Habitat change on Scotland’s coasts

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18 Habitat Change on Scotland’s Coasts

Stewart Angus, Jim Hansom and Alistair Rennie

Summary

1. Scotland has approximately 71% of Britain’s dunes (including machair) byarea, 60% of sea cliff by length, 13% of saltmarsh by area and less than5% of shingle by length. Information on lagoons is currently deficient.

2. Coasts are dynamic habitats where change is inevitable. However,difficulties associated with establishing baseline data in terms of eitherlength or area mean that any meaningful measurement of coastal changeis challenging.

3. We explore some of the issues and present a synopsis of the availableinformation on key coastal habitats. We also consider recent drivers ofcoastal change: sea level rise; sediment deficit and human intervention incoastal systems.

4. We argue that the need to monitor coastal change is a problem that mustbe addressed strategically, not only in respect of coastal habitats, but alsoin respect of the immense investment in settlement and infrastructure onScotland’s coasts.

18.1 Introduction

It is said that there are only two certainties in life: death and taxes. There is a third:coastal change. Most coasts composed of sediment will undergo change on everytide, and individual storms can exert significant foreshore change within a few hours.Large, storm-related change will be widely noticed, whereas the gradual erosionand accretion of beach and dunes will not. Such changes are daily, event-based,or seasonal, but they are not the subject of this paper, which deals instead with thedirect human impact and longer term changes that affect Scotland’s coastline.Paleao-environmental and historical data indicate that there have been extensive

Angus, S., Hansom, J.D. and Rennie, A. (2011). Habitat Change on Scotland’s Coasts – TheChanging Nature of Scotland, eds. S.J. Marrs, S. Foster, C. Hendrie, E.C. Mackey, D.B.A. Thompson.TSO Scotland, Edinburgh, pp 183-198.

changes to Scotland’s coast in the past, as at Skara Brae in Orkney (Vega Leinertet al., 2000), and on the west coast of North Uist, where the township of‘Hussaboste’, mentioned in the Charter of Inchaffrey of 1389, is now visible only asa heap of stones at low tide (Angus, 1997). The scale of these past changes mayserve as a warning of the possibility of future changes of equal or greatermagnitude, particularly in view of the more recent shifts in the drivers of coastalchange such as sea level rise, sediment deficit and human intervention in coastalsystems.

18.2 Measuring the coast

It is notoriously difficult to assess coastal change when establishing the physicalbaseline is problematic.

Official figures for the length of Scotland’s coast range from ‘over 10,000km’(Scottish Office, 1997) or ‘over 11,000km’ (Scottish Executive, 2005) to 13,115km(Scottish Development Department (SDD), 1998). Scottish Natural Heritage’s(SNH) measurement of the Ordnance Survey’s 1:25,000 coastal outlines yielded atotal coastal frontage (length at Mean High Water Springs) of 16,490km (Angus,2001) while more recent SNH measurement of the Ordnance Survey’s 1:10,000coastal outline using ArcGIS gave a figure of 18,670km.

Attempts have been made to subdivide these national figures into habitatcomponents (cliffs, dunes, shingle, saltmarsh, etc.) by the Joint Nature ConservationCommittee (JNCC, unpublished) and (for SNH) by Posford Duvivier Environment(1998). However, the fact that the conservation agencies rarely employ thesestatistics serves to acknowledge the difficulties involved in the subdivision of thecoast into particular habitats, and recognises that any use of such numbers shouldbe accompanied by lengthy definitions of habitats and methodology, as well ascaveats about use and accuracy. If linear measurement of the coast is difficult,obtaining figures for areas of coastal habitats presents even greater challenges,given the absence of any agreed definition of the coastal zone in terms of inland(and sometimes seaward) extent, as well as the problem of delineating boundariesbetween diffuse habitats. Additionally, much of the habitat area of cliff slopes hasa strong vertical component that is neither measured by conventional technologiesnor displayed on maps or vertical aerial photography. When establishing a baselineis problematic, meaningful measurement of change becomes particularlychallenging, and responses include a sampling approach, use of environmentalproxies, or falling back on expert knowledge. The legal requirement to report on theextent of habitats as part of Favourable Conservation Status reporting within theHabitats Directive, and current work on the National Ecosystem Assessment haverecently emphasised the extent of such problems.

