4.0 Introduction to Restoration Techniques
The overall aim of upland pathwork is to reduce and revert the environmental impact of erosion. Site restoration is a key element, with the objective to improve and safeguard the aesthetic appeal of the upland landscape. Effective revegetation and natural landscaping should make the ground look as if it has never been touched.
Before - wide erosion, bad braiding, eroding slope, edge collapse and breakup.
After - alignment defined, use contained, slope stabilised, vegetation restored.
Restoration is required on:
- Path edges
- Alternative paths, or desire lines
- Unstable slopes
- Eroded areas
It is important that the revegetation and landscaping of the area around a new path alignment uses appropriate techniques. These should define the path and channel use onto it. The highest quality pathwork, on a good alignment, is worthless if an eroding, or easier line, is seen as a preferable route, that encourages users to veer off the managed path. Numerous lines and shortcuts, will develop into visual scars and detract from the experience of walking in the upland landscape.
The function of the techniques used is to:
- Define and stabilise a new path alignment
- Channel and contain use onto restored or newly defined paths
- Stabilise eroded gullies, embankments and slopes
- Encourage re-vegetation of eroded areas, including where path materials have been taken from
Site restoration should improve the chances of natural revegetation, providing the basis of a better growing environment to encourage re-colonisation by native species. This is achieved by using naturally occurring byproducts of the pathwork including stone, turf and spoil gathered from the surrounding area. It is important that permission is obtained prior to moving, or using these materials.
On some sites there will be little natural material available, whether due to site designation or altitude, climate or erosion. Nutrient poor soils and dramatically shortened growing seasons will also slow down and reduce the rate of recovery. In these cases it may be necessary to import fertilisers, seed, mulches or geotextiles to artificially improve the process.
Whilst various techniques are used for this type of work, there are no definitive solutions. There is considerable scope for development of new and better techniques over the coming years.
ASSESSING THE SITE
Site restoration requires careful consideration of the landscape within which the work is taking place, to ensure that the correct approach is taken. Things to consider:
- the natural habitat of the area - vegetation, soil, hydrology
- the altitude and exposure - and its effect on revegetation
- designations - with possible restrictions on collection and use of materials
- the availability of materials - and implications of importing unnatural material
- land and path use - and their effect on success of restoration techniques
There are broadly two types of situations to consider:
- areas where path use and water damage has already caused erosion
- areas which may erode, or deteriorate, if users do not keep to the managed path line
For either situation, both the immediate environs of the path and the overall area through which the path runs, need to be to assessed.
Existing problem areas should be obvious, and identified during the path survey. They include:
- rough, wide path surfaces
- path edges, where walkers have trampled the vegetation on either sides of the path
- narrow braids caused by walkers leaving the main path and forming a number of path lines along the edges or close to the path
- wide braids merging to form areas of eroded ground, often with islands of turf remaining
- short-cuts, or alternative desire lines, where users cut a corner or avoid a badly eroded section of path
- scarred channels and gullies, where turf has completely broken down and sub-soil is eroded by water flow
- steep eroded slopes adjacent to the path line
- unstable slopes above or below the path line
The potential for damage by off-path use should be assessed by walking both directions of the new path alignment. This should identify the areas where it will be easy, or tempting for users to take alternative routes or use the softer path edges, remembering that more erosion will be caused by the predominance of downhill off-path use.
There are a range of techniques and itensity of site restoration - from minimal clearance of debris, to the reconstruction of larger slopes. The more common methods are:
- Movement of rough loose stone off a path
- Placement of blocking or edging boulders and stone.
- Turfing and in-filling of erosion scars, gullies, path edges and embankments.
- Slope, embankment and path edge stabilisation with revetments.
- Seeding and fertilising areas with no remaining vegetation cover
- Fertilising to encourage growth on areas of slow natural revegetation.
Flat, boggy path. Several braids on either side of the path, deep wet hollows forming
New geotextile path slightly raised over the bog, with cross-drains.
Turf edges of path. Turf to revegetate and deter use of braids beside the path.
Steep, rough zig-zagging path. Braids on both sides, short-cuts across corners.
Re-align and pitch the path with waterbars, and gradual curves to reduce gradient.
Turf edges of path, create side banks to contain path use. Use blocking boulders and turf binds to discourage short-cutting.
Very wide erosion on a moderate slope. Numerous braids merging with no defined path.
Construct a new aggregate path, with waterbars, on a curved line.
Turf path edges to define path. Spot turf, re-seed and fertilise remaining areas of erosion adjacent to new path.
Unstable eroding slope above established path line
Stone revetment to contain bank and stabilise slope
Turf over the top of the revetment and any gaps in the wall
MAIN PROBLEMS TO AVOID
Site restoration should promote the natural revegetation of damaged areas; stabilise and help the pathwork to merge with the landscape; and deter movement off the path. Failure to achieve these objectives can be attributed to:
- Wrong Position - features to contain path use or stabilise banks do not control the problem and damage continues
- Wrong Style - use of materials in a way that does not blend with the surrounding ground or landscape; unnatural landforms and formal lines created
- Poor Methods - cannot cope with the pressure of off-path use, or extremes of weather; features are trampled, or vegetation dies through bad timing of work
The following technical sheets give guidance on materials and the method of use, as well as the techniques used for the varying objectives of site restoration.