Bryophytes of springs and flushes - 2009 course notes - Plantlife

LOWER PLANTS AND FUNGI PROJECT - TRAINING DAY
BRYOPHYTES OF SPRINGS AND FLUSHES
COURSE NOTES
written for Plantlife Scotland by Gordon Rothero,
Course Leader and Consultant Bryologist
April 2009
Date of course: 15 th / 16th June 2009, 10.00am – 5.30pm
Venue:
Ben Lawers
Course Leader: Gordon Rothero
Scorpidium scorpioides © Gordon Rothero
1

BRYOPHYTES OF SPRINGS AND FLUSHES
Springs and flushes are an extremely important habitat for bryophytes and mosses and
liverworts often form a significant proportion of the biomass. Bryophytes have a significant
presence in at least 12 National Vegetation Classification (NVC)* spring and flush
communities and a number of these correspond to categories on Annex I of the Habitats
Directive; the more important of these are briefly described below. Spring and flush
communities vary widely in species composition, ranging from the acidic, and often
extensive, M6 Carex echinata – Sphagnum fallax mires to the strongly calcareous, and
usually small, M38 Palustriella commutata – Carex nigra springs. Springs and flushes may
be dominated by just a small number of common bryophytes or may have a diverse flora with
a number of rare and scarce species. There are 41 bryophyte species of conservation
interest that have at least some important populations in springs and flushes and some of
these are confined to this habitat; these species are listed with their status in Table 2. Of this
long list, 10 are BAP species, eight are considered Vulnerable or Endangered in the
Bryophyte Red Data Book, four are on Schedule 8 of the Wildlife and Countryside Act, one is
included in a list of the world’s most threatened bryophytes and one is listed in the Bern
Convention and on Annex IIb of the EU Habitats and Species Directive.
(*NB The National Vegetation Classification (NVC) is a comprehensive classification and description of the plant
communities of Britain, each systematically named and arranged and with standardised descriptions for each.
More details can be seen at http://www.jncc.gov.uk/page-4259 The NVC categories have been used as a
structure for describing species on this course).
What are springs and flushes ?
Springs are usually the point source of a burn, where the water-table meets the ground
surface, and so there is often a series of springs across the slope at much the same level,
which, appropriately enough, is called the ‘spring line’. Springs are usually small and welldefined
and often have a complete cover of bryophytes with just scattered flowering plants.
Flushes are areas where the flow of ground water is more diffuse, either where the water
table reaches the surface or where or where water flows widely over the surface of saturated
ground rather than in a well-defined channel. They can be areas of open, stony ground with
only a sparse plant cover or have a complete and often dense cover of vascular plants,
usually sedges or rushes, with the bryophytes forming a ‘ground layer’ under this ‘canopy’.
We tend to think of both springs and flushes as particularly associated with open habitat in
the upland areas of Scotland but they can occur right down to sea level and under a
woodland canopy, where they seem to be close to M36, but obviously the species
composition will tend to differ markedly in each case.
The vegetation associated with the various springs and flushes is determined by the physical
character of the habitat, particularly the temperature and the mineral content of the water. In
terms of diversity of species, the NVC communities M10, M11 and M12 where the
groundwater is moderately or strongly calcareous are by far the most important but the icy,
nutrient-poor meltwater springs and flushes M31, M33 and the higher level M32 stands are
also of conservation concern as they are so restricted in their distribution. However it is
interesting and perhaps instructive to note that the BAP species are scattered through a
variety of flush types, with the most threatened of them at relatively low level.
2