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The Changing Nature of Scotland

Sediment-based habitats are usually distinguished by sediment size rather thanby the vegetation they support, but sediments can be borderline or mixed, or can bezoned in relation to distance from the sea, so that allocation to one category inpreference to another can be arbitrary. Even the classification of saltmarsh, whichgiven its intertidal position should be straightforward, presents difficulties. Forexample: on exposed hard coasts, cliff-tops high above the sea may be subject tosuch marine spray or even inundation that they support functional saltmarshvegetation – should these ‘perched saltings’ be catalogued as saltmarsh or cliff-tophabitat? All sand dune habitat (including machair) has been mapped to a highstandard by the Sand Dune Vegetation Survey of Scotland (SDVSS) (Dargie,2000), and this provides an excellent basis for monitoring change in these habitats.

Though a range of remote sensing technologies is now available, and studiesusing satellite imagery and airborne sensors exist, they tend to be localised, andnational assessments such as Countryside Survey (Norton et al., 2009) designedto monitor change in the countryside, accept that they lack a facility to distinguishbetween coastal habitats and are thus unable to report on their changes. Theproblem of establishing baselines is not merely a bureaucratic issue for formalreporting. The pressing need to monitor change in order to identify trends arisingfrom climate change is a very real practical problem that has to be addressed at astrategic level, not only in respect of coastal habitats, but also in respect of theimmense investment in settlements and infrastructure around Scotland’s coasts.

18.3 Cliffs and rocky coasts

Scotland’s cliffs are generally composed of durable, hard rock, and even the softcliffs of till are generally underlain by rock at or near sea level, so that there are noScottish counterparts for the rates of cliff recession experienced in parts of easternand southern England (May and Hansom, 2003). Hard coasts are perceived as theleast dynamic of coasts, but this is not to say they are not subject to change, simplythat change is slow. The Old Man of Hoy in Orkney is a mere 600 years old andhad two ‘legs’ until one was removed in early nineteenth century storms (Hansomand Evans, 1995).

The JNCC Coastal Directories give a length of 4,061km for sea cliffs (in realityhard coasts) in Britain, of which 2,455km (60.5%) are in Scotland. Posford DuvivierEnvironment (1998) give a cliff length for Scotland of 1,778km, based on steeperslopes, but even this figure includes rock slopes that many would not regard as truecliff. In any case, when does a sloping rocky coast become a cliff, and how is a cliff-girt bay backed by cliffs classified? By their very existence, a spurious precision isafforded to such statistics.

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Although the coasts of the Northern and Western Isles and the northern mainlandwere known to experience infrequent episodic change, recent research hasquestioned the assumed slow rate of change. In all of these areas large blocks ofrock are known to have been quarried by large waves at altitude and moved tens ofmetres inland many times a year (Hansom et al., 2008). Exposed cliffs and cliff-topsmay be completely stripped of soil and vegetation by wave wash with transitionalareas supporting only soil and a few hardier, salt-tolerant plants. These extremehabitats are not endangered by increasing wave action or sea level rise – their zonemerely moves inland; the high wind speeds and salt spray in such situations tend topreclude types of land use that would inhibit such movement. In contrast, some deepclefts in cliffs in more sheltered situations may be entirely non-maritime and supportwoodland. However, in many situations land use changes pose a more widespreadthreat to cliff habitats than storm waves. A few ungrazed, inaccessible cliff ledges mayconstitute the most natural habitat in the UK, but in general a reduction or cessationin grazing poses problems by allowing taller grasses to shade out the many cliff-topplants with rosette growth forms, including the endemic Scottish primrose (Primulascotica), which requires grazing that is close without being excessive. Studies inOrkney have demonstrated that it is possible to adjust grazing to encourage a veryhigh level of biodiversity on cliff-tops, allowing even maritime heath to be restored(Harris and Jones, 1998). However, over much of Scotland, decades of heavygrazing, sometimes with the addition of artificial fertiliser, have led to the displacementof maritime heath by grassland, the Mull of Galloway being a notable example. Ineastern Scotland, cultivation close to the cliff edge creates the possibility of spray driftor run-off of agricultural chemicals to the cliff slope habitats.

Introduced species also pose problems. On Craigleith Island in the Firth ofForth, the spread of tree mallow (Lavatera arborea) resulted in puffins (Fraterculaarctica) abandoning their burrows (CEH, 2005). On Mull and Ulva, the remainingcliff sites for the endemic slender Scotch burnet moth (Zygaena loti scotica) aresubject to invasion by introduced Cotoneaster species as well as native bracken(Pteridium aquilinum) (SNH, 2007).

