Roadside Verge Management
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Joined: Dec 2008
16-10-2009, 12:09 PM
Roadside Verges have long been known to be valuable ecologically, although their intrinsic importance can also be very variable. They can provide a locally significant wildlife resource in themselves as well as provide wildlife corridors connecting sites within otherwise impoverished biodiversity landscapes. It has been estimated that there are 3000km of verges in Hertfordshire. However, in order to effectively look at the issue of the wildlife importance of roadside verges, a number of aspects need to be considered. These include:
Â¢ Why they are ecologically important
Â¢ How they have originated
Â¢ What management is required to conserve them
Â¢ How this can be achieved.
This brief report introduces some of these issues for discussion.
2. The Ecological Importance of Roadside Verges
2.1 Nature of verges
What is a roadside verge? One definition would be the area of ground that literally edges a road â€œ whether the road is a path, Green Lane, minor road or motorway. It could even be the strip of grass between a pavement and, kerb in the middle of an urban area â€œ most valuable if you are an ant. Often topographically distinct, they could have a bank, an embankment up or down, or simply be flat but distinct in their management or lack of it. They could also include a ditch, be less than a metre wide to tens of metres. In some ways, roundabouts or even narrow village greens could be effectively considered as wide verges; certainly wide Green Lanes with grassy edges can occur, such as at Gaddesden Row, whilst the central area of the M25 roundabout at Leavesden is floristically rich, supporting Pyramidal orchids.
In addition to such topographical variation their spatial disposition will add further diversity, together creating significant variation in aspect from hot, exposed and, dry south facing slopes to cold, shaded damp north facing slopes, and, every permutation in between. Verges can be very ancient features â€œ sometimes thousands of years old - or very recent, together providing potentially well established, consolidated soils or very disturbed, friable soils. All of these characteristics provide distinct ecological opportunities for a wide range of animals and, plants.
The ecological significance of verges is perhaps most commonly associated with grassland, and, this will vary in terms of species richness depending on the nature of the underlying soils and, verge management, as with any semi-natural grassland. However, a verge can equally, be considered to support hedgerows, or linear woodland, â€œ indeed, the latter may originate from the former. Unless there is an adjacent ditch, stream or pond, they are rarely associated with wetland, features â€œ roads would naturally avoid such places or be embanked to allow passage at most times. Scrub is another habitat that may be present, from scattered bushes to dense blocks. Woodland, could be present in various forms, including over mature hedgerows, secondary woodland, from scrub or the edge of ancient, semi-natural woodland. All of these are valuable in providing a habitat resource, of particular importance within landscapes where such features may otherwise be lacking.
There are probably many species which can be found on verges, although there is relatively limited survey work or data available compared to other recognised sites. In the north of Hertfordshire on the chalk, numerous county rarities such as Greater pignut can be found, whilst in the west colonies of glow worms survive on wide, chalky verges. The various aspects allow opportunities for basking reptiles including lizards and, slow worms, whilst butterflies can find floristically rich verges valuable â€œ if ever allowed to flower. Badgers and, rabbits can dig themselves into embankments, whilst dense scrub will be used by nesting birds. Apart from noise, vibration, pollution, fumes, litter, nutrient enrichment from adjacent fields or lay-bys etc. roadside verges can be relatively undisturbed places. They can, however, be subject to locally significant effects which are often damaging. For example salting and, associated spray from gritting can significantly affect the nature of plant and, animal communities in favour of coastal species which are spreading inland, along roadsides, such as Danish Scurygrass.
2.4 Wildlife Corridors
Verges can act as valuable wildlife corridors by virtue of their linear continuity between other recognised sites or features. These can provide relatively undisturbed areas along which species can physically move or even migrate. Mobile species such as birds or flying invertebrates can use such features readily, particularly where habitat features are otherwise lacking or poorly connected within the landscape. In this sense, roadside verges can be of value in both rural and, urban areas alike. However, wildlife will also want to cross roads between verges, especially where regular runs or traditional migration routes are present. This is a separate issue requiring site specific solutions but one which can have significant impacts for wildlife such as badgers, deer and, toads, as well as for humans given the danger from potential road traffic accidents. The management of adjacent habitat or special provision for dealing with particular site locations (e.g. toad crossings, deer deflectors) - can help alleviate this problem or at least raise awareness.
