Lejeunea mandonii (Steph.) Müll.Frib.

Atlantic lejeunea LEJEUNEACEAE SYN.: Microlejeunea mandonii Steph., Lejeunea macvicari Pearson, Inflatolejeunea mandonii (Steph.) Perss.

Status Bryophyte RDB - Endangered (2001) English Nature Species Recovery Status in Europe: Rare BAP Priority Species Lead Partner: Plantlife International

UK Biodiversity Action Plan This is the current BAP target following the 2001 Targets Review: T1 - Maintain at all known, new or re-discovered sites. Progress on targets as reported in the UKBAP 2002 reporting round can be viewed online at: http://www.ukbap.org.uk/2002OnlineReport/mainframe.htm The full Action Plan for Lejeunea mandonii can be viewed on the following web page: http://www.ukbap.org.uk/asp/UKplans.asp?UKListID=406. Plantlife published an Expanded Species Action Plan for Lejeunea mandonii in 1999.

Contents 1 Morphology, Identification, Taxonomy & Genetics................................................2

1.1 Morphology & Identification ........................................................................2 1.2 Taxonomic Considerations ..........................................................................4 1.3 Genetic Implications ..................................................................................4

2 Distribution & Current Status ...........................................................................5 2.1 World ......................................................................................................5 2.2 Europe ....................................................................................................5 2.3 United Kingdom........................................................................................6

2.3.1 England .............................................................................................6 2.3.2 Northern Ireland..................................................................................7 2.3.3 Scotland.............................................................................................7 2.3.4 Wales ................................................................................................7

3 Ecology.........................................................................................................8 4 Habitat Requirements .....................................................................................9

4.1 The Landscape Perspective.........................................................................9 4.2 Communities & Vegetation .......................................................................14 4.3 Dispersal & Strategy................................................................................15 4.4 Habitat Requirements in the UK - Conclusion ..............................................15

5 Threats / Factors Leading to Loss or Decline of Recovery....................................15 6 Management Implications ..............................................................................16 7 Current & Future Conservation Methods...........................................................17

7.1 In Situ Measures....................................................................................17

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http://www.plantlife.org.uk/http://www.ukbap.org.uk/2002OnlineReport/mainframe.htmhttp://www.ukbap.org.uk/asp/UKplans.asp?UKListID=406

7.2 Ex Situ Measures ...................................................................................18 7.3 Research Data ........................................................................................18 7.4 Monitoring Lejeunea mandonii & the Common Monitoring Standard................18

8 References ..................................................................................................18 9 Acknowledgements .......................................................................................20 10 Contacts...................................................................................................20 11 Links........................................................................................................20 12 Appendix 1. ..................................................................................................21

1 Morphology, Identification, Taxonomy & Genetics

1.1 MORPHOLOGY & IDENTIFICATION ‘Atlantic lejeunea’ (Lejeunea mandonii) is a small leafy liverwort that grows on basic rocks and tree bark. It has been found at only a few sites in Britain, located on the Lizard Peninsula of west Cornwall and in western Scotland. Elsewhere, it has been reported only from Ireland, Madeira, the Canary Islands, Portugal and western Spain. Its stems are very slender, usually less than 10mm long and form low or prostrate, bright yellow-green patches, often growing over low mosses. The leaves are in three ranks, comprising two rows of broadly lingulate leaves that each has a smaller, appressed antical lobe, and one row of much smaller bilobed underleaves. Distinction from allied species relies on careful appraisal of leaf shape, number and size of oil-bodies in the leaf-cells and the smooth perianth.

Figure 1 - Photomicrograph of Lejeunea mandonii. (Photograph by Natural History Museum).

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http://www.nhm.ac.uk/

Figure 2 - Photomicrograph of leafy stem of Lejeunealamacerina, a common species that differs from L. mandonii inlarger size and rounder postical leaf lobes. (Photograph by DavidHolyoak).

Figure 3 - Photomicrograph of mid-leaf cells ofLejeunea lamacerina showing four or five oil-bodies per cell. Lejeunea mandonii has morenumerous and smaller oil-bodies. (Photographby David Holyoak).

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Considerable care is needed to distinguish Lejeunea mandonii from other Lejeunea species and confident field identification only becomes possible after prolonged familiarity with them. ‘The Liverwort Flora of the British Isles’ (Paton, 1999) should be consulted for illustrations and detailed descriptions of all British Lejeuneaceae. Lejeunea (including Lejeunea mandonii) and Microlejeunea species are distinct from other British genera of Lejeuneaceae in the form of the underleaves. Of the Lejeunea species occurring in Cornwall, L. cavifolia differs microscopically in having the oil-bodies in each leaf cell much more numerous, smaller and glistening. L. lamacerina and L. patens have fewer, larger oil-bodies (commonly 4-6, sometimes 10 per cell) much as in Lejeunea mandonii (which has 8-13, rarely up to 23 per cell), but both of those species are larger with the postical leaf-lobe normally more rounded (broadly ovate, compared to broadly lingulate in Lejeunea mandonii) (see Figures 1-3). The perianth of Lejeunea mandonii is smooth whereas those of other Lejeunea species occurring in Cornwall are five-angled or winged above, but no Lejeunea mandonii perianths were seen in Cornwall in 1997-2004. Lejeunea mandonii is considerably larger than Microlejeunea ulicina and Cololejeunea minutissima. Given familiarity with both species, Lejeunea mandonii can be distinguished in the field from L. lamacerina using a x10 (or better, x20) hand lens by its combination of narrower and more curved postical lobes and smaller size. Well-grown plants of L. patens and L. cavifolia tend to resemble L. lamacerina more than the smaller Lejeunea mandonii. Some patches of both L. lamacerina and L. mandonii can have very slender stems with small leaves and when attenuated, shaded stems of all these species tend to produce leaves that are longer than usual. The size and leaf-shape of Harpalejeunea molleri closely resemble those of Lejeunea mandonii, but its underleaves are quite different. In Cornwall both Harpalejeunea molleri and Lejeunea patens are rarities that infrequently confuse identification of Lejeunea mandonii, but this is not the case in Scotland or western Ireland and it is therefore much more difficult if not impossible to obtain reliable field identifications of Lejeunea mandonii in those regions. In recognition of these difficulties, identifications need to be checked microscopically and voucher specimens should be retained. With these Lejeunea it is important that voucher specimens are sufficiently large to show variability in leaf-shape and that counts and descriptions of the ephemeral oil-bodies are made and carefully recorded before the plants are dried.

1.2 TAXONOMIC CONSIDERATIONS Taxonomically, Lejeunea mandonii is the only European species in Subgenus Inflatolejeunea (S. Arn.) Schust. (Grolle 1983: 422). K. Müller published its name as the combination used here in Rabenhorst’s Krypt. -Fl. Deutschl., ed. 3, p. 1281 (1958), shortly before the same combination was proposed by E.W. Jones (1958). The older records in Britain were given as L. macvicari Perss., but Persson noted that this is the same as the earlier Lejeunea mandonii from Madeira (Jones 1958: 373).

