Risk/opportunity:(from the Climate Change Risk Assessment for Scotland 2012):
SCCAP theme: Natural environment
N2: Support a healthy and diverse natural environment with capacity to adapt
UK BAP priority habitats
Coastal sand dunes (including machair)1
Coastal vegetated shingle3
Maritime cliff and slopes1
1.SNH: Ellis & Munro, 2004
2. SNH: Haynes, 2016
3. SNH: Murdock et al 2011; 2014
4. Source: Jones et al, 2011
- Scotland’s coastline is extensive and diverse; in many areas coastal habitats are of exceptionally high quality.
- Scotland’s coastal habitats are particularly noted for their extensive dune systems including machair, one of the rarest habitats in Europe and found only in Scotland and Ireland.
- Coastal habitats provide a range of ecosystem services of significant benefit to the economy and society, including carbon sequestration, flood protection and seascapes supporting tourism.
- Coastal habitats are particularly sensitive to climate change, as they are subject to changes in rainfall, temperature and storminess as well as coastal erosion and sea-level rise.
- This indicator measures the extent of coastal habitats in Scotland, and reports on the five coastal priority habitat types recognised by the UK Biodiversity Action Plan.
Scotland’s coastline is extensive (about 18,000km) and, as a result of geology, glaciation and large variation in tidal range and wave exposure, exceptionally diverse. It also contains over 790 islands. The relative lack of development in areas such as the Highlands and Islands means that many coastal habitats are in an outstanding condition (Ellis & Munro, 2004).
Scotland’s coastal habitats are particularly noted for their extensive dune systems including machair which is found only in Scotland and Ireland and is one of the rarest habitats in Europe. Much of Scotland’s machair is now internationally recognised for its conservation importance, and is included in Natura 2000, the EU network of protected areas under the Habitats Directive (H.R. Wallingford, 2012). Scotland’s coastline is also noted for its salt marshes which are structurally and biologically distinct from those in England (Ellis & Munro, 2004).
Coastal habitats provide a range of ecosystem services of significant benefit to the economy and society, including carbon sequestration, flood protection and seascapes that support tourism (Jones et al, 2011). The total value of the ecosystem services provided by the UK’s coast is estimated at £48 billion (adjusted to 2003 values). The ecosystem services of greatest financial value are tourism and leisure (cultural) and coastal defence (regulating), but the relative importance of these services differs according to location (ibid).
Climate change will impact coastal habitats in a number of ways. Sea level rise will cause inundation, accelerated erosion, more frequent and extensive flooding and saline intrusion. The ability of coastal habitats to provide sea defence will come under increasing pressure (Ellis & Munro, 2004). The dynamic, natural state of coastal margin habitats that supports their rich biodiversity depends on the key natural processes of supply and transport of sediment. The supply of sediment may be affected by sea level rise and coastal erosion; this may be either positive or negative subject to the local context. In either case, there will be an impact on the extent or character of habitats necessitating a management response (Jones et al, 2013).
This indicator measures the extent of coastal habitats in Scotland, and reports on the five coastal priority habitat types recognised by the UK Biodiversity Action Plan: 1) coastal sand dunes, 2) coastal saltmarsh, 3) coastal vegetated shingle, 4) maritime cliff and slopes, and 5) machair.
UK BAP priority habitats
Extent (best estimate)
Coastal sand dunes (includes machair)
Dargie, 2000 (Ellis & Munro, 2004);
Burd (1989) plus SNH knowledge (Ellis & Munro, 2004)
Partial survey; most area-based and vegetation data from 1980s (The National Archives, 2011)
Posford Duvivier Environment, 1998 (Ellis & Munro, 2004)
Coastal vegetated shingle*
SNH: Murdock et al, 2011; Murdock et al, 2014
2,045 ha plus 700km
BARS (2005): Mix of data in length and hectares; incomplete survey except for Solway (The National Archives, 2011)
670 ha plus 162.5 km
Ellis & Munro, 2004: amalgamated from various surveys
Maritime cliff and slopes
Posford Duvivier Environment, 1998
BARS (Pre-1995): Partial survey, from Coasts & Seas of the UK (JNCC publication) (The National Archives, 2011)
18, 452 ha
Dargie, 2000 and Angus (Ellis, 2004)
Dargie, 2000 (Ellis, 2004)
3rd UK Habitats Directive Report (JNCC, 2013)
Table 1 Estimated extent of coastal priority habitat types
Table 1 shows the estimated extent of the five coastal priority habitat types in Scotland (with UK figures for comparison) recognised by the UK Biodiversity Action Plan.
