Scottish Government

GROUP 9 Cultural Heritage

Working group members and contributors

Outline of the issue

Definition of archaeological and cultural heritage soils

10.1 The issues discussed in this section relate to the loss of a resource (heritage soils) and factors affecting its continued survival. Almost all soils in Scotland, formed since the end of the last glacial episode some 11,000 years ago, have been subject to direct or indirect human influences. In some cases anthropogenic soils have intrinsic value as reservoirs of Scotland's past cultural history, containing both buried archaeological deposits and a record, from the character and content of the soil itself, of past environmental conditions. (For simplicity, these are hereafter referred to as 'heritage soils'. This term is meant to be inclusive of palaeosols (true fossil soils) as well as archaeological & cultural soils where the soil value is defined in the physical material comprising and contained within the soil. This emphasis on soil content is in contrast to biological descriptions of the soil as a medium for microbial activity, food production or as a store of carbon products.)

Impacts on soils

Drivers of change

10.2 Agricultural and environmental policy and economics (especially market forces) will continue to be the major drivers of both land use change and land management practices and thus impact on surviving cultural soils. Public opinion will influence both policy and market drivers, for example, from attitudes to alternative energy or waste management systems through to demands for changes in farming methods, leading for example to more outdoor rearing of pigs and poultry. At a much more diffuse level, though of increasing importance, climate change will also alter land use and land management as well as directly influencing surviving cultural deposits.

10.3 Mechanical destruction of archaeological monuments in Scotland and their associated soils during arable cultivation has been recognized since the 18th century (e.g. Roy W Military Antiquities of North Britain). Detailed research identifying the extent of destruction and the nature of the threat is subject of a programme sponsored by English Heritage and Defra (Defra BD 1701, 1704 & 1705). A detailed regional case study in Scotland has been published by Historic Scotland (2008). The extent of deep ploughing, de-stoning, subsoiling and drainage on known heritage soils and deposits has not been quantified, and may in practice not be quantifiable, due to persisting issues of definition and a lack of accurate detailed information about land-using activities. This is not just restricted to arable areas: the impact of forestry ploughing and mounding remains a significant threat to heritage soils in upland areas, particularly as these are also related to erosion and geochemical changes.

10.4 Bioturbation by both microbial and macro fauna remains a significant threat to previously intact archaeological deposits and is exacerbated by the application of chemicals, fertilisers and other materials added to condition the soil for agricultural and forestry use. These impacts are poorly understood from a heritage perspective and have not been subject to systematic research.

10.5 Contamination may badly affect heritage soils, through dumping of contaminated materials. However it should be recognized that certain sites, contaminated from a biological point of view by heavy metals or other wastes, may also constitute important evidence for Scotland's industrial heritage. (They may also, of course, be reservoirs for rare flora and fauna due to the unusual chemical conditions that themselves produce distinct special soil types.)

10.6 Erosion of heritage soils occurs through both wind and water action and can be exacerbated by mechanical interventions such as ploughing, particularly if conducted under inopportune conditions. Sea level change will impact on heritage soils surviving in coastal areas, and may combine with inappropriate grazing and recreational use of areas such as dune systems. Forecast increased storminess and more concentrated precipitation episodes will undoubtedly have a widespread impact.

10.7 Sealing by both dumping and construction can hide or destroy heritage soils. In some cases this may be intended only to hide these deposits for a temporary period, but overburden pressure can alter the nature of the heritage soils, through compression of deposits and alteration of water tables. There is ongoing research into the benefits versus drawbacks of sealing as a means of preserving heritage remains, led by English Heritage.

Impact of change or loss of heritage soils

10.8 Heritage soils cannot be replicated, so measures to minimise loss of such soils should always be preferred. Changes in land use and management practices will certainly affect heritage soils, but the trajectory and intensity of change still need to be clarified. Important changes include new crops or cropping patterns, e.g. altered agrochemical regimes, will impact on surviving archaeological soils.