1.3 GENETIC IMPLICATIONS There is no information on population genetics of Lejeunea mandonii (e.g. from isozymes) and no genetic data (e.g. from DNA sequences) on its affinities to closely related species.

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2 Distribution & Current Status

2.1 WORLD Known only in Europe (including Macaronesia).

2.2 EUROPE Restricted to the Atlantic seaboard of western Europe and Macaronesia, with records from southwest England (Cornwall), western Scotland, Ireland, Portugal (mainland and Madeira) and Spain (mainland and Canary Islands). IRELAND Known in the Republic of Ireland only in three hectads (Hill et al, 1991: 262), all the records having been made since 1963, so presumably the species is still likely to be under-recorded. The Irish records are as follows: v.-c. H1: South Kerry: 'among boulders S. of Brandon Mt., Dingle, J. Fitzgerald, Aug. 1967' (Paton 1968: 628). v.-c. H2: North Kerry: 'shaded rock below Torc Cascade, Killarney, J.A. Paton, Aug. 1966' (Paton 1967: 404). v.-c. H29: Leitrim: 'shaded limestone rock crevices at 900ft alt., Peakadaw, Glenade, J. Fitzgerald & A.R. Perry, July 1963- New to Ireland' (Paton 1964: 721). PORTUGAL Jovet-Ast & Bischler (1976: 977-978) give: ‘Locality 185, Estremadura, Serra de Sintra, parc abandonné vers Penha Longa. 250m. 27.V.1969. Forêt de Q. suber’; they also cite an occurrence in the Algarve (p. 978). PORTUGAL (MADEIRA) This is the locality type (Jones 1958: 373). Listed by Eggers (1982: 290) and by Duell (1983: 70) [confirmed by correspondent]. SPAIN Buch (1934) records it at El Grove in Prov. Pontevedra. Jovet-Ast & Bischler (1976: 978) cite records in provinces Cadiz, Coruña and Pontevedra. Reinoso (1985: 20) records it under laurels on the Rio Rodeiro in the Fraga de Caaveiro, Prov. La Coruña [Galicia]. Albertos et al. (1997: 306) record it as occasional on rocks and soil in a relict ripariangrove of Prunus lusitanica at Poyales del Hoyo, Sierra de Gredos, Prov. Ávila. SPAIN (CANARY ISLANDS) Eggers (1982: 290) lists La Palma and Tenerife. Listed by Duell (1983: 70) [confirmed by correspondent]. Dirkse et al. (1993: 6-7) accept records for Gran Canaria, La Palma and Tenerife, giving following details: Gran Canaria (new record): Barr. de los Tilos, Los Tilos de Moya (400-500 m), 1989, GMD[irkse] 006291; La Palma (first reported from here in error as L. hibernica Bischl. et al. ex Grolle by Long et al. 1981). La Palma: Barr. de la Galga (350-500 m), 1990, GMD[irkse] 006660. On La Palma, common in lauriphyll forest on study area (González-Mancebo and Hernández-García 1996: 253).

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Table 1 – Country by country status of Lejeunea mandonii across Europe.

COUNTRY* STATUS STATUS NOTES SOURCE (S)

Br BRITAIN INCL. ORKNEY, ZETLAND & ISLE OF MAN

Rare ECCB (1995).

Hb IRELAND NORTHERN IRELAND & THE REPUBLIC OF IRELAND

Rare ECCB (1995).

Hs SPAIN GIBRALTAR & ANDORRA, EXCL. BL

Rare ECCB (1995).

Lu PORTUGAL

Rare ECCB (1995).

*Country codes are taken from Flora Europaea as of 1964. IUCN threat categories as revised by European Committee for Conservation of Bryophytes, 1995.

2.3 UNITED KINGDOM OVERVIEW In Britain Lejeunea mandonii is known only from a few localities on the Lizard Peninsula in Cornwall [England] and a few localities in western Scotland as represented in Figure 4.

2.3.1 ENGLAND Results of extensive search of literature and herbarium records were given in a report by Holyoak (1998). The three previously known sites were relocated in 1996-1998. During 1997-1999 all areas inland of the coast of the Lizard Peninsula with substantial (>2m tall) exposures of serpentinite and gabbro rock were visited and searched for Lejeunea mandonii, and two ‘new’ sites resulted from these searches during 1997. No more completely new sites were found during searches in 1998 and 1999, although several additional ‘patches’ were found in both years at or near the known sites. The five sites (or groups of sites) now known in Cornwall are as follows (precise details being withheld because the species is vulnerable to thoughtless collecting): (a) Kynance Farm NNR, SW68-13-; (b) Bonython, SW69-20-; (c) Poltesco, SW72-15-; (d) Gwendreath, SW73-17-; (e) Trevenwith, SW73-17-. During June-October 1997 the area (in cm²) of all individual patches of Lejeunea mandonii at its Cornish sites was estimated on the basis of measurements (mm) using a transparent plastic ruler. Because of uncertainty regarding the precision and reproducibility of the 1997 estimates, comparative data was collected in November 1998 and subsequent years using a transparent overlay marked with 1cm squares. Repetition of measurements using the transparent overlay suggested an accuracy of ± 5-10% was achievable where Lejeunea mandonii forms pure patches, but lower accuracy where it occurs intermixed with mosses so that its contribution to the total cover must be estimated. Further information on the methodology used for marking and monitoring the Cornish populations is given in the Appendix, which consists of a sheet which may be issued separately to site managers (Guidelines for in situ monitoring of populations of Atlantic lejeunea, Lejeunea mandonii).

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In late 1998 most individual patches in Cornwall were marked with small plastic labels, consisting of a 2x 1cm plastic strip to which a Dymo letter was attached. Most of these labels were still present in late 2001, although a few had been lost or had fallen because the twigs or ivy stems to which they had been attached had decayed. Although the surviving labels were still in good condition in 2001, most were replaced because the wire fixings had become corroded. The new labels were attached with thin ‘rot-proof’ garden string in positions far enough from the Lejeunea mandonii to avoid ill effects (from chemicals leaching from labels or string). By late 2003 many of these labels needed replacement. Annual repetition of the measurements of patches from 1997 to 2003/4 have shown erratic fluctuations at most sites, but a worrying declining trend at Bonython which was the most important group of populations in 1997 was identified. Total cover (in cm²) declined steadily: ca 6519 in 1997, 4343 in 1998, 3185 in 1999, 2473 in 2000, 1544 in 2001, 2058 in 2002, to 1170.5 in January 2004. The only break in the declining trend was in 2002 and this was not maintained in 2004. Since 1997 several large patches have been completely lost and others have been reduced to a few stems, with the few new patches found failing to compensate for the losses.

