rich woodland flora. Remote sedge
becomes common towards Peel in the same vicinity. Probably
the largest alder tree on the Island also grows here. A few
sessile oak trees present on the river banks are probably of
planted origin.
2.2.1.2 The Upper Sulby River. While a tiny
fragment of oak/hazel woodland occurs here at Bloc Eary, sites
such as Tholt-y-Will Glen have a surprisingly rich flora for
150m above sea level, with smooth-stalked sedge and wood
anemone. Beech fern was recorded up to Llergyhenny, now
possibly under the Sulby Reservoir and down to Bloc Eary,
where it was found up to 1990’s. Three nerved-sandwort, a
common ancient woodland indicator in Britain, was formally
found lower down the Glen from Ballakerka down to the Sulby
Claddaghs.
2.2.2 Alder Carr woodland. There are also clusters of
species rich alder carr. While much alder carr is a more recent
coloniser of marsh, there are places where it would seem to be
older such as:
2.2.2.1 Parts of the Central Valley Curragh,
particularly around Greeba Castle. Here the woodland is
particularly rich, with some widely scattered hazel and hairy
woodrush as well as marsh hawksbeard.
2.2.2.2 Fragments of Alder Carr at Cornaa and Port
Soderick Glen.
2.2.3 Planted Native Woodlands. The Native Oak Group
have raised tens of thousands of native trees over more than a
decade. Many of these have been planted by Government in
forestry plantations, particularly in ravines such as along the
Colden river. While these plantings will become a wildlife-rich
valuable woodland habitat, they will not be the equal of their
semi-natural cousins.
2.3 Which Oak?
The identification of the species of oak on the Isle of Man is a
difficult problem to solve. There are some trees that are clear
pedunculate oak or sessile oak, but the vast majority are fertile
hybrids. Telling apart hybrids from sessile oak is somewhat
difficult and a number of leaves (from the canopy) are needed
to be looked at to determine the species. Most hybrids are
close to the pure sessile species. Pedunculate oak is
somewhat simpler as its short petioles (leaf stalks) are very
diagnostic. Pedunculate oak is also more likely to be planted,
such as those in Glen Mona, that are clearly planted as a
roadside avenue. The only pure pedunculate oaks that could
be native were found in Elfin Glen and around Ramsey. Pure
sessile types are rather associated with stunted coastal trees
where the soil is skeletal and very dry, and where the plants
are surely native.
The hybrid oak is the common native type found in Scotland
and probably on the Island and is a good indicator that the
plant is native rather than planted, as a planted tree is likely to
be ‘pure’. It may also be a sign of planted trees from locally
collected native trees. While fertile hybrids are often thought
Sulby Glen
W i l d f l o w e r s o f M a n n P r o j e c t
Page 5
of as a corrupted species, in oak it is perfectly normal and
patterns of hybridisation are a part of the local biodiversity.
The Native Oak Group commissioned a genetic study of the
oak from various sites such as Narradale and Glen Tramman,
which showed the genotype belonging to a regional
north-western England type, and therefore likely to be native
to site.
2.4 Associate/Indicator Species
Note: The term ‘indicator’ in this context is rather misapplied as the species mentioned do not
so much indicate biodiversity as are the biodiversity. The term associate species is more
applicable in this situation.
These are the species that set the oak/hazel woodlands apart
from other woodlands, not only plants but also many
invertebrates, lichens and mosses. Most of these species
occasionally occur outside of oak/hazel woodlands but are
more likely to be found in or associated with them. These are
the woodland species that have poor dispersal mechanisms
and are rarely able to survive for long outside of the humidity
and shade of a woodland.
The number of ancient woodland indicator species on the
Island is rather small. In Keith Kirby’s (2004) compilation of
British ancient woodland vascular plants he lists 189 indicator
species. Of these 87 are native to the Island but more
significantly only about 29 have any value as indicators of
ancient woodland on the Island.
The main reason for this is that the Island‘s humid Atlantic
climate allows many woodland plants like wild garlic, primrose
and bluebell to thrive outside of woodlands, with these species
common on sea cliffs, hedge banks and rapidly colonising
secondary woodlands and plantations. Where soils have not
been enriched with chemical fertilisers such as phosphate,
secondary woodlands rapidly develop a rich woodland flora,
deficient in all but the few indicator species of the oak/hazel
woodlands.
Another problem with the use of indicator species is that most
occur in the most species rich W7 and W8/9 communities
which tend to be uncommon on the typical acid Manx slates.
On many of these sites oak and hairy woodrush are the only
plant indicators present, which without more corroborating
indicators makes differentiating planted and native trees
problematical.
The following species are those plants that are to some degree
strongly associated with relic oak/hazel woodlands. They are
all considered ancient woodland indicators in some parts of the
British Isles.
2.4.1 Oak (Quercus sp.). Very obviously a good indicator of
oak/hazel woodland. Native oak also grows as individual trees
in some areas such as the Corrany Valley and Glen Rushen, or
as stunted coastal bushes on sea cliffs. It is however
conspicuous by its absence in the wider countryside on the
Island, occurring neither in secondary woodlands or
hedgerows away from the immediate environment of a relic
oak woodland. The down side to the species as an indicator is
it was occasionally planted in the 19th and to a lesser extent
20th Centuries and it is difficult to tell apart native from
non-native plants as previously discussed.
2.4.2 Hazel (Corylus avallana). As with oak a definer of
oak/hazel woodland and probably less likely to have been
widely planted, though examples may well exist. Garrad
(1972) reports that cobs (a selected type of hazel) were
imported from Holland. Glen Mooar (of Laxey Wheel fame) has
a considerable number of hazel plants with the characteristic
large cob nut and it could be that the hazel woodland here is of
planted origin, indeed in Glen Roy the size of the site and the
density of the planting would have entailed infill planting of
hazel to create the industrial coppice seen here. While this sort
of infill would traditionally have been achieved through
layering native trees on site and collecting local seed, the
nature of landowners wanting to improve the countryside in
this period may have led to the import of young bushes for
planting.
Apparently pure sessile oak on cliffs at Dhoon Glen
W i l d f l o w e r s o f M a n n P r o j e c t
Page 6
Thus planted hazel is a possibility, but as the period of tree
planting gained momentum in the 19th century, the period of
coppice management was being replaced by the era of high
forest management that prevails today, thus the decline of
hazel as a useful species. It remains more likely that most
hazel is of native origin (though quite possibly locally
transplanted within a site). It is also true that hazel is much
more confined to ravines than oak, which is often found on the
flatter flanks of a ravine, where it is more likely to be planted.
2.4.3 Hay-scented Buckler-fern (Dryopteris aemula).
Recently discovered to be rather widespread on sea cliffs in
the south-west of the Island. In the remainder of the Island it
is strongly associated with oak/hazel woodlands, common in
Dhoon and Glen Mona and found in Brookdale and Ballure. A
Schedule 7 Wildlife Act 1990 species.
2.4.4 Hard Shield-fern (Polystichum aculeatum). Rare,
though probably rather under-recorded. Closely linked to
oak/hazel woodlands especially at Glen Roy. It has historically
been found in a few sites outside woodlands in the Douglas
area.
2.4.5 Beech Fern (Phegopteris connectilis). Traditionally
restricted to three districts; Glen Mona and Cornaa, Upper
Sulby Glen and Glen Roy (with a very old record for Glen
Killey). Most sites are by oak/hazel woodlands, though at Sulby
Glen the species appears to have ranged widely in a number of
different sites. Its latest site was at Glen Roy, recorded during
this survey. Attempts to re-find it in Sulby Glen and Glen Mona
have not yielded results. A Schedule 7 Wildlife Act 1990
species.
2.4.6 Wood Horsetail (Equisetium sylvaticum). A species
found in or near several oak/hazel woodlands, though also
found in many ravine sites outside of woodlands and is
particularly common in the Central Valley Curragh.
2.4.7 Wood Vetch (Vicia sylvatica). Only found in Glen Maye
and on a coastal cliff a mile to the north. Once found much
deeper into Glen Maye it is now confined to a few plants above
the river along the cliff section of the site below old hazel
bushes and one plant at the top of the cliff section. A Schedule
7 Wildlife Act 1990 species.
2.4.8 Bitter Vetchling (Lathryus linifolius). Found in several
shaded coastal cliff sites, the species is also found in a few
glens such as Crogga Glen, where it grows down as far as
Soderick Glen, and in Santon Gorge and Narradale. In St
Johns it is found along shaded hedge-banks by the River Neb.