Threats
Climate change
A number of flush communities, particularly those with Pohlia wahlenbergii var. glacialis and
Pohlia ludwigii which are dependant on the cold water associated with areas of late snow-lie
are clearly under threat if the pattern of snow accumulation and persistence changes. There
is good evidence that the pattern and duration of snow lie in Scotland is already changing.
Over time there may well be other changes as part of a complex shift in plant communities
and their spatial distribution as a result of what will probably be a warmer and wetter climate.
Pollution
Though most springs and flushes are well away from the sources of pollution, the vegetation
is still under threat from sulphur and nitrogen deposition which is enhanced by the heavy
rainfall and deposition in droplets of mist when the hills are cloud-capped. Mosses and
liverworts are particularly susceptible to this kind of pollution. A particular problem in the
higher hills is the concentration of pollutants in the snowpack, built up over the winter, which
can then be suddenly released through a rapid thaw, the ‘acid flush’ which can kill fish
downstream. The long-term effects of this pollution are unclear but it must have some effect
on the bryophytes which have no protective cuticle and so absorb water and pollutants
directly into the cells of the leaf.
Drainage
By their nature, springs and flushes occur in wet places and so have always been threatened
by changes in the local hydrology. The most obvious threat is by drainage, gripping an area
to improve it for grazing or the planting of trees. The more extensive flushes are often the
main casualty of this form of management through direct damage and a prolonged drying out
of the areas affected. It is quite remarkable how much of this went on, presumably when
grants were available, and it is not unusual to come across patterns of ditches in quite
remote upland areas.
This era has now passed and gripping in upland areas is rare but it this threat has been
replaced by that from the changes in hydrology that occur as a result of the construction of
the infrastructure necessary to service windfarms. All windfarms require service roads to
each turbine and these, plus the associated ditching and drainage will change the hydrology
of the affected area as well as having a more direct local effect. The only Scottish site for the
BAP liverwort Pallavicinia lyellii, in flushed Molinea caerulea grassland, is now part of the
huge Eaglesham windfarm. A planned windfarm in the Ochils will affect a large population of
Hamatocaulis vernicosus (Bern Convention, EU Directive Annex IIb, Schedule 8 WCA).
Apart from the flushes destroyed by the construction process, it is not known what the effects
of the changes in the hydrology in the flushes might be and it is unlikely that any monitoring
work has formed part of the mitigation.
Forestry
In the past, blanket aforestation has destroyed springs and flushes over a vast swathe of
Scotland but particularly so in the south and west. In Cowal, Argyll, for example, above the
valley bottom, there are very few slopes without commercial plantations, many well into their
second rotation. The process of blanket aforestation of open hill land with commercial
conifers has diminished considerably in recent years but springs and flushes, being small
scale features, are still vulnerable.
One, rather ironic, threat is from the commendable zeal for the expansion of broadleaf and
native Scots pine woodland, where the drive to increase woodland cover tends to overpower
the consideration of diverse small-scale habitats like springs and flushes. On Rhum, such
planting was probably responsible for the demise of Hamatocaulis vernicosus in its one site
on the island. Some crofting woodland schemes in Sutherland where sites have been
scarified before planting are also poorly designed in this respect. Even exclosures to
3

encourage natural regeneration by excluding grazing animals can be bad news for flushes as
the bryophytes can be overwhelmed by the growth of coarse vegetation or dense
regeneration of trees. There is a good (or should that be bad) example of this on the
Morrone NNR, where dense birch regeneration in exclosures is changing the nature of the
extensive flushes associated with the limestone there.
Trampling by livestock
Springs and flushes are attractive to livestock as they often offer localised patches of more
lush vegetation and a source of water during dry spells. Certain flushes seem to become
popular and attract large numbers of animals and can be badly poached. The damage by
poaching can look dramatic but as long as it does not persist for long periods, the bryophytes
can recover and some may even benefit. The obvious problem lies in those sites with a
small population of a particularly vulnerable species.
Management recommendations
Climate change and atmospheric pollution
The problems that face flushes on the higher hills are global in nature and regrettably are not
within the scope of the scale of management to which we might aspire!
Survey and assessment
Perhaps the most important management tool for the well-being of these diverse habitats is
to recognise both their presence and their local, and sometimes national, importance. This is
not always easy to achieve for features which are usually small in comparison to the area
being ‘managed’. Where large-scale changes to an area are being considered, be it for
woodland regeneration or windfarms, it is important that any prior assessment of the site is
competent to identify the conservation value of the bryophyte-rich springs and flushes that
may occur.
Drainage
To be effective, drainage has to target those areas where water movement can be enhanced
and by definition this means that the lines of flushes will be preferentially affected either by
drains running through them or water channelled into them. This means that if an area has
to be drained then any flushes will almost certainly be lost or at least radically altered.
Where the drainage is designed to protect installations or access tracks, it should be possible
to design this so as to have minimum impact on important spring and flush sites. At a
smaller scale it should be possible to avoid having ditches and culverts emptying into existing
flushes.
Forestry
Again, the best possibility of protecting flushes is at the design stage. It has to be accepted
that if the prime objective is to establish a woodland, then not all open flushes can be
preserved. However, if there are flushes of conservation interest on the site some effort
should be made to limit disturbance to these sites. Not only does this mean not planting
through the flush but also retaining an open buffer zone around the flush so that shading and
litter fall are also limited. It is probable that, over time, the nature of the run-off will alter and
even those flushes that are undisturbed will change in nature but may still have interesting
bryophytes.
Poaching by livestock and deer
Where poaching is limited in both extent and duration, its effects on the flush vegetation are
likely to be moderate given that these are dynamic habitats. Poaching may even be
beneficial in restricting the growth of rapidly growing, carpet-forming, vascular plants like
Montia fontana and Chrysosplenium oppositifolium. Where stocking levels are consistently
high it is likely that most flushes will have been altered by eutrophication as well as poaching,
4