2.3.2 NORTHERN IRELAND Not recorded.

2.3.3 SCOTLAND Recorded from two vice-counties (97 and 104): v.-c. 97: Westerness (Corley & Hill 1981: 53); [= W. Inverness of Smith 1990: 270]. Atlas shows two hectads, NM75 (post-1950) and NM77 (pre-1950) (Hill et al. 1991: 262). Birks (1974: 124) also shows NM76, but presumably that was an error, as it was later removed. Currently known only at two sites (both in hectad NM67), with several hundred shoots on a single Ash tree at each location. v.-c. 104: North Ebudes (Corley & Hill 1981: 53). On Skye recorded as new vice-county record by Paton (1970: 194) 'on shaded limestone, seacoast, Elgol Peninsula, Isle of Skye (104), Birks & Birks, July 1967'. Described as restricted to a single locality in the Elgol Peninsula, NG51 (Birks & Birks 1974: 57). Atlas shows two localities in Skye, post-1950 in NG51 and NG61 (Birks in Hill et al. 1991: 262). Currently known only in hectad NG61 with two patches (of 900cm² and 200cm²) on a single Ash tree. Gordon Rothero is continuing studies of the species at Scottish sites on behalf of SNH.

2.3.4 WALES Not recorded.

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http://www.snh.org.uk/

Figure 4 - British distribution of Lejeunea mandonii.

3 Ecology Lejeunea mandonii is an oceanic species, which is limited to those areas of Britain with a combination of a higher number of wet days per annum and a low number of days with

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frosts. Even within this area the plant appears to be restricted to humid sites with some degree of shading. However, it avoids places that are regularly inundated and prefers rather drier sites where there is a constant humidity, at most only a periodic irrigation. All the British locations are essentially coastal and at low altitudes but one Irish site in Co. Leitrim is at 360m. Ratcliffe (1968) includes Lejeunea mandonii in his list of southern Atlantic oceanic bryophytes. The liverwort grows on both rocks and trees but the substrate would always appear to be at least somewhat basic, recorded substrates being limestone, serpentinite, calcareous schist and Old Red Sandstone and from the Ulmus glabra and Fraximus excelsior in Moidart. All the Scottish sites seen in 1996 were on the Fraximus excelsior in fairly open ravines on markedly calcareous rock, with a southerly or westerly aspect, where humidity remains high but there will also be a good level of isolation. Lejeunea mandonii is autoecious and herbarium material usually has a number of perianths but this may reflect selective gathering of material. At best perianths are probably occasional and sporophytes appear to be decidedly rare. There is no specialised means of vegetative spread.

4 Habitat Requirements

4.1 THE LANDSCAPE PERSPECTIVE Detailed investigations into the habitat preferences of Atlantic lejeunea in Cornwall were made from 1997-1999 because an understanding of the requirements of the species may be vital to its conservation management, as well as offering guidance in attempts to locate new sites. Holyoak published detailed data on its habitats outside Cornwall and these are summarised here (Holyoak, 1998, 1999). HABITATS IN EUROPE In Galicia, northwest Spain, Reinoso (1985: 20) records it under laurels [= Prunus lusitanica] on the Rio Rodeiro in the Fraga de Caaveiro, Prov. La Coruña. In west-central Spain, Albertos et al. (1997: 306) record it as occasional on rocks and soil in a relict riparian grove of Prunus lusitanica at Poyales del Hoyo, Sierra de Gredos, Prov. Ávila. For Portugal, Jovet-Ast & Bischler (1976: 977-978) give a locality in ‘Estremadura, Serra de Sintra, parc abandonné vers Penha Longa. 250m’. as within ‘Forêt de Q. suber’, i.e. in cork-oak woodland. On La Palma, Canary Is. (Gonzalez-Mancebo & Hernandez-Garcia 1996), Lejeunea mandonii is reported as common in lauriphyll forest and rare in Erica-Myrica woodland; also in earthwalls of a cutting for a forestry track (p. 253). The lauriphyll forest was in a ravine at 450-850m; it was described as sub-tropical broad-leaved evergreen forest, with trees up to 15m tall, shading 90% or more of soil surface [see their paper for list of trees]. The Erica-Myrica woodland was on slopes at 850-1200m; it comprised a dense tree and shrub formation, basically of Myrica faya and Erica arborea [see paper for details]. From Ireland, in v.-c. H1, 1st record (see above) was given by Paton (1968: 628) as ‘among boulders, S. of Brandon Mt.’; in v. -c. H2, 1st record (see above) given by Paton (1967: 404) as ‘shaded rock below Torc Cascade’; in v. -c. H29, 1st record (see above) given by Paton (1964: 721) as ‘with Cololejeunea rossettiana, shaded limestone rock crevices at 900ft alt., Peakadaw, Glenade’. HABITATS IN SCOTLAND In Scotland, on Elgol Pen., Skye, at a single locality ‘occurs with Marchesinia mackaii on dry but shaded Jurassic limestone rocks in a large sea-cave’ [15m a.s.l.] (Birks & Birks 1974: 57). Paton (1970: 194) similarly gives it as ‘with Marchesinia on shaded

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limestone, seacoast’. More recently, Gordon Rothero (pers. comm. 1997-1999) reported its survival at three Scottish sites on single trunks of Ash (Fraxinus excelsior) trees. John Birks knew the species in both Skye and Cornwall and contributed the account for the National Atlas (Hill et al. 1991: 262), which states ‘On shaded but dry or periodically irrigated N. or E. facing rocks or cliffs in wooded ravines, sheltered sea caves or woods; on shaded N. facing limestone cliffs; and on sheltered coastal rocks. It frequently grows with other hepatics such as Frullania spp., Lejeunea spp., Marchesinia mackaii and Radula spp. The substrate is invariably basic (limestone, serpentinite, calcareous Old Red Sandstone, schist). It also occurs, more rarely, growing with other hepatics on Elm and Ash trees and on rotting logs in shaded ravines, near sea-level in its Scottish and English localities, extending to 360m in Co. Leitrim.’ That account was largely derived from an earlier one by the same author (Birks 1974). HABITATS IN ENGLAND (CORNWALL) Older records in Cornwall (Holyoak 1998) were mainly in close association with outcrops of serpentinite, such as those in Figure 5, or on old retaining walls of serpentinite, where many of the associated plants are basiphiles. It mainly occurs as an epiphyte on low pleurocarpous mosses themselves growing on rather dry overhanging or overhung rocks. It also appears in smaller quantities on rock surfaces and on adjacent ivy stems (and in the past at least, on tree trunks).

Figure 5 - Habitat of Lejeunea mandonii on serpentinite outcrops atKynance Farm NNR. At this location it is highly vulnerable to heathlandfires. (Photograph by David Holyoak).

Widespread searching for the species in the Lizard district gave the following additional information on its habitat preferences (modified from Holyoak 1999):

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Although gabbro rock outcrops look suitable and whole-rock analyses show they contain significant amounts of bases, they do not support several basicolous bryophytes that usually occur with Lejeunea mandonii (e.g. Porella arboris-vitae) and Lejeunea mandonii itself could not be found.