18.4 Shingle

Though it is known that the area of coastal shingle in Scotland is in excess of 700ha, the distribution is poorly known except for deposits on the coasts of the Morayand Solway Firths and larger deposits elsewhere. On the Solway, Randall andDoody (2001) identified a total of 39.7km of shingle between Stranraer and theEnglish border. Nevertheless the total length of shingle shoreline probablyrepresents less than 5% of the coastal length of Scotland, in sharp contrast to

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England and Wales where 30% of the coast is shingle (Randall and Doody, 1995).Much of Scotland’s shingle area is on emerged beaches now so far removed frommaritime influence that they support woodland or non-maritime grassland, whileshingle deposits close to the tideline are often so mobile that little can grow. Thusthe extent of true ‘maritime vegetated shingle’ is comparatively low in Scotland, andoften restricted to annuals on strandlines, where deposits of seaweed may providea local growing medium in an otherwise hostile environment. Some of the morestable sections of the shingle deposits on the Moray Firth as at Culbin consist solelyof large gravels, so that there is no growing medium for higher plants; insteadlichens flourish on the undisturbed shingle surfaces.

On some shingle systems in the Moray Firth, adjacent conifer plantations havespread onto the shingle expanse by self-sowing (Figure 18.1). West of the Spey,within 1-4 km of the river mouth, hitherto bare areas of shingle have been colonisedby successive waves of scrub and tree growth. As each tree grows it provides alitter layer on and between the gravels that allows new growth, and so the processcontinues. The Forestry Commission has embarked on a tree and scrub removalprogramme to restore parts of the original surface, in close co-operation with SNH.

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Figure 18.1 Extensive relict shingle at Spey Bay, Moray, showing scrub invasion of the type nowbeing cleared by the Forestry Commission, September 2006. © Stewart Angus

Active shingle is associated with high mobility, so significant shifts occur withina single storm: Spey Bay is arguably the most dynamic section of Scotland’s coast,subject to onshore storms and river floods.

18.5 Dunes, including machair

Scotland is fortunate in having a comprehensive inventory survey of all coastal sand-based habitat, the Sand Dune Vegetation Survey of Scotland (SDVSS) (Dargie,2000), which found around 50,000ha of ‘potentially vegetated sand’. Scotland has71.4% of Britain’s dunes by area but some 9,127ha (18%) of the Scottish resourcehas been lost to development and plantations. Nevertheless, Scotland is believedto have retained a high proportion of its dune resource in good condition comparedwith other countries in the UK, Ireland and mainland Europe.

Of the 40,875ha of sand dunes (including machair) in Scotland, that have notbeen afforested or developed, 8,487ha (21%) has been converted to improvedgrassland, where natural species have been displaced by sown perennial rye-grass(Lolium perenne) and crested dogstail (Cynosurus cristatus). The areas involvedcan be extensive, with 43% of the dune/machair area of Orkney affected. Insouthern Scotland improved grassland may be for amenity rather than agriculture(Dargie, 2000). The impact of grassland improvement varies greatly: on Tiree,grassland improvement has had a comparatively low impact, whereas on Scotland’smany links golf courses, there are strong contrasts between the intensivelymanaged areas of play and the ‘rough’, where the latter can retain high conservationinterest, albeit as a highly fragmented version of the original habitat.

The colonisation of dune systems (mainly the larger, acid systems) by self-sownconifers from nearby plantations, native trees and scrub, and bracken, is an issueand is particularly serious at Torrs Warren, Barry Links and Tentsmuir, where areduction in, or cessation of, grazing has allowed trees to spread, leading to watertable lowering that promotes further expansion of tree cover. The excavation ofdrains is believed to have exacerbated the problem at Barry Links, where SNH hasnegotiated some scrub clearance and the introduction of cattle to maintain dunegrassland. In the acid systems of the Grampian coast, trees are present, but do notspread, even in the absence of stock grazing. This may be determined by the watertable, but whether or not a fall in the water table is the control, any existing watertable issues will be exacerbated by any further changes in summer temperature orprecipitation associated with climate change.

Although immensely valuable, parts of the SDVSS date from the mid-1980s. Ifthis resource is to retain its full value as a portrayal of a highly dynamic habitat, thereis now an imperative need for a rolling programme of re-mapping of at least themore important dune systems.