often having only large stands of common, robust species. It is only where there is a spring
or flush with a species of conservation concern that the level of poaching needs to be
monitored, and again, knowledge of the site is all-important.
OUTLINE OF BRYOPHYTE SPECIES OF SPRINGS AND FLUSHES
NVC communities that have strong elements of flushing and where bryophytes are an
important constituent of the vegetation:
These descriptions are, of necessity, very brief and the NVC volumes (Rodwell, 1991) and
Averis et al (2004) have a lot more detail. Boundaries of spring and flush vegetation can be
very sharp but stands often contain a mix of flush types; for instance, M10 and M11 flushes
often have a Palustriella commutata spring at their head and M6 flushes may well contain a
line of M32 Philonotis fontana within them.
M6 Carex echinata – Sphagnum fallax
mire
Rather dull but often very extensive in the
west of Scotland with a sward of sedges or
rushes over species of Sphagnum. The
most prominent and extensive are M6c and d
with Juncus effusus and Juncus acutiflorus
dominant over lawns of Sphagnum palustre
and Sphagnum fallax with some Sphagnum
denticulatum in the wettest areas. The
groundwater is rather acidic and bryophyte
diversity is usually very low. Richer stands
with fewer Sphagna and much Calliergonella
cuspidata are probably closer to M23 Rush pasture.
M7 Carex curta – Sphagnum russowii mire
The upland extension of M6 but much less extensive, often in bands below springs in areas
where snow lies moderately late and often associated with upland plateau areas. The
important bryophyte components apart from Sphagnum russowii are two nationally scarce
species Sphagnum riparium (illustrated) and Sphagnum lindbergii.
5

M10 Carex dioica – Pinguicula vulgaris mire and M11 Carex viridula subsp. oedocarpa
– Saxifrage aizoides mire
Most calcareous flushes in the hills belong to these two communities and the two can be
difficult to separate. Both can occur as open, stony flushes but M10 generally has a more
prominent vascular plant cover. The bryophytes are often the same in both communities;
most consistent in the open stony areas are common species like Scorpidium scorpioides,
Drepanocladus revolvens, Blindia acuta, Aneura pinguis (below bottom right), Campylium
stellatum var stellatum, Ctenidium molluscum and occasionally Pseudocalliergon trifarium
(below bottom left). The hummocks and margins of the flushes often have a greater diversity
of species including rare and scarce species including Meesia uliginosa (top right) . The
BAP species Tayloria lingulata is restricted to these two flush communities and M12, usually
on hummocks within the flush. Another BAP species, Splachnum vasculosum, can form long
stands along the margins of the flush.
M12 Carex saxatilis mire
This uncommon flush type usually has a more complete and taller cover than M10 and M11
with Carex saxatilis dominant but usually with other sedges. It is often not as strongly
calcareous as the most diverse M10 and M11 flushes and is usually above 600m. The
bryophytes are similar to M10 and M11 but often less diverse but a number of rarities do
occur here including Tayloria lingulata.
6

M31 Anthelia julacea – Sphagnum denticulatum spring
A high altitude community with cold and acid groundwater and often associated with
snowbed vegetation. The grey mats of Anthelia julacea are easily recognised and
Sphagnum denticulatum is usually common but there is always an admixture of other
species particularly Scapania undulata, Scapania uliginosa and occasionally the rare
Scapania paludosa.
M32 Philonotis fontana – Saxifraga stellaris spring
This is the most common of the hill springs and flushes and is very variable, ranging from
stands that are moderately calcareous (where Philonotis fontana may be replaced by
7

Philonotis calcarea) to moderately acidic. The common feature is the often extensive mats of
Philonotis fontana usually with a mix of other bryophytes including Dichodontium palustris,
Brachythecium rivulare, Bryum pseudotriquetrum, Scapania undulata and on the margins
Sphagnum denticulatum. Higher stands may also have Bryum weigelii (the pink in the flush
above bottom right), Philonotis seriata and Scapania uliginosa (above bottom left). Lower
down many flushed areas have stands of Philonotis fontana, often with the typical associates
but the vascular plant component is usually different, often Montia fontana or
Chrysosplenium oppositifolium.
M33 Pohlia wahlenbergii var. glacialis spring
This is the arctic-montane equivalent of the
M32 flush characterised by large pure stands
of Pohlia wahlenbergii var. glacialis, which
are often visible from some distance.
Associated bryophyte species are often
limited but include Philonotis fontana, Pohlia
ludwigii, Scapania uliginosa, Scapania
undulata and Marsupella sphacelata.
M37 Palustriella commutata – Festuca rubra spring and M38 Palustriella commutata –
Carex nigra spring
These are the ‘brown moss’ springs characterised by large stands of Palustriella commutata
or Palustriella falcata, often to the exclusion of other bryophytes. They often occur as small
patches at the spring-head of other calcareous flush types but in limestone areas can form
extensive stands often with some tufa formation.
8