Serpentinite outcrops in places exposed to salt-spray, desiccating winds, or both,

appear to be unsuitable for Lejeunea mandonii, not only on sea-cliffs, but also on hillsides several hundreds of metres inland of exposed coasts. Promising looking areas at Gew Graze (SW67-14-) and near Trevenwith (SW74-17-) and just downstream of the occupied Poltesco sites apparently failed to produce Lejeunea mandonii for these reasons.

Serpentinite outcrops within the flood-zone of streams or close above their flood-

zones commonly produce Lejeunea lamacerina but consistently fail to produce Lejeunea mandonii, even when the latter occurs at slightly higher levels (as at Poltesco).

Small serpentinite outcrops in heathland or scrub that are affected by heathland

fires fail to produce Lejeunea mandonii. This observation may provide a warning that some sites on larger rocks in scrub or at edge of heathland may be at risk from exceptional fires, e.g. at Kynance and Gwendreath.

Serpentinite outcrops heavily shaded by conifers do not support Lejeunea

mandonii (e.g. in parts of Bonython Estate). This factor can be eradicated by removal of conifer species as in Figure 6.

Figure 6 - Habitat of Lejeunea mandonii on serpentinite outcrops inwoodland at Bonython. Planted conifers have been removed to reduceshade that was harming the liverwort. (Photograph by David Holyoak).

Roadside serpentinite outcrops at Bonython no longer support Lejeunea

mandonii, although they apparently did so in the 1930s (cf. specimen collected by W.E. Nicholson, in Herb. CGE, labelled ‘roadside, Bochym, 1930’). The roadside

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rocks now support few bryophyte species and much green alga, and the road nowadays carries heavy traffic, so it seems likely that pollution from vehicle exhausts as well as shading from trees may have adversely affected the habitat.

(g) Old records (1920s and 1930s) of Lejeunea mandonii on tree bark at Bonython have not been repeated with recent searches. This is despite close searching of Ash Fraxinus excelsior and Sycamore Acer pseudoplatanus trunks with good epiphytic bryophyte floras close to rocks that support Lejeunea mandonii at Bonython, and of promising looking Elm Ulmus spp. and Beech Fagus sylvatica trees in the valley west of Trevenwith.

urther studies of several aspects of the habitats of Lejeunea mandonii at its Cornish

ata on aspect and inclination of the rock surfaces occupied by patches of Lejeunea

Fsites were carried out during 1998. These studies were intended to provide background data on the requirements of the species, to aid in maintaining or enhancing suitable conditions for it at existing sites and to aid in identifying sites to which populations might be restored. Its strong preference for overhanging or overhung rock surfaces was investigated systematically, as was the aspect of rock faces on which it grows. In addition collection of data on associated plants, which was begun in 1997, was completed during 1998. Dmandonii are given by Holyoak (1998: Table 2). All data was recorded using a Silva Compass-Clinometer, aspect being measured to an accuracy of ± 5%, inclination to ± 5%. Care was taken to remove the observer’s wristwatch before taking bearings with the hand-held compass to correct for magnetic variations. At each location the largest patch of Lejeunea mandonii was used for the measurements, and mid-point values were recorded when aspect or inclination varied for different parts of a patch. Data was recorded on 48 patches of Lejeunea mandonii, representing all six Cornish

his data, on aspect of surfaces occupied by Lejeunea mandonii, was analysed by

seems clear therefore that Lejeunea mandonii is not directly limited by aspect of rock

ata on the inclination of the rock surfaces occupied by patches of Lejeunea mandonii

sites. This amounts to >95% of all the patches known in Cornwall, and probably >99% of the cover of the species at its Cornish sites. Since almost the whole population was investigated, i.e. no sampling was involved, use of sampling statistics in analyses of the resulting data would be inappropriate and it is therefore avoided. THolyoak (1998: Table 3). At different locations the preferred aspects differ markedly, with most facing eastwards at Bonython (Franchis), southwards at Kynance, but northwards on the Bonython Estate. However, the aspects recorded largely reflect the availability at each site of overhanging rock surfaces that are partly shaded. Thus Bonython Estate and to a lesser extent Poltesco have suitable rock surfaces with a wide range of aspects and at these sites Lejeunea mandonii occurs on rocks facing almost all points of the compass. In contrast, the crag occupied at Franchis faces mostly between north and east, whereas the Kynance crag mainly faces southwards. Itsurfaces at its Cornish sites. Given that the species usually grows in partly shaded places, it appears that it can find suitable and roughly comparable conditions on some north-facing rocks that are lightly shaded by trees, or on some south-facing rocks that receive more shade from trees or bushes. Dare listed by Holyoak (1998: Table 2). The preceding notes describe the methodology adopted. Of the 48 patches examined, only 2 and parts of a 3rd (i.e. ca 5% of patches) were not either beneath overhangs (35%, mainly under rock overhangs, less often under overhanging ivy) or on overhanging rock surfaces (60%). The preference for sites beneath overhangs or on overhanging surfaces becomes even clearer if data is corrected for the size of patches, with 46% of the total cover of Lejeunea mandonii growing

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sheltered beneath overhangs, 52% on overhanging surfaces, and a mere 2% unsheltered. Substrate angles of between 50° and 135° were recorded, but most were between 80

able 2 – Occurrence of Lejeunea mandonii at various angles of substrate.

and 130°, as shown in Table 2. T

ANGLE OF SUBSTRATE

50-59 60-69 70-79 80-89 90-99 100

- 1 09

110-

119

120 -

129

130-

139 Steep vertical overhanging

% patches, 6 - 17 15 8 5 overhung

7 22 15

% patches,

hung

- - 1 4 - - - - - not over% total cover, overhung

7 -

4.2 COMMUNITIES & VEGETATION Detailed lists with abundance values for vascular plant and bryophyte associates of

a mandoni Bonython Kynance and Poltesco are given by Holyoak (1998). tes at Gwendreath and Trevenwith is given by Holyoak

unea mandonii. he other sites are in groves of trees (Poltesco), small or larger areas of mainly

eRubus fruticosus agg. is lmost consistently present in at least small amounts, and various tree saplings are

he sites. The species involved sually include woodland elements along with plants of scrub and open rocky sites.