2.4.9 Wild Strawberry (Fragaria vesca). Not really found
within oak/hazel woodlands but often around the outside of
them such as at Narradale, Ballure and Groudle. In Glen Duff
the species is rampant, having spread through much of the old
quarry, and around Silverdale it is equally common in local
hedge-banks. The species is found elsewhere, but is
surprisingly scarce on the Island.
2.4.10 Spindle (Euonymus europaeus). A single plant found
in Santon Gorge. A Schedule 7 Wildlife Act 1990 species.
2.4.11 Aspen (Populus tremula). Perhaps as strongly linked
with riparian areas as ancient woodlands on the Island. Where
it is found within oak/hazel woodland such as at Groudle Glen
and at Glen Roy it would appear to be an integral part of the
relic flora, but in other sites such as Santon Gorge and
Brookdale it is found on the edge of the site and probably only
incidentally related to the oak/hazel flora.
Hay-scented Buckler-fern at Dhoon Glen
Wood Horsetail at Port Soderick Glen
W i l d f l o w e r s o f M a n n P r o j e c t
Page 7
2.4.12 Goat Willow (Salix caprea). The association with
oak/hazel woodlands is rather loose with this species and
mature specimens are rather uncommon on the Island, with
notable ones in Glen Auldyn, Lower Ballig Farm, and
particularly in Glen Roy. While found in other sites, particularly
younger plants, the presence of mature goat willow in
oak/hazel woodlands add an authentic flavour as oak is its
common associate in Britain.
2.4.13 Woodruff (Galium odoratum). Thought of as
non-native in Allen’s 1984 flora, woodruff has now been found
in many oak/hazel woodlands including Ballaglass, Glen Helen,
Brookdale, Glen Roy, Silverdale and Groudle and formally in
Dhoon. Its location in Glen Roy, Silverdale, Brookdale and
Ballaglass are rather close to (but not within) old gardens, so
the species cannot quite shake off its ‘non-native’ stigma, but
the number of woodruff populations in oak/hazel sites is fairly
conclusive. A small clump at the base of a mature oak below
Elfin Glen in someone’s front garden, is perhaps a little more
difficult to pin down, but could be quite a likely relic of a former
more extensive woodland. The species is found in many old
gardens on the Island, but escapes from these are fairly easy
to detect.
2.4.14 Wood Speedwell (Veronica montana). A fairly
reliable woodland Indicator in Britain the species had long
been known from the Lower Narradale area where the species
occurred from below the oak/hazel woodland down to the
Sulby River, where it grows with wood sedge, sanicle and
formally with three-nerved sandwort. The preliminary survey
revealed the species to also occur in Groudle Glen and then the
vascular plant survey found the species to be on the fringes of
Elfin Glen, growing down into an oak parkland suburban site
with remote sedge. A Schedule 7 Wildlife Act 1990 species.
2.4.15 Common Cow-wheat (Melampyrum pratense).
Long found in Narradale the last woodland site for this species
that was formally also found in Dhoon and Groudle Glens. The
species is also still found near the summits of North and South
Barrule. A Schedule 7 Wildlife Act 1990 species.
2.4.16 Marsh Hawksbeard (Crepis paludosa). Long found
in a small area of the Central Curraghs that may well be
ancient alder carr woodland, it is also found in open ground
above the Glen Roy oak/hazel woodland by the Glen Roy
reservoir. Its presence here, by a Victorian reservoir, indicates
it must have colonised from somewhere nearby since the site
was created. This population may well still be found. The only
clear ancient woodland site is at Brookdale where the species
grows in the deep shade of a ravine bottom below an oak
canopy in several locations along the woodland. A Schedule 7
Wildlife Act 1990 species.
2.4.17 Hawkweeds (Hieracium sp). A number of hawkweed
species occur on the Island but two would appear to have
strong relic woodland connections. H. scabricetium occurs only
in Santon Gorge and H. cravoniense only in Tholt-y-will. Other
species listed as under the umbrella classification of H.
vulgatum for the Island may well be separated in future.
2.4.18 Sanicle (Sanicula europaea). The wildflower species
most associated with oak/hazel woodlands, normally growing
where both hazel and oak occur together. Outside of oak/hazel
woodlands the species is found in two locations. One is by the
River Neb in St Johns where just one or two plants grow
together. The area is rich in other indicator species such as
smooth stalked sedge, remote sedge and bitter vetchling, thus
the woodland here may well be ancient in character. The other
site is the Sulby Claddagh, where the species grows with wood
vetch, wood speedwell and (formally) three nerved sandwort.
In many sites the species is rather restricted in distribution
such as at Glen Roy or Glen Maye, but in other sites,
particularly Elfin and Ballure Glens the species is common and
spreading out into secondary woodland. This would often
reflect the public access on these sites, with the species
particularly frequent near paths, where it can be dispersed via
its sticky seeds.
Common cow-wheat at Narradale
W i l d f l o w e r s o f M a n n P r o j e c t
Page 8
2.4.19 Hairy Woodrush (Luzula pilosa). A species with a
curious Island distribution. In the mild, humid southern hills it
abundantly grows in heathland, bracken and even mown
lawns. Despite a reoccurrence on the top of Snaefell, the
species is fairly confined to oak/hazel woodlands in the
remainder of the Island. It is also one of the only indicators to
grow in W17 acid woodland. This makes it a particularly useful
species.
2.4.20 Remote Sedge (Carex remota). Like hairy woodrush
this is a species with two characters. In southern rivers such as
the Silverburn, Colby and Neb Rivers and their tributaries, the
species seems to occur in many secondary woodlands and wet
places. In the north-east however, it is rather restricted to
oak/hazel woodlands like Groudle, Dhoon and Elfin Glens,
though especially in the latter is showing a capacity to migrate
out of its core sites where damp shaded conditions occur
nearby.
2.4.21 Wood Sedge (Carex sylvatica). The dual character of
this species is between native populations in oak/hazel
woodlands and probably-introduced populations around
Douglas, such as Summerhill Glen and the Nunnery. Most
native sites are between Groudle Glen and Narradale. It
reappears in Glen Maye, though only as a few plants.
2.4.22 Smooth Stalked Sedge (Carex laevigata). This
could well be called the ‘glen sedge’ for its close relationship
with glens. While it normally occurs in damp areas of oak/hazel
woodlands it can also be found in mire and alder carr
woodland in glens. It has also been recorded in one flushed
seaside location on the south-west coast which is the only
non-glen site for the species.
2.4.23 Pale Sedge (Carex pallescens). A rare species on the
Island normally found in a few damp lowland meadows in the
Northern Plain of the Island. It is also found on a road verge
emanating alongside Narradale. This may or may-not be a
co-incidence. The species was found in wood-pasture with
smooth stalked and wood sedge at 130m in Glen Roy during
this survey. This is clearly an ancient woodland relic site. A
Schedule 7 Wildlife Act 1990 species.
2.4.24 Wood Melick (Melica uniflora). A species that has
declined remarkably on the Isle of Man, indeed it was
considered extinct on the Island for many years until
discovered in Narradale on the preliminary survey. Of the
many Manx records for the species most are in oak/hazel
woodlands, particularly those that have been replanted with
beech and conifer such as Groudle and Glen Maye. A Schedule
7 Wildlife Act 1990 species.
2.4.25 Wood Fescue (Festuca altissima). Long found at
Dhoon, this woodland species has never been found
elsewhere. A Schedule 7 Wildlife Act 1990 species.
2.4.26 Wood Meadow-grass (Poa nemoralis). Listed in
Allen’s flora (1984) as non native, its presence in hedge-banks
around Glen Roy’s oak/hazel woodland would indicate a native
status for the species.
2.4.27 Extinct Species. Several other woodland species
now thought extinct on the Island may be refound including
hairy brome (Bromopsis ramosa), previously found in Glen
Maye, Silverburn, and Santon Gorge, Three Nerved Sandwort
(Moehringia trinerva) previously found in Sulby Glen and Field
Rose (Rosa arvensis) from Groudle Glen.
2.5 Flavour species. Many other species become more
significant when found within oak/hazel woodlands for what
they say about the vegetation, so pill sedge, goldenrod,
slender St Johns wort and wavy hair grass are distinctive floral
components in dry acid woodlands (W17) while the more
fertile W8/9 is picked out by enchanter’s nightshade, wych
elm and ground ivy. See Appendix 1 for more details.
