Contents - Plantlife

Cicerbita alpina (L.)
Alpine Blue-sow-thistle, Bliochdan Gorm Ailpeach
ASTERACEAE
SYN.: Alpine sow-thistle, Blue sow-thistle.C. alpina (L.) Wallr., Sched. Crit. 434
(1822). Sonchus alpinus (L.), Sp Pl. 794 (1753). Mulgedium alpinum (L.) Less., Syn.
Gen. Comp. 142 (1832). Sonchus caeruleus Sm., Fl. Brit., 2: 815 (1800) nom. Illegit.
Superfl. Pro Soncho alpino (L.). Lactuca alpina (L.) A. Gray, Syn. Fl. N. Amer., 1(2):
444 (1884).
Status
Restricted to 4 sites in Scotland
UK BAP Long List key species
Schedule 8 Wildlife & Countryside Act (1981)
Plantlife Back from the Brink species
4 10km squares
Status in Europe: not threatened
Contents
1
2
3
4
5
6
Morphology, Identification, Taxonomy & Genetics.................................................... 2
1.1 Morphology & Identification ............................................................................ 2
1.2 Taxonomic Considerations .............................................................................. 3
1.3 Genetic Implications ...................................................................................... 4
Distribution & Current Status ............................................................................... 5
2.1 World .......................................................................................................... 5
2.2 Europe ........................................................................................................ 5
2.3 United Kingdom ............................................................................................ 6
2.3.1 Scotland................................................................................................. 6
Ecology & Life Cycle............................................................................................ 9
Habitat Requirements ....................................................................................... 10
4.1 The Landscape Perspective ........................................................................... 10
4.2 Communities & Vegetation ........................................................................... 10
Management Implications .................................................................................. 11
Threats / Factors Leading to Loss or Decline or Limiting Recovery............................ 11
Work on Cicerbita alpina is supported by:
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7
Current Conservation Measures ..........................................................................
7.1 In Situ Measures........................................................................................
7.2 Ex Situ Measures .......................................................................................
7.3 Monitoring Cicerbita alpina & the Common Monitoring Standard.........................
7.4 Recommendations for Future Work ................................................................
8 References ......................................................................................................
9 Acknowledgements ...........................................................................................
10 Contacts .........................................................................................................
11 Links ..............................................................................................................
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1.1
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17
Morphology, Identification, Taxonomy & Genetics
MORPHOLOGY & IDENTIFICATION
Cicerbita alpina is a tall, robust, rhizomatous perennial with attractive blue-flowers. In late
summer its pale blue-violet, dandelion-like flowerheads open in tight clusters at the top of
the stem. Cicerbita alpina has an erect stem 50-250cm, simple or branched, usually with
dense, reddish glandular hairs on the upper part. Alternate leaves are 8–25 x 2-12 cm,
glabrous, glaucous beneath; lowest lyrate or runcinate-pinnatifid with a large, broadly
triangular, acuminate terminal lobe and a few pairs of much smaller triangular lateral ones,
with the base narrowed into a winged petiole; upper smaller and less divided, with a winged
periole widened into a cordate-amplexicaul base. Flowerhead is an elongated panicle;
peduncles with dense reddish glandular hairs. Involucre is 10-15 x 7-10 mm; bracts linear,
usually with numerous reddish glandular hairs. Petals are pale blue. Achenes 4.5-5 mm,
linear (Sell, 1986).
Specimens are held at a number of institutions including the Smith Herbarium (LINN),
Royal Botanic Garden Edinburgh (RBGE) (E) and the Natural History Museum (NHM).
George Don sent specimens from Lochnagar to Sir James Edward Smith who published a
description of the plant as Sonchus caeruleus SM. (Smith, 1811). Some of Don’s specimens
are housed in the Smith herbarium (LINN) while others were given to private collectors one
of whose sheets is now in the herbarium of the Royal Botanic Garden Edinburgh (E).
Chromosome number is 2n=18 (Clapham et al, 1987). No hybrids have been reported.
2
Figure 1 - Cicerbita alpina (L.) Alpine Sow-thistle.
(Photograph by Bob Gibbons,
© Bob Gibbons/Natural Image).
1.2
TAXONOMIC CONSIDERATIONS
The genus Cicerbita Wallr. belongs to the family Asteraceae (Compositae) subfamily
Lactucoideae tribe Lactuceae. It consists of about 18 species native to the mountains of
Europe, Asia, North Africa and North America. In the character of the pappus, Cicerbita is
closely allied to Wall Lettuce Mycelis Cass., Cephalorrhynchus Boiss and Steptorhamphus
Bunge. Mycelis is distinguished by its fewer involucral bracts, which are in two series, the
outer very inconspicuous, and by its yellow flowers. The long beak to the achene
distinguishes Cephalorrhynchus and Steptorhamphus. In Cicerbita the beak is absent or not
more than 0.5mm. The large genus Lettuce Lactuca L., in which all these small genera
including Cicerbita were once included, is distinguished by its pappus hairs all being of one
kind and more or less equal in length.
