SCOTTISH INVERTEBRATE HABITAT MANAGEMENT Lowland raised bogs Wester Moss © Paul Kirkland / Butterfly Conservation Introduction Scottish records of the Bilberry pug moth (Pasiphila debiliata ) is from Kirkconnell Flow There has been a dramatic decline in the area of (Dumfries and Galloway) while the Bog sun- lowland raised bog habitat in the past 100 years. jumper spider ( Heliophanus dampfi ) is known The area of lowland raised bog in the UK only from two sites in the UK – one of which is retaining a largely undisturbed surface is Flanders Moss (Stirlingshire). In addition, there is estimated to have diminished by around 94% a possibility that the Bog chelifer ( Microbisium from an original 95,000 ha to 6,000 ha. In brevifemoratum ) is likely to occur in Scottish Scotland, it is estimated that the original 28,000 bogs—highlighting that there may yet be ha of lowland raised bog habitat has now unrecorded species in this important habitat diminished to a current 2,500 ha. Most of the (Legg, 2010). remaining lowland raised bog in Scotland is Support for management described in this located in the central and north-east lowlands. document is available through the Scotland Rural Historically the greatest decline has occurred Development Programme (SRDP) Rural through agricultural intensification, afforestation Development Contracts (RDC). A summary of and commercial peat extraction. Future decline is this support (at time of publication) can be found likely to be the result of the gradual desiccation of in this document. bogs, damaged by a range of drainage activities and/or a general lowering of groundwater tables. Lowland raised bogs support many rare and localised invertebrates, such as the Large heath butterfly (Coenonympha tullia ) and the 6 spotted pot beetle ( Cryptocephalus sexpunctatus ). The Bog bush cricket ( Metrioptera brachyptera ) is known from only one sites in Scotland, both of Bog bush cricket ( Metrioptera which are raised bogs. One of only two recent brachyptera ) © Roger Taylor Threats infrastructure such as access and maintenance roads can cause significant hydrological Peat extraction disruption. Links to the national grid via landlines Peat extraction may be either domestic or or more usually pylons also have an impact on commercial, and results in habitat loss. very fragile raised bog during construction. Landfill development Climate change Use of cut-over bogs for landfill developments Changes in weather patterns (increased winter results in habitat loss. rainfall and severe summer droughts) may affect the condition of raised bogs. Afforestation Trees (and associated furrows) dry out the bogs they are planted on and neighbouring areas, Habitat Management while acting as an invasive seed source. The trees will continue to affect the hydrology and Maintain a stable high water table species composition of adjacent areas of bog as Maintenance of water levels and prevention of they mature and require more water. scrub invasion is important in maintaining raised Afforestation has generally been accompanied by bog habitat. Maintenance of a stable high water furrowing of the ground, and these highly table is critical for specialist bogland destructive drainage channels become a long- invertebrates; any management that alters or lasting scar. lowers the water table will probably be Timber extraction of afforested bogs can also detrimental to these species. In order to maintain cause damage to the structure of the bog—care water levels and prevent peat drying, existing should be taken to avoid the creation of trenches drainage ditches should be blocked wherever or roads that may alter the hydrology of the bog. possible. The ditches will rapidly fill with vegetation and Sphagnum species will colonise. Drainage Raising and stabilising of water levels should be Neighbouring agricultural areas lower water considered on sites that are drying out. levels through marginal ring-ditches and other intrusive drainage measures. Drying out the Prevent scrub encroachment raised bog through drainage allows invasion by Scrub invasion is likely to occur on sites where scrub and trees which in turn speed up the drying the peat is drying out as a result of a lowering of process and leads to the loss of this special the water table. If scrub is known to be spreading habitat and associated species. and invading open peatland habitats, clearance Water abstraction may be necessary. Once scrub clearance is undertaken on a site, it is essential that the site is Abstraction of water within the catchment area not allowed to scrub over again, as the will have an adverse effect on the hydrology of a alternation between open and closed habitats will raised bog. not provide the stable conditions required by Pollution diverse