Impact of heritage soils on environmental function

10.9 Cultural soils will not, in themselves, tend to affect environmental function. Their persistence is, however, an important indicator of long-term stable systems, while evidence of degrading cultural deposits is a sign of environmental change.

Heritage soils as reservoirs for carbon storage

10.10 Because heritage soils tend to be both physically stable and organic-rich, there is potential for disturbance and erosion to release of stored carbon out of proportion to the actual volume of such soils: impacts will generally be locally restricted.

Sustaining heritage soils

10.11 Heritage soils are important reservoirs of knowledge on our past and indicators of past environmental systems (Towers et al., 2006). The relationship between soil and biodiversity features in designated sites ( SSSI, National Park) has also been reviewed (Towers et al., 2006, 2007) and should inform management of protected habitats and species. Sustainable management is essential to delivery of conservation objectives and should be an essential component of any restoration project. Agri-environment schemes should be able to deliver positive benefits for the survival of such soils but only if reliable information on the location of such deposits and clear advice on appropriate measures are available. Even without such information, it is a reasonable assumption that any measure to prevent soil erosion is likely to be beneficial for heritage soils.

Soil Biodiversity and cultural heritage

10.12 There is limited information about the effects of microbial activity in soil on archaeological materials and deposits. However, if soil processes which are control by soil biodiversity change, previously well preserved material may degrade more rapidly. As well as microbial activity the effects of soil macro fauna (earthworms, rabbits, badgers, moles etc.) and roots are potentially of concern for the preservation of archaeological artefacts. The physical impacts of larger burrowing animals are relatively well-studied although management measures are less well developed, seldom extending much beyond physical exclusion.

Soil chemistry and the survival of heritage soils and archaeological evidence

10.13 Changes in soil chemistry through the addition of lime or other materials to alter pH, fertilisers (both organic and inorganic), pesticides, air pollution and dumped materials all impact on the preservation of cultural soils and archaeological artefacts, particularly metals and organic remains.

Impacts in Scotland

10.14 Heritage soils, because they are relics of past land use and settlement, are by their very nature restricted and subject to decay and degradation by entropic processes. However, significant information on both the cultural and environmental history of Scotland still remains, and can be sustained in the medium and longer term if impacts described are controlled.

Climate change

10.15 There is some evidence to support the specific impact of climate change in Scotland on cultural soils but also major gaps in current knowledge, which will be described in next section. How adaptable are cultural soils to climate change? The impact of climate change on cultural soils is likely to be negative overall, though specific climatic impacts for different regions remain uncertain. The following effects may be predicted:

10.16 Direct effects

• Climatic changes will directly affect the soil environment (temperature, wetness). This will directly impact on the metabolic rate and other biochemical process controlled by soil biodiversity. There is as yet an unknown degree of resilience and resistance of soil biodiversity to change and suspected redundancy of functionality in the soil microbial community.
• Higher rainfall is likely to reduce soil oxygen levels. This should be of benefit to organic heritage soils and organic material contained within them. However soils where increased water tables might be of benefit are in most cases already degraded or degrading, rather than stable, environments, and (unlike biodiversity interests) are unlikely to benefit from re-wetting. Increased rainfall could exacerbate leaching of the soil profile particularly in upland acid soils. It will almost certainly increase physical erosion of exposed heritage soils, particularly when linked to more frequent storm events.
• Coastal erosion will destroy an estimated 12,000 archaeological sites within the next 10-20 years (Dawson 2007). It will not be feasible to save the heritage deposits contained within most of these sites and strategies will be need to be adopted to maximize the value and amount of information that can be salvaged for these sites.
• Indirect effects
• Many possible technologies which are likely to be introduced, and infrastructure constructed, to reduce CO ₂ emissions (biomass, biofuels, windfarms etc.) are likely to impact on heritage soil survival, however carefully planned - the issue here is the very limited extent of knowledge of the extent of heritage soils, given that knowledge is imperfect of much more easily-defined assets when these are not visible as surface remains, and the imperfection of detection techniques for formal sites, let alone soils.
• Higher temperatures may have some impact, particularly if accompanied by reduced rainfall in the east, encouraging faster drying and thus greater erosion of organic soils (including those with heritage deposits).

