Heather moorland and mixed heath

Overall vulnerability

Feature assessed:

• Heather moorland and mixed heath

Special qualities:

• Beautiful views created by contrasting landscapes and dramatic geology
• Internationally important and locally distinctive wildlife and habitats
• An inspiring space for escape, adventure, discovery and quiet reflection

Feature description:

Heathland is found on acidic and nutrient poor soils - usually on shallow peat or podzolised soils in the PDNP. It is characterised by the presence of dwarf shrubs, such as common heather or bilberry, covering at least 25% of the area but often dominating. This category refers to those areas of dwarf shrub heath with heather dominating (commonly referred to as heather moorland) as well as mixed heath with multiple dwarf shrub species such as cowberry and crowberry and other plants such as cotton-grasses interspersed. The rarer wet heath habitat is covered in another section, as is blanket bog. Dwarf shrub assemblages growing on dry blanket bog sites are not considered.

Large areas of well-connected heathland exist in the Dark Peak and South West Peak, the majority being found in the Dark Peak. Some patches of limestone heath exist on nutrient leached soils in the White Peak, but these are small and fragmented. There are approximately 13,500 hectares in the PDNP, the vast majority of this being priority habitat.

Heather dominated moorland is common in the PDNP, partly as a result of management for red grouse shooting. Rotational burning has allowed fast growing heather to dominate large swathes of heathland. Heathland is important habitat for species such as mountain hare, bilberry bumblebee, meadow pipit and their predators, including the internationally important merlin.

How vulnerable are heather moorland and mixed heath?

Heather moorland and mixed heath in the Peak District National Park has been rated ‘high’ on our vulnerability scale. This score is due to high sensitivity and exposure to climate change variables, with a relatively poor but recovering current condition, and a moderate adaptive capacity.

Current heath condition in the PDNP is generally poor due to historical stressors and poor management. Modelling suggests that areas such as Eyam Moor and heathland around Chatsworth (for example Brampton East Moor) are likely to be some of the most vulnerable to climate change due to their south-easterly location and lower altitude. Changes in human behaviour may have an important impact on this managed environment. Less biodiverse areas are likely to have the lowest adaptive capacity, meaning moorland with high heather dominance is at risk from climate change. Heathland does however have the advantage of economic and organisational resources dedicated to its conservation, and has high connectivity across large areas. Large areas are protected under Site of Special Scientific Interest (SSSI) and Special Area of Conservation (SAC) designations. In the future, PDNP moorlands are likely to become important habitat for species that currently have a more southerly distribution, such as the Dartford warbler.

Current condition:

Heathland in the Peak District is generally in unfavourable but recovering condition, with some areas threatened and at high risk. This is due to multiple factors including high levels of air pollution in the recent past, habitat loss to conifer plantations and historical high levels of burning and grazing stock. Large areas of dwarf shrub heath are now protected with Special Site of Scientific Interest status as part of the Dark Peak, Eastern Moors, and Leek Moors SSSI areas, and large areas have Special Area of Conservation designation as part of the South Pennine Moors SAC.

Despite vast reductions in air pollution, the legacy of industry is still present in the form of heavy metal ions and increased nitrogen levels in the peat. Bare ground and increased nutrients have allowed generalist colonisers such as rosebay willowherb to move in. Nitrogen deposition especially is damaging to the low nutrient environment, causing root damage to heather and increasing its susceptibility to heather beetle infestation. The native heather beetle is a persistent presence and affects some areas. Its impact is greatest in areas of high heather densities, but small outbreaks may in fact help to diversify the species richness and age structure of the vegetation.

Much of the heathland of the PDNP is managed for either grouse shooting, sheep farming or both. In the past, overgrazing, wildfire, and war activity (such as firing practice on Bradfield) led to problems such as lower plant diversity, changing dwarf shrub extent, and the opening up of bare ground which facilitated erosion. Without appropriate management, heath is invaded by willow and birch scrub, and may begin to succeed to woodland. This can be seen on some sites, such as lower Woodhead Moor and Dove Stone.

