looking after bryophytes and lichens of scotland’s …...back from the brink management series 3...

B AC K F RO M T H E B R I N K M A N AG E M E N T S E R I E S

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Looking after bryophytes and lichens of Scotland’s oceanic ravines

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Looking after bryophytes and lichens of Scotland’s oceanic ravines

24216_Bryophytes_ascophyllum leaflet 14/01/2010 14:49 Page 3


We are Plantlife.The UK’s wild plants and fungihave been marginalised and takenfor granted for too long. Plantlifedevelops natural partnerships toconserve wild plants and fungiand build understanding of theirvital role in sustainabledevelopment.

Conservation of these species is delivered

through the charity's Back from the Brink

species recovery programme, which is jointly

funded by Countryside Council for Wales,

Natural England, Scottish Natural Heritage,

charitable trusts, companies and individuals.

These leaflets are here to give you the

information you need to conserve Back from the

Brink species and their habitats. With your help

we can stop the decline.

Steep but not too shaded crags provide a good habitat for bryophytes and lichens © Gordon Rothero

Plantlife Scotland

Balallan House

Allan Park

Stirling

FK8 2QG

Tel. 01786 478509

[email protected]

24216_Bryophytes_ascophyllum leaflet 14/01/2010 14:49

How you can help to conserve thelichens and bryophytes of Scotland’soceanic ravines

Oceanic ravines in Scotland are important forlower plants and fungi, particularly mosses,liverworts and lichens. Many are rare andthreatened and this habitat is important fortheir continuing survival. Threats includepollution, invasive species such as Rhododendronponticum and hydro-electric schemes which canradically alter hydrology and habitat.

This leaflet explains how to identify if you have anoceanic ravine in your care, describes the habitatand the species that can be found there, and theirnational and international conservationimportance. At the back of the leaflet is a full listof actions you can take to ensure their continuingsurvival but, in summary:


● Eradicate Rhododendron ponticum where at allpossible, using suitable techniques for the site

● Ensure that commercial plantations do notshade ravines and design any re-stockingprogrammes accordingly

● Ideally establish a broadleaf buffer zonebetween plantation and ravine

● Take Beech seriously – Beech can threatenoceanic ravines and action should be taken tomitigate this threat

● Avoid connecting ditches into ravines● Monitor all exclosures and remove fencing /

protection once trees are established● Assess proposed hydro-schemes in the west

of Scotland on watercourses with ravinesections as these schemes will result in areduced flow for bryophytes and lichens

It is difficult to believe but there is a deep ravine in here somewhere… © Gordon Rothero

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Why are Scotland’s oceanic ravinesof conservation importance?Oceanic ravines provide niches for a greatdiversity of special bryophyte and lichenspecies. Some ravines can have more than 200species of moss and liverwort and more than300 lichen species growing in them - some 20%of the British bryophyte and lichen flora. Thereare five species of bryophyte listed on the UKBiodiversity Action Plan (UK BAP), which havealmost all of their populations in oceanicravines. Eight UK BAP lichens also occur inoceanic ravines and all of these lichens andbryophytes are of conservation concern withinthe EU as a whole. A number of species have avery restricted distribution throughout Europeand a few of them are globally rare, making theravine communities that contain these speciesinternationally important and giving Scotland aresponsibility for their conservation.

What are ‘oceanic ravines’?Ravines come in a variety of shapes and sizes


but essentially they are steep river or burnvalleys with a sharp break in slope at the top oftheir craggy sides; they often contain waterfalls,deep pools and boulders. Ravines on theoceanic west side of the Scotland, as well asbeing spectacularly beautiful, also providehabitat for some of the richest plant and fungalcommunities in the country. This results from ahappy coincidence of climate, landscape,geology, geography and management. The westcoast of Scotland has an ideal climate formosses, liverworts and lichens, with few dryspells and few frosts giving generally humid andmild conditions. This equable climate isenhanced by the nature of the ravine habitatwith its steep, often precipitous slopes,waterfalls and jumbles of large boulders, allfeatures of a recently glaciated landscape.Geology has also been kind in providing a rangeof rock types, from old, hard sandstone andquartzite to much softer limestones andcalcareous schists plus many basalt dykes whichoften provide the line of the ravine.