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Machair can be regarded as an extreme form of dune grassland, and someaspects of the habitat have been included within the above sand dune analysis.Though an expanded definition of machair habitat in respect of its listing on AnnexI of the EU Habitats Directive is now available (Angus, 2006), this has not yet beenapplied throughout the range of the habitat, so there is no official figure for itsextent, but it is believed to be in the order of 17,500ha (included within the50,000ha figure above).

Machair has been affected to a lesser extent by many of the land uses listed above,although the windy climate has limited the amount of forestry. Tiree and parts ofOrkney are particularly affected by grassland improvement, which tends to be moreintensive in Orkney. Though most machair areas are believed to have been cultivatedto some extent in the past, this is now confined to the islands of North and South Uist,Benbecula and Berneray, with a small area on Oronsay managed by the Royal Societyfor the Protection of Birds (RSPB). However, machair is a habitat that has never beenentirely natural, having evolved in tandem with human settlement (Angus, 1994). Thecultivation is unusual in being rotational and in delivering high biodiversity in both cropand fallow. The first cycle of SNH’s Site Condition Monitoring identified a dramaticloss of biodiversity in 2004, but subsequent work suggests that this wasunrepresentative and that biodiversity has substantially recovered. Nevertheless thereare issues that need to be addressed regarding the relationships between land use,funding measures and biodiversity to ensure that both the crofting system and thebiodiversity it supports are maintained (Angus, 2009).

18.6 Saltmarsh

The whole of the UK saltmarsh was surveyed at a basic level in the 1980s and therewas found to be 6,089ha of saltmarsh in Scotland, 13% of the British resource(Burd, 1989); but gaps in the survey and known under-estimates mean that the totalarea in Scotland could be as much as 7,000ha. A major inventory survey of theentire Scottish saltmarsh resource, jointly commissioned by SNH and SEPA,commenced in summer 2010 and will report on vegetation and condition by 2012.

Scottish saltmarshes differ from their southern counterparts in terms of substrateand species composition. There are fewer muddy saltmarshes and most Scottishsaltmarshes are sandy (May and Hansom, 2003). Scottish saltmarshes are also lesslikely to include a pioneer zone, terminating instead in an abrupt scarp (Burd, 1989).

The invasive cord-grasses (Spartina spp.) form extensive patches only in theSolway, though there are outliers elsewhere. There is little information on howmuch, if at all, Spartina has spread in recent years within sites, and opinions differas to its impact on pre-existing coastal habitats (Lacambra et al., 2004).

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The main firths have been subject to extensive land claim in the past; it has beencalculated that 2,860ha (51%) of the saltmarsh and mudflat area of the Forth werelost to land claim over the last 400 years (Hansom et al., 2001). The loss in theTay over the period 1800-1900 was 150ha (1% of intertidal area) (Buck, 1993).RSPB has successfully undertaken a managed realignment project at Nigg in theCromarty Firth and has recently (2009 to 2010) initiated a tidal exchange schemeat Skinflats in the Firth of Forth.

There has been very little land claim in recent years, although some claim in theMoray Firth for the expansion of Inverness harbour and industrial estates hasaffected mainly mudflats. Though embankments were built on the Solway Firth,these were for flood protection rather than land claim (Geodata Institute, 2003).The extent to which the landward transition has been truncated by embankmentsand other infrastructure is believed to be less than elsewhere in the UK.

18.7 Lagoons

Low-lying areas of the Scottish coast where water-filled rock basins exist arefrequent in the Outer Hebrides and the north-western mainland. Where these arecoastal, flooding by salt water can occur on some or even all high tides, formingbrackish lochs or ‘saline lagoons’. Elsewhere on the coast, but particularly inOrkney and Shetland, banks of shingle have impounded water bodies in such away as to promote brackish conditions.

Though a national UK inventory of saline lagoons has been published by theJNCC (Covey et al., 1998; Thorpe, 1998; Thorpe et al., 1998), the Scottishreports are more accurately described as accounts of sites surveyed as potentiallagoons. More rigorous application of habitat criteria to this dataset has provedproblematic: only 23 sites out of 139 give records of diagnostic lagoon ‘obligates’,and the total number of records is only 40, possibly because most obligatesbelong to difficult groups (Charophytes, Gammarids, Mysids and Hydrobiids).The study also failed to take account of the variability of salinity in each waterbody. The functionality of the habitat is poorly known and improvements inmonitoring are currently being explored at UK level.

Many lagoons have been altered by construction of roads, the installation ofculverts and sluices. Charophytes have disappeared from some lagoons, notablythe Loch of Stenness, Orkney, and this loss has been attributed to inflow ofartificial fertilisers, though changes in salinity could also be involved (Stewart etal., in press).

