Blanket bog

Overall vulnerability

Features assessed:

• Blanket bog/peat
• Active living bogs with Sphagnum
• Extensive peat deposits with pollen and fossil record

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

Feature descriptions:

Blanket bog requires wet conditions (high rainfall and low evapotranspiration) on flat areas or gentle slopes in order to form peat, often over many thousands of years. Blanket bogs are ombrotrophic environments – depending on atmospheric moisture for their nutrient input - and when active (i.e. accumulating peat) are dominated by mire species, especially Sphagnum mosses. In the PDNP blanket bog is found in large areas in the Dark Peak and to a lesser extent the South West Peak totalling approximately 25,000 hectares. 19,500 ha of this being priority habitat.

These areas are nationally and internationally important, accounting for around 12% of the blanket peat soil resource in England, and being a large store of carbon. The waterlogged and acidic nature of peat means it can hold an important historical record of preserved organic material such as pollen and trees, alongside other archaeological artefacts.

How vulnerable is blanket bog?

Blanket bog and associated features in the PDNP have been rated ‘very high’ on our vulnerability scale. This score is due to high sensitivity and exposure to climate change variables, coupled with a very poor ‘non-functional’ current condition, and a low adaptive capacity.

Historically in an extremely degraded condition, many areas are recovering under Site of Special Scientific Interest (SSSI) and Special Area of Conservation (SAC) designations and through landscape scale conservation works. Areas undergoing conservation works are likely to be less vulnerable than those which are not; and modelling suggests that the lower altitude bogs on the eastern edge of the Dark Peak may be among the most vulnerable areas, whilst the more continuous and higher altitude areas in the north of the PDNP may be less vulnerable. The area and quality of active blanket bog in the PDNP may be reduced by climate change.

Current condition:

Much of the blanket bog in the PDNP is under SSSI and SAC designations. The majority of these SSSI units are categorised as ‘unfavourable recovering’ condition, reflecting their historically extremely degraded condition, now being addressed through landscape scale conservation works and management changes.

PDNP bogs suffered from the impacts of severe historic industrial pollution leading to low plant species diversity and a loss of Sphagnum mosses. Despite vast reductions in pollution, they remain highly contaminated and are still above their critical load for nitrogen oxide pollution and acidity.

Wildfires have stripped large areas of remaining vegetation, in which overgrazing and erosion have prevented recovery, resulting in a bare peat landscape – which has proved highly susceptible to further erosion. Extensive gullying of the peat blanket, along with deliberate drainage has negatively impacted its hydrological state, meaning many bogs are no longer functional and lack a capacity for resilience.

Invasive and nuisance species including windblown rhododendron and conifers are present and are able to exploit the dry conditions, and in many areas blanket bog has come to be dominated by heathland species such as heather due to managed burning. The very poor condition of PDNP blanket bogs means they are currently a source of carbon, rather than the significant carbon sink which they have the potential to be.

What are the potential impacts of climate change?

Overall potential impact rating

Direct impacts of climate change

Climate change has the potential to have a severe negative impact on PDNP blanket bog, both directly and through multiple indirect effects. Blanket bog is not generally found further south-east in Europe due to its requirement for a high level and continuity of precipitation, low levels of evapotranspiration and limited seasonal temperature variability. Several of the plant and animal species it supports are at their ecological range limit in the PDNP. Data Certainty: High

The bare peat surfaces of damaged PDNP bogs are very sensitive to direct effects of changed rainfall patterns - predicted to occur through wetter winters and an increase in frequency and severity of storm events. The impacts of such changes in precipitation coupled with increased mean temperatures and hotter drier summers are likely to lead to the dominance of non-mire vegetation (for example drought-adapted species such as common heather) changing the character of the habitat, perhaps moving further towards heather moorland. Colonisation by lowland bog species may also become more common in some areas. Data Certainty: High

The opportunity to return degraded bogs to an active state may be lost if Sphagnum can no longer tolerate future climatic conditions. Where bogs are already degraded, existing gullies are likely to be widened and deepened, with new gullies and peat pipes forming. Drought conditions mean oxidation of windblown peat will increase, also further hampering or even reversing efforts to restore damaged bogs. Increased surface runoff during wet winters and storm events mean peat will continue to be lost and along with it an important archaeological record including pollen, tree remains and other organic matter. (For further information see ‘Buried soils, archaeological remains and deposits’). Loss of peat will also negatively affect water quality downstream and decrease reservoir capacity through build-up of sediment. Bare peat is unable to support any macro life-forms, and the biodiversity of the PDNP is likely to be further reduced. Climate change is also likely to increase carbon release and reduce the capacity to revert the blanket bog from a carbon source to a sink. Data Certainty: High