Lejeune i at , Comparable information for the si(1999). The present account is limited to a summary of this information. Trees are absent at the Kynance and Gwendreath locations, where overhanging rocks and scrub provide the shade and shelter necessary for occurrence of LejeTdeciduous woodland (Trevenwith and Bonython respectively), or an extensive coniferous plantation with a few hardwoods (Bonython). The taxonomic identity of the trees at outcrops with Lejeunea mandonii is probably not of much significance, as many of them were evidently planted. However, Sycamore Acer pseudoplatanus is often prevalent as it is throughout west Cornwall, and other trees present include much Ash Fraxinus excelsior at Bonython and Elm Ulmus spp. at Poltesco. Among shrubs occurring on and close to rocks with populations of Lejeunea mandonii, Ivy Hedera helix is usually present and often plentiful, Bra mblacommon. A varied range of other shrub species and vines were recorded, but with relatively few of them common to most or all of the sites. Long lists of associated plants are recorded for the herbaceous vegetation of the ground-layer, although no real rarities were recorded at any of tuAmong those most consistently present being Herb-Robert Geranium robertianum, Ivy Hedera helix, Intermediate Polypody Polypodium interjectum, Red Campion Silene dioica, Wood Sage Teucrium scorodonia, Navelwort Umbilicus rupestris and Common Dog-violet Viola riviniana. Nevertheless, there were marked differences between sites. The unwooded character of the Kynance site and its location just inland of floristically varied sea-cliffs and slopes with coastal heathland are reflected in the presence of Thrift Armeria maritima, Danish Scurvygrass Cochlearia danica, Bloody Crane’s-bill Geranium sanguineum and Sea Campion Silene uniflora, whereas the damper and more sheltered environment of the woodland inland at Bonython has Enchanter’s-nightshade Circaea lutetiana, Scaly Male-fern Dryopteris affinis, Broad Buckler-fern D. dilatata, Bluebell Hyacinthoides non-scripta, Hart’s-tongue Phyllitis scolopendrium, Soft Shield-fern Polystichum setiferum and Common Nettle Urtica dioica. Poltesco and Trevenwith tend to share the humid, fern-rich character of the vegetation at the Bonython sites. Gwendreath has more in common with the records from Kynance. The lists of associated cryptogams are also rich in species and include two rarities (the moss Leptodon smithii in the only west Cornwall locality at Gwendreath; the lichen Sticta anariensis at Bonython). Weak growth of several mosses provides the commonest c

substrata on which the Lejeunea mandonii grows, mainly of Eurhynchium praelongum, Isothecium myosuroides var. myosuroides or Thamnobryum alopecurum, but sometimes instead or in addition with Metzgeria furcata, Neckera complanata, Radula sp. and others. The patches of pleurocarpous mosses on which the Lejeunea mandonii typically grows are usually small and weak, and often more or less dried or even moribund at places where the Lejeunea mandonii does well, whereas these moss species are often much better grown on moister, less shaded surfaces nearby. These moister surfaces are commonly shared with a luxuriant growth of Porella arboris-vitae and sometimes also with Pterogonium gracile. Rocks even drier than those preferred by Lejeunea mandonii usually have few or no bryophytes, except that the low-growing patches of Marchesinia mackaii are characteristic of these microhabitats. Several basiphiles are recorded among the bryophytes associated with Lejeunea mandonii, notably Homalothecium sericeum, Marchesinia mackaii and Porella arboris-

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vitae, and it may be presumed that for these species as for Lejeunea mandonii the high Magnesium concentrations in the serpentinite somehow substitute for its lack of Calcium. However, the frequent presence of Grimmia lisae (which is usually regarded as a calcifuge moss) is nevertheless testimony to the serpentinite offering different conditions to those of limestone.

4.3 DISPERSAL & STRATEGY Atlantic lejeunea is a perennial that can be located in all months of the year, although it

oticeabl en its substrates are very wet than it is under drier conditions. is less n e wh The species is autoecious and often produces perianths, which have been seen on several gatherings from Cornwall collected between the 1920s and 1991 (Mrs J.A. Paton, ers. comm.). Presence of perianths was also recorded on all of several recent Scottish

h some may have been verlooked they were undoubtedly at least scarce. They were definitely absent from

he rarity of Lejeunea mandonii in the UK is only partly explained by its restricted requir dently it i iphile

pcollections, but they were very sparse and not detected in the field (G.P. Rothero, in litt.). Capsules are reported to be rare and recorded in spring. No perianths were seen during field examination of considerable amounts of Cornish material of Lejeunea mandonii during 1997-2004, so althougoseveral voucher specimens collected in Cornwall during 1997.

4.4 HABITAT REQUIREMENTS IN THE UK - CONCLUSION Thabitat ements. Evi s a bas that prefers lightly shaded sites, on rock

teor tree bark, and it commonly grows as an epiphy on cover of larger bryophytes.

eading to Loss or Decline of Recovery i has proved vulnerable to a range of threats, some which directly

illegal

Humid, overhanging, basic rocks and bark of Ash trees are of course not rare habitats, so habitat limitation alone cannot account for the rarity of the species. However, all the localities for the species are in areas of Atlantic climate with high rainfall in many months of each year and Cornwall has the most obviously Atlantic climate of any English county. Furthermore, all the sites have enjoyed relative stability for centuries and this need for historically stable habitats within the Atlantic climate zone may be the key to the limited occurrence of the species.

5 Threats / Factors LLejeunea mandoniimpact on the habitat supporting the population, but also from the risk ofharvesting etc.

SHADING FROM PLANTED CONIFERS - Parts of the largest population in Cornwall (at Bonython) are shaded by planted Western Red Cedars Thuja plicata. Unless some of the trees are removed before they mature, they will cast heavier shade and

r suitable habitat if the shading were reduced by removal of groups of trees.

adversely affect the Atlantic lejeunea. After several years of negotiations by Plantlife International a proportion of the trees involved was removed in late 2003, but others remain and will cast increasingly heavy shade as they mature.

Several rock outcrops at Bonython do not support populations of Atlantic lejeunea because of heavy shading from the planted conifers. These outcrops would offe

SHADING FROM YOUNG DECIDUOUS TREES - Other parts of the largest population in Cornwall (at Bonython) are partly shaded by saplings of Sycamore

Acer

pseudoplatanus. Unless many of these saplings are removed before they mature, they will eventually cast heavier shade and adversely affect the Atlantic lejeunea. The landowner is currently unwilling to allow removal of these trees.

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SHADING FROM RHODODENDRON SCRUB - Small amounts of Rhododendron Rhododendron ponticum bushes grow adjacent to rocks with Atlantic

lejeunea at

one Cornish locality (Trevenwith). This invasive shrub needs regular cutting back

to prevent its spread which would otherwise shade the rocks and cause loss of populations.

SHADING FROM IVY AND PLANTS - Individual patches at several Cornish sites are at risk from incr

eased growth of ivy, bushes or saplings.

RISK FROM HEATHLAND FIRES - Three Cornish populations (Kynance, Gwendreath, to

lesser extent Trevenwith) are in scrub or at edges of areas of scrub that are subject to occasional accidental fires or more regular fires started for heathland

management. Maintenance of the existing small firebreaks will minimise any risk of damage.

RISK FROM ROAD WIDENING - A Scottish population on a tree trunk is reported to be potentially a

t risk from tree felling if a nearby road is widened.

RISK FROM COLLECTION OF SPECIMENS - Because Atlantic lejeunea is often present in

small quantity at any one station, several populations and many individual patches are vulnerable to collecting. However, identification of the species

requires that small samples of material are collected for microscopic study and these specimens need to be retained to provide vouchers for future checking.

RISK FROM DEATH OF PHOROPHYTES - Populations at each of the three currently known Scottish sites are restricted to single Ash trees. Potentially serious loss of hab

itat

will therefore occur if any of the host trees die.