C. alpina is the only native species to the British Isles but three others, Common Blue-sowthistle C. macrophylla, (Willd) Wallr. subsp uralensis (Rouy) P.D.Sell, Hairless Blue-sowthistle C. plumieri (L.) Kirschleger and Pontic Blue-sow-thistle C.bourgaei (Boiss.) Beauverd,
have been recorded as naturalised (Sell, 1986). These three naturalised species are
distinguished by the following characteristics. C. plumieri is glabrous with a very scattered
distribution in England and Scotland as a result of garden escapes. C. bourgaei is not
rhizomatous with sparse, simple non-glandular hairs. It has a very scattered distribution in
England, Scotland and the Isle of Man as a result of garden escapes and appears to be on
the increase. C. macrophylla has lower leaves hairy on veins beneath with a cordate
terminal lobe and usually only a single pair of lateral lobes, panicles are wider, more or less
corymbose and achenes narrowly elliptical. This is another garden escape with a generally
lowland distribution but reaching 320m at Tomintoul.
3
1.3
GENETIC IMPLICATIONS
It is possible that there is a genetic issue that needs to be considered with regard to the
conservation of C. alpina in Scotland. Despite repeated efforts, collection of viable seed over
the last 20 years has not been successful. Seed collected has consistently been described as
‘shrivelled’ and has not germinated. Historically there is some evidence of viable seed being
produced in the latter part of the 19th century and the early part of the 20th century at
Coire Fee and Caenlochan, with samples of seedlings preserved at the Natural History
Museum, London. Seed production is described as sporadic in other parts of C. alpina’s
continental and Scandinavian range (J. Birks, pers. comm.), and viable seed production may
depend on seasonal variation. However, C. alpina of continental origin growing in a garden
south of Edinburgh is reported to seed prolifically every year (I. Bainbridge, pers. comm.).
Cicerbita plants of continental origin grow easily at the Royal Botanic Garden Edinburgh,
from seed that is sown in January or February in pots, and grown on in a cold glasshouse or
frame (R. McBeath, pers. comm.). As the species has a continental distribution, this would
suggest optimum conditions of hot summers and cold winters. Seedlings at Lochnagar were
observed in 1977 after the long, hot summer of 1976, which may have been significant.
Self-incompatibility (SI) is common in the Compositae (Richards, 1997). Work has been
undertaken by RBGE to assess whether populations are uniclonal, and to what extent they
are differentiated from one another, in order to assess if inbreeding depression could result
in reproductive failure (Oliver et al, 2000). The study used Randomly Amplified Polymorphic
DNA (RAPDs), analysed from plants sampled at the four locations in Scotland at which
Cicerbita alpina occurs. Although the number of individuals sampled from each extant
population limited interpretation of the results (see Table 1), the work showed that variation
exists between all populations and that all populations are genetically unique from each
other.
Table 1 - Number of genotypes identified at the four locations for Cicerbita alpina in
Scotland (Oliver et al, 2000).
SITE
Coire fee
Lochnagar
Coire
Kander
Caenlochan
NO.
INDIVIDUALS
SAMPLED
5
4
OF
NO. OF GENOTYPES
IDENTIFIED
1
2
9
3
1
n/a
However, even though different clones between populations were identified, these clones
may be of the same self-incompatible type and may not be compatible mating types.
Furthermore, the low level of within-population genetic variation, compared to betweenpopulation variation, indicates that mating events between close relatives are more likely.
Further work is required for clarification; although it is possible that population isolation is a
factor in the lack of seed production in Scotland.
4
2
2.1
Distribution & Current Status
WORLD
Cicerbita alpina grows in all the main mountain ranges of Europe, including the Pyrenees,
Alps, the Apennines and Balkans and throughout the mountains of Scandinavia, as well as
the Scottish highlands.
2.2
EUROPE
Cicerbita alpina was first described from Lapland in 1720 (Nordsted, 1920). It is a
widespread and locally abundant species of submontane birch and pine forest in Scandinavia
and in European mountain ranges southwards to the Pyrenees, northern Apennines and the
mountains of the Balkan peninsula (see Figure 2).
Figure 2 - European distribution of Cicerbita alpina. © Koeltz Scientific Books.
