Purple moor grass and rush pastures

This species-rich habitat occurs in areas of high rainfall, mostly in south-west England, on poorly drained, shallow peat or peaty mineral soils with a range of pH conditions. They have low available nutrient concentrations and are usually maintained by low intensity grazing or mowing.

It is a priority habitat in the UK as it has been vastly reduced in extent. 92% of the habitat has been lost since 1900 in Devon and Cornwall, where it is known as Culm Grassland.

To date attempts to re-create this habitat have largely centred on agricultural land, with no known use of mineral extraction sites. However, at sites within the habitat range where suitable conditions allow, re-creation of purple moor-grass and rush pasture should be considered.

Establishment techniques

The priority will be to establish suitable hydrological and soil conditions at the restoration site - generally this will involve a permanently high water table, close to the surface throughout the year, on generally level, peaty soils.

Natural colonisation

Natural colonisation is most likely to produce species-rich habitats appropriate to local conditions, and will be more natural than created grassland. If natural colonisation has started, assess its development before continuing with other methods.

Colonisation will usually succeed where a suitable seed bank is present, or existing suitable grassland is adjacent. A suitable seed bank may survive in the restoration topsoil if it supported lowland calcareous grassland previously and was properly conserved. This can be tested for.

Prevent rank grass species from suppressing the establishment of new species. Where such species occur, cutting and collecting, grazing or selective herbicides can be used. Early introduction of grazing, especially during the spring, has been shown to promote species diversity in new grasslands. Natural regeneration on nutrient-poor soils produces sparse, diverse floras, so may not require management for some time, especially if grazed by rabbits.

Vegetation transfer

Material cut and collected from local, donor sites after flowering will contain seeds from many of the plants present. Most grassland species set seeds between June and August. Cutting in early July should mean that most of the seeds are still attached. A second cut would catch later seeding species. Actual timing of cuts will depend on location and species composition.

If the material is collected fresh, e.g. by forage harvester, and is spread and rolled immediately the chances of vegetative take by some plants, e.g. purple moor-grass and mosses, will be higher. This method may also collect more seed than baled hay.

Seeding

Seeds may be collected from a local donor site using a brush harvester, or acquired from commercial sources – but if so, ensure the seeds have native provenance and are from a local source (see www.floralocale.org website). Only a restricted range of species is commercially available. These can be used as a starter sward, as other species will colonise over time.

The following method should be used to introduce seeds:

Use a moderately fine and firm seedbed.
Fertiliser is not required.
Control perennial weeds pre-seeding: let them germinate in spring / summer and treat with glyphosate.
Sow seed in September / October at 10-15 kg ha-1 depending on fertility and the urgency for green cover.
Encourage light at ground level by repeated cutting; this relieves competition for wildflower seedlings. Three cuts may be necessary on fertile soils, less or none at all on the poorest. Remove arisings.

Hand/machine broadcasting and hydro-seeding

Broadcasting is a cheap and usually suitable technique, using conventional tractor-mounted spreaders. Mix with inert material such as sand to prevent seeds of different sizes sorting in the hopper. Broadcast by hand on small, steep or inaccessible areas.

Hydro-seeding where seeds and mulch are sprayed together, seeds areas normal techniques cannot reach, and unstable substrates. It requires expensive machinery and specialist contractors.

Use small machines (700-1,000 l) for seeding small areas (< 0.5 ha / day). Larger machines are capable of seeding up to 4 ha a day. Seeds are suspended in an aqueous mixture and can be sprayed up to 60 m from the machine.

Using container-grown plants and plugs

This is only applicable for introducing species such as orchids that:

do not grow easily from seed,
spread vegetatively,
and/or flower only after a number of years.

Plant out from September to mid-November or mid-February to early April on bare, or sparsely vegetated areas, in combination with seeding or to complement natural colonisation. Keep plugs moist, and water in. Dib a hole the same shape as the plugs. Manage competing species by cutting them above the height of the inserted plants and removing cut material.

Appropriate planting density depends on a variety of factors, including the species ability to spread and the density of cover in the sward, and varies between 2 and 10 plants m-2. Planting at 3 plugs m-2 will cost in the region of £7,000 ha-1; container-grown stock is likely to cost 3 times more. Plantings of 5-10 species, planted in drifts covering 30-50% of an area will produce a natural effect if combined with seeding. Planting designs should reflect the natural distribution of species as much as possible.

Long-term management

These are typically managed by grazing. Stocking rates depend on sward productivity and are best prescribed locally - aim to produce a mosaic of tussocks and shorter turf. Where grazing is not an option, cutting and collecting a hay crop may be necessary.

Wet grasslands require low intensity or no grazing until July, to ensure that breeding birds are not affected by nest trampling, followed by more increased grazing in order to reach optimum sward heights for the next season. Where grass growth is particularly rapid, it may be necessary to introduce a low level of grazing earlier in the year to maintain the community structure.

Relevant case study

We currently have no case studies for this habitat type. If you know of one and would like it to feature on the site contact us.

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