POSSIBLE RISK FROM ATMOSPHERIC POLLUTION - Much of the sustained and progressive decline at Bonython, Cornwall (see 2.3.1 abov

e) recorded from 1997 to 2004

cannot be explained by increased shade from trees or ivy or other local site factors. There has also been loss of the plants since the 1920s from the roadsides and from tree bark at this locality and apparent cessation in perianth production since the early 1990s. Research is needed into possible atmospheric pollution at this site. Possible sources of such pollution include traffic on the busy A3083 road at the western edge of the site and military aircraft based at Predannack Airfield just over 3 km to the south-south-west or Culdrose Airfield further north (besides the long-established heavy usage by helicopters, fixed-wing Hawk jets began to use these bases in the late 1990s).

anagement Implications

6 Me 3 highlights the management implications for the maintenance of suitable habitat

s. Tablto support Lejeunea mandonii population Table 3 – Management Implications.

TYPE MANAGEMENT IMPLICATIONS Planted conifers Negotiations should continue to seek removal of more of

the planted Western Red Cedars (Thuja plicata) from the Bonython estate.

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TYPE MANAGEMENT IMPLICATIONS Young deciduous trees Negotiations seeking removal of some saplings of

Sycamore (Acer pseudoplatanus) should be continued. Notification of the site as a SSSI would strengthen arguments for removal of these trees and provide other sources of funding for their removal.

Rhododendron scrub Annual trimming of re-growth on rhododendron (Rhododendron ponticum) bushes at Trevenwith should be continued.

Ivy and plants Annual trimming of encroaching growth of ivy, bushes or saplings that affect individual patches at several Cornish sites should be continued.

Heathland fires Annual maintenance of the existing small firebreaks at Kynance and Gwendreath should be continued.

Road widening SNH should continue to liase with the highway authority regarding a Scottish population on a tree trunk that is potentially at risk from tree felling if a nearby road is widened.

Collection of specimens Bryologists should be strongly discouraged from collecting specimens at known sites, many of which are now individually marked and subject to annual monitoring. As a further precaution against thoughtless collecting, the precise localities should be regarded as confidential. However, identification of the species requires that small samples of material are collected for microscopic study and these specimens need to be retained to provide vouchers for future checking.

Death of phorophytes Because populations at each of the three currently known Scottish sites are restricted to single Ash trees, potentially serious loss of habitat will occur if any of the host trees die. In the long term the availability of other Ash trees should therefore be ensured in the close proximity of the existing sites. In the short term, if a host tree dies the possibility of translocation of supporting bark to a nearby alternative host should be assessed.

Atmospheric pollution Annual monitoring of all patches of Lejeunea mandonii at Bonython should be maintained and sufficient monitoring at other Cornish sites should be carried out to provide comparative data (as a control). Research is needed into levels of pollutants at Bonython, although potentially harmful incidents such as occasional discharges of jet fuel overhead may prove hard to detect.

7 Current & Future Conservation Methods

7.1 N SITU MEASURES IRegular monitoring of known populations should be carried out in Cornwall and in Scotland. The progressive decline documented at Bonython argues for continuation of annual monitoring in Cornwall. Markers should be maintained to allow all populations there to be refound (an increasingly important consideration if they dwindle in size because they then become very hard to relocate!). Digital photos of all locations should be recorded to monitor localised habitat changes and guide small-scale management intervention.

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Habitat management work in Cornwall should be carried out annually as described under section 6 above (trimming rhododendron at Trevenwith; trimming encroaching ivy etc. at all sites; maintaining firebreaks at Kynance and Gwendreath). There is no statutory protection for the most important site in Cornwall at Bonython. Renewed attention should be given to the possibility of notifying the Bonython site as a SSSI in view of the progressive decline of its populations of Lejeunea mandonii. Notification of the site as a SSSI would strengthen arguments for removal of harmful trees and provide other sources of funding for their removal. Negotiations to remove trees that cast increasing amounts of shade on populations at Bonython should be maintained, despite removal of 31 trees in 2003 and the landowner's refusal to allow any more felling. Regular contact should be maintained with private landowners and site managers at all sites so that they remain aware of the species, its locations, the concern over its survival and the habitat management needed to ensure its persistence. Also see Appendix 12 – ‘Guidelines for in situ monitoring of populations of Atlantic lejeunea (Lejeunea mandonii)’.

7.2 EX SITU MEASURES Establishment of ex situ cultures of the species will be worthwhile as a precaution since natural populations are at risk of being lost. The genetic diversity of natural populations needs to be investigated to establish the extent to which populations differ (between Cornwall and Scotland, and within Cornwall and within Scotland) so that sampling for the ex situ work is adequate and any reintroductions involve appropriate genotypes.

7.3 RESEARCH DATA Gordon Rothero is continuing studies of the species at Scottish sites on behalf of SNH.

7.4 MONITORING LEJEUNEA MANDONII & THE COMMON MONITORING STANDARD See Section 7.1 IN SITU MEASURES.

8 References Anon. (1999). Species Action Plan for Atlantic lejeunea (Lejeunea mandonii). Plantlife in

partnership with English Nature’s Species Recovery Programme. Albertos, B., Lara, F., Garilleti, R. & Mazimpaka, V. (1997). Estudio briofloristico de una

formación relictica de Prunus lusitanica L. de La Sierra de Gredos (Ávila, España). Cryptogamie, Bryologie, Lichénologie, 18: 303-313.

Birks, H.J.B. (1974). Distribution maps of Bryophytes in Britain and Ireland. Lejeunea mandonii (Steph.) K. Müll, Journal of Bryology, 8: 124.

Birks, H.J.B. & Birks, H.H. (1974). Studies on the bryophyte flora and vegetation of the Isle of Skye. 1. Flora. Journal of Bryology 8: 19-64, 197-254.

Blockeel, T.L. & Long, D.G. (1998). A check-list and census catalogue of British and Irish bryophytes. British Bryological Society, Cardiff.

Buch, H. (1934). Muscinées recoltées dans le Nord-Ouest de la Péninsule Ibérique (15 Juin- 1 Octobre 1930). Revue Bryologie Lichénologie 7: 238-248.

Church, J.M., Hodgetts, N.G., Preston, C.D. & Stewart, N.F. (2001). British Red Data Books. Mosses and liverworts. JNCC, Peterborough.

Corley, M.F.V. & Hill, M.O. (1981). Distribution of bryophytes in the British Isles. A Census Catalogue of their occurrence in vice-counties. British Bryological Society, Cardiff.

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http://www.snh.org.uk/

Dirkse, G.M., Bouman, A.C. & Losada-Lima, A. (1993). Bryophytes of the Canary Islands, an annotated checklist. Crytogamie, Bryologie, Lichénologie 14: 1-47.

Duell, R. (1983). Distribution of the European and Macaronesian liverworts (Hepaticophytina). Bryologische Beiträge 2: 1-115.