The popularity of the moors for leisure can also cause problems. Path erosion, both from heavy footfall and vehicle damage, is a continual though localised issue. Areas with high visitor numbers, such as those close to the cities of Sheffield and Manchester, are also at much greater risk of wildfire due to arson and accidental ignition, especially by highly portable and very flammable disposable barbeques. Wildfires have historically burnt large areas of heather moorland, and will likely continue to do so.

What are the potential impacts of climate change?

Overall potential impact rating

Climate change may have a variety of effects on heather moorland and mixed heath. Some of these effects may act to break heather dominance, or remove dwarf shrubs entirely, causing changes to the composition and diversity of this habitat. As a habitat that is in large part sustained by human intervention, some of the risk will be from changes in human behaviour as a result of climate change.

Direct impacts of climate change

Changes to annual precipitation patterns are a risk to heathland communities. Waterlogged conditions in winter can cause anoxic conditions in the soil, leading to root dieback. Dwarf shrubs are particularly susceptible to this, although the well-draining nature of heathlands in the Peak District will reduce the effect. Summer droughts may also cause increased sensitivity of heather to heather beetle and loss of less drought tolerant species such as crowberry. Data Certainty: High

Increased winter rainfall may lead to higher levels of nitrogen deposition in the uplands if atmospheric nitrogen levels do not decrease. Excess nitrogen input increases sensitivity of heather to drought, frost, and heather beetle outbreaks. Heather growth could become stunted, which would change habitat density and character. Community composition could be altered, with heather dominance decreased. Provided the plants were replaced by other dwarf shrubs, this could be beneficial to the community resilience. Data Certainty: Moderate

Higher annual temperatures will likely lead to a longer growing season for moorland plants, giving more competitive plants such as some grasses an advantage over slower growing species such as heather. This could cause heathland community composition to move towards an acid grassland assemblage and therefore some may be lost. Data Certainty: Moderate

Other indirect climate change impacts

A hotter, drier climate is expected to heighten the risk of wildfire. This will not only increase erosion and remove habitat in the short term, but in the long term will encourage heather or purple moor-grass dominance and possibly open up bare ground for fast colonisers such as bracken to invade in some places. Data Certainty: High

Changes in climate may lead to loss of key species as the habitat becomes unsuitable for mountain hare, and birds such as red grouse, merlin, ring ouzel, and twite, as well as altering food web interactions. Potential gains may be seen in other species such as nightjar, stonechat, hobby, and Dartford warbler. Phenological changes (changes to the timing of natural events) may lead to decreased numbers of key species such as the invertebrates which many species depend upon. Data Certainty: Moderate

Human behaviour change

Increased visitor numbers due to hotter, drier summers may exacerbate problems already present at popular sites. Higher footfall will lead to greater path erosion, as well as increased disturbance of ground nesting birds. The wildfire risk associated with popular sites is likely to increase, especially in hot, dry conditions. Data Certainty: Very High

Future changes in management will have important consequences for heathland, especially heather moorland. Usual management actions may be disrupted by changing weather conditions. Spring heather burning is likely to have an increased risk of out of control blazes due to the earlier dry season. Autumn heather cutting could also be hampered due to earlier rains causing wetter ground conditions and bogging down cutters. It is feasible that this may lead to cessation of management in some areas, allowing birch and willow scrub to encroach and the habitat character to change. A shifting climate envelope for some species, such as red grouse, may also lead to changes in moorland management. Data Certainty: Moderate Conversely, increased productivity due to greater grass growth could potentially lead to more grazing land use. Higher stocking levels, increased erosion and nutrient loading could potentially shift the community composition towards acid grassland. Data Certainty: Low

Invasive or other species interactions

Warmer conditions may lead to greater populations of species such as heather beetle and Phytophthora. Data Certainty: High The effect of these pests would be greatest in areas with high heather or bilberry dominance. Community composition could be altered, with other heathland species outcompeting stunted heather and bilberry. In extreme cases, the bilberry component of the habitat could be lost, threatening the continued survival of bilberry dependent species such as bilberry bumblebee and green hairstreak. Data Certainty: Moderate