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18.8 Future change

Though there continues to be localised pressure on coastal habitat fromdevelopment, impacts can usually be mitigated by conservation advice andsignificant direct threats to coastal habitats from development are uncommon. Byfar the most significant driver of change on coasts in the coming decades will beclimate change, but the human response to climate change will itself bring coastalchange. The impact of the latter will depend on the extent to which adaptation isadopted as opposed to structural intervention and defence. There is a clear casefor defending major existing infrastructure such as the refinery installation atGrangemouth, but less of a case for permitting new coastal development in similarsituations. Similarly, localised iconic features like Skara Brae may be defended bystructures but all such sea defences have a knock on effect on adjacent coastlinesthat must be considered in strategic planning.

One of the main drivers for climate-related change on the coast is relative sealevel, and this has been rising in all parts of Scotland, with recent tide gauge datarevealing an increase in the pace of the rise (Rennie and Hansom, 2011). Althoughrising sea level will have a gradual impact on all coasts, impacts associated withsingle storm events could bring long term changes to sediment coasts. Coastalflood risk has been mapped, but there are problems of vertical resolution as well asuncertainty regarding storminess (Ball et al., 2008). Although the evidence forincreasing storminess is inconclusive (Dawson et al., 2007), there is a mountingcase for increasing storm severity evidenced by increasing storm wave heights(Hansom et al., 2008). Rising sea level is cumulative and storms – occasionallysevere storms – will act in concert with rising sea level, so that coasts willexperience increased marine flooding, erosion, and deposition. Redistribution ofsediment will occur, but the rate and pattern will be influenced by any vegetationpresent. Marram (Ammophila arenaria) has an extensive rooting system and is ableto adjust rapidly to sediment movement, so that where space exists to landward ordowndrift mobile dune habitat will quickly align itself to any new dune landform.Where such space is absent, there will be a loss of habitat. Atlantic saltmarsh inScotland (i.e. all Scottish saltmarsh except the pioneer zone) tends to form a verydense mat with a strong, resistant rooting system, which in turn will affect erosionpatterns within estuaries. In the Solway, however, where marsh surfaces are themost extensive in Scotland, physical change in the form of frequent erosion andredeposition may be more related to changing channel patterns as sea level risealters the lower courses of rivers.

It is possible that high-energy systems based on shingle, such as the mouth ofthe Spey, could become increasingly mobile, with these rolling inland where space

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is available, to create new coastal habitat inland by displacing existing habitat. Themore exposed beaches of the outer Firths could be the first mainland dune systemsto mobilise (Pethick, 1999) and recent observations by the authors at the MorrichMore in the Dornoch Firth suggest that this process may already be under way. Inmany cases beach sediments that were once available to support developing dunehabitats are now much depleted and many Scottish coasts are now affected bycoastal steepening where Low Water Spring Tide advances landward at a fasterpace than High Water Spring Tide (Hansom, 2010).

In the Outer Hebrides as sea level rises, lagoons within rock basins will becomeincreasingly saline, and eventually fully saline, but replacements will be created asrising seas flood fresh-water lochs. In the Northern Isles, the same process willoperate on existing lagoons, possibly with an additional role played by stormswhereby shingle barriers will be dismantled or rolled landward. Again, numerouscoastal shingle-bound fresh water lochs will become increasingly saline, as hasalready been observed as a result of rapid relative sea level rise in Nova Scotia(Carter et al., 1989). Individual saline lagoons must be regarded as ephemeralhabitats due to sea level rise: even management of the inflow/outflow may only delaythe inevitable. The lagoon ‘obligate’ species of these water bodies are rare becausethey have limited dispersal powers, but will they make their own way to their analoguesites as sea level rises, or should conservationists intervene in this process?

One of the greatest issues, however, could be on the flatter, outlying islands,where relative sea level rise has been in progress for several thousand years, and isnow accelerating. Preliminary analysis of the topography of South Uist derived fromairborne LiDAR (Light Detection and Ranging) remote sensing suggests that thereare extensive inland machair areas below the altitude of Mean High Water Springson adjacent beaches (Figure 18.2). However, the nearest tidal reference ports aretoo far away from this coastline to be reliable, and work by SNH and the UKHydrographic Office is progressing to obtain better correlations between ChartDatum and Ordnance Datum in these areas. These low-lying areas are separatedfrom the sea by a semi-continuous low dune cordon; gaps in which will allowoverwash and marine flooding which would then spread laterally across the low-lying hinterland, infiltrating significant areas with saline water.