Data on the extent of coastal habitats is compiled from a variety of sources, and differing definitions or classifications of habitats (Jones et al, 2011). Therefore there are still significant knowledge gaps for some habitats. Alternative estimates are also included in Table 1 where available.
Coastal sand dunes: 50,000 ha
The sand dune vegetation survey of Scotland (Dargie, 1997-2000) included both coastal sand dune and machair. Some known small areas of sand dunes were not included (Ellis & Munro, 2004).
Coastal salt marsh: TBA
From 2010-2012 all known saltmarshes larger than 3 hectares were surveyed across the Scottish mainland and islands, compiling the first comprehensive national survey of this habitat. All saltmarsh and brackish swamp has been mapped using the National Vegetation Classification (Haynes, 2016).
Coastal vegetated shingle: 1,120 ha
Due to the lack of comprehensive data on the extent of coastal vegetated shingle in Scotland, Scottish Natural Heritage (SNH) commissioned an inventory to draw together existing data, supported by field validation work across a number of sites (Murdock et al, 2011; Murdock et al, 2014).
Maritime cliff and slopes: 1,778.5 km
There are uncertainties in existing data. The estimate produced by Posford Duvivier Environment (1988, in Ellis & Munro, 2004) correlates well with OS 1:50,000 maps however it does not include some known cliff areas, e.g. on the Berwickshire coast (Ellis & Munro, 2004). The current estimate of 1,778.5 km accounts for just under 10% of Scotland’s total estimated coastline.
Machair: 18,452 ha
The estimated extent of machair is from an unpublished dataset held by Stewart Angus, based on Dargie’s (2000) Sand Dune Vegetation Survey of Scotland. Accurate and consistent measurement of machair is difficult because of the difficulty of classifying machair habitat at the edges of its range (Ellis & Munro, 2004).
It is difficult or impossible to identify trends for coastal habitats due to the limitations of existing data detailed above. The trends shown in Table 2 are identified for coastal habitats in Scotland in the UK National Ecosystem Services Assessment:
Coastal sand dunes
Coastal vegetated shingle
Maritime cliff and slopes
Table 2 Trends in extent of coastal priority habitat types
Source: Jones et al, 2011.
At a UK level, ‘coastal margin habitats have declined by an estimated 16% since 1945 due to development and coastal squeeze, but this is poorly quantified. All habitats have been affected by coastal development for industry, housing and tourism. Sand Dunes and Saltmarsh have also been affected by agricultural development (including forestry). Although the introduction of greater statutory protection in the 1980s has slowed the rate of loss and fragmentation of many sites, coastal margin habitats are still being lost today.’ (Jones et al, 2011).
The Third UK Habitats Directive Report (JNCC, 2013) states that no trends were identified in the extent of machair for the period 1987 to 2012.
Sea level rise and climate change, together with pollution and continued development pressures, present a major threat to our coastal margins in the coming decades. Vulnerability to such threats is increased by the linear nature of the habitat; it is subjected to pressure from every side (Jones et al, 2011). Climate change therefore impacts them not only through changes in temperature, rainfall and the frequency and severity of storms, but also through sea level rise and coastal erosion (Jones et al, 2013). Increased frequency of gales and storm surges may also change the structure of coastal habitats (Ellis & Munro, 2004).
Coastal erosion is currently occurring on about 12% of the Scottish coastline, one of the lowest levels in Europe (H.R. Wallingford, 2012); however changes in rates of erosion and accretion may lead to habitat loss, particularly where landward migration of sand dunes and salt marshes is constrained by coastal defence structures and other development (coastal squeeze). Coastal erosion is a particular problem for Scotland’s inner and developed firths that are composed of soft coastlines and rare habitats (Ellis & Munro, 2004). The composition and range of shallow marine habitats may therefore change as sea levels increase.
Future losses will increase throughout the UK as storm erosion events increase in magnitude and sea-level rise further outstrips isostatic readjustment.
Appropriate management may enhance both biodiversity and other ecosystem services. Sustainable management options include:
- Allowing Coastal Margin habitats room to migrate inland with rising sea levels in order to mitigate coastal squeeze (‘managed realignment’).
- Managing sediment supply by allowing erosion to contribute new sediment to the coast, and allowing natural transport processes to proceed where possible.