Nordhagen details associated species in Norway in fern-rich sub-alpine birch woods, lowalpine tall-herb vegetation, in sub-alpine Willow Salix scrub and in herb-rich sub-alpine birch
woods (Nordhagen, 1943). In western Norway, Cicerbita alpina seems to avoid the extreme
5
oceanic areas and tends to be found in the more continental inner fjord areas. It avoids the
west coast; like many boreal species, it tolerates or even needs high summer temperatures,
occurs in areas of cold winters and tends to be absent from areas with mild winters. Its
European distribution coincides with temperatures of –4oC in the coldest month for the
highest point in the 50 x 50 km grids of Atlas Flora Europaeae and annual maximum
temperatures for the highest point of 28oC (Dahl, 1998). Eastern Scotland is therefore right
at the western edge of a continental boreal climate with cold winters and warm summers
(Birks, pers. comm., 1996).
Its distribution in Europe differs from Scotland in being a mainly submontane species more
typical of damp, open, lightly grazed woodland and scrub in contrast to the steep mountain
crags of the Scottish sites. It is a characteristic species of Scandinavian tall herb meadows
and one of its synonyms, Lactuca alpina (L) A. Gray, lends its name to the alliance Lactucion
alpina (McVean & Ratcliffe, 1962) where moist conditions prevail. In Scandinavia, C. alpina
is commonly a ditchside plant. It is not a priority for conservation throughout the rest of its
range due to its common and widespread status.
2.3
UNITED KINGDOM
Cicerbita alpina is restricted within the UK to Scotland.
Figure 3 – Scottish distribution of Cicerbita alpina.
2.3.1
SCOTLAND
Cicerbita alpina was first discovered in Scotland in 1801 by George Don on one of the
precipitous ledges in the northeastern corrie of Lochnagar. The species is extremely local
and confined to 4 x 10 km squares at 4 locations in the Eastern Grampian mountains in
6
Angus (v.c. 90) and South Aberdeen. (v.c. 92) (see Figure 3). The species grows on north
or northeast facing or well-shaded ledges or gullies moistened by late snowmelt, between
approximately 600m at Coire Fee and 1000m at Lochnagar. Few other montane vascular
plants are confined to the eastern highlands of Scotland with the exception of Purple Colt’sfoot Homogyne alpina, which is a possible introduction known from one location in the Clova
Mountains, Angus. There is evidence (Gardiner, 1848 and Ewing, 1887 in Marren et al,
1986) that C. alpina occurred at more locations in the past within Caenlochan Glen, within
Glen Doll and at the lost site at Canness Glen. C. alpina in Scotland will have occurred as
part of the tall herb communities of the sub-alpine tree line communities. It is therefore
likely that its current limited distribution is a result of the increase in grazing pressure from
the late 19th century onwards, which has forced its retreat to inaccessible ledges.
SITE DESCRIPTIONS
Site details for the locations of Cicerbita alpina in Scotland are given in Table 2. C. alpina
sites are difficult to access and ropes are required for safety at Lochnagar and Coire Kander.
Once on site it can be difficult to locate the colonies and reference should be made to a
number of site reports (Alexander, 2000; Clarke & Clarke, 1995; Marren et al, 1986).
Table 2 - Site details for locations of Cicerbita alpina in vice-counties in Scotland.
LOCALITY
VICE COUNTY
(VC)
VC
NO.
NO. OF
COLONIES
6
Coire
Fee:
Glen Doll
Angus
90
Coire Kander
South
Aberdeen
92
Caenlochan
Glen
Angus
90
2
“several”
FLOWERHEAD COUNT
DATE
RECORDER
W. Gardiner
A.G. Payne
L. Alexander
200
67
1848
1979
1999
1866
1958
1977
c.155
c.165
c.58
1978
1979
1995
A.G. Payne
A.G. Payne
P & J Clarke
1999
1848
1975
1976
1977
1978
1979
1980
1981
1983
1984
L Alexander
W. Gardiner
F.H. Perring
C. Geddes
A.G. Payne
C. Geddes
NCC
NCC
C. Geddes
“
anon.
44
239
a) 176
b) 66
12
3
30
20
8
41
14
45
c. 35 plants
7
Ratcliffe
R.E.Randall
SOURCE
Marren et al 1986
“
Alexander 2000
Ratcliffe 1958
“
Marren et al 1986
“
“
Neiland & Wilcock
1996
Alexander 2000
Gardiner 1848
Marren et al 1986
“
“
“
“
“
“
“
SNH files
LOCALITY
Lochnagar
VICE COUNTY
(VC)
South
Aberdeen
VC
NO.