2.5 Wildlife Sites
Where high quality habitats meet Wildlife Site criteria, roadside verges can be identified and, recorded formally as Wildlife Sites. There are around 81 verges specifically identified within the HBRC database, of which around 50 are Wildlife Sites. In other counties, similar high quality features have also been identified as Roadside Verge Nature Reserves by local authorities or Wildlife Trusts.
3. Roadside Verge Origins
Historically, grassland, roadside verges lined ancient trackways and, routes through the countryside, both national routes between regions such as the Icknield Way, local routes to and, from Market Towns, and, between smaller settlements and, buildings such as churches. In addition to human movement for trade or other commerce, a dominant factor was the movement of livestock, herded across the country along droving roads for finishing on new grazing pastures or to and, from major or local markets. Animals also needed the availability of watering holes (ponds), food (they grazed the grassland, edges or adjacent pastures) and, may have required retaining features (hedges). Thus, traditional road use itself was a functional activity that actually helped maintain these features for perhaps hundreds of years. Their role and, contribution to ecology and, the wider landscape was effectively as a by-product.
In those rural areas where arable farming now dominates, they can be almost ploughed out of existence, although new agri-environment support standards expect broad buffers to ensure Ëœgood agricultural and, environmental conditionâ„¢ (GAEC). Where they have survived in such situations they are locally important. Equally, in urban areas built development and, management have destroyed many verges but where they survive they contribute to greening the townscape and, providing ecological corridors, linking open spaces and, gardens both at the large and, small scales, whether as grassland, hedgerows or tree lines.
4. Management of verges
4.1 Grass verges
Where the special interest lies in the quality of the grassland, itself or a rare plant species, in the absence of grazing, management should aim to cut and, remove standing vegetation at appropriate times. This is no different to grassland, management for wildlife anywhere. This also helps to reduce the likelihood of scrub invasion. Rank grassland, immediately adjacent to highways reduces visibility and, will need to be avoided for safety reasons. Elsewhere, rank grassland, can at least provide a linear habitat feature of local significance.
4.2 Hedge verges
As with any hedgerow, these could be left to mature, then laid or coppiced after 10 â€œ 15 years, or be regularly trimmed. Both approaches will retain hedges as features. Regular trimming can limit structural diversity of individual hedgerows or of the resource within the wider landscape but will ensure they remain as dense structures, while over-mature hedges can become very thin and, ultimately be in danger of collapse. However there are other reasons why control of hedgerows is important for Highway considerations.
4.3 Woodland, verges
Safety would be the main consideration, largely in respect of the potential danger from falling trees. Often wooded edges are in fact ancient laid hedges, but these can become very unstable with large canopies over weak stems, unless self-thinning has occurred to leave what would become standard trees. One way of maintaining such features is to re-coppice them, assuming browsing pressure from deer or rabbits will not destroy the regrowth. If this is not done, it is likely that lines of straggly trees will result, largely from self thinning, which will also eventually destroy the historic hedgerow feature as well due to shading. However, such trees may then be managed as standards, if they are stable enough. Each situation is different and, needs to consider the options taking into account the origin of the feature, as well as the needs of road users.
The quality and, nature of verges are no longer maintained as a functional result of the use of roads themselves. They are now largely managed specifically by Highway Authorities on behalf of road users so as to ensure safety at all times. Consequently the habitat features once associated with them also change â€œ and, in some cases such change represent a decline or loss in the habitat or species resource. Examples include:
Â¢ Linear woodland, belts exist until they collapse, or are managed for safety, after which recovery may be poor if there is adjacent shading.
Â¢ Hedgerows become over-mature if not trimmed, very thin or leggy, will eventually self thin themselves and, may result in a line of scattered trees at best.
Â¢ Grasslands either:
Â¢ get regularly gang mown for amenity / safety, rarely allowing flowers or grasses to flower, with cuttings left on adding to nutrient enrichment (which may also happen if adjacent land, is sprayed with fertilizer), or
Â¢ get generally left if not in the way to get more rank and, coarse, gradually increasing nutrients and, smothering more sensitive herbs and, grasses. Cutting may take place once a year, with cuttings left to smother vegetation beneath, leading to die back and, significant nutrient enrichment.