Human behaviour change

The most significant indirect effects of climate change may result from changes in human behaviour. Drier ground conditions caused by lower summer precipitation levels and higher average temperatures, and changes to vegetation growth rates as a result of increases in atmospheric carbon dioxide and nitrogen, for example, could lead to significant changes in upland agricultural economics. Higher livestock levels particularly around moorland edges and intensification of management practices could not only lead to changes in vegetation composition, but also to increased incidence of disease, for example Cryptosporidium ‘Bulgy Eye’ in red grouse Data Certainty: Moderate. Conversely, urban flooding events downstream from blanket bog watercourses may lead to a strengthening of efforts to restore bog hydrology through revegetation, damming and the creation of woodland or scrub to stabilise bog edges. Data Certainty: Low

Drought conditions and increased evapotranspiration are likely to lower bog water tables. Coupled with an anticipated increase in visitor numbers, particularly during hot summers, the frequency and severity of wildfire incidents are likely to rise. This in turn would lead to increased erosion, peat loss and uneven surfaces, making hydrological restoration more difficult than at present. Data Certainty: High Invasive or other species interactions

The character of vegetation present on damaged bogs is also likely to be altered by increased opportunities for invasive species and plant diseases, along with naturally occurring species such as the heather beetle. A longer growing season may give species such as rhododendron a competitive advantage (which could further increase evapotranspiration) Data Certainty: Moderate, and damage to the bog surface from extreme events could lead to increased opportunities for such species to occur. Data Certainty: Low Warmer wetter winters, may increase incidence of diseases such as Phytophthora which can impact several species including bilberry. There may also be increased survival and grazing of heather beetle which could alter landscape aesthetics. Data Certainty: Moderate

What is the adaptive capacity of blanket bog?

Overall adaptive capacity rating

While blanket bog is one of the less fragmented habitat types found in the PDNP, the very slow rate at which peat forms coupled with the strong geological, geomorphological and climatic constraints which limit where it has the potential to exist, mean that this habitat has a low adaptive capacity, especially within the PDNP. Data Certainty: High

As a wetland habitat, blanket bog is reliant on almost continual water input and probably has limited ability to recover from severe drought. While different Sphagnum species do have differing tolerance to drought, using different strategies to do so, in its current inactive state natural recovery of PDNP blanket bog after damage (e.g. fires) without human intervention is unlikely in most locations. Data Certainty: High

Areas which have undergone restoration work are in a better position to regenerate than the former bare peat landscape, but they still have severe lack of resilience and are very unlikely to recover well from damage compared to intact ‘functioning’ blanket bog. Although bogs are naturally less biodiverse than many other habitat types, historic damage means that those in the PDNP are particularly species poor and often dominated by non-mire species such as heather, or other species well adapted to fire such as purple moor-grass. This lack of species diversity, coupled with topographical uniformity (particularly on the eastern side of the Dark Peak) reduces the capacity for the habitat to adapt to future change. Data Certainty: High

Blanket bog restoration has been supported by the UK government for over 30 years, and funding is likely to continue to be available, particularly in the light of increasing recognition of the importance of peatlands in climate change mitigation. There is a diversity of well-established institutions able to research and carry out conservation management, with a good range of different management options at their disposal. Good availability and diversity of funding, institutions, information, land-ownership and conservation management techniques, while very important for increasing potential resilience, are likely to offset climate change stressors only partially. Data Certainty: High Further complications may arise if the current relative agreement between moorland stakeholders about the need to revegetate bare peat gives way to more disparate aspirations for the future use of blanket bog - for example grouse and sheep farming, wildlife conservation, water collection and public amenity - which may not necessarily be fully compatible. Data Certainty: Moderate

Key adaptation recommendations for blanket bog:

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 effort to restore hydrology and raise the water table.
• Increase effort to revegetate any remaining bare peat areas.
• Increase Sphagnum re-introduction, including as diverse a mix of appropriate species as possible.
• Research is needed to look into promoting the growth of bog edge woodland or scrub where appropriate, through tree establishment and natural regeneration, to reduce wind effects, provide shade and stabilise peat blanket edges.
• Cease the use of burning for heather management on blanket bog sites – but consider alternative techniques such as cutting if there is a high fuel load (e.g. bog is or has become dry heath on peat) as an interim measure until the bog is wet enough.
• Develop fire contingency plans, and ensure management of habitats reduces fire risk e.g. rewetting and increasing species or structural diversity.
• More research into peat pipes is needed.
• Consider the impact on key views when planning adaptations.

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.

• Identify key areas to focus work on; especially those, which are likely to remain hydrologically suitable. Further study required.
• Develop visitor management plans to influence public behaviour in areas of high wildfire risk.