4.5 Restoring Vegetation
Where the natural landscape and fragile habitats have been damaged by upland path use the eroded areas are restored by encouraging natural re-vegetation.
The objective is to return the vegetation as closely as possible to its natural state prior to erosion. This includes minimising the visual impact of the path on the surrounding landscape. Vegetation may need restoring on:
- eroded ground at the side of newly surfaced or defined paths
- alternative path lines
- eroding, or unstable slopes above or below a traversing path
- trampled path edges or braids alongside an established path
Bill of Quantities (example)
Turf eroded areas to blend in with surrounding undamaged ground. All turf edges and joins should look natural. Turf cover of bare ground should be at least 75%. Apply seed and fertiliser with stone scatter to areas with less than 50% turf cover.
Revegetation of damaged areas can be achieved by using the following methods:
- turf transplants
- seeding and fertilising
- adding spoil and stone scatter
- stabilising and improving the soil structure with fibre matting, or mulches
The methods used are dependant on the size of the area to be restored and the availability of materials.
The following materials are used to restore and encourage revegetation:
- Seed, and fertiliser
- Small stones
These materials and the general principles for using them are detailed in Materials and Use.
Blanket turfing is labour intensive but it provides an instant effect of full revegetation, and the success rate is high. The availability of turf is a key consideration. Restrictions will be placed on some sites due to conservation designations and fragile habitats.
Spot turfing can be used to give partial coverage. The turfs will also act as a nurse crop either for the natural seed source, or in conjunction with seeding, and fertilising. By providing shelter and better conditions turfs encourage seed germination and growth. Total revegetation cover will be slower than blanket turfing, particularly if growing conditions are poor.
Seeding is a slower and less reliable way of restoring vegetation. If the site has a favourable climate and soil conditions, recovery can be successful. Most upland sites have low fertility soils, and a colder climate which slows down the growth and recovery rate of a seeded site. Applications of fertiliser will help to address this. Over-grazing of new shoots by sheep or deer can dramatically hinder the success of seeding. Temporary fencing to exclude stock and deer may be needed - this will also prevent physical damage from trampling by both animals and people.
Problems can also arise from walkers trampling over seeded areas, if they stray from the path line. Random stone scatter will deter this and will also aid germination and growth by providing small moisture retaining pockets.
Spoil from excavations can be used to spread over areas where the soil has been totally eroded. If the spoil is organic and nutrient rich, it will provide more fertile and stable growing conditions. If not, fertilisers can be added. Only the top 100mm or so of soil is "active" and will immediately boost plant growth. Soil from below this level, particularly dark wet peat, will not on its own support successful plant re-establishment.
Where no turf is available or slopes are too steep, natural fibre matting can be used in conjunction with spoil, for soil and water retention. This will provide a more stable base for seeding, or for turf transplants.
Key points to watch:
- avoid creating unnaturally smooth turfed areas - incorporate undulations, mix plant species and stone, if appropriate to the site
- make sure that seed and fertiliser is suitable for the site - consult a specialist
- always follow the guidelines given with the product
The following maintenance may be required:
- re-turfing or re-seeding any areas that are not recovering
- further applications of fertiliser to areas that have not achieved full vegetation density
- checking for trampling or grazing, and taking appropriate action to stop disturbance, if necessary
- do not use seed mixes that will introduce "alien" species to the area
- be cautious in the use of fertilisers - over-green vegetation is unnatural in an upland landscape
- don't use fertilisers where water run-off or leaching may affect natural or fragile vegetation
- geotextiles can be intrusive on steep slopes - use only where they can be effectively hidden
HEALTH AND SAFETY HAZARDS
- wear gloves if handling seed or fertilisers
- remove excess fertiliser from the site, on completion of work
- not all areas will require revegetation - a certain amount of erosion is acceptable in an upland landscape.
- developments in site restoration are happening all the time - consult an expert, or other pathworkers, to find out latest developments and the success of other techniques