M36 Lowland flushes
There are a variety of flushes on lower ground and in woodland which may have some of the
species of the upland communities, particularly Aneura pinguis, Calliergonella cuspidata,
Philonotis fontana, Dichodontium palustris and Brachythecium rivulare but also containing a
range of other species. The base status of the water and shading are both important. In
woodland the flushes can range from those dominated by Sphagnum squarrosum to more
diverse swards with Plagiomnium elatum and Trichocolea tomentella.
9

The species
Table 1. Bryophyte species of conservation interest with at least some important
populations in springs and flushes.
Species BAP RDB status National WCA Europe
status
Amblyodon dealbatus
Scarce
Andreaea nivalis BAP Near threatened Scarce
Aplodon wormskjoldii BAP Critically endangered Rare
Barbilophozia quadriloba Near threatened Rare
Bryoerythrophyllum BAP Near threatened Rare
caledonicum
Bryum schleicheri var BAP Critically endangered Rare WCA
latifolium
Bryum weigelii
Scarce
Catascopium nigritum
Scarce
Cinclidium stygium
Scarce
Dicranella grevilleana Near threatened Rare
Dicranum undulatum BAP Vulnerable Scarce
Hamatocaulis vernicosus Scarce WCA Bern
Convention,
EU Species
Directive
Harpanthus flotowianus
Scarce
Hygrohypnum molle Vulnerable Rare
Jamesoniella undulifolia BAP Endangered Rare WCA Red list
Leiocolea gilmanii Near threatened Rare
Liochlaena lanceolata BAP Critically endangered Rare
Meesia uliginosa
Scarce
Moerckia hibernica
Scarce
Odontoschisma
Scarce
elongatum
Oncophorus virens
Scarce
Oncophorus wahlenbergii Near threatened Rare
Pallavicinia lyellii BAP Vulnerable Scarce Red list
Palustriella decipiens Near threatened Scarce
Philonotis seriata
Scarce
Plagiomnium medium Near threatened Rare
Pohlia ludwigii
Scarce
Pseudobryum
Scarce
cinclidioides
Pseudocalliergon trifarium
Scarce
Pseudocalliergon
Vulnerable Rare WCA
turgescens
Rhizomnium magnifolium
Scarce
Scapania degenii
Scarce
Scapania paludosa
Rare
Scapania uliginosa
Scarce
Sphagnum lindbergii
Scarce
Sphagnum platyphyllum
Scarce
Sphagnum riparium
Scarce
Splachnum vasculosum BAP Near threatened Scarce
Tayloria lingulata BAP Endangered Rare
Tomenthypnum nitens
Scarce
Tritomaria polita
Scarce
10

Typical flush species
Sphagnum palustre & Sphagnum fallax
These two bog mosses often dominate the ground layer to the exclusion of all else in acid
sedge or rush dominated flushes – the M6 community. This floristically rather dull
community is widespread in the W of Scotland.
Calliergonella cuspidata
Where the ground water is a bit more
productive the Sphagnum species are
much less prominent and this moss can be
overwhelmingly dominant under the
rushes.
Philonotis fontana
This is the characteristic species of many hill
springs and flushes where the water is not
base-rich. The rather stiff erect, bright green
stems and the often present, round capsules
make it very easy to recognise. It can form
dense patches, covering the whole spring or
can form patches with the next three
species.
11

Scapania undulata
This common riparian liverwort is also
frequent in acid flushes where it is often
reddish-purple in colour. Higher up the hill it
often occurs with the rather similar Scapania
uliginosa.
Dicranella palustris
The bright yellow-green colour of the patches
of this moss stand out from a distance and
the reflexed leaves give the shoots a star
shape viewed from above.
Sphagnum denticulatum
This bog-moss is common in a variety of
habitats but it is characteristic of the margins
of many M32 flushes. In springs it almost
always has an ochre-ish tinge and this and
the curved branches mean that it is easily
recognised. Higher up the hill where the
water is colder, it also forms a flush
community (M31) with the next species.
Anthelia julacea
A tiny liverwort but one which often forms
large swelling cushions in flushes over acid,
stony ground in the higher hills, often below
snow beds. In the M31 community usually
occurs with Scapania undulata and Scapania
uliginosa and Sphagnum denticulatum. This
community can have very large stands on
easy-angled ground on high plateaux.
12

