Palaeoenvironmental remains and sequences'

Overall vulnerability

Feature assessed:

• Palaeoenvironmental remains and sequences

Special qualities:

• Landscapes that tell a story of thousands of years of people, farming and industry

Feature description:

The soils, sediments, and peats in the PDNP are a very important source of palaeoenvironmental information.

They help provide an insight into how the climate has changed, along with past vegetation, habitats and human activity, and long-term environmental changes.

In good condition, the waterlogged peatlands of the Dark and South West Peak in particular should provide a good level of protection for palaeoenvironmental evidence buried beneath the surface. These environments are scarce in England, hence their value as a source of preserved organic remains. In addition, organic remains can also be found in the White Peak where pollen for example has been found in tufa - a porous limestone sediment.

Valuable palaeoenvironmental evidence can also be contained within any buried soils and archaeological deposits (see ‘Buried soils, archaeological remains and deposits’). Sediments within caves and cave systems are also a very valuable, yet fragile, source of palaeoenvironmental information.

How vulnerable are palaeoenvironmental remains and sequences?

Palaeoenvironmental remains and sequences in the PDNP have been rated ‘high’ on our vulnerability scale. This score is due to high sensitivity and exposure to climate change variables, and a variable current condition and a moderate adaptive capacity.

The current condition of these features is largely unknown due to their hidden nature, but certain areas such as the peat bogs of the Dark and South West Peak are known to be at risk. Climate change effects that expose deposits or alter soil conditions are likely to be damaging. As these features are buried any change in the surface conditions from extreme weather events will have a key potential impact. Sediments in underground sites, fissures and caves are equally important and must not be overlooked. These may be particularly vulnerable to environmental change.

There is very limited capacity for adaptation as once they are damaged the information that they contain cannot be recovered. However there are adaptations that can be made to help preserve the existing resource. These features are particularly significant where they can be related to other heritage features such as prehistoric settlement and field systems or human activity within caves, for example.

Current condition:

The current condition of palaeoenvironmental remains and sequences in the PDNP is difficult to ascertain and is likely to be variable. The survival of organic remains and deposits is dependent on the environment into which they were originally buried, as well as subsequent conditions. It has been found that certain materials are better preserved in acidic, and some in alkaline, environments.

In the Dark and South West Peak for example, peat bogs are a very important due to their value in preserving buried organic material. This is because numerous materials survive better in anoxic environments (i.e. those without oxygen) and the waterlogged nature of these bogs mean that the majority of soil microorganisms along with fungi are not able to operate as decomposers.

Unfortunately, PDNP peat bogs are generally in an extremely poor condition with a low or erratic water table (see assessment of ‘Blanket Bog’) which means it is likely that some items have already been lost or degraded. Previous human drainage of bogs and other soils across the PDNP will have already degraded or destroyed buried soils and some archaeological deposits. In addition, ploughing, development and other farming practices are very likely to have affected the condition of these features.

Tufa has also historically been exploited in the PDNP as a source of lime for agriculture and as a construction material, but evidence for this is limited to a small number of quarry sites. Sediments in underground sites, caves and fissures are also a significant source of potential palaeoenvironmental information. Relatively few investigations have been carried out on these deposits.

What are the potential impacts of climate change?

Overall potential impact rating

Direct impacts of climate change

Drier summers and wetter winters could have a significant impact on palaeoenvironmental remains and sequences including those within caves, fissures and underground deposits. Drier summers could also have a significant impact on sites with good organic preservation. Drying of soils may increase the cracking of the surface allowing oxygen to enter the subsurface region and increase microbial action activity and oxidation of materials. In addition, the cycle of wetter winters and drier summers will cause further damage to waterlogged archaeological deposits. In PDNP peat soils in particular these changes could see the destruction of organic remains. Data Certainty: High. Information may be lost where valuable palaeoenvironmental and organic remains are vulnerable to changes in groundwater levels. Data Certainty: High

Increased surface water run-off in extreme storm events could see peatlands damaged and hydrology impaired as gullies are formed and widened, putting organic remains put at risk. River valleys at risk of flooding could also experience a significant impact on remains. There may be changes to the water table or degradation of riparian habitats. Data Certainty: High

Increased annual temperatures could also accelerate microbiological activity that could lead to the destruction or degradation of organic remains that are sensitive to such change. Data Certainty: Moderate

Human behaviour change

Drier summers could lead to changes in the economics of upland farming. For example, drier heathlands become more suitable for intensive management and grazing regimes may be changed. Erosion may be increased by overgrazing and high stocking levels, damaging remains and deposits. Agricultural improvement may lead to changes in soil chemistry - such as changes in pH. This could affect preservation of materials. Data Certainty: High

Temperature changes leading to longer growing seasons could see new types of crop and marginal areas becoming more viable. Pasture converted to arable crops and associated ploughing and drainage may disturb soil layers while physical buried remains could be damaged. Data Certainty: Moderate

Increased pressure for construction of renewable energy installations such as wind turbines, particularly on exposed areas, could affect the feature, as soils will be sensitive to installation of equipment, compaction and disturbance. This may cause an increase in erosion and change the hydrology or an area leading to drying of site. However, current planning policies make renewable energy installations such as wind turbines on moorlands less likely. Data Certainty: Moderate