In some cases, new road schemes may take many years to re-vegetate if cuttings expose underlying geology, creating very steep ground with little or no topsoil, but such situations may be beneficial for the ecology of sparsely vegetated habitats. Equally, artificial seed mixes associated with new schemes or Highways restorations which do not reflect the local character of plant communities can be considered inappropriate ecologically.
6. Conservation Action
If the ecological value of the roadside verge resource is to be fully appreciated, maintained and, enhanced, there is a need to:
Â¢ know where the most important verges are;
Â¢ identify them to the appropriate authorities;
Â¢ ensure these receive appropriate management.
There have been a number of plans / actions which have attempted to address this, including:
Â¢ A list of valuable Herts verges was drawn up in 1970.
Â¢ Raising of the issue by HCC Landscape on 1990.
Â¢ A limited Heritage Road Verge project and implimentation initiated in 1991. Heritage Sites were effectively the forerunners of Wildlife Sites.
Â¢ A detailed report on roadside Verges by HMWT in 1993 â€œ a discussion document following a survey.
Â¢ A Road Verges Working Party established in October 1994 partly under the auspices of the Herts Countryside Forum with the aim of developing the ecological features of roadside verges through design and, management practice. This group included County Councillors, Herts Assoc. of Local Councils, Herts and, Middx Wildlife Trust, HBRC, HCC Landscape, CMS, Herts Highways.
Â¢ Numerous Roadside Verges were identified and, mapped by HBRC on a number of occasions, although these datasets are likely to be incomplete with a bias towards North Herts, and, are now dated and, possibly unreliable.
Â¢ A number of verges were identified as ËœHeritage Road Vergesâ„¢ in the mid 1990s.
Â¢ Chalk grassland, verges in the north of the county were specifically referred to within the original county Biodiversity Action Plan, published in 1998.
Â¢ However, the Roadside Verges Group came to the end of the road around 2001 when it fizzled out. It had generated many meetings, a good deal of paperwork and, angst at times. There was a lot of good intention but the presence of real â€œor apparent â€œ difficulties associated with Highways verge management, including contracts, management requirements and, cost implications meant that, unfortunately, there was relatively little effective result. The Group did, however, produce a really nice leaflet (see attached).
Â¢ In the revision of the County BAP in 2006, the Grassland, and, Heathland, Action Plan has, as Objective 5, the Promotion and, positive management of road verges, with an aim to secure sympathetic management of all roadside verge Wildlife Sites by 2010. Another action is to re-establish the roadside verge working party â€œ by 2007. HBRC is identified as the lead partner, along with Butterfly Conservation, CMS, HMWT and, HCC Highways.
7. The way forward?
7.1 Despite the laudable objectives of roadside verge conservation for biodiversity, in Hertfordshire this has, despite a not inconsiderable effort, never really succeeded. Currently there appears to be little enthusiasm to progress the Roadside Verge objectives within the BAP, at least by HBRC. Current planning workload and, reduced staffing at HBRC, in addition to a low likelihood of real achievement in anything other than an ad-hoc manner, means that it is unlikely that roadside verge conservation will be taken forward in a co-ordinated manner in the foreseeable future, or without another lead partner. This is partly a function of the pressure Hertfordshire is under, both from development as well as land, use change, which in themselves generate a considerable workload for HBRC and, others.
7.2 here are already other initiatives which seek to take forward habitat and, species conservation, including those identified within the BAP, that are already being undertaken and, achieving results. One which could bring some benefits to perhaps a wider community is the Living Churchyards project and implimentation. This is community based with some HBRC support, and, has recently been generated as a result of local activity and, interest in several places in the county â€œ such as Weston, Abbots Langley and, Tring Parish. Management of churchyards is equally fraught with similar problems, but, for example, on an individual basis these may be more easily overcome or addressed by a wider community than trying to negotiate a complex verge management system, which may be too complicated or costly to generate real enthusiasm amongst the limited number of people who are directly involved. In this context, it is probably better to progress initiatives that can deliver on the ground, as this is a better use of limited resources
see cotswoldsaonb.org.uk/userfiles/file/General/MANAGEMENTOFROADSIDEVERGES.pdf for little more have
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