Pale sedge on the Narradale Conservation Verge
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2.6 Invasive Non-natives
All sites contain non-native species with some capacity for
self-regeneration, but most of these species like sycamore or
pink purslane cause little ecological harm. Many other species
however can be to some extent damaging ecologically in that
they tend to shade out or otherwise out-compete native
species. Control measures for many species are well
researched with plenty of literature available, though for
others such as fuchsia, control will be a site-specific solution.
The list starts with the most damaging.
2.6.1 Beech (Fagus sylvatica). Native to Europe including
southern Britain, this tree species has been widely planted in
most glens and forms large rather magnificent mature trees
which considerably add to the amenity value of many sites.
They have a strong capacity to regenerate under quite shaded
conditions, which they do very well particularly in more acid
and humid conditions. Their strong competitive edge in these
conditions means that the next generation of trees in many
glens or parts thereof will be beech. The down side to this is
that beech casts a very heavy shade and has an acidifying
leaf-litter. The combination of these factors is that the ground
flora is much reduced creating significant and sometimes
widespread biodiversity damage.
As one of the few broadleaves that does not coppice well when
cut down, control of beech is probably easier than for most
invasive exotic species and should be achievable using entirely
mechanical means by cutting saplings down before they
become large ‘valued’ trees. With persistence, beech can be
gradually phased out from oak/hazel woodlands without too
much public concern so long as the mature trees are allowed
to age and die out naturally.
Ballaglass Glen is probably where the species is most prolific
with early 19th and early 20th Century planted cohorts and a
more recent self sown cohort. The mid 20th Century cohort is
most damaging as it was planted beneath the finest oak stand
on the Island, not only do the beech shade out the ground
flora but they will also overtop and eventually crowd out the
nearly 200 year old oak trees as their vigour begins to diminish
with age. Here and in Groudle Glen it may be necessary to
remove some mature trees where they threaten valued native
specimens.
It should be noted that in secondary woodland beech can
make a valuable contribution to the ecology of the site.
2.6.2 Japanese knotweed (Fallopia japonica). A notorious
invasive exotic from the far east and already the subject of
control measures on the Island. The species grows in the same
riparian habitat as most of the rare and notable native
woodland species and can grow vigorous enough to smother
some species. Japanese knotweed generally spreads using
watercourses or humans as a vector for dispersal.
Control in oak/hazel woodlands could be more damaging than
the having the plant however as an indiscriminate overhead
spraying programme could yield significant collateral damage
to the surrounding flora. Fortunately the more targeted direct
injection method is gaining acceptance as a preferred control
method and should be considered best practice in oak/hazel
woodlands. Douglas Corporation and the Water Authority are
trialing this control method on their properties. Biological
control is also being considered for trial.
Glen Maye is the site where this species is most problematic as
it directly competes for habitat with wood vetch along the
watercourse. Hairy brome has already apparently disappeared
from the site where it grew in areas now occupied by
knotweed.
2.6.3 Cherry Laurel (Prunus laurelcerasus) Native to
southern Europe this continues to be widely planted for
amenity reasons. This evergreen shrub spreads vegetatively
by layering its stems along the woodland floor and via its bird
dispersed fruit. By casting a dense shade and being shade
tolerant cherry laurel smothers all ground vegetation and
prevents the natural regeneration of trees. Control is by
cutting down stems and winching out stumps or spraying
re-growth.
Control in parts of Glen Helen has been very successful, indeed
cleared areas have revealed smooth stalked sedge,
reappearing from buried seed.
2.6.4 Rhododendron (Rhododendron ponticum). Similar to
cherry laurel in appearance and in the damage it does to the
ecology of a site, it is not yet a significant problem in oak/hazel
woodlands, though it is present in many, such as Glen Roy and
Dhoon Glen where it is gradually increasing.
Evidence from the rest of the British Isles where the species is
often a significant problem would indicate that early control
would save an expensive problem in future.
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2.6.5 Fuchsia (Fuchsia magellenica). A South American
species, that is well adapted to the cool temperate humid
conditions prevailing on the Island. It is able to tolerate most
soil conditions from waterlogged to skeletal types and is
surprisingly shade tolerant. It is widely planted and rarely
causes any ecological harm. In some conditions it can become
an ecological pest, smothering the ground flora beneath its
layering branches. These conditions are found in Brookdale
where a mixture of windblown trees falling on bushes and a
gravel based stream allow for the rapid layering of the species,
affecting populations of the rare marsh hawksbeard. Fuchsia
is found in many glens and in some it is gradually spreading
along watercourses. In many of these sites it has the potential
for a rapid increase, as has happened at Brookdale.
2.6.6 Salmonberry (Rubus spectabilis) This shrub is
currently only a problem species in Crogga Glen, although it is
also spreading into Glen Roy. This species spreads by seed
with the potential to spread greater distances via birds. Like
most other problem species it is both shade tolerant and
castes a dense shade. Control is either through cutting and
spraying or by pulling out smaller plants.
2.6.7 Himalayan Balsam (Impatiens glandulifera). An
annual Asian species frequently found spreading along
watercourses and wet areas. While very invasive, the
ecological harm done to riparian woodlands is rather minor
and control (hand pulling or spraying) is unlikely to be
successful in the long term. A policy of tolerance is advised.
2.6.8 Pyrenean Valarian (Valeriana pyrenaica). A species
that is locally rampant in Glen Roy sometimes covering many
square metres. This is a wind dispersed herbaceous plant that
can be sprayed or dug out, however complete control would
be very difficult. It would appear to have reached a steady
state in Glen Roy and should it remain at its current abundance
it is probably little cause for concern, but will need to be
monitored.
2.6.9 Hybrid Bluebell (Hyacinthoides x massartiana). This
hybrid between native and Spanish bluebell (Hyacinthoides
hispanica) is common in the wider countryside, but so far
rather limited to the edges of oak/hazel sites where it does
occur. It is likely that over time it will become more frequent as
it hybridizes with the native species further. Little can be done
to stop this process.
2.7 Veteran Trees
Perhaps one of the most significant ecological developments
across Manx woodlands today is the gradual maturing of the
tree population, probably the first time in a millennium that
significant numbers of large mature trees have existed on the
Island. While natural death, wind-blow and human
intervention put a considerable rate of attrition upon trees, a
reasonable proportion of the large tree species (oak, ash, elm,
sycamore, beech and sweet chestnut) are becoming mature
Salmonberries
Rampant fuchsia in Brookdale
Hybrid Bluebell
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and veteran trees. Loosely defined, a veteran tree for an oak
or beech is about a 200 year old tree (they mature at about
120 years), (English Nature 1999). A 300 year old oak or
beech could reasonably be called an ancient tree. Other
species become veterans rather faster, so a 100 year old birch
would be a significant veteran.
A veteran tree will generally support vastly more biodiversity
than a mature tree, which in turn supports more diversity than
a sapling. This happens partly due to the accrual of dependent
species such as lichens and invertebrates over time, but also
as the number of niche habitats such as deadwood, holes and
epiphytic plant species increase.
Many of the sites contain significant populations of veteran
trees. Probably the most important are the stands of maiden
oak trees in Glen Roy and Narradale that are now 200 or more
years old; in Brookdale they are probably well over 150 years
old. The most impressive stand is in Ballaglass with many well
grown trees nearly 200 years old, but probably planted in
origin (though wildlife does not care if a tree is planted or
native!). Mature stands of stunted coppice stools in Lower
Ballabeg (in Baldrine) and Santon Gorge are probably over 200
years old. Glen Maye and Ballaglass likewise have individual
old coppice (200+/-year old) stools. A few stunted coastal oak
trees at sites such as Glen Maye, and particularly at Dhoon are
veterans and possibly ancient (300+years) trees.
Non-oak veteran trees are also common with ash and
sycamore on the fringes of Brookdale particularly notable.
The generation of mid to late Victorian plantings are now
approaching veteran status, particularly plantings of beech in
sites such as Glen Helen, however the shallow-rooted beech
tends to fail before reaching 200 years on most ravine sites.
A veteran tree register does not yet exist for the Isle of Man,
though it is likely that a good proportion of entries would be
within oak/hazel woodlands.
2.8 Wych Elm
Most oak/hazel sites contain some mature wych elm trees,
probably native to site. Given the much diminished nature of
the species in the British Isles due to Dutch elm disease, the
Island’s population is significant, with major concentrations in
native oak/hazel woodland.
2.9 Natural Processes
As important as the biodiversity are the natural processes
within a woodland, indeed the two are closely linked.
