The SPM provides multiple ecosystem services to humans, wildlife and the environ- ment, both within and beyond the SAC, although its degraded status reduces these benefits, and presents potential hazards as a result.
Carbon
UK peatlands hold 40 % of all national terrestrial carbon, in only 8 % of its land area, representing the equivalent of 20 years of all UK CO2 emissions (Lindsay, 2010). When in healthy condition, active blanket bog acts as a carbon sink, making a positive contribution to climate change reduction as atmospheric carbon dioxide levels are reduced.
However, the loss of vegetation in the SPM, and subsequent drying and erosion of the peat has led to elevated levels of particulate and dissolved organic carbon (POC and DOC) entering the fluvial systems. The majority of both POC and DOC has been found to ‘de-gas’ into CO2 either while in the fluvial system or when re-depos- ited on floodplains (Evans et al., 2013). These emissions have transformed the SPM into a significant source of CO2, as the store of ‘locked in’ carbon is released back into the atmosphere.
Natural flood risk management
Blanket bogs are characterised by at/near-surface water tables, with low available water storage capacity as compared to other systems. As a result, catchments with a high proportion of blanket bog often exhibit a rapid runoff response, although the dense mats of mixed vegetation present on healthy blanket bogs slow down the flow of water over the peat surface. Intact systems also often have relatively sparse drain- age networks, meaning that the time taken for any individual raindrop from landing
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08 LANDSCAPE-SCALE RESTORATION OF SEVERELY ERODED BLANKET BOG IN THE SOUTH
PENNINE MOORS, ENGLAND
on the surface to arriving in a stream channel may be relatively long.
In degraded peatlands, the bare peat surfaces generate much faster surface runoff, and the severe extent of historic erosion has led to a dense network of drain- age channels, gullies and subsurface peat pipes, meaning that the raindrop’s travel time to the stream channel is significantly reduced. Therefore, the ‘flashiness’ of peatland hydrological systems increases with the level of degradation, resulting in an increase in the severity of flood events further down the river system (Grayson et al., 2010).
Biodiversity
The SPM comprise a mosaic of habitats including blanket bog, upland heathland, acid grasslands and upland woodlands and are of great importance for biodiver- sity. The moors support plant and bird assemblages of national, European and in- ternational importance which are protected under UK and European conservation legislation.
The historic damage to the peatlands due to industrial pollution has led to the severe decline of moorland specialist insect, mammal and bird species relying on vegetation for cover and food which, in turn, led to the decline of raptors and other predators.
Water quality
The SPM, as uplands receiving high rainfall surrounded by areas of high population density, are important sources of freshwater for humans as well as aquatic flora and fauna. The PDNP alone holds 55 reservoirs, with associated abstraction licences to- talling more than 450 billion litres of raw water per year (Bonn et al., 2009).
Compared with other blanket peats globally, those of the PDNP are amongst the most contaminated in the world following the industrial revolution, with pollutants including lead, zinc, nickel and titanium (Rothwell et al., 2005). The peat surface represents a store of these contaminants which, if stable and vegetated, would re- strict their mobility. However, the extensive areas of bare peat produce faster surface runoff, which generates higher rates of erosion and therefore higher levels of con- taminants in the water flowing out of the moors.
The financial cost of decontaminating this water to make it suitable for drinking is considerable, meaning that there is a significant economic incentive for the utility companies managing the reservoirs to invest in restoration and erosion control works in the headwater catchments.
Wildfire risk
Wildfire is one of the top 25 priority risks to UK biodiversity and causes substantial environmental and economic losses in upland habitats (Sutherland et al., 2009). In the SPM there are approximately 50 wildfires per year (Walker et al., 2009), mostly resulting from arson or carelessness, and which are particularly frequent in highly visited areas. Healthy active blanket bogs, where water tables are high and vegeta- tion communities are diverse, are relatively resistant to wildfire. However, in the de- graded peatlands of the SPM, extensive areas of bare dry peat, combined with large
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areas of single age single species vegetation, constitute high fuel loads, meaning that wildfires, once established, can easily get out of control and cause widespread damage to wildlife, habitats and the peat body.
Health and wellbeing
Uplands provide health benefits to humans through the activities undertaken within them, while also providing more ‘passive’ benefits for mental and emotional health. Climbing and walking, for example, provide both physical and mental health ben- efits, as people experience reductions in stress both from the exercise and from the tranquillity and beauty of the landscape around them. The PDNP, in close proximity to several major urban conurbations, all with easy access by road and rail, receives around 22 million visitor days each year. The park, while offering benefits to health and wellbeing to a large number of people, is also impacted by this weight of visi- tors. If paths are not robust and well-maintained, erosion from trampling can be severe.