Higher temperatures, especially warmer winters, are likely to create more suitable conditions for bracken to colonise heathland. Heath at higher altitudes will be at risk of bracken invasion, which may replace heather in some cases and cover large areas. Data Certainty: High

An increase in winter rainfall, particularly during storm events, may have important consequences for heathland. Heavy rain and severe winds damage plants, and increased runoff can cause soil erosion. As heathland in the PDNP is often on mineral soils or thin peat soils less than 40 cm deep, such erosion can lead to root damage, although the effect may be reduced by existing drainage. Root damage increases susceptibility of dwarf shrubs to winter desiccation, meaning community composition may be altered. Data Certainty: High

What is the adaptive capacity of heather moorland and mixed heath?

Overall adaptive capacity rating

Resources are available for the management and restoration of heathland through multiple sources. Environmental stewardship options are available to individual landowners that have an interest in conserving their land. Data Certainty: High There are also many organisations operating in the PDNP that can conduct or facilitate works to increase the resilience of heathland including Moors for the Future Partnership and The National Trust. Data Certainty: High However, although management action can be taken to partially offset the effects of climate change, there is limited agreement about future land use due to the conflicting interests of different stakeholders; the aims of conservation organisations potentially conflict with those of landowners managing their land for sheep farming or grouse shooting. Data Certainty: Moderate

Heather regrows and spreads relatively quickly, so can react to change and recover from damage, although this may be at the expense of other plant species, increasing its dominance and reducing diversity. Data Certainty: Moderate Less mobile species such as Sphagnum may be restricted to their original sites and unable to adapt to change. Data Certainty: High The seed bank may be vulnerable to erosion if left exposed, meaning recovery may be slower with increased erosion. Heather brash and plug plants of dwarf shrubs are currently used for revegetating sites, so it is possible to assist with recovery from damage. Data Certainty: Moderate

Both the large size and variability in topography and habitat mosaic provide some resilience for PDNP heathland. Data Certainty: High Large areas dominated by heather are more vulnerable than mixed heath areas, which will be more adaptive to change. Upland heath grades into lowland heath and blanket bog, and so heathland overall is relatively diverse and resilient along climactic gradients. Data Certainty: High

Key adaptation recommendations for heather moorland and mixed heath:

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.

• Continue program of moorland rewetting.
• Identify sites within the uplands that can act as climate change refugia due to complex micro-topography, robust hydrology, and high species diversity, and manage these accordingly.
• Minimise erosion through management of access, appropriate grazing levels, and reduction of burning.
• Develop fire contingency plans, and ensure management of habitats reduces fire risk e.g. rewetting and increasing species or structural diversity.
• Bracken may need to be controlled through grazing and other management.
• Consider the impact on key views when planning adaptations.

Improve current condition to increase resilience: Increase structural diversity to improve resilience at a landscape scale

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations focus on increasing the structural diversity of the area or habitat in which the feature is found. This can help to offset the effects of climate change on the feature, as well as to allow it to be in a better position to recover from future climate changes.

• Increase the diversity of heather dominated areas - adapt to mixed heath.
• Maintain and enhance structural diversity within heathland vegetation, including wet heath patches, diverse age classes of dwarf shrubs, and scattered trees and scrub.
• Continue clough woodland creation/restoration to increase scrub and woodland cover within upland mosaic which will help improve habitat heterogeneity and provide refugia for sensitive plants and invertebrates.

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.

• Develop visitor management plans to reduce fire risk on areas of high wildfire risk.
• Cease the use of burning for heather management on vulnerable sites – but consider alternative techniques such as cutting.
• Strengthen footpaths and manage increased visitor access to minimise disturbance in key areas.

Adapt land use for future conditions

These recommendations are adaptations to the way in which people use the land. Flexibility in land management - reacting to or pre-empting changes caused by the future climate - should afford this feature a better chance of persisting.

• Adapt management intensity to changing characteristics of heather moorland – alter grazing pressure, types/breeds of livestock, and burning/cutting cycles to suit future climatic conditions.
• Consider that designated natural and cultural site features of interest may change.