Many of the sites looked at showed extremely natural
conditions, which was unexpected for such a small resource.
Natural regeneration of most native species was observed,
including for oak and hazel. Some regeneration was in canopy
gaps but more commonly occurring as advance regeneration
under shade. Most commonly observed was regeneration into
open ground initiating seral succession to woodland. Habitats
becoming colonised include bracken, gorse, bog, marsh and
pasture. In areas such as Glen Roy, Narradale and Santon
Gorge the fringing area of recent semi-natural woodland is
many times the size of the core oak/hazel site.
Fallen trees have allowed large quantities of deadwood to
accumulate in many sites, often in streams where significant
deadwood dams have formed. Indeed in Glen Roy these dams
Veteran oaks in Ballaglass
Deadwood dam in Glen Roy
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have been colonised by sapling trees and appear to be very
long-term features, capturing silt and raising the riverbed by
up to a metre or more.
The deadwood beetle fauna of the Island is thought to be very
poor and it is likely that most other deadwood taxonomical
groups are also impoverished. This probably reflects a history
of woodland management, that persisted probably even in
remote sites, depriving the Island of a continuity of deadwood
habitats. The generous amounts of deadwood currently seen
in many sites may well be the first time this habitat has existed
on the Island in quantity for many centuries.
Many areas of stream continue to gouge the ravines deeper,
with sites such as Brookdale showing evidence from exposed
tree roots of the deepening of the river-bed by over 30cm in
the past century. This in turn has made them vulnerable to
land slips during periods of heavy rain. Brookdale and Glen Roy
contain some of the most interesting recent slips that form
natural glades in dense woodland, with young trees and
wildflowers gradually establishing on the bare ground.
In sites replanted as pleasure grounds in Victorian times, the
process of reversion back to a more semi-natural state is well
underway as that generation of planted trees begins to fail and
a species rich ground flora colonises. Glen Helen has seen
major wind-blow events fell stands of beech to be replaced by
more mixed semi-natural vegetation. The non-native plantings
have however left a legacy of non-native species as described
earlier.
2.10 Geography
As can be seen from the Distribution Map (right), oak/hazel
woodlands are generally found on the upland fringes around
the Island. The main concentration is between Sulby and
Douglas and no sites are found in the south-west (Rushen
Parish) or the northern plain of the Island.
Some sites go down to sea level, but 150m is a fairly consistent
upper limit for oak and hazel with only Glen Killey reaching
160m. The reason for this is unclear as in sheltered sites
broadleaves are able to make reasonable growth up to 200m,
beyond which native broadleaves are rarely little more than
scrub. The most likely explanation is that the most steep, deep
ravines seem to occur at 50-150m, coinciding with the vast
majority of the resource. Above and below this altitude the
ground tends to level out.
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3.1 The Preliminary Survey
This survey was conducted by the author, occasionally with
the help of other interested individuals. Likely sites were
identified from aerial photographs, biological records and
finally speculative hunting in ravines around the Island. Much
of the work was as part of ‘Rare Species Action Plans’, with
later work continuing to early 2011 for the specific benefit of
this report.
The National Glens were looked at first and it was here it soon
became apparent that sites with the presence of oak and or
hazel were of significantly greater botanical interest than those
without. Hairy woodrush was one of the most useful species,
almost always occurring in the footprint of native hazel or oak,
and as an evergreen, allowed for a long season of recce
surveys.
Preliminary surveys noted the presence of oak and or hazel in
sites and looked for a few other key indicators and rarities to
give an impression of the ecological interest of sites.
Crawford’s (2009) list of Scottish Ancient Woodland Indicators
as well as Kirby’s (2004) list formed the basis of drawing up a
Manx List.
Interesting records obtained in this survey were wood
speedwell in Groudle Glen, wood melick in Narradale and the
rediscovery of wood fescue in Dhoon after several decades
without it being recorded. It is fair to say these finds wetted
the appetite for a more in depth study.
3.2 The New Flora of the Isle of Man
While the recce surveys where taking place another survey
initiated by the Wildflowers of Mann Project was starting. This
survey led by the Wildflowers of Mann Project, the Manx
Wildlife Trust, the Botanical Society of the British Isles, Manx
National Heritage and the Isle of Man Government’s Wildlife
and Conservation Division (now integrated within the
Department of the Environment, Food and Agriculture). This
involved the complete survey of the Island’s flora by a team of
volunteers, a survey still underway.
This wider survey has already given a much clearer picture of
the Island’s flora, including its woodland plants. Pertinent finds
include hitherto unknown colonies of hay-scented buckler fern
on cliffs along the south-west coast, a very wide distribution of
hairy woodrush in the Southern Hills and many more locations
for smooth stalked sedge. The survey has still a few years to
run and will no doubt help our understanding of the Island’s
woodland flora further.
3.3 The Vascular Plant Survey
Conducted in the spring and summer of 2011, this involved a
walkover survey of each site recording all vascular plant
species present. The survey covered the footprint of the
oak/hazel woodlands and their associate species where
clusters of these occurred beyond the oak and hazel trees. As
well as the footprint of the sites, the edge habitat was also
surveyed, as were small glades and rides with in the sites.
Of the 30 identified oak/hazel sites 15 were fully surveyed,
covering all the more interesting sites as well as a selection of
the smaller sites. Surveys took an average of one day per site
depending upon the size and difficulty of terrain.
As anticipated, the survey uncovered several new populations
of Schedule 7 species. Wood speedwell was found next to Elfin
Glen, hay scented buckler fern was found in Brookdale, as was
marsh hawksbeard, the first ancient woodland site for this
species on the Island. Also a first ancient woodland location
was found for pale sedge in Glen Roy. Beech fern was re-found
in Glen Roy and Glen Mona after nearly two decades of the
species not being recorded on the Island. Southern Polypody
(the second Island site after Glen Maye) was found in Santon
Gorge, on the same woodland edge location as the only Island
site for the hawkweed Hieracium scabrisetium and spindle. All
these finds have contributed to giving a clearer picture of the
importance of many of these sites for the Island’s biodiversity.
Not surprisingly the vascular plant survey revealed that the
largest site (Glen Roy) had the greatest species number (195
species). Other much smaller sites such Santon Gorge
recorded impressive totals for sites below 1ha in size. Of
greater interest is the number of associate species found per
site with good sites getting between 8 and 14 species (out of
30). This ‘key species’ list also includes those historically
recorded at the site, but not found in the survey.
In the case of Glen Maye and Santon Gorge the key list
includes the non-woodland but notable species- maidenhair
fern and Southern polypody.
3 THE SURVEY
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3.4 The Mollusc Survey
To increase, depth, reliability and academic validity of the
research it was decided that a corroborating taxa investigation
was desirable.
While lichens and bryophytes are often used in ancient
woodland research (Coppins and Coppins 2002), a history of
coppicing and the mild Atlantic climate could render these taxa
less useful on the Isle of Man. It was decided therefore to
concentrate on an invertebrate group, molluscs, which are
known to have a suite of ancient woodland indicator species.
Dr Keith Alexander, an invertebrate ecologist, was contracted
to survey woodland sites for a week in August 2011. The
survey and background research in museum collections and
biological records, revealed that ancient woodland molluscs
did indeed inhabit most oak/hazel woodland sites. He used a
mixture of sweep-netting, ground searches and the inspection
of leaf-litter under a microscope.
Of the nine species known to be good indicators of British
ancient woodlands, six occur on the Isle of Man and four of
these where found during the survey, and one other (the
plated snail (Spermodea lamellata) was found to have been
previously (1968) recorded in Glen Roy.
The Ash Black Slug (Limax cinereoniger) associated with
old-growth forest was the most important species found. This
was found in Brookdale, one of the sites where it was last
recorded in 1909 (Fern Glen), thus a significant rediscovery.
The species is widespread but uncommon throughout Europe.
Brown snail (Zenobiella subrufescens) was perhaps the
easiest snail to detect as it can be sweep-netted from lush
vegetation such as greater woodrush. It was found in three of
the 8 sites looked at. (Ballure, Narradale and Glen Roy).
The English chrysalis snail (Leiostyla anglica) was found in
Ballure, Elfin Glen and Narradale. This species mostly occurs in
leaf litter and under deadwood and debris.
Point Snail (Acicula fusca) was only recorded from Ballure
Glen, (a single specimen), a site that was notable not only for
the greatest number of species, but also the only site where
large numbers of woodland molluscs were found.