Edwards, B., Duckworth, J. & FitzGerald, R. (2000). Conservation of plant biodiversity on the Lizard: report on the 2nd in situ meeting, held on 15th-17th May 2000. Plantlife Report no. 157.

Eggers, J. (1982). Artenliste der Moose Makaronesiens. Cryptogamie, Bryologie, Lichénologie 3: 283-335.

European Committee for Conservation of Bryophytes (eds). (1995). Red data book of European Bryphytes. ECCB, Trondheim.

FitzGerald, R., Holyoak, D.T. & James, P. (1999). Conservation of plant biodiversity on the Lizard: Report on the in situ meeting held 10-12 May 1999. Plantlife Report no. 132.

Gonzalez-Mancebo, J.M. & Hernandez-Garcia, C.D. (1996). Bryophyte life strategies along an altitudinal gradient in El Canal y Los Tiles (La Palma, Canary Islands). Journal of Bryology 19: 243-255.

Grolle, R. (1983). Hepatics of Europe including the Azores: an annotated list of species, with synonyms from the recent literature. Journal of Bryology 12: 403-459.

Hill, M.O., Preston, C.D. & Smith, A.J.E. (1991). Atlas of the Bryophytes of Britain and Ireland. vol 1. Liverworts (Hepaticae and Anthocerotae). Harley Books, Colchester.

Holyoak, D.T. (1998). Atlantic lejeunea (Lejeunea mandonii). Report to Plantlife on work carried out during 1997. Plantlife - Back from the Brink Project/English Nature - Species Recovery Programme, Report no. 92 (35 pp.).

Holyoak, D.T. (1999). Atlantic lejeunea (Lejeunea mandonii). Report to Plantlife on work carried out during 1998. Plantlife - Back from the Brink Project/English Nature - Species Recovery Programme, Report no. 108 (43 pp.).

Holyoak, D.T. (2000). Atlantic lejeunea (Lejeunea mandonii). Report on work carried out during 1999 and summary of results of work during 1997 and 1998. Plantlife - Back from the Brink Project/English Nature - Species Recovery Programme, Report no. 142 (39 pp.).

Holyoak, D.T. (2001). Atlantic lejeunea (Lejeunea mandonii). Report to Plantlife on work carried out during 2000. Plantlife Report no. 171 (14 pp.).

Jones, E.W. (1958). An annotated list of British hepatics. Transactions of the British Bryological Society 3: 353-374.

Jovet-Ast, S. & Bischler, H. (1976). Hépatiques de la Péninsule lbérique: énumération, notes écologiques. Revue Bryologie Lichénologie. 42: 931-987.

Long, D.G., Crundwell, A.C. & Townsend, C.C. (1981). New records of bryophytes from the Canary Islands. Journal of Bryology 11: 521-536.

Paton, J.A. (1964). New Vice-County records and Amendments to the Census Catalogues. Hepaticae. Transactions of the British Bryological Society, 4: 711-721.

Paton, J.A. (1967). New Vice-County records and Amendments to the Census Catalogues. Hepaticae. Transactions of the British Bryological Society, 5: 392-405.

Paton, J.A. (1968). New Vice-County records and Amendments to the Census Catalogues. Hepaticae. Transactions of the British Bryological Society 5: 618-629.

Paton, J. A. (1969). A bryophyte flora of Cornwall. Transactions of the British Bryological Society 5: 669-756.

Paton, J.A. (1970). New Vice-County records and Amendments to the Census Catalogues. Hepaticae. Transactions of the British Bryological Society 6: 185-194.

Paton, J.A. (1999). The Liverwort Flora of the British Isles. Harley Books, Colchester. Reinoso, J. (1985). Contribucion al conocimiento de la flora briofitica de Galicia. Briofitas

de La Fraga de Caaveiro. 11. Hepaticas. Acta Botánica Malacitana 10: 17-26. Rilstone, F. (1949). A bryophyte flora of Cornwall. III. Hepaticae. Transactions of the

British Bryological Society 1: 156-165.

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Rothero, G. (1997). Lejeunea mandonii – Species dossier. Action Plans for Lower Plants in Scotland Project – Bryophytes. Scottish Natural Heritage & Royal Botanic Garden, Edinburgh.

Smith, A.J.E. (1990). The Liverworts of Britain and Ireland. Cambridge University Press, Cambridge.

9 Acknowledgements Jeremy Clitherow (EN), Prof. Jeff Duckett, Nick Hodgetts, Ray Lawman (EN), Dr David Long, Mrs Jean Paton, Ron Porley (EN), Gordon Rothero, Stephen Ward (SNH), the late Dr Harold Whitehouse. Several landowners have kindly allowed repeated access to their land for study of Atlantic lejeunea. The Natural History Museum for permission to reproduce photomicrograph images of Lejeunea mandonii. David Holyoak for permission to reproduce photomicrograph images of Lejeunea lamacerina, and also habitat pictures taken at Kynance Farm and Bonython. James Taylor and Sarah Garnett, Plantlife International volunteers, for their contribution to the editing of this dossier.

10 Contacts Plantlife International The Wild Plant Conservation Charity 14 Rollestone Street Salisbury Wiltshire SP1 1DX. Tel: 01722 342730

Jenny Duckworth – Jenny.Duckworth@plantlife.org.ukOr Dominic Price - Dominic.Price@plantlife.org.uk

David Holyoak david@dtholyoak.fsnet.co.uk

11 Links ARKive species web page for Lejeunea mandonii:

http://www.arkive.org/species/ARK/plants_and_algae/Lejeunea_mandonii/

British Bryological Society: http://www.britishbryologicalsociety.org.uk/

Plantlife International wishes to acknowledge the financial support of English Nature, Scottish Natural Heritage and the Countryside Council for Wales for the Back from the Brink (species recovery) programme. Work on Lejeunea mandonii is supported by:

ISBN: 1 90479-10-0

Original draft by David Holyoak Edited by Plantlife International

First draft dated March 2004 Last revised 12 May 2005

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mailto:Jenny.Duckworth@plantlife.org.ukmailto:dominic.price@plantlife.org.ukmailto:david@dtholyoak.fsnet.co.ukhttp://www.arkive.org/species/ARK/plants_and_algae/Lejeunea_mandonii/http://www.britishbryologicalsociety.org.uk/http://www.english-nature.org.uk/http://www.snh.org.uk/http://www.ccw.gov.uk/http://www.plantlife.org.uk/html/species_and_conservation/species_and_conservation_bfb_programme.htmhttp://www.plantlife.org.uk/html/species_and_conservation/species_and_conservation_bfb_programme.htm

