Blanket Bogs

SCOTTISH INVERTEBRATE HABITAT MANAGEMENT

Blanket bogs

Claish Moss © Scottish Natural Heritage

Introduction that may also provide important sub-habitats. Britain has about 10-15% of the total global area Invertebrates in upland moorland or bog habitats of blanket bog, making it one of the most are an essential component of the diet of many important international locations for this habitat. bird species; cranefly larvae and adults have 80-85% of Britain’s blanket bog habitat is found in been shown to be important food for grouse Scotland, covering 1.8 million hectares, and chicks and breeding waders, such as Golden representing 23% of the country’s land area. This plover. Adult grouse may also eat craneflies to makes Scotland an internationally important supplement their diet of heather shoots. country for blanket bog. Managing habitats to benefit these invertebrates Blanket bog is found in cool, wet, typically is thus likely to have a significant impact on the oceanic climates, where it can cover whole survival of upland birds. landscapes, such as in the North-West of In addition, the Scottish Invertebrate Species Scotland. Peat accumulates slowly over many Knowledge Dossiers: Pseudoscorpiones years and can reach depths exceeding 5m, indicated the possibility that the Bog chelifer although 0.5-3m is more typical. Blanket bog is (Microbisium brevifemoratum ) is likely to occur in “ombrotrophic”, that is, the water and mineral Scottish bogs—highlighting that there may yet be supply comes entirely from atmospheric sources unrecorded species in this important Scottish (rainwater, mist, cloud-cover). The water habitat (Legg, 2010). chemistry is nutrient-poor and acidic and the Support for management described in this habitat is dominated by acid-loving plant document is available through Scotland Rural communities, especially Sphagnum mosses. A Development Programme (SRDP) Rural blanket mire landscape may also contain Development Contracts (RDC). A summary of minerotrophic systems (those that are affected by this support (at time of publication) can be found ground-water and the nutrients in it), such as in this document. springs, flushes, stream margins and valley mires. These support different vegetation types Threats eroding peat both in gullies and flatter areas. Peat extraction Eutrophication of water supply Peat extraction may be either domestic or Examples of potential causes of eutrophication commercial, and results in habitat loss. (nutrient enrichment) include run-off from road drainage, agricultural pollution, and nutrient Drainage enrichment from sewage. Drainage ditches, both new and old will lower the Water-course liming water table and may initiate erosion and oxidation of the peat. Even unmaintained old drains will Blanket bog habitats are naturally acidic. If lime is continue to affect the hydrology of a site. added to lochs, lakes and rivers as a treatment Lowered water tables will alter the species for acidification, this may have a detrimental composition of the surface vegetation and have a effect on adjacent areas of blanket bog. detrimental affect on specialist invertebrates. Fertilisers Drainage at the margins of bogs will lower the The application of fertilisers and lime to increase water table and may modify the surface stock grazing productivity will inevitably modify patterning, such as loss of Sphagnum hollows. the ecology to the detriment of the blanket bog Afforestation by exotic conifers invertebrate fauna. Coniferous trees have been planted on extensive Atmospheric pollution areas of blanket bog in the past. The trees will Many bogs, especially those in the North of continue to affect the hydrology and species England, have been affected by atmospheric composition of adjacent areas of blanket mire as pollution. This alters nutrient availability, and they mature and require more water. hence the plant community composition. Afforestation has generally been accompanied by furrowing of the ground, and these highly destructive drainage channels become a long- lasting scar. Habitat management Development Maintain the hydrology The construction of wind farms and As a peat bog consists of 95-98% water held by communication masts, together with associated Sphagnum peat, the water level is the most infrastructure such as access and maintenance crucial aspect to consider when managing this roads can cause significant hydrological Priority habitat type. Operations some distance disruption. Links to the national grid via landlines away from the ombrotrophic Sphagnum or more usually pylons also have an impact on communities can therefore have a devastating very fragile blanket bog during construction. effect if they are on sites within the same hydrological unit. In order to conserve the Livestock & game management characteristic bog communities, it is necessary to Heavy grazing (by Sheep, Red deer, Cattle and look at the whole system, which may extend Horses) will have a significant impact on mire beyond the boundaries of a particular site. vegetation, especially if there is supplementary Drainage ditches and forestry plantations will feeding (which will increase the nutrient input) remove water from surface layers of the bog and and other management measures such as ultimately lower the bog surface, favouring plants drainage, burning or fencing. which grow in drier conditions, thus adversely affecting any specialist invertebrate species. Wet Burning blanket bog is of great importance to many Serious fires can result in the loss of surface invertebrates such as spiders and leaf-hopper vegetation and the death of peat-forming species. bugs. Drying peat will shrink and oxidise, creating These can slowly recover over time (>20 years), erosion problems and increasing vulnerability to but invertebrate communities and populations will fire damage, so it is essential to maintain water be seriously affected. levels. On sites that are drying, raising the water Erosion levels should be considered. Erosion on blanket bog exposes more of the peat Blocking any existing drains to retain rainwater to the atmosphere, increasing drying and will allow the water table to re-stabilise and peat- oxidation of the peat. Hag erosion may be forming Sphagnum species to colonise areas that instigated, resulting in extensive patches of bare have dried or been affected by peat cutting or milling. Unless the peat has been removed down