Ravines can provide sites for oceanic bryophytes in largely treeless areas © Gordon Rothero

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Geography has also played its part as most ofScotland’s oceanic ravines are quite remote andwell away from the centres of economic activityof the past. This means that pollution has onlyhad a limited impact. The inherent inaccessibilityof the ravines has also meant that managementof the surrounding land has had a more limitedimpact; felling and extracting trees from ravinesis difficult and there is often only limited accessfor grazing animals so that a good and oftenvaried tree cover persists. This fortuitouscombination means that oceanic ravines provideus with a habitat that has retained an element ofwildness within a managed landscape.

Where are they?The majority of oceanic ravines are situated inthe west of Scotland, within the West CoastImportant Plant Area (IPA) which stretches upthe western seaboard of the country fromArgyll to West Sutherland, and also in theHebrides, but good sites also occur as farsouth as Galloway. The best ravines are oftenset within areas of oceanic broadleaf woodlandand contain the same characteristic oceanicspecies of bryophytes and lichens, usually ingreat abundance. Wooded ravines also extendthis community into otherwise largely treelesslandscapes, providing a remnant tree cover and

Fingered Cowlwort (Colura calyptrifolia), a tiny

liverwort of rocks and trees in ravines

© Gordon Rothero

buffering from changes in humidity. Theenhanced humidity in ravines also means thatoceanic bryophyte and lichens can extendmuch further east in such places, reachinginteresting outposts as far east as the Findhornvalley in Nairnshire.

SPECIES OF OCEANIC RAVINES

The bryophyte communitiesRavines are very ‘mossy’ places withbryophytes carpeting rocks and festooningtrees but most of the special plants areliverworts. The general flora is the same asoceanic woodland with robust species likeLittle Shaggy-moss (Rhytidiadelphus loreus),Glittering Wood-moss (Hylocomium splendens),Greater Fork-moss (Dicranum majus) on theground and Slender Mouse-tail Moss(Isothecium myosuroides var. myosuroides) andWestern Earwort (Scapania gracilis) on treesand rocks. The fine oceanic liverworts typicalof oceanic woodland are also frequent hereand Prickly Featherwort (Plagiochila spinulosa)and Spotty Featherwort (Plagiochila punctata),the best indicators of an oceanic flora, can beparticularly abundant on trees and rocks.

The humid ravine conditions usually lead to agood epiphytic flora with both mosses andliverworts festooning the trees and shrubs,truly a temperate rain forest. While commonspecies remain the most abundant there are anumber of small oceanic liverworts which canbe frequent in the more wooded ravines.These usually include tiny species of thePouncewort (Lejeunea) family includingToothed Pouncewort (Drepanolejeuneahamatifolia), Pointed Pouncewort(Harpalejeunea molleri) and FingeredCowlwort (Colura calyptrifolia) on hazel and

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ash, and Wedge Flapwort (Leptoscyphuscuneifolius) on birch and alder. The very rareAtlantic Pouncewort (Lejeunea mandonii)apparently occurs on just three trees in threeseparate ravines in the west of Scotland.

The stable rocks in and by the watercourserunning through the ravine, which are regularlyinundated but not heavily scoured, have anabundance of common species. More acidrocks in the burn are usually dominated bycushions and patches of Yellow Fringe-moss(Racomitrium aciculare) and Rusty Feather-moss(Sciuro-hypnum plumulosum), often with a bandof the oceanic moss Flagellate Feather-moss(Hyocomium armoricum) at the margin, and

occasionally large patches of Holt’s Mouse-tailMoss (Isothecium holtii), particularly bywaterfalls in the bigger rivers. These speciesmay be partially replaced by Fox-tail Feather-moss (Thamnobryum alopecurum) and Long-beaked Water Feather-moss (Platyhypnidiumriparioides) where the rocks are more basic.Sheltered sites on rock-faces in and by thewater are the prime habitat for the rareroceanic liverworts and this means that ravineswith lots of boulders are more productivethan those ‘box’ ravines with crags plungingstraight into the water. The steep faces ofthese rocks, close to the water but free ofcompetition, usually have a community ofspecies of the Pouncewort (Lejeunea) family

Holt's Mouse-tail Moss (Isothecium holtii), a

splendid moss carpeting rocks by waterfalls

Hutchins' Hollywort (Jubula hutchinsiae), a

distinctive liverwort of wet, shaded sites

Flagellate Feather-moss (Hyocomium

armoricum), a common and often abundant

oceanic moss in acidic ravines

Pearl Pouncewort (Lejeunea patens), the most

frequent of the Lejeunea species in ravines

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plus a number of other oceanic species,including some rarities.