Pohlia wahlenbergii var. glacialis
The arctic equivalent of the M32 Philonotis
fontana flush the M33 community has large
stands of this large moss which probably
holds the record for “a moss identified at a
distance”. The white-green patches are
easily picked out from over a kilometre away
once you know what to look for.
Pohlia ludwigii
Another distinctive moss with arctic affinities
forms large stands in flushes over stony
ground in areas of late snow-lie.
Scorpidium scorpioides
In more open stony flushes on somewhat
more basic ground, this is often the first
moss to attract the attention, its patches over
the stones looking much like a mass of
wriggling worms. It usually occurs with the
next two species.
Drepanocladus revolvens
Usually coppery in colour and with very
falcate (hooked) leaves and shoot-tips, this
moss often forms large patches at the edge
of stony M10 and M11 flushes.
13

Blindia acuta
In stony flushes, this moss is almost
ubiquitous on the surface of the stones,
forming a short dark-green turf or scattered
open patches.
Palustriella commutata
Usually forming dense, yellow-brown patches,
sometimes very extensive, in calcareous
springs and flushes and often encrusted with
lime.
Hamatocaulis vernicosus
Listed on the Species Directive and Berne
Convention, this species is locally frequent in
parts of Britain and has a number of sites
Scotland. It occurs in moderately base-rich
flushes, usually in sedge-rich vegetation and
can form extensive patches. It is easily
confused with other species, particularly
Drepanocladus cossonii.
14

The BAP species
Andreaea nivalis
This handsome species is restricted to areas
of late snow-lie; usually a species of wet
rocks, it also occurs over flushed gravels
where it can form extensive stands, often
with Pohlia ludwigii. It is abundant in the
snowbeds of the Cairngorms and the Ben
Nevis massif but is rare away from these
areas.
Aplodon wormskjoldii
This species is a member of the Splachnaceae, the dung mosses but most records in the UK
are from carrion. Not seen in Britain since the 1970s, it may well be extinct. The most recent
record was from a dead sheep in a bog but most records are from carrion in base-rich
flushes.
Bryoerythrophyllum caledonicum
A Scottish endemic with scattered sites on
the calcareous schists of the central
Highlands with two outlying populations on
Skye and Rum. Most sites are on wet silt on
rock ledges but it also occurs in flushes on
steep slopes.
Bryum schleicheri var latifolium
A large and easily recognisable moss which has always been rare and is now seemingly
restricted to one, rather non-descript spring near Stirling.
15

Jamesoniella undulifolia
The one British bryophyte to grace the list of the world’s most threatened species. Restricted
to three sites in Scotland, all in flushes below basic rocks on low ground by the coast in
Argyll.
Liochlaena lanceolata
Now apparently reduced to one UK site in a flush on the calcareous, Cambrian fucoid beds
near Loch Clare in Torridon. It is not thriving here and is perhaps the most threatened
bryophyte in Scotland.
Pallavicinia lyellii
Its one Scottish site is on a slope of flushed Molinea caerulea grassland – a very nondescript
habitat. The whole site is now part of the vast Eaglesham windfarm SW of Glasgow
and the fate of Pallavicinia lyellii is not known
16

Splachnum vasculosum
Another member of the Splachnaceae, this
species has declined markedly over the
years. It grows in at least moderately basic
flushes and can persist in the same site long
after the dung on which it presumably first
grew has gone.
Tayloria lingulata
And yet another member of the
Splachnaceae growing on organic material in
calcareous flushes and limited to a few sites
in the mountains of the Central Highlands
and only at all frequent on the Ben Lawers
SSSI.
Contacts for further advice and support
Dr David Genney, SNH Policy & Advice Officer,
Bryophytes, Fungi and Lichens
Gordon Rothero, Consultant Bryologist
david.genney@snh.gov.uk
gprothero@aol.com
Matilda Scharsach, Lower Plants & Fungi Officer, matilda.scharsach@plantlife.org.uk
Plantlife Scotland Tel 01786 469778
References
Averis AM et al., 2004, An illustrated guide to British upland vegetation, Joint Nature
Conservation Committee, Peterborough.
Averis AM, 2003, Scotland’s living landscapes: springs and flushes, SNH, Inverness.
Rodwell JS (ed), 1991, British Plant Communites Volume 2: Mires and Heaths, CUP,
Cambridge.
17