Acidification - diffuse pollution and contamination

10.17 Increased acidification will have a negative impact on most heritage soils, increasing the rate of degradation. It may also encourage, through leaching, the greater formation of panning, leading in turn to increased desire to undertake pan-busting and sub-soiling. This will, in turn accelerate the destruction of heritage soils.

Data and evidence gaps

10.18 The keys gap for the purposes of soils strategy are clustered around the definition and quantification of the values attached to heritage soils and the evidence of the past environmental history they contain.

10.19 An ecosystem approach, with heritage values related to broader assessment of the environmental, societal and economic values of soils, seems most appropriate. Valuing stable environmental systems in Scotland should be a high priority for all in the development of positive management of soil resources, and will of itself favour the preservation of heritage soils. However, the vocabulary and rationale for inserting heritage considerations into this discourse is poorly developed.

10.20 In the absence of overarching soil protection policy, risk-based approaches to soil protection conducted by sectoral interests or designed to address single threats can lead to the development of increasingly overlapping exclusion zones. Therefore prioritisation of risk and threats (such as degradation, erosion, flooding) becomes key to the process of valuing heritage soils. This will likely be driven by wider land-use policy requirements than those of soil protection alone.

New and Emerging policies

10.21 Some of the emerging issues have already been discussed in previous section. This includes the change in set aside, uncertainty on land use and land practices change uptake.

10.22 Not discussed here, but highly relevant is the draft EU Soil Framework Directive http://ec.europa.eu/environment/soil/index.htm. Although not dealing directly with heritage soils its implementation will drive forward the soil protection agenda and soil monitoring activities in UK.

10.23 The outcome of policy formulation around Soil Framework Directive may change how heritage soils are perceived and acted on in other EU and international frameworks.

References

DEFRA, Science & Research Projects: Theme: Landscape, history and amenity:

• BD 1701 Management of archaeological sites in arable landscapes [1999-2002]
• BD 1702 Attitudes of farmers and land managers towards features of landscape and historic interest [1999-2000]
• BD 1704 Conservation of scheduled sites in cultivation ( COSMIC) [2003-2005]
• BD 1705 Trials to identify Soil Cultivation Practices to Minimise the Impact on Archaeological Sites [2005-2010] ( www.rand.defra.gov.uk)

Burke, A.D. 2004 Patterns in archaeological monument loss in East Central Scotland since 1850. PhD thesis, University of Stirling

Countryside Survey (2000) -
http://www.countrysidesurvey.org.uk/archiveCS2000/

Darvill, T. and Fulton, A. 1998. The Monuments at Risk Survey of England 1995: Main Report. Bournemouth: School of Conservation Sciences, Bournemouth University.

Dawson, T 2007 A review of the Coastal Zone Assessment Surveys of Scotland, 19967-2007: Methods and Collected Data (unpublished report recently submitted to Historic Scotland)]

Historic Scotland 2008 The Management of Cropmark Archaeology in Lowland Scotland - a Case Study from the Lunan Valley, Angus. ( HS Research Report series)

NSRI (2005) Impacts of climate change on soil functions, SP0538. Final project report to DEFRA.

RELU (2005) 'Soils - the foundation of the Rural Economy'
http://www.relu.ac.uk/research/projects/Watson.htm

Roy, W. 1793. Military Antiquities of North Britain

Scottish climate change declaration -
http://www.sustainable-scotland.net/climatechange/index.asp

SNIFFER - report
http://www.sniffer.org.uk/climatehandbook/index.html

SNIFFER 2004 The role of the planning system in protecting and enhancing soil. UKLQ01

Towers et al. 2006 - Scotland's soil resource - current state and threats. A report to SEERAD.
http://www.scotland.gov.uk/Publications/2006/09/21115639/21

Wilkinson, K., Tyler, A., Davidson, D., Grieve, I. 2006 Quantifying the threat to archaeological sites from the erosion of cultivated soil. Antiquity 80, 658-670.