Most frequent of these species is PearlPouncewort (Lejeunea patens) which oftenforms quite extensive whitish-green patchesover both the rock surface and otherbryophytes. Related species in the same habitatare Toothed Pouncewort (Drepanolejeuneahamatifolia), Pointed Pouncewort (Harpalejeuneamolleri) and Fingered Cowlwort (Coluracalyptrifolia), which are all really tiny plants. Twoother species can be locally frequent; Hutchins’Hollywort (Jubula hutchinsiae) can form largepatches and prefers wet, shaded sites, often incaves by waterfalls, while Brown Scalewort

Brown Scalewort (Radula aquilegia), a locally

frequent liverwort in the better ravines

Pale Scalewort (Radula voluta), a scarce liverwort

with a very restricted global distribution

Irish Daltonia (Daltonia splachnoides), a

vulnerable moss of trees and rocks in ravines

(Radula aquilegia) prefers more open sites ondamp, slabby rocks. Pale Scalewort (Radulavoluta) is a scarce species which is recordedfrom the west of Britain and Ireland withscattered records from the tropics and easternN America. The UK BAP species Wilson’sPouchwort (Acrobolbus wilsonii) has some 25sites in Scotland, almost all in ravines and itsonly other sites are in western Ireland, theFaroes, the Azores and Madeira. Most of theravine rarities are liverworts but one moss is ofinterest; Irish Daltonia (Daltonia splachnoides)has a handful of sites in Scotland but elsewherein Europe is known only from western Irelandin a sparse distribution pattern that is mostlytropical but also includes New Zealand.

Wilson’s Pouchwort (Acrobolbus wilsonii), a

rare liverwort

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All images on this spread © Gordon Rothero


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The Nationally Rare Blackberries-in-custard

(Pyrenula hibernica), found in ancient oceanic

ravine woodlands on hazel and more rarely on

holly and rowan © John Douglass

Large, leafy Lobarion lichens can thrive in oceanic ravines on broadleaved trees and rocks

The lichen communitiesThe best ravines for lichens are those withshallow sloping sides and bends which allowlight to the ravine floor. Narrow steep sidedravines where light levels are low providepoor conditions for lichen development.

Oceanic ravines can support lichencommunities of international importance.Ravines with remnants of ancient woodlandare particularly important for certain epiphytic

lichen species such as the Graphidion, Lobarionand Parmelietum laevigatae communities.

The young bark of ash, oak and particularlyhazel can support the Graphidion lichencommunity. This community includes the‘Script’ lichens resembling scribbles and dotson the bark. These include species of Arthonia,Arthopyrenia, Arthothelium, Graphis, Graphina,Phaeographis and Pyrenula.

The Lobarion community of large leafy lichenscan also be found in sheltered well-lit ravineson broadleaved trees and rocks. The Lobarioncommunity includes species of Degelia,Leptogium, Lobaria, Nephroma, Pannaria, Peltigera,Pseudocyphellaria and Sticta.

The Parmelietum laevigatae community can belocally abundant in oceanic ravines on oldbirch, alder, oak and willow. Species of thiscommunity include the leafy lichensHypotrachyna laevigata, Hypotrachynataylorensis, Treeflute (Menegazzia terebrata)and the crustose Powdery Saucer Lichen(Ochrolechia androgyna).