While in any survey it is commonly noted that the absence of
evidence is not evidence of absence, this rings particularly true
for this aspect of the oak/hazel woodland survey. Most records
related to just one or two specimens found, with a mixture of
careful searching and good fortune responsible for many finds.
It was noted by Dr Alexander that the survey should be seen
as ‘very much an initial exploration’. The mollusc survey
conclusively shows that ancient woodland molluscs are found
in most good oak/hazel sites on the Island.
3.5 Historic Maps
Looking at historic maps (See Elfin Glen and Glen Maye maps
overleaf) is the most direct way of assessing the historical land
use. The first really reliable map on the Island is the 1869 map,
which has been digitised which allows for easy analysis. In
many places it is very revealing, showing that sites such as
Dhoon Glen, Groudle Glen and Glen Maye had a very mixed
picture of woodland coverage with a third of the current
species rich oak/hazel woodland open ground prior to 1869.
Dr Alexander inspecting a sweep-net for brown snail
Ash-black slug in Brookdale
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Most sites did show that they were predominately woodland
however, with even small sites such as Ohio showing tree
cover. The wider picture shows that the Island was already
well wooded by this time with estate plantations common and
already obscuring the distribution of relic oak/hazel
woodlands. This makes any historical analysis of sites such as
Glen Tramman, Glen Duff, Glen Helen and Glen Killey
impossible with these maps. This is particularly frustrating as
these are the most difficult sites to ecologically interpret on the
ground. In some areas, such as Glen Roy, the reproduction
quality of the map was too poor to assess the woodland cover.
Two very small sites (Colby Glen and Santon Gorge) did not
show woodland cover, indeed Santon Gorge is not shown as
woodland on the 1929 or the 2009 Ordinance Survey maps.
Further study of historic maps is recommended particularly
older early 19th Century maps.
Table 1 Oak/hazel Sites Ranked by Key Species
Site name Key Plant
Species
Protected
Species*
Recorded
Species
Size
(Ha)
Mollusc
Species
Ancient
Woodland
Molluscs **
Woodland
Presence on
1869 Map
Glen Roy 14 2 195 20.0 16 1(2) Not Clear
Groudle Glen 14 3 168 6.0 9 (1) 70%
Dhoon Glen 13 3 146 4.3 ns (1-3) 60%
Ballure Glen 10 2 144 5.2 23 3 (4) 90%
Narradale 10 3 139 5.6 15 2 80%
Glen Maye 9 4 159 4.2 ns (1-3) 50%
Silverburn 9 1 ns 0.9 14 (2) Not Clear
Brookdale 8 2 139 3.6 18 1 90%
Santon Gorge 8 3 157 0.7 4 (1) 0%
Glen Helen 7 0 149 15.0 ns 100%
Elfin Glen 7 1 131 6.0 15 1 100%
Garwick Glen 6 0 ns 1.2 ns 30%
Glen Mona 5 2 ns 9.8 ns 40%
Crogga Glen 5 0 ns 5.0 ns (1) 70%
Ballaglass 5 0 145 5.5 ns (2) 100%
Glen Duff 5 0 ns 2.6 ns 70%
Nut Glen 5 0 79 2.6 ns 80%
Glen Tramman 4 0 ns 10.3 ns 100%
Lower Ballabeg 3 0 ns 1.1 ns 50%
Barnell 3 0 ns 0.2 ns 50%
Block Eary 3 1 ns 0.1 ns 100%
Glen Killey 3 1 74 5.4 ns 100%
Glen Auldyn 3 0 96 2.5 ns 80%
Glen Dhoo 3 0 ns 0.7 ns 70%
Glen Kylley 2 0 ns 0.3 ns 100%
Bishop’s Court 2 0 74 1.3 ns 100%
Glen Mooar (Laxey) 2 0 ns 1.4 ns (1-3) 100%
Skyhill 2 0 69 0.5 ns 50%
Ohio 2 0 ns 0.1 ns 100%
Colby 1 0 ns 0.4 ns 0%
ns=not surveyed *Wildlife Act 1990 Schedule 7 plant species, (not including heath spotted orchid) **Figures in brackets refer to totals including
previously recorded mollusc species. Where a range of numbers is given this indicates unlocalised records most likely in this location.
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3.5.1 Elfin Glen in an 1869 Historic Context
The Elfin Glen 1869 map on
the left clearly shows the oak
hazel area as woodland
present at this time. It also
shows that the species rich
areas where remote sedge,
sanicle and wood speedwell
occur outside of the oak/hazel
woodland were woodland or
tree lined paths 140 years
ago.
At this time much of
Claughbane and Llergy Frissel
plantations had already been
planted, which is apparent
from some of the large
Douglas fir and other large
tree specimens found in the
plantation now.
Not yet present on the map
are the Mountain Road
(Hairpin), Manx Electric
Railway or Ramsey suburbs
which were built during the
following 80 years.
This map shows that the
process of Victorian woodland
creation was well underway
by this time.
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3.5.2 Glen Maye in an 1869 Historic Context
The Glen Maye 1869 map
clearly shows that woodland
only covered about half the
site.
Much of the remainder of the
site is marked open ground
with trees, presumably
woodland pasture, or open
ground around mine
workings. This latter area is
still mostly open ground,
though the woodland pasture
area is now dense
sycamore-dominated
woodland, differentiated from
the older woodland by the lack
of hazel in the understorey
that is very characteristic of
the north half of the site.
The sanicle and hairy
woodrush that is found along
the paths in the southern half
is either a relic of the
woodland pasture or has
spread into this area from the
northern part. The wood
sedge is only found in the
northern part.
The wood vetch, Southern
polypody and (formally) hairy
brome are in an area that was
clearly more open in 1869
than it is now.
Older maps would show if the mine works were woodland prior to mining activities, joining the eastern dense woodland with the
cliff-side hazel on the western side.
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4.1 The Survey
This is the first attempt at a comprehensive survey of the
Island’s ancient woodland resource. Linking ancient
woodlands to the oak/hazel populations has proved to be
valid, with a consistent suite of associate species of plant. The
mollusc survey has corroborated the vascular plant survey
very well and confirms that this is a useful taxonomical group
for the study of Manx ancient woodlands.
While the study has given a good insight into Manx ancient
woodlands its limitations should also be noted. Oak and hazel
have probably been widely planted on the Island over the past
200 years or more. In the case of hazel, planting is most likely
to have been on sites where hazel was already present to
thicken up the density of stools for exploitation of the coppice
products. Oak is more difficult. In some cases such as at
Ballaglass the magnificent oak stand is likely to be of planted
origin, while Narradale and Brookdale are most likely to be
native. In other sites such as Glen Helen and Glen Tramman it
is much more difficult to determine, indeed we will probably
never know and the answer is likely to be that these sites
contain both planted and native trees. There are also many
species rich wet woodlands on the Island that would never
support oak or hazel or many associated species and would
not easily be determined as ancient or recent.
4.2 The Sites
The 30 sites can be ranked into three groups, Tier 1 sites of
significant Island value where most woodland biodiversity is
concentrated, Tier 2 sites containing interesting woodland
species and communities and Tier 3 sites are of historical note,
but little wider biodiversity importance beyond that of a
mature secondary woodland.
4.2.1 Tier 1 Sites. These eight sites are the elite woodland
biodiversity sites. None can be considered above the other as
all have unique attributes not found elsewhere. It is
recommended that the management of these sites would best
be to prioritise the biodiversity above other management
goals.
Prioritising biodiversity essentially means that public access,
recreation, field sports, landscape and timber production are
all secondary in importance to biodiversity and natural
processes, but would normally continue as traditionally
practiced where this does not harm biodiversity. It should be
assumed that these sites are managed towards a semi-natural
vegetation, thus replacing planted exotics such as beech and
conifers with natives as and when they fail. It would also mean
that the natural regeneration of these exotics should be
removed before they can contribute to the canopy. The
non-native sycamore is not practical to replace due to its
capacity for natural regeneration, but does little ecological
harm, so it can be treated as an exception. Replacement is
most desirable by natural regeneration, which can be copious
in ungrazed stands. If this does not occur then planted trees of
native stock should be used.
The control of invasive non-native species such as cherry
laurel should be prioritised in these sites.
Returning some of these sites to traditional hazel coppice with
standards is appropriate where they are not part of the
National Glen network. The sites are a mixture of private and
publicly owned properties and government leadership would
be required to move forward a coherent strategy for the
management of these sites.
The enlargement of these woodland sites would be of great
benefit and in most sites this is happening through natural
regeneration into abandoned farmland. In sites such as Ballure
and Brookdale that are hemmed in by conifer plantation, there
exists the opportunity for significant expansion after clearfell.
