Upland heathland

Upland heathland occurs on mineral soils and thin peat (<0.5 m deep) throughout the uplands of England. Dwarf shrubs, heathers in particular, dominate the characteristic vegetation (>25% cover). Upland heathland usually occurs between about 600-750 m and around 250-400 m above sea level. Dry upland heaths occur on free-draining mineral soils, and wet heath on organic soils that hold moisture. Former mineral workings can be ideal opportunities for creation.

Upland heathland often occurs in mosaics with blanket bog and other mires, grassland, bracken, scrub, trees and woodland, freshwater and rock habitats. High quality heaths are generally structurally diverse, containing stands of vegetation with heather at different stages of growth.

Establishment techniques

When establishing heathland it is important to bear understand that success depends on meeting number of physical criteria:

Soil fertility must be very low. Test soils before developing detailed plans. The availability of soil phosphorous (P) is critical.This should be less than 10 mg kg-1 to avoid competition from weeds.
Upland heathland creation is only viable on acidic soils with a pH 3-5.
Locally available vegetation material (seeds, turfs etc) – heathland vegetation characteristics vary geographically and it is important to maintain local distinctiveness - hence seeds and turfs should be sourced carefully and be from the same vegetation communities as the target community.

It is important to create topography that replicates the natural heathland landform, including variations in slope and aspect as appropriate. Retain some bare ground features where possible.
Wet heath establishes where seasonal waterlogging with base poor water occurs.

Mire vegetation develops where waterlogging is permanent.
Dry heath will only develop on free-draining soils

Which method is used will depend on local circumstances, such as the availability of local seed material. It is very important to establish heathland and not just heather - heather may be only a relatively small part of the typical community.

Soil preparation – topsoil is usually only necessary where the substrate does not lend itself to seed establishment. Topsoil must be low in nutrients and be from a suitable source with appropriate chemistry.

Natural colonisation

Natural colonisation will occur on very nutrient-poor soils, where an adjacent seed source is available. Seeds blown from adjacent heathland will be very slow to establish, as ericaceous seeds are not adapted for wind blown dispersal. This is an appropriate method if plenty of time is available to establish the habitat.

Weed species (birch/pine seedlings, bracken, rough grasses) need to be kept at low thresholds. Even where only scattered ericaceous plants have established in the first few years, heathland may still develop if competition is kept low, as these plants will flower and seed within the first three to five years of life.

The mosaic of acid grassland, bare ground and developing heath that occurs in the interim can have significant wildlife benefits. Bare and sparsely vegetated ground is host to specialist early pioneer species of plants, invertebrates and birds. Bare ground habitat should therefore also be planned into the long-term design for the site.

Taking turves to re-establish heathland vegetation

A seed bank will exist in the upper c.10 cm of undisturbed heathland soil - in the organic horizon immediately below the fresh litter and in the top 5 cm of the mineral soil.
Laying turfs in a block will establish a total heathland cover, and suppress competition, but scale will be limited by availability of turfs. Instead, space the turfs across the site and rely on seed from them to fill the gaps. This will provide diversity to the vegetation structure.
Smaller turfs are easier to transport and can be spread further - turfs can be spaced and seed from them will infill the spaces between. Larger turfs are less prone to desiccation and to damage but can be difficult to transport. Dig turfs deep enough to avoid damage to roots (these are close to the surface). Around 10-20cm should suffice but ideally research this on site.
Turfs need to be lifted, transported and laid before desiccation of the rootstock occurs, and taking care to exclude air pockets beneath the turfs, e.g. with light roller.
Lift turfs in the autumn/winter, when plants are dormant and there is less risk of desiccation.
Turfs should be dug in so the edges are flush with the ground surface to avoid desiccation of the rootstock.
Watering may be required in dry weather in the year following laying.

Using topsoil to relocate the seed material from a donor area.

Remove standing vegetation to 2-5 cm prior to soil removal - fresh organic matter will compost when stored and risk killing the seed. The cut material can be spread on the receptor site as an additional seed source. Cut in autumn (post-flowering) and collect with suitable machinery (double chop forage harvester or hi-tip type mower) to retain seed for use during restoration (see section on litter and brush transfer below).
Use a machine that will strip material to a determinable depth so that the organic horizon and the seed-bearing soil are taken together plus a few centimetres to ensure all seed material is gathered.
Lift, transport and lay topsoil in one operation. Where storage is unavoidable, prevent composting (this can cause increased temperatures and if heated above 50oC ericaceous seeds will be killed). Heaps should be less than 1.5 m high, on free-draining ground, preferably on geotextile sheeting. Ericaceous seeds can remain viable for over 14 months if properly stored, but vegetative material of species such as purple moor-grass or bilberry will be quickly killed.
Spread topsoil using e.g. a manure spreader as this is quick and cost effective. Any clods can be broken up with a light harrow. Alternatively dump piles of material and spread using an excavator or similar.
An even and complete cover of vegetation is not necessarily desirable, as it will cause a more even stand structure. However, if required rapidly, spread material to a depth of 2.5 cm. Note this requires extensive areas of donor heath.
Spread material more thinly to give sparser early distribution. Small gaps will infill with seeds from established plants creating a structural diversity.
On coarse, mineral, substrates with low sand content, spreading fine, sandy, mineral subsoil would help water retention and improve soil-plant nutrient exchange.A nurse grass crop will help stabilise vulnerable soil and help protect germinating seedlings from desiccation. However, it is not normally necessary other than in particularly exposed locations. Chose nurse species with care to have a low nutrient demand (hence no need for additional fertiliser), and short viability so they die out after 3-4 years without the need for control. The sward should be sparse, in order to leave space for heathland species to develop. Sow a nurse crop in spring or late summer/ early autumn, by broadcasting onto a moderate seedbed and roll-in with a Cambridge roller. Geotextile sheeting may be needed to stabilise steep slopes.
Spread topsoil in late winter or early spring, when relatively dry. The first germination can happen relatively quickly and this gives a full growing season. Spring or late summer/ early autumn are the times to sow and establish a nurse crop.