Lobaria virens – International Responsibility

species © John Douglass

Sticta canariensis – Nationally Rare, Red Data

Book Vulnerable © John Douglass


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Hypotrachyna laevigata © John Douglass

Members of the Parmelietum laevigatae community can be found in oceanic ravines

Hypotrachyna taylorensis – International

responsibility species © John Douglass

Rock type is an important factor forsaxicolous (rock dwelling) lichens. Siliceousand basic rocks support different lichen florasfrom highly calcareous rocks, and a ravine witha variety of rock types can therefore oftensupport a wide range of lichen species.

Lichens found on siliceous and basic rock inoceanic ravines may include: Bacidiacarneoglauca, Bacidia trachona, Collema flaccidum,Lecidea phaeops, Lecidella anomaloides,

Dog-tooth Lichen (Peltigera britannica) – Nationally

Scarce, International Responsibility species

© John Douglass

Dog-tooth Lichen (Peltigera leucophlebia)

© John Douglass

Leptogium teretiusculum, Tattered Jellyskin (L.lichenoides) Porina spp, Protopannaria pezizoidesand Rhizocarpon infernulum subsp. Sylvaticum.

Some lichens are semi aquatic and can grow onsiliceous or basic rocks at the edges of relativelywell lit and wide ravine watercourses such asCollemopsidium angermannicum, Bacidia inundata,Brook Lichen (Dermatocarpon luridum), D.meiophyllizum, Rusty Brook Lichen (Ionaspislacustris), Polyblastia cruenta, Porina lectissima,


Porpidia hydrophila, Rhizocarpon amphibium, R.lavatum and Verrucaria praetermissa. Otherlichens are truly aquatic and can live in similarlywell-lit ravine habitats on siliceous and basicrocks. These lichens live submersed for most ofthe year and are only exposed in dry summerconditions. They include the crustose lichens:Lakezone Lichen (Staurothele fissa), Verrucariaaethiobola, V. aquatilis, V. rheitrophila and V. scabra.

Shaded underhangs of siliceous rockoutcrops and large boulders of oceanic

Protopannaria pezizoides © John Douglass

Lichens of siliceous and basic rocks in oceanic ravines

Rhizocarpon infernulum subsp. sylvaticaum –

Nationally Scarce © John Douglass

Dirina massiliensis f. sorediata can be found on

rock underhangs in oceanic ravines

© John Douglass

Common Chocolate Chip Lichen (Solorina saccata) a

species of calcareous rocks, which can be found in

open ravine situations © John Douglass

ravines can support species includingArthonia endlicheri, Dirina massiliensis f.sorediata, Llimonaea sorediata and species ofLepraria. These species cannot toleratedirect wetting; their water requirements arefulfilled by the humid atmosphere.

Calcicole lichens which can grow onlimestone in ravines can include Lecaniacuprea, Common Chocolate Chip Lichen(Solorina saccata), Thelidium and Verrucariaspecies.

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Threats

Invasive non-native speciesThe spread of Rhododendron ponticum inoceanic broadleaf woodland is a huge threat tointernationally important bryophyte and lichencommunities and the threat is no different forravines. Rhododendron ponticum in ravines is insome ways more of a threat, as ravine sites arealready heavily shaded and even a modestRhododendron ponticum cover may reduce lightlevels to a point at which most species will notgrow. Ravines are also difficult to access andclearing established Rhododendron ponticumfrom them is very expensive.

Beech trees are often magnificent and wereand still are a popular addition to many policywoodlands from the 18th century onwards.From these woodlands they have spread into

oceanic broadleaf woodland where the denseshade cast by the canopy and the copious andpersistent leaf litter present problems forbryophytes and lichens. Again this isparticularly true of ravines where beechseedlings find it easy to establish and soonmake an already shaded habitat very darkindeed. A similar problem can also occurwhen non-native conifers seed into andbecome established in ravines.

Forestry and exclosuresIn the past, insensitive planting of commercialconifer crops too close to the edge of ravineshas meant that a large number of ravine sites,particularly smaller ones, have lost a significantproportion of their bryophyte and licheninterest. Guidelines are improved now but we

The dense shade and copious leaf litter created by invasive Beech trees in ravines causes problems for

lichens and bryophytes. © Gordon Rothero



are left with a legacy of damaged sites whichmay never recover; observing these ravinesafter clear-felling is a depressing experience.The run-off from commercial coniferplantations may also have an effect on waterquality in the ravines, both in terms of siltloading (thus increasing scouring) and acidity(which seems to encourage algal growth at theexpense of bryophytes).