While natural regeneration should be the preferred method of
woodland expansion the planting of native oak at very wide
spacing would ensure this species becomes part of the canopy
of the first generation of trees. Natural regeneration will
probably require some cleaning operations to eliminate
concentrations of Sitka spruce, lodgepole pine and beech,
though these species are quite acceptable at low
concentrations.
The production of management plans for these sites should be
a long-term goal that will bring together landowners,
woodland users and ecologists to produce a positive
consensus.
Part ii of this report contains the full site descriptions and
locations.
4 DISCUSSION
W i l d f l o w e r s o f M a n n P r o j e c t
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The Sites:
Glen Roy. The largest site with beech fern and pale sedge
populations. What sets this site apart is that its size and
naturalness give natural processes an opportunity to develop.
Groudle Glen. Heavily replanted and much diminished,
Groudle still has an impressive diversity of flora and niche
habitat types and could be gradually restored to a more
semi-natural state.
Dhoon Glen. The most studied and well known of the
oak/hazel woodlands This ASSI is the only recorded site for
wood fescue on the Island. While heavily replanted in places,
its semi-natural core is intact and remains a biodiversity
hotspot.
Glen Maye. Also an ASSI, little semi-natural woodland
remains in this heavily replanted and somewhat diminished
site, however at its seaward edge it remains extremely species
rich with a large suite of rare flora and fauna.
Santon Gorge. Containing so much in its very small area
including the only Island site for spindle and the British
endemic Hieracium scabricetium, this is a completely unspoilt
fragment of oak/hazel woodland.
Ballure and Elfin Glen complex. Two sites with their
adjoining plantations that are gradually becoming one
ecological unit to form a large significant woodland area with
relic spots penetrating into the suburbs of Ramsey town. While
the sites are heavily replanted in places, the majority of the
glen areas remain ancient semi-natural woodland. They are
identified in this study as the most important woodland
mollusc sites on the Island.
Brookdale. At its core this is an un-spoilt ancient semi-natural
oak/hazel woodland and the site of the rare ash black slug and
marsh hawksbeard. Around its fringes the woodland has many
relic fragments as well as expanding boundaries.
Narradale. Largely un-spoilt semi-natural oak/hazel
woodland with the only Island site for wood melick. Narradale
has long been known as one of the Island’s best relic woodland
sites and has the largest stock of native veteran oak trees on
the Island.
4.2.2 Tier 2 Sites.
These are the sites that contain significant ancient woodland
characteristics and can be considered ancient woodland at
least in part. Some sites such as Glen Helen and Glen
Tramman are large, but the oak and/or hazel interest is widely
dispersed throughout, with the majority of the site secondary
or plantation in nature. In these sites the high botanical quality
of the secondary woodland is probably a reflection of the
intimate mixing with ancient woodland areas that has allowed
local colonisation of species such as hairy woodrush and
smooth stalked sedge to occur in to the secondary woodland
areas.
The sites are markedly more interesting than secondary
woodlands and some such as Lower Ballabeg in Baldrine,
Crogga Glen and Glen Mona are worthy of further study as
they are likely to contain many unrecorded species of interest
and potentially be Tier 1 sites.
While often species rich, these sites tend not to contain the
unique features, habitats and species that are found in Tier 1
sites.
Management in these sites should as a minimum be to retain
their current level of native canopy; though a policy of
returning to 100% native canopy would naturally be of further
benefit. Otherwise the sites should be managed with
biodiversity as a key objective. The expansion of these sites is
likely to be of significantly greater biodiversity benefit than the
expansion of secondary woodlands.
The sites are: The Silverburn series, Glen Helen, Garwick Glen,
Glen Mona, Crogga Glen, Ballaglass Glen, Glen Duff, Nut Glen,
Glen Tramman, Lower Ballabeg and Glen Killey.
4.2.3 Tier 3 Sites.
Generally small and without significant known features that set
the sites apart from secondary woodland (beyond the
presence of oak and/or hazel). These relic sites are of
historical interest and may well contain unrecorded species of
interest.
These sites should be managed to retain their relic features
and would make suitable nuclei of semi-natural woodland
creation schemes.
The sites are: Barnell, Block Eary, Glen Auldyn, Glen Dhoo,
Glen Kylley, Bishop’s Court Glen, Glen Mooar (in Laxey),
Skyhill, Ohio and Colby Glen.
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4.3 Further Research
A key objective of identifying the top 8 woodland sites is that
this will help direct future research and survey effort. While
molluscs have proved a rewarding subject for study, other taxa
from bryophytes (mosses and liverworts) and lichens to
diptera (flies) and coleoptera (beetles) would further enlighten
our knowledge of the natural history of Manx ancient
woodland.
While this study has uncovered a great deal about the flora
and mollusc fauna of the sites, it is by no means complete, and
there doubtless remains much more that can be discovered,
both in the more studied sites and in those where time did not
permit in depth surveys. The exceptional size and diversity of
Glen Roy in particular should mean this site could still contain
many undiscovered natural treasures.
The cultural history of Manx oak/hazel woodlands is poorly
known, with the narrative really only picking up from the 19th
Century early tree planting, tourist and industrial eras. Most of
the sites have a strong heritage of mining and milling leaving
behind mill races, wheel pump casings and engine houses.
Mine adits still remain in some sites, often carved into
stream-sides (Ohio and Glen Roy) or as in the case of
Brookdale, behind a waterfall. The tourist infrastructure is a
more recent human deposit and of active interest to many.
Bohan’s 1989 studies showed that studies of old Manx maps
are revealing and closer study of maps pre-1869 will be a
necessary first stop in the further investigation of the history of
these sites.
Ancient tree research including good age estimation is now
possible with modern wood-coring techniques. This could well
shed more light on the history and age of stunted relic coastal
specimens as well as veteran trees in sites such as Narradale
and Brookdale. With an ageing tree population it may well
now be time for the creation of an ancient tree register.
Dr Alexander’s mollusc survey has also highlighted the
ash-black slug as a particularly notable species whose Island
population should be investigated further.
Manx ancient woodlands contain a rich seam of potential
undergraduate and post graduate studies.
4.4 The Future of Oak/Hazel Woodlands
The great expansion of semi-natural woodland on the Island,
often with oak/hazel woodland at its core, is a process that
would appear to have some way yet to go, as large areas of
the upland fringe are able to develop into woodland faster than
a low intensity of grazing can keep it clear in gorse and
bracken dominated areas.
Along the north scarp of the Northern Hills this allows the
possibility that many oak/hazel woodlands are gradually going
to coalesce into larger blocks of woodland. With a little
imagination and perhaps some Government policy guidance a
forest from Sulby to Ramsey can be allowed and encouraged
to develop. The benefits to biodiversity are evident, but public
recreation, water quality, flood control, carbon storage and the
landscape are all benefits that would accrue.
While woodland is spreading comparatively fast across the
landscape, the specialised biodiversity of the oak/hazel
woodlands will be rather slower to follow and the importance
of these core sites will remain for centuries to come. Within
these sites some positive management will be required to
negate the impact of invasive exotic species. In some sites the
reintroduction of hazel and oak coppice management will be
needed for the vulnerable woodland edge species, though
minimal intervention to maximise the naturalness, veteran
trees and deadwood resource in most sites would be the most
sensible way forward.
Leadership from Government will be the key to the future of
the resource. It is the largest landowner and bringing all its
own sites into a favourable condition will take over 100 years.
While the costs are very low, the time commitment is great. It
has a leadership role to play for the wider resource as well,
bringing together landowners, ecologists and stakeholders to
produce management plans for important sites with multiple
landowners. Fortunately time is on our side, as the most
positive management action is often to do nothing. This should
not mean however that action is not required now, as
developing partnerships and taking collective action could take
years to negotiate.
Some threats are more imminent, such as in Brookdale where
fuchsia is threatening the rare marsh hawksbeard. On the
same site providing the rare ash black slug with a regular and
large supply of deadwood, to promote the spread of the
species, could be a long-term positive intervention.
The first step for oak/hazel woodland conservation should be
their recognition, and inclusion and provision in the up coming
Biodiversity Strategy for the Island.
