Healthy soil

Overall vulnerability

Feature assessed:

• Healthy soil

Special qualities:

• Vital benefits for millions of people that flow beyond the landscape boundary

Feature description:

The PDNP contains varied soil types. In the Dark Peak blanket bog, peat soils are fringed with acidic loamy soils, often with a wet peaty surface. The White Peak has predominately slightly acid but base-rich loamy soils, with some areas of shallow lime-rich soils over limestone. The South West Peak contains a mixture of soils, including blanket peat and seasonally wet, acidic loamy and clay soils. For assessments of related subjects, see ‘Blanket bog’, ‘Buried archaeological soils and deposits’, and ‘Palaeoenvironmental remains and sequences’. Healthy soils are a living system and provide many important ecosystem services. They are an important store of carbon, vital for biodiversity, water quality and the agricultural economy of the PDNP.

How vulnerable is healthy soil?

Healthy soil has been rated ‘high’ on our vulnerability scale. This score is due to high sensitivity and exposure to climate change variables, a varied current condition, and a moderate adaptive capacity.

Soil health in the PDNP is likely to have followed the general nationwide decline over the past 50 years, with Dark Peak peat soils being in the worst condition. Erosion caused by extreme droughts and storms are one of the major potential impacts on healthy soils. A change in soil moisture levels and chemistry have the potential for a significant impact on soil biota and therefore health.

While some soils can recover without intervention, most will require active management steps to be taken. Replenishing organic matter and making radical changes to landscape level management including the creation of woodland, scrub and diverse flower-rich meadows would increase the adaptive capacity of soils.

Current condition:

In England and Wales in recent decades there has been a loss of soil organic carbon. This is due to changes in land use and management. Intensification of arable agriculture has been an important driving factor in this national loss. While this farming type is relatively uncommon in the PDNP, the intensification of agricultural in general has had a negative effect in soil health since the Second World War. The conversion of semi-natural to agriculturally ‘improved’ grassland, the loss of hay meadows, the creation of conifer plantations and the increased use of fertilisers are just some of the contributory factors.

In addition, the peat soils in the Dark Peak are in a particularly poor condition. Pollution from the industrial revolution has had a major impact stripping vegetation and leaving large areas of bare peat exposed. Much of this area is still heavily contaminated and acidified. This soil type has also suffered from extensive erosion, with deep gullies present.

However, there have been agri-environment schemes that can contribute to the management of soil carbon. In 2016, 78 percent of the PDNP was covered by such schemes, although this figure is now significantly lower .

What are the potential impacts of climate change?

Overall potential impact rating

Sedimentation or erosion

Climate change could have a significant impact on the health of soils across the PDNP. Periods of drought during hotter, drier summers could lower the water table significantly and potentially alter its hydrological behaviour for long periods. This could lead to increased erosion of dry soils, peat oxidation and carbon loss. Data Certainty: High Drier summers could also inhibit carbon storage and increase soil loss during rainfall events, as well as an increase the risk of wildfire.

Wetter winter conditions could also lead to increased erosion - rivers may be realigned and there may be changes to slope and soil stability. Greater amounts of sediment may enter watercourses and soil fertility is likely to be reduced. Data Certainty: High An increase in storm event intensity and frequency could cause a rise in dissolved organic compound levels in waterbodies that require water treatment, the silting up of reservoirs and negative effects on aquatic habitats. Data Certainty: High

Direct impacts of climate change

Soil health will be sensitive to changes in water content - both from drier summers or increased winter precipitation. Not only could this change the soil habitat and biota – i.e. the organisms living within the soil - but also the chemical content of water siting within the soils. This could lead to a short-term release of carbon dioxide and have long-term effects on carbon sequestration, and temporary effects on the appearance of the landscape. These changes could lead to a reduction in abundance of earthworms and other soil invertebrates, could alter soil fertility and vegetation cover, and increase the risk of soil becoming compacted. Data Certainty: High

An increase in intense rainfall events may lead to the loss of more topsoil and nutrients due to erosion. Where this occurs, vegetation is likely to be slower to recover. Data Certainty: High

Hotter summer soil temperatures could speed nutrient cycling and increase the release of nitrogen and carbon into the atmosphere. Following dry summers there may also be a delay in re-vegetation. Data Certainty: Moderate

Soil structure and chemistry is sensitive to atmospheric composition. Further increases in carbon dioxide and nitrogen compounds and the resulting acidification of the soil may affect plant growth and water quality by mobilising minerals or heavy metals. The already acid soils of the Dark and South West Peak are likely to be more vulnerable than the more neutral or alkaline soils of the White Peak. Data Certainty: Low