Litter and brash transfer

Collecting and spreading litter and/ or vegetation containing viable seed of a range of heathland plants is relatively cheap, non-destructive, and repeatable. Use local donor sites with similar characteristics to optimise success.

Prepare a relatively compact seedbed on the receptor site - any roughness will help shelter young plants from desiccating winds. A nurse crop should not be necessary on reasonably flat ground as the chopped brash shelters the seedlings.
On the donor area, cut well grown but not old heath to ground level with cut and collect machinery e.g. a double-chop forage harvester – cutting then baling sheds many seeds and thereby reduces success.
Cut between late September and late November when ripe seeds are in the capsules. Small amounts of topsoil are inevitably picked up, which imports heathland soil microbes and the mycorrhizal fungal associate that is thought to benefit establishment of ericaceous species.
Transport the cut material to the receptor site and spread it immediately. Store if necessary in low piles to prevent heating.
Spread the material with e.g. a clean manure-spreader. Tease apart any clods with a light harrow. Use a Cambridge roller to press seeds into the ground to promote better rooting.
If desired, to establish a quick dense cover, spread material 1 cm deep. Approximately one hectare cut will provide for two hectares of spread. Spread more thinly for less dense cover and the material will go further.
Heather germination rates are variable - some germinate within six months, others over two years –wait to assess success. Mature ericaceous shrubs produce thousands of seeds per metre square, and the new seedlings are tiny so are easy to miss!

Litter collection

The humic litter from old unmanaged heathland will contain a high number of seeds. Litter removal can be used as part of restoration work on appropriate donor sites.

Test the seedbank in advance to determine that sufficient viable seeds are present.
Strip litter to the mineral soil surface - regeneration will occur from the seedbank.
Collect material using e.g. a grading blade with a very sensitive control to scrape without digging into the mineral soil, lift into trailers, or
loosen the litter with a light harrow, let it dry and then vacuum into a trailer
transport and spread on the receptor site in the same way as heather cuttings

Harvesting and sowing seed from donor sites

Seed harvesting is usually done by specialist contractors. It limits the species imported, but will give good take of heather. Machines brush the seeds from the plants and collect them with limited damage to the vegetation. The seed is usually cleaned and heat or smoke treated to increase germination. Collection is expensive, but transport and spreading costs will be relatively low because volumes are low. This of all methods will produce uniform stands of heather without any species richness.

Ericaceous seeds are extremely small and light, so a nurse crop of fine grasses may be necessary on exposed areas (see above). It is usually preferable to harvest the whole crop (see above) to provide some mulch with the seed.

Soil surface stabilisation can b achieved using a grass nurse crop. This helps to stabilise soil, shelter germinating seedlings from desiccation and trap warmth. Nurse species selected must have the following:

low nutrient demand, so don’t need fertiliser,
short viability; they die out after three or four years without the need for control.

The sward should not be dense, to provide space for heathland species to develop.

Note: in most situations, a nurse crop is not necessary and may compete with the desired vegetation (Gilbert and Anderson 1998). Locations most likely to require soil stabilisation include higher altitude and deep peat sites.

Sowing commercially available seed

Unless local progeny can be guaranteed, do not buy commercial seed. Potentially genetically ‘alien’ heather must not be introduced into a local heathland community. In addition, this will create a monoculture of heather, with low wildlife value in all but the very long-term.

Planting seedlings and plants

This is labour intensive and consequently expensive. Seedlings have to be collected or grown from seed, grown on, then hardened off before transplanting. Once planted, they need plenty of care to avoid drought and suppress competition. Many thousands of plants are needed to cover even a small area. Fewer plants are needed at relatively wide spacings, and once established they seed into, and fill, the gaps (competition will need to be managed). This method could be used to introduce ‘missing’ species after monitoring of early regeneration.

Long-term management

Keep establishing heathland free from competing plants, and keep soil fertility low. Management must avoid introducing nutrients through incorporation of organic matter.

Options include:

Light spring and early summer grazing – to control competing grasses etc. Timing of introduction is not critical and can be left until a problem with the level of competition is identified
Rabbit browsing – though if intensive this inhibits heather development. The heather will have a prostrate growth, which with open ground is a valuable pioneer community for plants, invertebrates and birds like woodlark.
Rabbit-proof fencing – if fencing is deemed necessary, maintain for about five years
Mowing and removing cuttings – to reduce grass dominance. The heather will survive in a prostrate form.

Herbicide – necessary to control bracken, optional to control gorse, birch and other weeds. Bracken will require application of Asulam by prescribed methods. For others, a weed-wipe application of relevant herbicide will avoid damage to heather.

Relevant case study

Plenmeller case study

The information set out within this advisory sheet in no way constitutes legal or regulatory advice and is based on circumstances and facts as they existed at the time Nature After Minerals compiled this document. Should there be a change in circumstances or facts, then this may adversely affect any recommendations, opinions or findings contained within this document