W i l d f l o w e r s o f M a n n P r o j e c t
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Manx oak/hazel woodlands are by no means the equal of their
cousins in Great Britain, the resource is small and the Island’s
floral diversity is modest which is reflected in the woodland
diversity. The extremely temperate Atlantic conditions
prevailing on the Island also mean that the sharp floristic
divide between ancient woodland and other habitats is much
less pronounced here than in an area such as lowland England,
therefore the relative importance placed upon ancient
woodlands is also somewhat reduced.
While recognising that the Island’s ancient woodland resource
has little significance in the British context, its local significance
has now at last been recognised, surveyed, inventoried and
conclusions made. These are summarised below;
The long held link between relic oak and ancient
woodland has been firmly established and widened to
include hazel.
Most oak/hazel woodland sites are predominantly, or
at least partially ancient, though have somewhat
dynamic boundaries, expanding and contracting due to
human influence over time.
At least 30 of these woodland sites occur on the
Island covering an area of about 125ha. More may well
lie unfound in the many tiny ravines that thread their
way through the Island’s hills.
The 1869 map is not particularly useful at defining
the ‘ancientness’ of oak/hazel sites as it occurs
sometime after significant woodland planting took
place.
A group of about 30 plant species and up to six
mollusc species have been identified as ‘associate’
species in that they are to some degree only found, or
most commonly found, within oak/hazel woodlands.
Many of these species are associate species in eastern
glens but occur in the wider countryside in the southern
hills and coast.
The resource is gradually expanding as oak, hazel
and associate species move into surrounding
plantation, scrub and secondary woodland.
The oak/hazel woodland resource is important for
many rare species on the Island, particularly Schedule
7 Wildlife Act (1990) species.
The resource has become a hostile environment for
some associate species due to levels of shade from
planted species and lack of traditional management.
Some of these species have become very rare or
extinct as a result.
There are many invasive exotic species in oak/hazel
woodlands that require management intervention to
prevent them from causing ecological harm.
The identified sites are an irreplaceable part of the
Island’s natural capital.
Gradually steering the modified and replanted sites
back to a semi-natural state through the natural
regeneration of native species should be a conservation
priority in the Tier 1 sites and good practice in the other
sites. Any planting should be of native species of Manx
origin.
A return to traditional coppice management in
selected sites will be required to maintain long-term
biodiversity in the resource.
Further study of the resource is recommended.
5 CONCLUSIONS
W i l d f l o w e r s o f M a n n P r o j e c t
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6 Acknowledgements
This report has been many years in the making, accruing a weighty list of people who have helped along
the way. Doubtless the following list of thanks could be much expanded.
In the Project’s gestation Andrew Millichap (Mill) of the Native Oak Group was a tireless supporter.
Without Mill it is hard to imagine that this report would have ever existed. Further along Dr Philippa
Tomlinson and Dr Peter Davey’s academic scrutiny sharpened and refined initial ideas.
The continued support of the Wildflowers of Mann Steering Committee Chaired by Bill Henderson MHK
has provided the ‘green light’ to progress beyond initial stages. Thanks also go to the staff and volunteers
of the Manx Wildlife Trust for most notably engaging in many one-sided woodland ecology discussions as
well as providing the essential support and infrastructure.
Elizabeth Charter, the Isle of Man Government’s Principal Biodiversity Officer was instrumental in the
successful funding application to the Joint Nature Conservation Council, whose funding enabled the
completion of this report. It should also be mentioned the continued funding from the Isle of Man
Government to the Wildflowers of Mann Project, particularly the Department of Infrastructure,
Department of Economic Development and Department of Environment Food and Agriculture.
Dr Keith Alexander proved to be a true expert conchologist whose contribution was way above and
beyond that contracted. His tenacious background research as well as site surveys created a picture of
woodland mollusc distribution that has proved to be a pillar of support for the research.
Isle of Man Government foresters, past and present for their help and guidance.
Dr Peter McEvoy and Dr Richard Selman of the Isle of Man Government and the British Pteridological
Society who helped round off the surveys with a master class in fern identification in many oak/hazel
sites. The re-finding of Wilson’s filmy fern in the Colden Stream near a single hazel bush and some
scattered oaks may well make this site the 31st Island oak/hazel site though too late and perhaps rather
too tenuous to be included in this report.
Thanks to Dr Stephen Jeffcoate, a woodland enthusiast as well as lepidopterist and chair of the Manx
Wildlife Trust for kindly writing this report’s foreword.
Also thanks to Aline Thomas for support and proof reading, and to the many others including Amber
Cordwell, David Bellamy and Brian Cousins for important snippets of information that added depth and
scope to the report.
W i l d f l o w e r s o f M a n n P r o j e c t
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Alexander K.N.A (2011) A Survey of Ancient Woodland Indicator Molluscs in selected sites on the Isle of Man. (Draft report)
Allen D.E. (1956) The Vanished Forests. Peregrine, 2, 2-9.
Allen D.E. (1984) Flora of the Isle of Man. Manx Museum and National Trust, Douglas.
Bohan R. (1998) Manx Woodland History and Vegetation. In Kirby K.J. & Watkins C. (eds) The Ecological History of European Forests.
Cab International.
Chiverrell R. & Thomas G. (Eds) (2006) A New History of the Isle of Man. Volume 1: The Evolution of the Natural Landscape. Liverpool
University Press. Liverpool.
Coppins A.M. & Coppins B.J. (2002) Indices of Ecological Continuity for Woodland Epiphytic Habitats in the British Isles. British Lichen
Society.
Crawford C.L. (2009) Ancient Woodland Indicator Plants in Scotland in Scottish Forestry. Vol 61, 1.
Dubbeldam A. (2007) Supporting Rare Wildflowers: A Wildflowers of Mann Programme. Manx Wildlife Trust
Dubbeldam A. (2011) New Flora of the Isle of Man: Survey Database. Manx Wildlife Trust (unpublished)
Garrad L.S. (1972) The Naturalist in the Isle of Man. David and Charles, Newton Abbot.
Kirby, K. English Nature (2004). Table of Ancient Woodland Indicator Plants. in Rose F. (2006). The Wildflower Key. Updated by O’Reilly C. Warne. London
Peterken G.F. (1981) Woodland Conservation and Management. Chapman and Hall. London
Rackham O. (1976) Trees and Woodlands in the British Landscape. Dent. London.
Rodwell J.S.(ed) (1991) British Plant Communities. Volume 1: Woodlands and Scrub. Cambridge University Press. Cambridge.
Stace C. A. (2010) New Flora of the British Isles (3rd edition). Cambridge University Press. Cambridge
Watkins C. (1990) Britain’s Ancient Woodland ; Woodland Management and Conservation. David and Charles. Newton Abbot
7 References
W i l d f l o w e r s o f M a n n P r o j e c t
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W1 Grey Willow-Marsh Bedstraw woodland
This is a broad community of varied willow woodland types
and makes up one of the Ballaugh Curragh vegetation types.
In this survey this community refers to pioneer woodland on
mineral soils on former open marsh and wet riverside habitats.
Initially very open with rush dominated vegetation like that of
the marsh. As the canopy closes in with grey and eared willow,
the rush is shaded out leaving just the shade tolerant species
such as tufted hair grass, yellow pimpernel, devils bit, bugle,
heath spotted orchid and marsh bedstraw. The community
here is temporary as ash, sycamore, alder and downy birch
colonise and overtop the canopy and species such as
enchanter’s nightshade and opposite-leaved golden saxifrage
enter the ground flora marking a transition to the W7
Alder-Ash-Yellow Pimpernel community.
Many glen woodlands such as Elfin Glen and Nut Glen contain
this community at their upper edge, often a mobile colonising
front along stream-sides. Above 200m it may well be a climax
community type as it is beyond the natural limit for W7, but the
increase in acid peaty soils means the community tends to be
replaced by the W4 Downy Birch-Purple Moor-grass
community.
W4 Downy Birch-Purple Moor-grass woodland
Similar to W1 this woodland type generally occurs on the Isle
of Man where downy birch, eared willow and grey willow
invade an acid peaty bog habitat. It typically has sphagnum
moss and purple moor-grass ground vegetation. Unlike W1
woodland however, this is less likely to be a transitory
succession phase, but instead remain as climax scrubby
woodland, though with increasing birch dominance. If
however the trees dry out the underlying peat it is likely further
successional changes will take place, most likely to W17
Sessile Oak-Downy Birch-Greater Fork-moss
community.
This community is somewhat uncommon within oak/hazel
woodlands (though good examples can be found well within
Glen Helen and Glen Roy), but form a colonising scrub where
woodlands are adjacent to wet upland vegetation such as at
Brookdale. Incidences of the community increase greatly
above 150m. W4 is by far the dominant vegetation type of the
Ballaugh Curragh.