NO. OF
COLONIES
92
2 sites
3 sites
2
Canness glen
Angus
90
1
FLOWERHEAD COUNT
“Abundant”
“Part of dense
vegetation”
A: few; B: many
B: 30+
B: 42
A: 6; B: many
B: many; C: 2+
A: 3; B: 120+; C: 22+
A: 6; B: 160; C: 51
B: 222; C: 75+
A: 8; B: 311; C: 73+
B: 53; C: 50+
A: 7; B: 46; C: 15+
A: 3; B: 163; C: 85+
A: 50+; B: leafy
shoots only; C: 110
a) 110 b) 239
“large number”
2-4 annually
DATE
RECORDER
1801
1927
1932
G. Don
1972
1973
1974
1975
1976
1977
A.G. Payne; C.
Geddes
SOURCE
LINN. E.
Cairngorm Club
Journal Xi; p.314 &
XIII p.91
Marren et al 1986
“
“
“
“
“
1978
“
1979
1980
“
“
1981
1982
L Farrell; F Leney
1983
“
SNH files
Marren et al 1986
1985
AG Payne; P
Rothwell
SNH files
1999
1885
1937
1947-1976
L. Alexander
Alexander 2000
BM, Oxford
Holden 1952
Marren et al 1986
R.M. Adams
COIRE FEE
In the 19th century, Glen Doll was the best known and the most accessible of the C. alpina
sites with a least 6 colonies recorded. It was thought to have been lost from the glen until it
was re-discovered in 1979 by A. G. Payne in a narrow north-facing gully now referred to as
the Coire Fee site. The gully is cold, and the wet substrate comprises loose rock. Associated
species include Purple Saxifrage Saxifraga oppositifolia, Yellow Saxifrage Saxifraga aizoides
and Alpine Lady-fern Athyrium distentifolium. Plants grow profusely within the main gully
and on a ledge above the main gully to the right while climbing. A total of 239 flowering
stems were counted in 1999 (Alexander, 2000). A few young plants have also been
recorded below the chockstone.
COIRE KANDER
Cicerbita alpina grows on 2 ledges at Coire Kander. The site is steep, wet and very slippery
in places and ropes are required for safety. The plant grows vigorously on the lower northfacing ledge at about 840m and is co-dominant with Alpine Lady-fern Athyrium
distentifolium. In addition, a large colony of Athyrium distentifolium also grows just beneath
the ledge. Other associated species include Alpine Lady’s-mantle Alchemilla alpina, Wood
Crane’s-bill Geranium sylvaticum and Mountain Sorrel Oxyria digyna. A total of 176
flowering stems were counted in 1999 (Alexander, 2000). The upper ledge is above and to
the west and is smaller with a total of 66 flowering spikes counted in 1999 (Alexander,
2000).
CAENLOCHAN GLEN
Several colonies were known in the 19th century and according to Gardiner (1848) it grew
“in several places by the sides of streams at the head of Caenlochan Glen”. Only one colony
is known today and this is probably the best-known site for the species in Britain (Marren et
al, 1986). This population occupies a north west-facing ledge at about 840m with steep
overhanging rock walls on the southern and western sides. The site is very open and
8
exposed and limited by the extent of the ledge. The soil is stony but deep and rich, flushed
by water from ledges above. Associated species include Alpine Lady-fern Athyrium
distentifolium, Great Wood-rush Luzula sylvatica, Sheep’s-fescue Festuca ovina and
Hogweed Heracleum sphondylium. A total of 31 flowering stems were counted in 1999
(Alexander, 2000).
LOCHNAGAR
All of the known sites lay within the north east corrie in at least three main areas, all of
which are damp, shady gullies and rock chimneys or broad ledges kept moist by percolation,
and which often carry snow until later in the summer. Two colonies were counted in 1999.
The first lies in a cool, dark, west-facing gully with little direct sun. The main group in this
colony had 99 flowering stems with two separate smaller groups of five and six flowering
stems making a total of 110 flowering stems. The Cicerbita alpina is co-dominant with
Alpine Lady-fern A. distentifolium. The second colony is a broad north east facing ramp
sloping at about 45o and is one of the best known localities for C. alpina as the flowers can
easily be viewed from a distance. Associated species at this site include Tufted Hair-grass
Deschampsia cespitosa, Red Campion Silene dioica and Broad Buckler-fern Dryopteris
dilatata. A total of 239 flowering stems were recorded for this colony in 1999 (Alexander,
2000).
