Transport Corridors

Durham Lowland Priority Habitats
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Transport Corridors Action Plan

Priority Habitats: Road Verges of Conservation Importance

Priorities

  1. Review the extent and status of the current habitat resource within transport corridors in the DBAP area.
  2. Maintain and where possible, improve the biodiversity value of transport corridors.
  3. Raise awareness of the biodiversity value of transport corridors, and the importance of sensitive management.

Road Verges of Conservation Importance Targets
Vision Statement: For the best examples of species rich road verges to receive protection and appropriate management, and for the whole road verge resource to be managed to maintain or improve it’s overall biodiversity.

Target Type Unit Value
1. To extend the area of road verge designated as Local Wildlife Sites by local authorities. expand ha tbc
2. To maintain the condition of designated roadside reserves. maintain number of sites (sample) tbc

Many road, rail and cycle/walking routes have semi natural habitat associated with them. The linear nature of these strips of habitats means that for some species of plant and animal they could provide migration or dispersal routes between larger habitat patches.

Rough grassland and scrub associated with these corridors is often ideal for common invertebrates, small mammals, and consequently for barn owl and kestrel amongst others.

Many road verges are known to harbour areas of species rich grassland, which often approximate to the communities which exist or would have existed in farmland nearby. They are often the last remnants of a wildflower rich grassland in a locality, sometimes supporting rare invertebrates, which has been destroyed by intensive agriculture.

Some plants and invertebrates have undergone such a dramatic decline in the farmed countryside that the road verge is now their principal habitat (e.g giant bellflower), or an essential component of it (small pearl-bordered fritillary).

Railway corridors similarly provide ideal conditions for other Durham BAP species such as our reptiles which find good basking conditions and hibernaculaand for the dingy skipper which likes the early successional nature of many embankment sites. Damp cuttings are also good sites for amphibians such as the great crested newt, and for developing fen vegetation.

There is a great variation in transport corridors in the plan area from disused railway cycle paths to major trunk roads. However, as recent surveys have shown, all of these corridors have the potential to support wildlife.

Road verges of conservation importance

In the Durham BAP area road verges of conservation importance have been defined as those roadside verges within a sensible management unit (i.e. between road junctions, field entrances etc.) which contain five or more species from a specified list within a 20m linear section (see Habitat Definitions for species list). This allows road verges which may not meet the size criteria for Local Wildlife Site designation as a grassland community, to have their importance recognised by those responsible for their management.

Road verges in the North Pennines are of particular importance to a number of rare lady’s mantles (Alchemilla species). Nine species of lady’s mantle  grow in the Durham area, of which 5 are rare. Alchemilla acutilobaA. glomerulans, A. subcrenataA. monticola and A. wichurae are all red-listed under the 2001 IUCN criteria. All five are found on road verges in Teesdale and/or Weardale, while their former strongolds in haymeadows and some pastures have declined. See upland haymeadows plan.

Threats

  • Management of village and urban verges for non-native species, such as daffodils, removes local distinctiveness provided by a wild flora, and will eventually lead to loss of wild flora.
  • Lack of management. Road verges that receive no treatment will eventually scrub over. Although this is not always undesirable, it is where scrub replaces wildflower-rich grassland.
  • Excessive mowing where not entirely necessary for safety reasons leads to large areas of grassland slowly loosing botanical diversity, and any invertebrate value  immediately declines.
  • Ground disturbance from utility companies, especially when the ground is reinstated with foreign or enriched soil, will encourage ruderal and/or competitive species.
  • Tree planting in inappropriate places shades out wildflower rich grassland.
  • Salt piles leach into the surrounding soils and kill plants. Placed in sensitive locations this leads to a rapid deterioration in habitat quality.
  • Disused railways becoming multi-user routes could lead to habitat loss, without careful planning of routes.
  • Overzealous clearance of railway routes for safety or visual amenity could damage a number of habitats, especially for bats and birds.
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