W7 Alder-Ash-Yellow Pimpernel woodland
This is the standard community of wet areas within oak/hazel
woodland. Occurring in patches from less than a metre across
and rarely covering more than 500m2. Sometimes it forms thin
ribbons along stream-sides, occasionally as marsh in flat river
terrace areas, but most frequently as wet flushes on a ravine
side. While nominally an alder woodland community, some
localised parts of the Island like Ramsey and Glen Auldyn lack
this species completely so ash, birch, grey willow and
sycamore make up the canopy.
Almost always the most species rich community in a woodland
and in sites dominated by the rather species poor W11
Oak-Downy Birch-Wood Sorrel community the contrast in
species richness can be dramatic. Better examples of the
community can contain wood horsetail, sanicle,
smooth-stalked sedge, heath spotted orchid and in one case
marsh hawksbeard. Almost all will have enchanter’s
nightshade, bugle, opposite-leaved yellow saxifrage and
yellow pimpernel along with many others.
W7 woodland tends to be a tangle of bramble and fallen trees
among waterlogged ground, thus a difficult terrain to traverse.
Appendix I National Vegetation Class (NVC) Woodland Types in Manx Oak/Hazel Woodlands (from Rodwell 1991)
W7 at Groudle Glen
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W8/9 Ash-Field Maple-Dog’s
Mercury/Ash-Rowan-Dog’s Mercury woodlands
These are the standard communities on the Island of
woodlands on somewhat base rich (though often still quite
acid) soils. Occurring in valley bottoms on colluvial soils or on
soils over less acid bedrock. While field maple and dog’s
mercury are not native to the Island, they are ably replaced
here by wych elm and enchanter’s nightshade respectively.
Similar to W7 they lack the species dependent on woodlands
in wet conditions such as opposite-leaved golden-saxifrage,
wood horsetail and alder and gain a suite of species that
demands more freely drained soil such as wood false brome,
bluebell and herb robert. Many species such as sanicle, remote
sedge, primrose, bugle and wood anemone are equally at
home in W7 and W8/9.
W8 and W9 are lumped together here as the differences are
slight, with W8 being the lowland counterpart to the upland
W9. As many glen woodlands start in the lowlands and climb
some 100m or more, the common situation is the lower part of
the glen is W8, normally the distinctive wild garlic dominated
sub-community and the upper part is W9 as garlic falls away
and ferns become more numerous. The dividing line is rarely
clear on the ground and the differences are slight hence the
reasons for lumping the communities together. Ballure Glen is
a useful Island example, with most of the woodland below the
reservoir W8 and the riverside woodland above the reservoir
W9.
Like W7, W8/W9 is a very species rich community, indeed,
even where wild garlic seems to overwhelmingly dominate,
there will still be significant species richness. This community
is also the most important for many of the rarer woodland
species such as wood speedwell, wood fescue and hard
shield-fern.
W10/W11 Pedunculate Oak-Bracken-Bramble/Sessile
Oak-Downy Birch-Wood Sorrel woodlands
These are the classic bluebell woodlands, most beloved on the
Island, with bluebells forming a dominant vegetation carpet in
spring. They occur on free draining, more acid and base poor
soils than that of W8/9.
The most common vegetation types found in oak/hazel
woodland, W10 is the lowland counterpart to the upland
W11. They are lumped together for the same reasons as W8
and W9, indeed the differences between the two communities
are so subtle as to be hardly noticeable, with an abundance of
wood sorrel that can be seen after the bluebell has died away
in W11 the main diagnostic feature that differentiates it from
W10.
The typical tree in the community is hybrid oak, but it only
locally dominates the canopy and where the community forms
secondary woodland adjacent to a glen it tends to be absent.
Sycamore, birch, beech (mostly planted) and planted conifers
and sweet chestnuts form the majority of the remainder of the
tree cover, though ash and wych elm do occur occasionally. In
some glens hazel is a common understorey, but holly or
bramble can be locally abundant or dominant, as can cherry
laurel and rhododendron.
As has been said, it is the dominance of bluebell that is most
distinctive in the ground flora, with male-ferns and broad
buckler-ferns also common, whilst other species such as
greater stitchwort are infrequent. As the bluebell dies off in the
summer the ground flora takes on a grassy look with sweet
vernal grass, Yorkshire fog and creeping soft-grass the more
common species. Greater woodrush can become a local
monoculture and while most common in this type of woodland
it can also form local monocultures in W7, W9 and W17.
While aesthetically very attractive the community is not
blessed with a great variety of vascular plants, though where
large mature oak trees are present a great deal of lower plant
and invertebrate interest is assumed.
W15 Beech-Wavy Hair-grass woodland
Created by the planting of beech trees over acid soils, it can be
considered a species poor type of W17 on the Isle of Man and
Typical W11 at Glen Helen
W i l d f l o w e r s o f M a n n P r o j e c t
Page 26
not an indigenous woodland community to Mann. Where
mature beech occurs near W17 woodland however, the
natural regeneration of beech into this community could
gradually convert the site to W15 as is happening in places
such as Ballaglass. The acid leaf litter also has the potential to
convert the more acid W10/11 sites to W15 in time.
These woodlands are open and attractive to people, and while
generally species poor they can develop an interesting fungal
assemblage.
W17 Sessile Oak-Downy Birch-Greater Fork Moss
woodlands
The woodland type on the most acid soils. This tends to occur
in the uplands, but at lower altitudes it can form small patches
on very thin soils over rock, so is not uncommon at the top of
narrow ravines, where it can form small patches above W8/9
woodland.
This woodland type is dominated by downy birch with
occasional oak, holly and rowan. Where this woodland type is
colonising open heath, rowan tends be the more common
pioneer species, often with some lodgepole pine where conifer
plantations are nearby. Beech readily seeds into this
community, but mature trees are planted in origin.
The ground flora looks very grassy or mossy with an absence
of showy species such as bluebell or wild garlic. The near
absence of bramble and dense scrub further add to the
pleasant aesthetic of the community. Pill sedge, hairy
woodrush, goldenrod, slender St Johns wort and wood sage
are the more noticeable vascular species. Bilberry, greater
woodrush and bracken can be locally dominant.
While found in most of the larger glens this is not a particularly
abundant vegetation type and tends to occur on the boundary
of glens and conifer plantations or open heath. While
considered species poor, its distinctive flora adds somewhat to
the diversity of the woodland where the vegetation type
occurs.
Bare Rock Ravine woodland
Sitting somewhat outside any NVC communities (though
perhaps closest to W11) the stone gouged humid rocks in
most glens support a rather consistent community. The bare
rocks are dominated by mosses and liverworts and the
frequent cracks between them contain species tolerant of the
acid rocks, and frequent base rich flushing. Many of these sites
are extremely shady thus the vascular plant flora can be
sparse but there is an interesting assemblage of
wet-demanding (such as lemon-scented fern and devil’s bit),
along side drought-tolerant (but humid dependent) species
such as hairy woodrush and wood sorrel. Other species
frequent here are tutsan, opposite leaved golden saxifrage,
greater woodrush and goldenrod. Hay-scented buckler-fern,
and beech fern are rarer Manx species that are most likely
found in this community.
Oak/hazel woodlands of the Isle of
Man is a report by the Wildflowers of Mann Project.
The Project undertakes all aspects of research, practical conservation,
consultancy and public engagement
in the field of Wildflowers and habitat conservation on the Isle of
Man. Part of its scope has been the creation of a showcase garden
open to the public, the publication of a best selling book, ‘The Wild-
flowers of Mann’, as well as
running a wildflower nursery producing native plants and seeds
to create new native woodlands, meadows, wetlands and other
habitats across the Island.
Run out of the Manx Wildlife Trust the Wildflowers of Mann is a
partnership project between Isle of Man Government departments and
local conservation organisations who together form a steering
committee for the Project chaired
by Bill Henderson MHK.
Andree Dubbeldam MIEEM has
been the Wildflowers of Mann Project Manager since 2002. Born
and brought up in Sussex he has been in work or education in the
field of conservation and the
countryside for 25 years.
As a forestry graduate from Bangor
University, ancient semi-natural woodland is an area of particular
expertise and interest.
Top: Brookdale; Middle: speckled wood butterfly in Ballure; horned stag-beetle in Dhoon; Bellow: Dr Keith Alexander showing David Bellamy an invertebrate sweep-net sample; native bluebell
Wildflowers of Mann Project