THE LOST SITE – CANNESS GLEN
This site for Cicerbita alpina was photographed in 1937 (Holden, 1952) when a large
number of flowering stems are evident. The site occurred beside the Canness burn and was
described as “well shaded with ‘bushy’ vegetation”. Access was described as difficult for
sheep and deer. The colony occurred on a rich, stony soil with Great Wood-rush Luzula
sylvatica. A small population of two to four flowering shoots persisted each year to the
1970s but since 1977 C. Geddes has recorded no plants during three monitoring visits in
August 1978, July 1995 and September 1999.
3
Ecology & Life Cycle
Flowering shoots rise annually from a rhizome and the flower buds usually open in late July.
The plant typically grows in large clumps and the broad, sagittate leaves cast a heavy
shade. When the flowers first appear they are an attractive shade of blue but they soon
wither to a dull bluish violet. Flowers open for at least one day but last longer if pollination
does not occur (Mejias, 1994), and wind and rainstorms often batter the plants by late
summer. The seeds are surmounted by a pappus of long, stiff hairs, but ripe seed is not
usually produced in Scotland. The species is pollinated by long-tongued bees and butterflies,
which seek the nectar in deep-seated nectaries (Willis & Burkhill, 1902). Hoverflies have
been observed on flowers (Alexander, 2000), and small tortoiseshell butterfly observed by
A.G.Payne (Marren et al, 1986). Knuth (1909) states that self-pollination within the flower
does not occur, although fertilisation between adjacent flowers may be possible.
Experiments at Aberdeen University (Neiland & Wilcock 1996a) have shown that seed
formation in Scottish populations is a rare event and examination of herbarium material,
dating back to 1837 from Glen Doll, suggests that this has been the case for a long time. In
contrast, seed set in central European and Scandinavian populations appears to be much
more frequent, although Cicerbita alpina is more common there and cross fertilisation is
more likely. Neiland and Wilcock (1996a) concluded that the reproductive biology in
Scotland is probably different, although the mechanisms remain unclear. For example, it is
not clear whether pollen from C. alpina in Scotland is intrinsically infertile or whether, as
Sell (1986) has suggested for C. macrophylla, subsp. uralensis, there is a selfincompatibility system operating to prevent fertilisation by self-pollen (see section 1.3).
9
While Stace (1997) states that C. alpina is not rhizomatous, Neiland and Wilcock (1996a)
demonstrated that the plant has a rhizome, which in the examined specimen was at least
eight years old. Marren et al (1986) also reflect that the clumped habit of a Scottish colony
is likely to signify clonal propagation.
4
4.1
Habitat Requirements
THE LANDSCAPE PERSPECTIVE
GEOLOGY & SOILS
The geology of the C. alpina sites is complex. Although the soils associated with C. alpina
have not been exhaustively analysed, these soils are probably analogous to those of other
tall herb associations on mountain ledges which are typically periodically irrigated, skeletal
brown loams and mull humus and slight podsolization. The ledges on which C. alpina grows
usually carry luxuriant vegetation. The parent rocks are all acidic but they commonly
contain base-rich intrusions. The parent material at Coire Kander is syenite, acid granite
with prophyritic crystals of quartz and felspar. The Lochnagar sites occur within or close to
gullies containing crushed rock associated with fault zones where the typical grey or pink
Lochnagar granite is replaced by cream or greenish, heavily weathered rock in which the
base-rich minerals epidote and calcite may be frequent (Marren et al, 1986). There is a
strong likelihood that nutrients are transported to the C. alpina sites from base-rich rocks
both by percolation and by rock falls. Ellenberg Indicator values (Hill et al, 1999) for C.
alpina are as follows:
Light – LO=6; LO=7+
Moisture – FO=6; F=6
Reaction – RO=6; R=6
Nitrogen – NO=8; N=6
Salt – SO=0; S=0
ASPECT
Cicerbita alpina grows in moist mountain rock-ledges and gullies. It is found in Scotland in
areas with richer soils, winter snow accumulations and summer moisture at high altitudes
with severe winters. Its sites in Scotland are all on north and east facing slopes where snow
cover is likely to be more reliable and longer lasting. As a consistent feature of its European
habitats, winter snow cover protects plants from winter frosts and additional moisture in
early summer. However, C. alpina does not seem suited to the exposures it receives in
these montane locations and by the time flowering occurs in July and August the plants are
often battered and have browning leaves.