Woodland regeneration schemes often includeravines and these may act as refugia for manyspecies and provide an important seed sourcefor natural regeneration. To encourageregeneration, many schemes resort to fencingto exclude all grazing animals which can havetwo deleterious effects on the bryophytes andlichens that grow there. Firstly, denseregeneration, particularly birch, can shade outimportant lichen communities on old treesand on bryophytes growing on low rocks.Secondly, growth of a coarse herb and dwarfshrub layer can completely cover importantcommunities on rocks and tree bases. Both ofthese processes also produce a lot of leaflitter which can smother bryophytes andlichens on the woodland floor.

PollutionAll the bryophytes that grow in and nearravine burns are susceptible to changes inwater chemistry, particularly to eutrophicationby nutrient run-off from fields or frominefficient sewage systems. Some are directlyaffected but most are just out-competed bythe growth of robust common species ofhigher plants, bryophytes and algae in responseto the nutrient enrichment.

Hydro-electric schemesA particular threat to oceanic ravines comesfrom the development of large numbers ofsmall-scale run-of-river hydro-electricityschemes. These schemes take water out ofthe river, pipe it down to the powerhouse andthen return it to the river. This leaves astretch of the watercourse between theintake and the powerhouse with thehydrology radically altered. There are nolong-term studies of the effects of a lowerlevel of discharge down ravines butknowledge of the ecology of the bryophytesand lichens involved and observations on theextant communities in ravines altered byhydro-schemes tens of years ago gives somepointers. The most likely effects are:

● a downward shift to the new median waterlevel of riparian species;

● a growth of more robust, woodland floorspecies on the rocks above this;

● a loss of habitat for the community oflichens and small liverworts on rock facesas a result of increased competition;

● a decrease in frequency of spate flows andresultant erosion which frees-up habitat forlichens and the smaller liverworts.

The interplay between the various factors iscomplex and it is not always clear what thelimiting factors for any one plant are, but theprecautionary principle suggests that hydro-schemes should not be sited on ravines withnationally and internationally importantbryophyte and lichen communities


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Management recommendations forravines to benefit lichens andbryophytes

Invasive non-native speciesEradication of Rhododendron ponticum shouldbe a priority action in any management planfor Atlantic oak woodland and the same istrue for managing ravines. Unfortunatelyravines are often difficult to access and haveRhododendron ponticum growing high on crags,so removing Rhododendron ponticum will beboth expensive and involve rope-accesstechniques. However, failure to removeRhododendron ponticum from ravines becauseof access difficulties means that not only is theravine itself under threat but the site providesa seed source that can infect the wider area.Beech and non-native conifers are a lessobvious problem and there is often some

resistance to removing mature trees. Periodicremoval of seedlings, particularly from ravinesites, would go some way towards reducingthe threat posed by these trees.

Forestry, woodland regeneration and exclosuresFortunately, the current guidelines with regardto commercial plantations and watercoursesare far better than in the past and no longershould good ravine sites for bryophytes andlichens be shaded out. However, even withcurrent guidelines, mature conifers will still havesome shading effect and there is a strongargument for a much wider buffer zone forthose ravines which have an existing, full orpartial, broadleaf canopy and which are thuslikely to have good bryophyte and lichendiversity. Conifers should be planted farenough back from the break in slope that forms


Conifers planted too close to ravines completely alter their flora © Gordon Rothero

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the ravine so that no shading of the ravineoccurs when the trees are mature. The effecton ravine sites of direct run-off fromcommercial conifer plantations can be mitigatedby not having ditches running directly intowater-courses and this is current good practice.This does need occasional maintenance anddoes not deal with older plantations.