Work by SNH following the severe storm of January 2005 suggested a relationshipbetween the salinity of surface water in seasonal lochs and the fresh water table, sothat the water table restored low salinity levels following a short-term marineinundation. Such inundations are short-lived because an extensive and complexartificial drainage network established prior to 1805 allows the drains to discharge atlow tide, when inland loch levels are higher than sea level. However, sea level hasbeen rising over the intervening 200 years, and the drains have now lost the most

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efficient part of their tidal discharge range. SNH is conducting further work to identifythe inter-relationship of sea level rise and the drainage network, and SEPA hascommissioned a study of the machair water table (Johan Schutten, pers. comm.).

Overall, in both North and South Uist, it is possible that sea level rise will resultin the net displacement of machair (an uncommon habitat) by saltmarsh (a morewidely distributed habitat), and a reduction in the area of high-biodiversity machaircropping if the water table becomes increasingly saline.

18.9 Conclusions

Almost all of the impacts of climate change on terrestrial habitats will also apply tocoastal habitats, with the added complication that coastal sediments will mobiliseand sea level will rise, both at faster rates than before. There will be impacts on thebuilt heritage as well as the natural heritage, and conservationists, planners andpoliticians will be under intense pressure to ‘do something’ about coastal changeand the associated degradation of habitats and infrastructure.

It is critically important that any intervention is designed to work in concert withnatural processes, in view of the long history of ill-planned intervention at the coast

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Figure 18.2 Digital Elevation Model (DEM) from, LiDAR, super-imposed on Ordnance Survey map ofsouthern South Uist. The gradual narrowing and lowering of the dune reach towards Cille Pheadair isclear, as is the extensive low-lying area inland of the dune ridge, which is the bed of a drained loch.LiDAR data captured November 2005. High to low DEM scale is: red, orange, green, beige, paleyellow. © SNH for Western Isles Data Partnership, map base Crown Copyright and database right2010. All rights reserved. Ordnance Survey licence number SNH 100017908.

making matters worse, not only at the pressurised location but also on adjacent coastsboth up and down drift. Such planning requires reliable data, information andknowledge, such as beach and habitat configuration via remote sensing, at both localand synoptic levels, that are presently either scarce or non-existent. Storm-basedevents may be one-off impacts or they could contribute to, or exacerbate, long-termtrends. Long-term datasets are required to separate events from trends and at thesynoptic level these are most effectively obtained by remote sensing, to enable rapididentification of low-lying and/or particularly vulnerable sections of coast. SNH and itspartners have begun this process for parts of the Outer Hebrides, Tiree and Coll,along with targeted commissioned research projects that review the implications ofclimate change for a range of coastal situations. It is already clear that a systematicand coordinated rolling programme of such work is required and that Scotland needsto increase its capacity to gather and analyse such datasets and address theemerging problems described above.

Close liaison between all the organisations involved will be required to addressthe multiple problems of coastal change. The primary role of conservation should beto facilitate natural adaptation, with a secondary role of investigating the options forthe limited number of sites where a range of intervention processes may be justified

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Plate 18.1 At Eshaness and the adjacent Villians of Hamnavoe, Shetland high energy storm wavesimpact the coast so that in places, the cliff-top vegetation is stripped away at altitude. Cliff top wavequarrying may also result in cliff-top storm deposits formed of individual blocks that are transportedlandward into boulder beaches and spreads. © Lorne Gill/SNH

and appropriate. The coastal environment has never been static, and temporaryattempts to stabilise this dynamism must be carefully evaluated and implicationsunderstood. Conservationists need to accept that change-related pressures frompeople will have impacts on the natural heritage that raise fundamental questions. If,for example, geomorphological features and the habitats they support, are allowed to‘roll back’, as part of an ‘adaptive management’ response to sea level rise, what arethe implications for owners and occupiers, whose holdings do not ‘roll back’?

Acknowledgments

We are grateful to James Dargie of Scottish Natural Heritage for calculating thecoastal length for Scotland. The later part of the SNH work on the impacts ofclimate change on the habitats of the Uists was supported by CoastAdapt, fundedby the Northern Peripheries Programme. We also thank Professor Robert Duck ofthe University of Dundee and Dr Susan Watt of SNH for their comments on aprevious draft of this paper.

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Documents

Habitat change on Scotland’s coasts