4.2
COMMUNITIES & VEGETATION
Cicerbita alpina typically occurs with a mix of tall herbs and Alpine Lady-fern Athyrium
distentifolium, a species of late snow–beds that is a frequent associate of C. alpina in its
higher sites. Other species which are usually present in abundance are Hogweed Heracleum
sphondylium, Lady’s-mantle Alchemilla glabra, Tufted Hair-grass Deschampsia cespitosa,
Broad Buckler-fern Dryopteris dilitata, Great Wood-rush Luzula sylvatica, Wood-sorrel Oxalis
acetosella, Common Sorrel Rumex acetosa and Goldenrod Solidago virgaurea. A fuller list of
close associates is given in Marren et al (1996). The ledge vegetation with which C. alpina
grows is related to the NVC CG13a Dryas octopetala – Carex flacca heath community
(Rodwell, 1992). On more accessible areas next to current C. alpina populations, modified
versions of this community continue to exist, suggesting that C. alpina may also have
10
occurred here. C. alpina is listed as a component of the U16 Luzula sylvatica –
Vaccinium myrtillus tall herb community (Rodwell, 1992; Averis et al, 2004).
In Europe, C. alpina is more widespread above the tree line, but also occurs below the tree
line in open upland woodland, alpine meadows and avalanche trails.
GRAZING
In Scotland, Cicerbita alpina only grows in places where grazing is minimal. The plant is
extremely palatable to large herbivores, notably sheep and deer, and mountain hares have
been observed eating it in Scotland. The tall herb communities of which C. alpina is a
component can be visually dramatic in terms of their lush growth, in stark contrast to
surrounding plant communities that are accessible to grazing animals.
5
Management Implications
Cicerbita alpina has managed to sustain itself at four of its five historic sites in Scotland
over the last few hundred years, reflecting some kind of stability. However, the habitat in
which it survives is climatically fragile, and under current climate change predictions, will
decline in range. Its rock ledges are also susceptible to rockfall and unstable slopes. In
addition, current populations may be too isolated to allow sexual regeneration and the
production of viable seed. However, conservation of C. alpina in Scotland depends largely on
grazing management that would:
Maintain populations by ensuring that current populations are not grazed. No other
management seems necessary to protect current populations, given their longevity
to date.
Create suitable, adjacent habitat for future spread and increase chances for
population survival in the future.
Management for this species offers very real opportunities to improve the conservation
status of this species:
Habitat conservation should focus on restoring a lightly grazed mountain habitat that
could ultimately include areas of open upland woodland with tall herbs. This may
enable C. alpina to expand out of its relic sites into areas that are more akin to its
stronghold sites in Scandinavia, and allow it to increase population size and genetic
integrity in the face of environmental change. This would mean controlling grazing at
current sites, and preferably at adjacent sites that are suitable for colonisation and
spread either naturally or by introduction of plant material. At its current locations C.
alpina grows vigorously in association with other tall herbs and it is likely that it
would compete successfully against other herbaceous species if grazing pressure
were reduced.
Species management needs to ensure sufficient stock is held ex situ to allow
continued experimentation and research, and to support translocation trials where
appropriate and possible.
6
Threats / Factors Leading to Loss or Decline or Limiting Recovery
Although of an extremely restricted distribution today, Cicerbita alpina may have been less
restricted for most of the Holocene period, before the increase in grazing pressures from the
11
19th century. However, evidence of early to mid Holocene distribution of this plant is
difficult to find as the pollen of C. alpina is indistinguishable from certain other members of
the Asteraceae family (Bennett, 1994). It is clear that colonies have been lost since records
began and there may be a number of explanations for this, including: the isolation of
populations; increased sheep and deer grazing pressure; over collecting; one-off events,
and the vagaries of climate. The key factors limiting the current and future distribution of C.
alpina are as follows:
C. alpina appears to be at the western limit of its climatic tolerance in Scotland.
Grazing pressure by sheep and deer restricts the distribution of the plant to
inaccessible ledges and gullies: control of grazing has been initiated at three of the
sites and this may reap benefits in the longer term, as long as robust monitoring
protocols are in place.
Population isolation, genetic self-incompatibility and inbreeding depression may be
resulting in no viable seed being produced: research undertaken by the Royal
Botanic Garden, Edinburgh has given some insight into the genetics of the four
populations but further research is required with larger numbers of samples.
Populations are susceptible to rockfalls potentially wiping out entire colonies.
Over-collection in the past, although this is no longer considered an issue.
As C. alpina is not a UK Biodiversity Action Plan Species, the resources available for
research and management are limited.
The unknown effects of climate change: Kerr et al (1999) used the UKCIP98 climate
scenarios to investigate climate impacts in Scotland for the Climate Change: Scottish
Implications Scoping Study. These scenarios (Hulme and Jenkins, 1998) suggest that
over the next century, Scotland will become warmer. Average temperatures are
likely to rise by between 1.2 to 2.6°C, with relatively more warming in winter than
summer. It is not known what impact this kind of scenario would have on C. alpina
but the effect may be to minimise the continental type conditions which prevail
within the area of distribution of C. alpina and on which the species appears to
depend.