12 Appendix 1. GUIDELINES FOR IN SITU MONITORING OF POPULATIONS OF ATLANTIC LEJEUNEA (LEJEUNEA MANDONII) Management of habitat to benefit Lejeunea mandonii is urgently needed at certain localities where planted conifers are beginning to shade its sites, whereas at other localities it may be at risk from scrub burning during heathland fires, or effects of tree-felling and road widening. Effective management requires knowledge of the locations of Lejeunea mandonii populations and, ideally, estimates of the abundance of the species. These notes consider various difficulties that arise in estimating its abundance and suggest appropriate monitoring methods. Locating Lejeunea mandonii On first acquaintance with the species non-bryologists are surprised by its diminutive size and the resulting difficulties in finding it at all, let alone in locating it consistently. Hence, monitoring is unlikely to be effective unless it is carried out by bryologists who are familiar with small liverworts. The bryologists involved need to get to know Lejeunea mandonii so they can identify it in the field, and develop the ability to recognise suitable habitats in order to locate it reliably. Because in some regions the species occurs both on tree bark (especially Elm and Ash) and base-rich rocks, care should be taken to search both kinds of substrata. Identification Considerable care is needed to distinguish Lejeunea mandonii from other Lejeunea species and confident field identification only becomes possible after prolonged familiarity with them. Species of Lejeunea and Microlejeunea are distinct from other genera of Lejeuneaceae in the form of the underleaves. Of the Lejeunea species occurring in Britain, living plants of L. cavifolia and L. holtii differ microscopically from Lejeunea mandonii in having the oil- bodies in each leaf cell much smaller and more numerous. L. lamacerina and L. patens have fewer, larger oil-bodies (commonly 4-6, sometimes 10 per cell) much as in Lejeunea mandonii (which has 8-13, rarely up to 23 per cell), but both of those species are larger with the postical leaf-lobe more rounded (broadly ovate, compared to broadly lingulate in Lejeunea mandonii). The perianth of Lejeunea mandonii is smooth whereas those of the other Lejeunea species occurring in Britain are five-angled or winged above, but perianths appear to be rarely produced by some populations of Lejeunea mandonii. Lejeunea mandonii is considerably larger than Microlejeunea ulicina and Cololejeunea minutissima. Given familiarity with both species, Lejeunea mandonii can be distinguished in the field from L. lamacerina using a x10 (or better, x20) handlens by its combination of narrower and more curved postical lobes and smaller size. Well grown plants of L. patens and L. cavifolia tend to resemble L. lamacerina more than the smaller Lejeunea mandonii, although some patches of both of them can have very slender stems with small leaves and when attentuated, shaded stems of all of these species tend to produce leaves that are longer than usual. The size and leaf-shape of Harpalejeunea molleri closely mimic those of Lejeunea mandonii, but its underleaves are quite different. In Cornwall both Harpalejeunea molleri and Lejeunea patens are rarities that infrequently confuse identification of Lejeunea mandonii, but this is not the case in Scotland or western Ireland and it is therefore much more difficult if not impossible to obtain reliable field identifications of Lejeunea mandonii in those regions. Because of the difficulties in field identification, it is important that when population monitoring is undertaken, small scraps of material are regularly checked microscopically. If new populations are located it is important that voucher specimens of adequate size (sufficient to show variability in leaf-shape, e.g. patches of leafy stems of ca 1cm², or smaller samples with perianths in good condition) are retained and accompanied by counts and descriptions of the [ephemeral] oil-bodies. However, care must be taken to avoid exterminating a population through collecting voucher specimens.

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Measurements of abundance Lejeunea mandonii grows as intricately branched mats that can be pure or intermixed with other bryophytes. Measurements of the areas of substrate covered by these mats provide the best non-destructive measures of abundance obtainable under field conditions, since there can be no question of counting individual plants. Measurements of the areas covered by pure patches of Lejeunea mandonii can be reproduced with reasonable accuracy (within about ± 10%) if the patches are overlain with a piece of clear plastic having a ruled grid of 1 x 1cm squares. Such plastic overlays are easily prepared on a square of Perspex or similar plastic glazing material by ruling lines with the permanent pens sold for use on overhead projector acetates. Greater accuracy is achieved if the detailed outline of individual patches of Lejeunea mandonii is traced onto a stiff sheet of acetate and then the acetate is laid onto the gridded Perspex. Accurate measurement of patches can be difficult when they are in awkward locations on overhanging rock faces among boulders or in deep crevices. However, the main cause of inaccuracy encountered during work in Cornwall has been due to Lejeunea mandonii growing intermixed with other bryophytes, a problem tackled only by roughly estimating the fraction of it in each 1 x 1cm square of the transparent grid. Best months for monitoring Individual patches of Lejeunea mandonii commonly live for (at least) several years and those that have been revisited regularly have not shown seasonal changes in size. Hence it is clear that they can be identified, located and measured in all months, although warm dry weather is obviously best for making prolonged and rather tedious measurements. At some sites it may be easier to measure patches in spring and autumn, rather than in summer when trees are in full leaf and the sites are therefore heavily shaded. Marking sites At locations with only one or two patches of Lejeunea mandonii detailed notes, accompanied by sketch-maps, photographs and measurements, should suffice for relocating the plants to make measurements in successive years. Where patches are more numerous it is important to mark them individually and have a system of letters or numbers so each of them can be refound without ambiguity. At a secluded Cornish site on jumbled boulders and small crags in woodland three types of marker have persisted successfully over two years: large markers to show approximate locations (initially strips were cut from plastic supermarket carrier bags knotted around tree branches or ivy stems; these were later replaced by less conspicuous 20cm lengths of green/brown plastic coated wire as used for vehicle wiring), and numbered markers to show precise locations (these were letter printed on plastic strip with a Dymo, the strip was then stuck on to a rectangle of white plastic cut from an old margarine tub, the whole label was then fixed to a twig or rock away from any bryophytes with thin wire or waterproof garden string). Different methods may be needed under other circumstances, e.g. if sites are monitored (and markers replaced) at longer than annual intervals, or in places open to the public. If any sites are found in places that are regularly visited by the public it will be necessary to use only very inconspicuous markers to avoid drawing attention to locations, or running the risk of having the markers removed. It should also be kept in mind that only chemically inert markers (stainless steel, aluminium or certain plastics) can be placed close to rare bryophytes and that copper, brass or galvanised steel are highly toxic to them and should be avoided (or at least kept to a safe distance away). At present there does not appear to be any inexpensive, non-toxic, inconspicuous system of unique markers that will last for many years but which can readily be relocated by researchers. However, English Nature has carried out trials combining use of electronic chips (set in glass and implanted in the rock) with a digital camera and associated software.

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Morphology, Identification, Taxonomy & GeneticsMorphology & IdentificationTaxonomic ConsiderationsGenetic Implications

Distribution & Current StatusWorldEuropeUnited KingdomEnglandNorthern IrelandScotlandWales

EcologyHabitat RequirementsThe Landscape PerspectiveCommunities & VegetationDispersal & StrategyHabitat Requirements in the UK - Conclusion

Threats / Factors Leading to Loss or Decline of RecoveryManagement ImplicationsCurrent & Future Conservation MethodsIn Situ MeasuresEx Situ MeasuresResearch DataMonitoring Lejeunea mandonii & the Common Monitoring Standar

ReferencesAcknowledgementsContactsLinks12 Appendix 1.