17th Jan 2017

Dark Low Res : Steve Ashworthdark2 copyright Steve Ashworth-65

The event area contains a network of hill lakes, rivers and stream. Did you know these are sensitive environments that may be home to Otters and Water Vole? Please read our advice below.
© Steve Ashworth (from Marmot Dark Mountains 2016 in the Northern Fells)

The events organised by Ourea Events are often located in Britain’s greatest upland areas that often contain features of outstanding biodiversity value and importance. Marmot Dark Mountains™ is no exception. Occasionally, the features that provide this interest can be vulnerable to the wear and tear that may result from the passage of event participants. The risk of ecological damage is carefully assessed during early stages in the planning process for each event, when every effort is made to avoid sensitive ecological interest areas that could be disturbed by the event. The following ecological briefing is written to help participants understand the ecological value of the landscape they are in and how to minimise their impact.


The 2017 Marmot Dark Mountains event area extends across some of the highest ground in the northern Pennines, and includes some of the most important areas of upland wildlife habitat in northern England. The event area is characterised by a varied sedimentary geology that includes limestone, sandstone and mudstone bedrock strata that are crossed by the Whin Sill volcanic intrusion.  The varied geology and generally high elevation of the event area has resulted in the development of an extensive cover of distinctive and important upland vegetation types and wildlife habitats.

Of particular ecological interest is the considerable extent of uncultivated semi-natural upland vegetation that is present throughout most of the event area. This includes heather moorland, blanket bog, montane heath and grassland. The geological variety of the event area is revealed at locations where a complex mosaic of acidic and calcareous vegetation types is present. These vegetation mosaics often contain upland plant species that are noted for their great rarity. The event area is known as a key upland wildlife area, in particular where extensive heather moorland areas are used during the late spring and summer by internationally important breeding bird populations. 

The distinctive upland wildlife habitats and vegetation types within the 2017 Marmot Dark Mountains event area include two extensive areas of International nature conservation importance, and five areas of National nature conservation importance. Participants will need to cross some of these areas while completing individual courses, potentially passing through various types of upland habitat. 

We are keen to encourage personal route selection choices by participants on our events to further avoid the risk of local ecological disturbance. This Ecological Briefing Note has been prepared for the 2017 Marmot Dark Mountains event to identify key ecological interest features that contribute to the special character of the event area, with route selection comments to help minimise the risk of localised ecological disturbance. Wherever possible, participants are encouraged to use existing hill paths and tracks when travelling between controls. 

  • Dry acid grassland is a relatively widespread vegetation type within the event area, where centuries of livestock grazing has converted heather moorland to open grassland. These areas provide a relatively robust vegetation type that can generally withstand the trampling effects of fell running. 
  • Extensive areas of dry acid grassland can include mosaics of other upland vegetation types such as blanket bog, heather-dominated heath vegetation and wet acid grassland creating areas of local vulnerability to a concentration of trampling by Marmot Dark Mountains participants. 
  • Heather moorland is an extensive vegetation type within the event area, including montane heaths on high level, sloping ground that is relatively well-drained. These vegetation areas are generally resistant to significant adverse impacts of trampling.
  • Blanket bog is an important nature conservation feature that extends across much of the event area at higher elevations, typified by areas of wet heath vegetation interspersed with shallow pools, often with abundant Sphagnum mosses. Disturbance of blanket bog by runners churning through wet heath vegetation and saturated peat has the potential to trigger peat erosion by de-stabilising the peat surface. Wherever possible, route choices in these areas should try to link strips and patches of better drained moorland vegetation between areas of wet peat. These moorland vegetation patches are often relatively resistant to the trampling effects of running. 
  • Areas of wet acid grassland will be encountered on courses where impeded drainage occurs within relatively level hill grassland areas or where groundwater emerges at the surface as seepages across more steeply sloping ground. Wet acid grassland can be of special nature conservation interest, in particular where groundwater seepages provide conditions for communities of specialised mosses, liverworts and other specialised plants. These vegetation types can be vulnerable to trampling disturbance and should ideally be avoided wherever possible by selecting routes that keep to dry acid grassland to by-pass wet grassland patches.
  • Wet acid grassland at groundwater seepages on steep ground can be difficult to avoid where they cross valuable contouring lines. Avoidance of these areas could involve a significant route change and deviation from the desired contour level. Despite this, it would be ideal if damage to seepage zone vegetation could be minimised, often located within shallow gulleys, re-entrant features or associated with ground level rock outcrops that cross steep slopes.
  • On hillsides, soil movements within dry and wet acid grassland areas can develop well-defined micro-terrace systems, often referred to as sheep walks or trods. These typically follow contours and can provide extremely useful running lines. Grassland vegetation at the edge of these micro-terraces is often friable and easily broken off. Care should be taken when using these features for contouring to avoid running on the edge of these terraces to minimise grassland damage.
  • Specialised rock ledge plant communities are present at a number of locations within the event area. If Marmot Dark Mountains participants need to negotiate low rock outcrops great care should be taken to minimise disturbance of ledge vegetation.
  • The event area has a number of hill lakes that contribute to the area’s upland nature conservation interest. Often this interest is associated with complex and specialised vegetation areas that develop at the margins of hill lakes. There is no need for Marmot Dark Mountains participants to enter any water body within the event area, and all lake margins should also be avoided.
  • The event area contains a complex network of streams and rivers, some of which are potentially vulnerable to ecological disturbance from repeated crossing by runners. Some of the rivers within the event area contribute to the special nature conservation interest of the area, including watercourses that could support internationally and nationally threatened animal species such as otter and water vole. In many cases, the nature conservation interest of these rivers and streams concerns use of the banksides by these animals. As a consequence, great care should be taken by Marmot Dark Mountains participants at stream crossings, minimising bank disturbance when entering and climbing out of stream channels. Handrailing streams should ideally avoid the immediate stream channel margins where ground conditions are often saturated and vulnerable to significant trampling disturbance.