7
7.1
Current Conservation Measures
IN SITU MEASURES
COIRE FEE
Coire Fee is included in a Section 7 area agreement for deer control, which includes Coire
Kander and Caenlochan Glen. This has been in operation since 2002 and the effects of this
will become apparent in the longer term. Another current proposal for the species at Coire
Fee being discussed between Scottish Natural Heritage (Airlie) and the Angus Glens Ranger
Service is to uproot some plant material under licence for introduction into a 64ha exclosure
in Corrie Sharroch (K. Slater & I. Langford, pers. comm.).
COIRE KANDER
Coire Kander is included in the deer control area, as above, and the C. alpina may benefit in
the longer term being able to establish on other more accessible ledges.
12
CAENLOCHAN GLEN
There is much evidence that grazing intensity has increased markedly in Caenlochan Glen
over the past 200 years. The main evidence for this comes from pollen analysis, which
shows that during the last two hundred years, grass pollen has increased significantly while
pollen from other species has decreased (Loizou, 1999). Reduction of grazing is a priority
for the SSSI and this is being addressed through the Section 7 agreement. Additional
grazing pressure from sheep coming in from the neighbouring estate of Invercauld is being
addressed through the Scottish Executive. There does appear to be a very welcome
concerted effort to reduce grazing pressure over a huge area covering these three Cicerbita
sites.
LOCHNAGAR
There is currently no monitoring of C. alpina populations at Lochnagar. The deer
management strategy on the Balmoral Estate aims to sustain a level of 12 deer per km2,
which has almost been achieved, but it is unlikely that this level of grazing would allow C.
alpina to expand to any great extent.
7.2
EX SITU MEASURES
SEED BANKING
Cicerbita alpina seed is not currently stored in the Millennium Seed Bank at Kew, owing to
the lack of production of viable seed in the field.
MATERIAL HELD IN CULTIVATION
Rootstock was collected in 1996 from Lochnagar and Coire Fee and grown on at the
Aberdeen University Cruikshank Gardens. The plants doubled in sized between 1996 and
1998 but had not flowered during this time. Unfortunately these 2 plants have since been
lost. Plant material collected from Lochnagar and Coire Kander in 1998 is still held at the
Royal Botanic Garden, Edinburgh and this is being bulked up for re-introduction where
possible. It would, in addition, be useful to collect material under licence from the remaining
2 sites – Caenlochan and Coire Fee. The best method of propagation is by division of the
rhizomes in spring, i.e. March or April, or taking root cuttings, which should allow
approximately 12 plants to be generated from each source plant over a period of 2 years (J.
Mitchell, pers. comm.).
7.3
MONITORING CICERBITA ALPINA &
THE
COMMON MONITORING STANDARD
Methods for monitoring have changed over time and previously a combination of counting
flowering stems, non-flowering stems and the number of clumps was undertaken. It is
recognised (Geddes pers. comm.), that monitoring by counting flowering and/or nonflowering stems can result in damage to the plants and disruption to the substrate. In order
to clarify whether the plants are still present and flowering it is possible to observe the
colonies from a distance during the second half of July and August when the blue of the
flowers can be seen through binoculars. However, field counts have been shown to vary by
between 10-15% between individuals monitoring colonies using this method, so
standardised vantage points plus the use of a margin of error should be included (Scott,
1996).
The distant count method is the technique used by Scottish Natural Heritage for monitoring
the Coire Kander site. C. alpina is a notified feature for the Glen Callater SSSI of which Coire
Kander is a part and which will be included in Site Condition Monitoring as part of European
requirements for monitoring on a 6-yearly cycle. Last monitored in 2002 this will be
repeated in approximately 2008. C. alpina should also form part of the national vascular
13
plant tall herb monitoring contract in 2004 for the notified features on the Glen Callater
SSSI.
The population at Coire Fee is not routinely monitored but the Angus Glen Rangers may be
able to undertake this work.
There is currently no monitoring at Lochnagar. The Balmoral Estate Ranger Service may
undertake monitoring but this is yet to be confirmed.
Monitoring by Scottish Natural Heritage at Caenlochan Glen is problematic due to
restrictions on access imposed by the estate and no monitoring has been undertaken since
1999 at this site.
7.4
RECOMMENDATIONS FOR FUTURE WORK
GENETIC RESEARCH Further work is required to sample more plants, to sample any
material which could originate from seed, and to undertake experimentation in
controlled crosses in cultivation to either produce viable seed or to confirm
inbreeding depression. If there are no differences in levels of seed set between
crosses involving genetically clearly differentiated parents, and those involving
genetically similar parents, then other explanations should be sought for lack of
successful seed set in the wild. Genetic research would further clarify genotypes
present and the extent of intra-population variation.