Page 2 Blanket bogs to the level of the mineral substrate, secondary Prevent nutrient enrichment and pollution of bog vegetation will return over time. Water flow is the water table essential for some species, such as the caddisfly Pollution incidents and nutrient enrichment lead Oxyethira mirabilis , so care should be taken that to the loss of Sphagnum bog vegetation reducing any work does not compromise the survival of its ability to support species. these invertebrates. The use of pesticides should also be avoided. Maintain habitat diversity Prevent invasion of scrub and trees It is important to maintain a habitat mosaic both within and beyond the bog. The natural structure If water table levels are maintained then of the surface of an undamaged blanket bog significant scrub invasion should not present a provides a variety of aquatic and semi-aquatic major problem as the very wet, infertile ground habitats each supporting different invertebrates. conditions, altitude and exposure of the blanket Management should aim to recognise and bogs often makes tree or shrub growth difficult. monitor these valuable microhabitats: boggy However, in areas of bog that have already pools, flushes, wet peat, sedge ( Carex spp.) and begun to dry as a result of drainage or rush ( Juncus spp.) stands and localised poor fen. agricultural operations, scrub invasion can be Retaining extensive areas of inundated prevented by cutting or light grazing, but it is Sphagnum is particularly important for important not to overgraze. Grazing can cause invertebrate species with a high nature problems to blanket bog habitats, causing conservation status. damage to the vegetation by trampling and affecting the species composition if nutrient It is also important to consider the fringes of bogs enrichment occurs by the deposition of dung. and ensure that they support a rich marginal vegetation. Tussocky vegetation of taller Molinia Afforestation is a major threat to this habitat and spp., Carex spp. or Juncus spp. and the should be discouraged. associated litter build-up provides cooler, more Minimise disturbance sheltered microhabitats for adult craneflies and Excessive trampling through over-grazing or drier sites for over-wintering invertebrates such large numbers of ramblers is a problem, as it as spiders. Ericaceous dwarf shrubs also support affects the growth of fragile Sphagnum mosses many heather-feeding moths and other insects, and can ultimately alter the species composition as well as providing a well-developed vegetation or lead to erosion of the peat. structure for spiders. Scrub on the fringes of blanket bog in habitats such as streamsides Natural pools within the Sphagnum lawns should supports its own fauna and provides shelter; be left unmanaged and not cleared or deepened. sallow catkins may be the best spring nectar source for many adult insects. Exceptions to general habitat management Avoid burning Ampedus pomorum is a nationally scarce click Burning destroys large numbers of invertebrates, beetle associated with the dead heartwood of potentially entire populations of species living mature birch trees and is characteristic of the wholly in the above-ground parts of plants. In fringes of peatlands where ancient broadleaved acid sites it can also encourage Purple moor- woodland and birch woodland has developed on grass ( Molinia caerulea ) at the expense of other bogs. Another nationally scarce click beetle vegetation. Too hot a burn can kill bog-moss and Ampedus nigrinus , primarily a woodland species, burn into the peat, altering plant communities and has also been found in rotten heartwood of birch damaging invertebrate interest. and Scots pine around the margins of blanket Heather management through burning appears to bogs. In these cases, clearance of woody growth be especially damaging to plant-hopper bugs, and scrub prevention is detrimental. sensitive species taking a long time to return. Some invertebrates like small patches of bare Burning should be therefore replaced with a more wet peat so trampling in confined rare strips may sympathetic form of management such as cutting actually be beneficial. or low-level grazing.

Page 3 Agricultural scheme grants and subsidies • SRDP RDC-RP Axis 2 Option 31: Off-wintering Support for management is available through of Sheep. Scotland Rural Development Programme (SRDP) • SRDP RDC-RP Axis 2 Option 32: Muirburn and Rural Development Contracts (RDC): heather swiping. • SRDP RDC Rural Priorities (RP) Axis 2 Option • SRDP RDC-RP Axis 2 Option 41: Habitat 13: Control of Invasive Non-native Species. Grazing Management. • SRDP RDC-RP Axis 2 Option 26: Wildlife • SRDP RDC Package 7: Supporting Biodiversity Management on Upland and Peatland Sites. offers support for specific species or more • SRDP RDC-RP Axis 2 Option 27: Management general biodiversity management. of Moorland Grazing. • SRDP RDC Package 14: Upland and Peatland. • SRDP RDC-RP Axis 2 Option 28: Moorland Applicants for Rural Priorities Options must Grazings on Uplands and Peatlands. demonstrate how the option will contribute • SRDP RDC-RP Axis 2 Option 29: Moorland towards the priorities for the particular region. Not Stock Disposal. all Options are compatible with each other and eligibility criteria may apply. Further information is • SRDP RDC-RP Axis 2 Option 30: Away- available on the SRDP website (details below). wintering of Sheep. Further information Scotland Rural Development Programme: http://www.scotland.gov.uk/Topics/farmingrural/SRDP Legg, G. 2010. Scottish Invertebrate Species Knowledge Dossier: Pseudoscorpiones. Buglife – The Invertebrate Conservation Trust. Contact Initiative for Scottish Invertebrates c/o Buglife – The Invertebrate Conservation Trust Balallan House 24 Allan Park Stirling FK8 2QG Tel: 01786 447504 Email: [email protected] Web: www.scottishinvertebrates.org.uk

This document should be referenced as: Buglife. 2010. Scottish Invertebrate Habitat Management: Blanket Bogs . Buglife – The Invertebrate Conservation Trust. This habitat management factsheet was produced as part of the ‘Action for Scottish Invertebrates’ project. This project is grant-aided by Scottish Natural Heritage and delivered on behalf of the Initiative for Scottish Invertebrates (ISI) by Buglife – The Invertebrate Conservation Trust.