Other indirect climate change impacts

An increase in wildfire due to hotter, drier summers and longer periods of drought, coupled with a rise in visitor numbers as an ignition source may lead to increased erosion and damage to soil health. Heathland and degraded bog habitats are likely to be most vulnerable. Data Certainty: High

Human behaviour change

Hotter, drier summers could see the loss of pastoral farming and a move towards cultivating arable crops in areas with higher soil fertility such as the White Peak. This could leading to the removal of boundaries to create larger fields, the removal of trees and an increase in the use of large agricultural machinery creating soil compaction. A rise in tourist numbers during hot summers could see increased trampling and compaction of soils at certain sites. Data Certainty: Moderate

Soils and their vegetation cover are sensitive to changes in soil moisture. Drier summers and wetter winters could affect crop yields, leading to a change in the type of crops planted or livestock chosen. An increased demand for water resources would be likely, potentially lowering the water table in places. Data Certainty: Moderate

Invasive or other species interactions

Increased temperature and water table changes leading to changes in soil nutrient availability could affects the ability for invasive and nuisance species to colonise or dominate new areas. This would be likely to have a negative impact on the soil biota and structure. It could also lead to changes in existing vegetation, for example, heather growth on blanket bog was significantly affected by the 2018 drought, and invasion by grass species into such habitats may be likely. Data Certainty: Moderate Changes in soil moisture could also play an important role in determining the severity of future plant disease epidemics. Data Certainty: Moderate

Nutrient changes or environmental contamination

Increased winter rainfall and intense rainfall events after dry periods could see the increased leaching of nutrients from soil. This will also depend on the land use across the PDNP with crop type, and application of fertiliser playing an important role. There could also be increased movement of other contaminants – such as heavy metals - from soil into water catchments. Data Certainty: Moderate

What is the adaptive capacity of healthy soil?

Overall adaptive capacity rating

There is potential for some soils to recover from damage without intervention. Severely damaged soils may need management interventions to enable them to become more resilient to climate changes. Examples include the planting of vegetation cover on eroding areas, a reduction in ploughing, a reduction in the use of large machinery, and reduced livestock density. In addition, reducing nutrient and pesticide input will help to improve soil health. Data Certainty: Moderate

The PDNP has a diverse geology, and wide varieties of soils types are present. This increases the adaptive capacity of the soil resource as a whole. Data Certainty: Very High However, there are many large expanses of homogenous land management types within areas of the PDNP. For example, the improved grassland landscape of the White Peak and the deforested grazed valleys of the Dark Peak mean that within these areas soil health faces similar pressures and will have a lower adaptive capacity as a result.

Agri-environment schemes are available which can help improve soil health, but the current trend is for a reduction in uptake in the PDNP. The future of such schemes is also very uncertain. However, water companies and other landowners are investing funds into restoration particularly in the uplands. Data Certainty: High Some degree of resilience is aided by organisations such as Natural England and the SSSI designations covering some areas of the PDNP. Planning policy and the work of PDNPA partnerships also help to safeguard the existing resource. Data Certainty: Moderate

Information on best practice in soil management is widely available, and is subject to ongoing research. There has been shift in recent decades away from the perception of soil as an abiotic growing medium, towards recognising the importance of soil biota and viewing soils as habitats. This shift in perception may help to secure sensitive land management practices and therefore aid the adaptive capacity of soils. Data Certainty: High

Key adaptation recommendations for healthy soil:

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.

• Increase woodland and scrub creation schemes in appropriate locations to reduce run-off and replenish soil organic matter.
• Strongly discourage the removal of native woodland or trees in planning cases, and increase mitigation needed when it does occur.
• Shift perception of the landscape away from being fixed to a more dynamic system. Accept that change should happen and habitat types need to be allowed to change in some areas for a net environmental gain, where it would benefit the special qualities of the PDNP.
• Significantly reduce artificial fertiliser and pesticide use in agriculture.
• Encourage farmers to reduce ploughing or change ploughing implements and use cover crops on any arable land.
• Create and maintain diverse hedgerows and buffer strips around fields.
• Create more flower-rich meadows.
• Continue reducing bare peat areas and revegetate other bare patches on blanket bogs.
• Pilot a ‘rewilding’ or ‘wilding’ trial scheme with no fixed conservation aims and monitor the impact on soil health.

Improve current condition to increase resilience: 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.

• Reduce livestock levels and trampling especially in areas vulnerable to erosion.