RESEARCH INTO POLLINATION AND SEED SET The reasons behind the lack of seed set from
fertile seed in Scotland need to be clarified. For example, seed set may be restricted
by self-incompatibility and/or resource limitations. Pollen from C. alpina in Scotland
may either be intrinsically infertile, or there could be a self-incompatibility system
operating to prevent fertilisation of self-pollen, as proposed by Sell (1986).
Alternatively, low seed set could be a result of problems at a post-pollination or postfertilisation stage. It would also be useful to set up hand pollination experiments in
the field to test these hypotheses, as well as conducting experiments on material
already in propagation at the Royal Botanic Garden, Edinburgh.
RESEARCH INTO VEGETATIVE SPREAD It would be useful to assess whether vegetative
spread does occur in Scotland as this has important management implications.
POPULATION MONITORING There is a need for a standardised procedure that would be
based on counting flowering heads from a distance to minimise disturbance, but from
a permanent vantage point (recognised through a Global Positioning System [GPS]
reading for example) and including a 10% margin of error. It might be possible to
find a calibration for this technique by comparing distance counts with actual counts
conducted by an appropriately trained climber.
EX SITU MEASURES Efforts should be made to collect material from all sites, to preserve
the genetic variation of Scottish populations, and to provide material for bulking up
for further research and translocation. This material should in the first instance be
vegetative.
MONITORING OF GRAZING Monitoring of the effects of exclusion of large herbivore
grazers, and mountain hares, should be standardised and maintained.
14
TRANSLOCATION EXPERIMENTS Suitable sites for translocation of bulked up material from
the Royal Botanic Garden Edinburgh, subject to IUCN guidelines, should be
identified. Established plants should be used in these translocations, as meticulous
after-care is likely to be impossible. If cross-pollination is demonstrated to be
important in the production of viable seed, then translocations of mixed populations
into current sites should be considered.
RE-INTRODUCTION INTO THE LOST SITE AT CANNESS GLEN C. alpina was last recorded at
Canness Glen in 1976, when four flowering stems were recorded (C. Geddes, pers.
comm.). There is potential to establish plant material from the Caenlochan ledge in
the tall herb community where it was originally recorded.
WOODLAND INTRODUCTION The feasibility of an introduction of C. alpina into a woodland
site more typical of its continental and Scandinavian habitat was undertaken as part
of the Action Plan research for Scottish Natural Heritage (Alexander, 2000). Two
woodland sites were proposed in this report – Morrone National Nature Reserve and
a wooded gully on the Balmoral Estate. Neither of these proposals has been further
investigated and there is resistance in principle to introductions where there is no
recorded evidence of past presence. Further debate on this issue would be useful to
resolve how we conserve and manage species whose habitat has been completely
altered by human activity over time.
UPLAND WOODLAND & TREE-LINE REGENERATION C. alpina should be included at
appropriate regeneration sites where the relevant lost habitat is being re-instated.
This would be useful both as a conservation practice to extend and consolidate its
range but also at some sites to increase public understanding.
ECOLOGICAL RESEARCH Research into the ecological requirements of C. alpina on the
continent and any management work being undertaken there would be useful in
informing conservation activity in Scotland.
8
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9
Acknowledgements
Thanks to Claire Geddes, Michael Scott, Chris Sydes, Lynne Farrell and Peter Marren for
their valuable comments on this dossier, to Peter Hollingsworth for generously providing
additional information, and to Plantlife Scotland volunteer Jill Williams for her editorial work.
10 Contacts
Back from the Brink contact:
Dr Deborah Long, Conservation officer,
Plantlife Scotland
SNH Species Recovery Programme:
Dr Chris Sydes, Species Group Manager,
Scottish Natural Heritage.
Plantlife Scotland, Balallan house, Allan Park,
Stirling, FK8 2QG
Tel: +44 (0) 1786 478509
Fax: +44 (0) 1786 479382
[email protected]
Scottish Natural Heritage, 2 Anderson Place,
Edinburgh, EH6 5NP
Tel: +44 (0) 131 447 4784
Fax: +44 (0) 131 446 2405
[email protected]
11 Links
Plantlife International wishes to acknowledge the financial support of Scottish Natural
Heritage, the Countryside Council for Wales and English Nature, for the Back from the Brink
(species recovery) programme.
ISBN: 1 904749-15-1
Original draft by Leonie Alexander
Edited by Plantlife Scotland
First draft dated March 2004
Last revised 20 March 2006
17