There is no easy answer to the problemsposed for bryophytes and lichens byexclosures although, where possible, areduction in the number of grazing animals inthe general area to remove the need for anexclosure should be considered as an option.Some grazing is helpful in sustaining goodhabitat for lichens and bryophytes but there isno doubt that, in the long term, expansion ofbroadleaf woodland will also be ofconsiderable benefit. Exclosure fences shouldbe seen as a temporary measure, to beremoved once tree regeneration has reacheda stage where it can sustain some grazing.Where dense regeneration threatens old trees


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with good lichens, some sort of ‘halo-thinning’might be required. This would involveremoving, or at least thinning, regenerationaround particular trees and occasionally rocksand again emphasises the need to know wherethe species of conservation concern occur.

PollutionMost of the oceanic ravines are in parts of thecountry where levels of pollution, bothcurrent and historic, are low. Pollution fromrun-off from agriculture or sewage is likely tobe of very local occurrence but may have asignificant effect and all such run-off should beprevented from entering ravine sites.

Hydro-electric schemesAny bryophyte or lichen interest on potentialsites for hydro-schemes is best identified asearly as possible in the planning process. Theinitial environmental assessment shouldinvolve surveyors sufficiently competent toassess or at least indicate that this interest ispresent. Most if not all oceanic ravines will

The humid rocks around waterfalls are often exciting places for oceanic bryophytes © Gordon Rothero



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Summary of management recommendations:

● Eradicate Rhododendron ponticum, using suitable techniques for the site● Take Beech seriously – Beech can threaten oceanic ravines and action should be taken to

mitigate this threat by removing seedlings and parent trees where possible● No plantations should shade ravines and any re-stocking programmes should be designed

accordingly● Ideally there should be a broadleaf buffer zone between plantation and ravine.● No ditches should run into ravines● Monitor all exclosures and remove fencing / protection once trees are established● Assess proposed hydro-schemes in the west of Scotland on watercourses with ravine

sections as these schemes will result in a reduced flow for bryophytes and lichens.

Who to contact for advice

Plantlife ScotlandBalallan HouseAllan ParkStirlingFK8 2QGTel 01786 [email protected]

Scottish Natural HeritageDr. David Genney, Policy & Advice Officer –Bryophytes, Fungi and [email protected]

British Bryological Societyc/o Gordon RotheroStronlonagGlenmassanDunoonArgyllPA23 [email protected]

British Lichen Societyc/o Dept. of Botany, The Natural History Museum,Cromwell Road, London SW7 5BD, [email protected] www.thebls.org.uk

probably fall into this category. Much can bedone with careful planning and micro-siting toavoid damaging bryophyte or lichen interestduring the construction process, by avoidingcertain trees and boulders and by carefully re-siting rocks. The change in hydrology willalter both the riparian habitat and thehumidity regime in the ravine and this willhave an effect on the plants; there is noobvious mitigation for this. Unfortunatelywhat little monitoring of these effects that hastaken place has been ‘after the event’ andwithout baseline data for comparison, and thisshould be rectified. If the scheme precludesall but the highest spate flows then it is likelyto have a greater effect than one that allowsthrough more than just peak flows. There isuncertainty with regard to the extent of theeffect of the reduced flow on humidity-demanding oceanic species and this suggeststhat the best ravines for oceanic bryophytesshould not be used for hydro-schemes.

This leaflet was written for Plantlife Scotlandby Gordon Rothero (Bryologist) and JohnDouglass (Lichenologist)


B AC K F RO M T H E B R I N K M A N AG E M E N T S E R I E SB AC K F RO M T H E B R I N K M A N AG E M E N T S E R I E S

Fro

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ove

r im

age:

Oce

anic

rav

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Ardn

amur

chan

Pen

insu

la ©

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.co

.uk

www.plantlife.org.uk [email protected]

Plantlife International – The Wild Plant Conservation CharityPlantlife Scotland

Balallan House, Allan Park, Stirling FK8 2QGTel. 01786 478509

ISBN: 978-1-907141-14-0 © December 2009

Plantlife International – The Wild Plant Conservation Charity is a charitable company limited by guarantee.

Registered Charity Number: 1059559 Registered Company Number: 3166339. Registered in England

Charity registered in Scotland no. SC038951

A fine bouldery ravine with good oceanic bryophytes © Gordon Rothero

British Lichen Society


looking after bryophytes and lichens of scotland’s …...back from the brink management series 3...

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