invertebrate communities. Run-off from agricultural land (fertilisers and On sites where the water levels are stable, pesticides) will damage the ecology of the bog. scattered scrub can provide habitat for interesting While pesticides have an obviously adverse invertebrate communities. Native peatland scrub impact, fertilisers cause nutrient enrichment, species found either across central areas or resulting in the loss of suitable habitat. associated with the natural margins of raised bogs include Bog myrtle ( Myrica gale ), birch Livestock & game management (Betula spp.), Alder buckthorn ( Rhamnus Heavy grazing (by Sheep, Red deer, Cattle and frangula ) and willow ( Salix spp.). These natural Horses) will have a significant impact on bog scrub margins should not be removed, unless vegetation, especially if there is supplementary they are encroaching on a drying bog. feeding (which will increase the nutrient input) Scrub margins can be important habitat for and other management measures such as invertebrate species. For example, the 10 spotted drainage, burning or fencing. pot beetle ( Cryptocephalus decemmaculatus ) Development has only been recorded from small specimens of The construction of wind farms and birch ( Betula spp.) and willow ( Salix spp.), while communication masts, together with associated these margins can also support Procas granulicollis , a rare weevil. Therefore, scrub Page 2 Lowland raised bogs removal and scrub maturation may both be However, peat digging, even domestic cutting, is threats to these species, while drainage may be always damaging to the habitat when carried out an indirect threat through increased scrub on a part of the bog surface which has not growth. However, invasive species such as previously been cut for peat. Nor should it be Rhododendron ( Rhododendron ponticum ) and, in done in areas where past peat cutting has been the south outside its native range, Scots pine so extensive as to leave only a thin covering of (Pinus sylvestris ) should be removed from both peat over the mineral soil, as any nutrients from the bog and the scrub fringe, as unchecked they the mineral soil will encourage the development will act as a seed source and threaten the bog of fen rather than bog communities. habitat in the long term. Avoid grazing Ensure a diverse vegitational structure Grazing on Sphagnum -dominated bogs can Relatively undisturbed lowland raised bog cause extensive damage by trampling and surfaces are not uniform; they are made up of an nutrient enrichment of the water supply through almost continuous carpet of Sphagnum with dung and urine. hummocks and hollows providing a range of Avoid burning conditions that support different invertebrate communities. It is important to minimise human Burning is a highly damaging practice for activity on undisturbed raised bogs; wet invertebrates, as it will destroy large numbers or Sphagnum communities are fragile and easily even entire populations. On acid sites, burning damaged by trampling. can alter the plant species composition, encouraging the growth of Purple moor grass Bog pools (Molinea caerulea ). The heat can kill Sphagnum Shallow bog pools should never be deepened or and burn into the peat, damaging invertebrate cleared, as their invertebrate interest is likely to habitats both above and below ground. be far greater than any larger pool that is created. Agricultural scheme grants and subsidies Small-scale peat cuttings The Scotland Rural Development Programme Existing small-scale peat cuttings are very (SRDP) offers support for management effective in providing and maintaining early described in this document through Rural successional stages, small pools, bare peat and Development Contracts (RDC). At the time of low vegetation, thus diversifying vegetation publication, Options include the following: composition and structure. The typical mosaic • SRDP RDC Rural Priorities (RP) Axis 2 Option created by domestic hand-cutting of peat 13: Control of Invasive Non-native Species. provides a range of small-scale structures across a site, and this is good for invertebrates. Large- • SRDP RDC-RP Axis 2 Option 20: scale peat extraction is extremely damaging. Management / Restoration of Lowland Raised Peat cutting methods involving drainage of the Bogs. peat are also extremely harmful. • SRDP RDC-RP Axis 2 Option 23: Buffer Areas On a site with a falling water table, domestic peat for Fens and Lowland Raised Bogs. cuttings can provide areas of wet bog which may • SRDP RDC-RP Axis 2 Option 26: Wildlife act as valuable refugia. However, lowering the Management on Upland and Peatland Sites. surface of the bog by removal of peat is an • SRDP RDC-RP Axis 2 Option 28: Moorland unsatisfactory way of maintaining such conditions Grazings on Uplands