Maintaining or encouraging natural formation of early successional habitats where these are threatened or have disappeared (Jones et al, 2011).
Major knowledge gaps remain regarding the extent of Scotland’s coastal habitats (Jones et al, 2011). There is a lack of standardised information, with multiple estimates using different methodologies and definitions of habitat types. Some habitats, such as sand dunes, saltmarsh and machair, are highly dynamic and their extent will vary significantly, for example seasonally (Angus, S., personal communication. 22 July 2015). SNH is developing a Habitat Map of Scotland (one of the objectives of the 2020 Challenge for Scotland’s Biodiversity, part of the Scottish Biodiversity Strategy). This will bring together all the habitat information available for Scotland, with habitats classified by the European Nature Information System (EUNIS). The complete map will be available by 2019 (SNH, 2015). Provided this data is updated regularly, e.g. reporting for the EU Habitats Directive, the 2019 Habitat Map should provide a baseline against which to measure future trends.
The National Archives (2011) Biodiversity Action Reporting System [online] Available at: http://tna.europarchive.org/20110303145238/http:/www.ukbap-reporting.org.uk/default.asp (Accessed August 2015)
Ellis, N.E. and Munro, K. (2004). A Preliminary Review of the Distribution and Extent of BAP Priority Habitats Across Scotland. Scottish Natural Heritage Commissioned Report No.044 (ROAME No. F00NA02).
Haynes, T.A. (2016) Scottish saltmarsh survey national report. Scottish Natural Heritage Commissioned Report No.786.
Joint Nature Conservation Committee (JNCC) (2013) Individual Habitat Reports – 3rd UK Habitats Directive Reporting 2013 [online] Peterborough, JNCC. Available at: http://jncc.defra.gov.uk/page-6392 (Accessed July 2015)
Jones, L., Garbutt, A., Hansom, J., and Angus, S. (2013) Impacts of Climate Change on Coastal Habitats. MCCIP Science Review 2013: 167-179. http://uknea.unep-wcmc.org/
Jones, L., Angus, S., Cooper, A., Doody, P., Everard, M., Garbutt, A., Gilchrist, P., Hansom, J., Nicholls, R., Pye, K., Ravenscroft, N., Rees, S., Rhind, P. & Whitehouse, A. (2011) UK National Ecosystem Services Assessment, Chapter 11: Coastal Margins. Murdock, A.P., Hill, C.T., Randall, R. & Cox, J. (2011) Inventory of coastal vegetated shingle in Scotland. GeoData Institute, Scottish Natural Heritage Commissioned Report No. 423
Murdock, A.P., Hill, C.T., Randall, R., Cox, J., Strachan, I., Gubbins, G., Booth, A, Milne, F.,
Smith, S.M. and Bealey, C. (2014). Inventory of coastal vegetated shingle in Scotland – field
validation. Scottish Natural Heritage Commissioned Report No. 739.
No author (2014) UK National Ecosystem Assessment Follow-on Phase UKNEAFO Work Package 4 - Coastal/marine ecosystem services: Principles and Practice – Summary http://uknea.unep-wcmc.org/Resources/tabid/82/Default.aspx
Scottish Natural Heritage (2015) Habitat Map of Scotland [online] Inverness: Scottish Natural Heritage. Available at: http://www.snh.gov.uk/about-scotlands-nature/habitat-map-of-scotland/(Accessed July 2015)
HR Wallingford (2012) A Climate Change Risk Assessment For Scotland, report compiled for DEFRA. Available at http://randd.defra.gov.uk/Document.aspx?Document=10069_CCRAforScotland16July2012.pdf (Accessed July 2015)
Angus, S., Rennie, A. (2014) An Ataireachd Aird: The storm of January 2005 in the Uists, Scotland. Ocean & Coastal Management. 94, June 2014, 22-29.
Angus, S. (2014, The implications of climate change for coastal habitats in the Uists, Outer Hebrides. Ocean & Coastal Management. 94, June 2014, 38-43.
Young, E., Muir, D., Dawson, A. & Dawson, S. (2014) Community driven coastal management: An example of the implementation of a coastal defence bund on South Uist, Scottish Outer Hebrides. Ocean & Coastal Management. 94, June 2014, 30-27.
Suzanne Martin (Forest Research/CXC) contributed to this indicator as a co-author.
Stewart Angus (SNH) helped identify the best available data and provided additional information about coastal habitats.