Periods of extreme drought could lead to demand for more water to be taken from the ground or rivers. Resulting changes to the water table could negatively affect riparian habitats and see biological remains damaged if land dries out. Data Certainty: Low

Nutrient changes or environmental contamination

Atmospheric changes, for example increased carbon dioxide levels that result in the chemical composition of water being altered could have an impact on the anoxic environment found in soils and sediments. It has been shown that micro-organisms are very sensitive to even small changes in water chemistry and are also important for maintaining an anoxic environment. If this environment is not maintained some remains may be lost or damaged. Data Certainty: High

Sedimentation or erosion

Degraded bogs in particular are sensitive to erosion, so an increase in summer droughts and winter storms could result in bare peat damaged by water and wind. This also applies to other soils across the PDNP including cave and fissure deposits. However, the deposition of eroded sediment could protect other sites. For example, while some remains could be exposed by increased erosion, some could also be buried further by the silt and material that has been moved. The uncovering of new sites and materials through increased erosion should only be considered a positive result of climate change if there is resource to record the new information - exposure also is likely to see the new sites damaged or lost. If erosion rates increase, remains and deposits may also be exposed to oxygen as water table falls. Data Certainty: High

Other indirect climate change impacts

Drought and drier ground conditions could lead to an increased incidence of wildfire in the PDNP, particularly on degraded bog and heath sites. Potentially large areas of peat and vegetation could be lost further increasing erosion and peat loss. In such conditions dry peat also becomes more susceptible to damage from managed burns and there is more potential for them to get out of control. Fire can damage remains within or below the peat and mean they are lost or severely affected. Data Certainty: High

Invasive or other species interactions

If warmer winters lead to higher populations of burrowing mammals such as badgers, moles and rabbits buried archaeological deposits could be disturbed and hydrology of the area in question could be changed, with drier sites leading to less preservation of organic materials. Data Certainty: Moderate

The fragile surface of damaged bogs is sensitive to increased erosion if winter storm events increase in frequency and intensity. In other habitats the areas where trees are uprooted and remains are therefore exposed or damaged could increase. Erosion may lead to more opportunities for invasive species to colonise, potentially drying soils further and increasing the risk of damage to remains and deposits. Data Certainty: Low

Buried deposits could be sensitive to more rapid scrub and tree colonisation as a result of increases in atmospheric carbon dioxide and nitrogen levels and increased average annual temperatures. Not only can they be disturbed directly by root systems, but also an increase in evapotranspiration could lead to drying of some sites. Data Certainty: Low

What is the adaptive capacity of palaeoenvironmental remains and sequences?

Overall adaptive capacity rating

Although the features can be found across the PDNP in a wide diversity of locations, some of the most important places are probably the waterlogged peatlands - but there are few where the upper layers are waterlogged. Important pollen records may be retained in non-waterlogged soils. Because these are hidden features, it is unknown exactly where important remains can be found lowering the capacity for human adaptive measures to be implemented. Data Certainty: Moderate

Some money from grants and partners is available for peatland restoration activities, but there is currently a decrease in the uptake of agri-environment schemes in the PDNP. The future of environmental land management schemes after the UK has left the European Union is also very uncertain. Archaeological deposits, apart from those in peat, are at risk because they often do not have sources of funding available to secure the habitat in which they are situated. Those areas that do not come under planning control and do not have funding sources available to secure them outside of environmental land management schemes will be some of the least adaptable. Data Certainty: High

Several organisations carry out or oversee peatland and other habitat restoration projects in the area, in order to help safeguard these features. They include Moors for the Future Partnership, National Trust, Royal Society for the Protection of Birds and South West Peak Partnership. These increase the capacity for adaptive measures such as habitat restoration to be taken. However, only a small proportion of the park is in public ownership and the involvement of private landowners taking advantage of current land enhancement opportunities will be mixed in uptake and extent. Data Certainty: High

There is a lack of clear information about what and where remains and sequences are. Most of these features will be at unknown sites that do not even have a status as a ‘non-designated heritage asset’. Some management to protect features could be taken, however it is unlikely that there will be a co-ordinated approach on the landscape scale. Information and expertise is however available from the organisations highlighted above and others including Historic England and PDNPA Planning and Cultural Heritage teams. Data Certainty: Low

Key adaptation recommendations for palaeoenvironmental remains and sequences:

Improve current condition to increase resilience

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations are aimed at improving the condition of the feature at present, therefore making it better able to withstand future changes to climate.

• Habitat enhancement to stabilise the water table, which will create stable environmental conditions for preserving remains and deposits.
• Integrate heritage protection into moorland restoration schemes.
• Create research partnerships, for example with universities, to provide a better understanding of these deposits across the PDNP, to include scientific dating.
• Phase out burning on blanket bog. Develop fire contingency plans, and ensure management of habitats reduces fire risk e.g. rewetting and increasing species or structural diversity. Influence visitor and behaviour management plans and practices to minimise ignition risk.

Targeted conservation efforts for important sites and at risk areas

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations are conservation measures aimed at those sites that will have the biggest impact for this feature – either because they are particularly important for the feature or because they are most at risk from climate change.

• Investigate funding for strategic survey to locate and catalogue sites of archaeological interest and potential (deposit modelling).
• Improve the knowledge of cultural heritage features to help target conservation efforts