Grassy clearings, glades and woodland edges are amongst the most important habitats for invertebrates and birds associated with woodland. Many of these ‘woodland’ species cannot survive the shade of a closed canopy, but require the sunlight, warmth and nectar- bearing plants of sunny woodland edges. Many invertebrates, whose larvae develop in leaf litter, soil and dead wood, in their adult stage require nectar from sun-loving plants.
With the exception of the shade-loving green-veined white and speckled wood, nearly all butterflies breed only in sunny, sheltered rides and glades. These habitats provide the specific plants for egg-laying and larval development, as well as nectar sources for the adult butterflies. Many moth species breed on tree and shrub species, notably sallow and aspen, so the shrubby borders of rides are very important.
Many bird species are adapted to the woodland edge habitat, and to the type of growth provided by young plantations and young to middle age coppice. Managing the margins of rides and open spaces to increase this type of habitat will benefit birds.
The fauna and flora of woodland rides and spaces has in some places survived better in woodlands converted to commercial forestry than in unmanaged woods, because of the importance of maintaining rides for management purposes. Neglected coppices have too much shade to be of value for most invertebrates or birds. The creation and maintenance of open space are often the most important management operations to benefit invertebrates and other fauna in former coppice woodland.
Permanent open space in woodland includes grassy clearings, rides or tracks, some of which may be very ancient. Temporary open space is created in coppiced woodlands when a coupe is newly cut, or along rides or other open spaces where areas are cleared in rotation. Permanent and temporary open space support a different assemblage of flora and fauna.
Permanent open space supports plant and animal species adapted to open, sunny conditions, some of which may also occur in habitats other than woodland glades. Other plant and animal species rely on the interface between grassland and woodland, and are mainly confined to woods and wood edges. The flora of woodland glades and rides depends on periodic cutting and grazing, both to control the more competitive species of grasses, herbs and shrubs, and to provide ground disturbance which encourages the germination of seeds.
Temporary open space, as in newly cut coppice coupes, supports plants and animals adapted to take advantage of the sudden increase in light and space after cutting.
When planning new woodlands, sufficient area must be left unplanted and then managed to maintain open space. Rides and tracks are essential for management and must be planned from the outset. It is much more difficult to create rides or glades by clearance of trees at some future date, both because of the work of removing the trees, but also because the removal of trees will cause instability in adjacent trees which are suddenly exposed to the wind. Ground flora will also be more difficult to establish.
To maintain sunny conditions, rides and glades need to be at least 1.5 times as wide as the height of the surrounding trees. This width can include margins of broadleaved shrubs and scrub which do not shade the rest of the ride. Rides and open spaces which appear generously proportioned in newly planted woodlands will shrink as they become shaded as the woodland matures. In general it’s easier and more effective to create and maintain fewer larger spaces, rather than a complicated network of smaller open spaces or narrow rides.
The Woodland Grant Scheme for new woodland planting includes up to 20% open space, which is a minimum at which to aim when planning new woodland. For areas not subject to the grant scheme, up to 50% open space can be left unplanted to create a type of parkland or wood-pasture, attractive for recreation and wildlife. However, management of the open space must be planned from the outset, as this will be a continuing requirement which will be more expensive in time, labour and equipment than the management of the wooded areas.
Open areas must be maintained by regular mowing or grazing. Mowing is expensive, and cuttings must be removed to prevent enrichment and to allow the more interesting flowering herbs to flourish. Mowing can be carefully timed, but it is non-selective, resulting in less interesting plant communities than those created by grazing. Grazing by wild or domestic animals requires protecting the trees by fencing or individual protection. Domestic animals need looking after. Ancient or existing wood-pasture landscapes may be relatively ‘low maintenance’, but they are costly and difficult to establish. There is always a conflict, as the level of grazing which promotes maximum floristic diversity has adverse effects on woodland regeneration.
Glades
Existing glades and other open spaces in mature woodland are relatively stable habitats, and should be maintained as such. In some areas the grassy nature of the habitat is kept free of tree seedlings or scrub growth by the grazing of deer, rabbits, cattle or ponies. If the grazing pressure decreases for any reason, mowing may be necessary to prevent shrinkage of the open space. It is not a good idea to plant trees in existing grassy clearings, which may have taken decades to develop their specialised flora and fauna.
Where glades have to be mown, cuttings should be removed from the site to prevent them smothering desirable ground flora or causing nutrient enrichment. Various machines are available that are suitable for woodland sites, which may have narrow access, rough or soft ground conditions. These machines include mini-balers, and cut-and-collect machines. Mini-balers are either pedestrian operated machines, or pulled by mini-tractors. Cut-and-collect machines are powered by a tractor and have a hopper for collection of the cut material. For further details see Practical Solutions Handbook, English Nature (2001).
Various mowing regimes can be used according to the type of grassy sward, and to encourage flowering at certain times of year, mainly for the benefit of invertebrates.
Rides and tracks
A ride is a permanent unsurfaced route within a woodland, which may be used for access, extraction of timber, demarcation and shooting. In commercial woodlands, rides are normally classified as main rides, 6-9m (20-30’) wide, or secondary rides, 3-5m (10-16’) wide. Forest roads are surfaced with gravel or tarmac for use by heavy machinery, with wide verges to avoid tree growth overhanging the road and obstructing machinery, giving a total width between the forest trees of 20-30m (65-100’).
Old, established rides which have a stable grassy vegetation, maintained by deer or rabbits, should normally be left as they are. Areas of bare ground, including sunny dry areas and damp shady muddy ground can be important for invertebrates.
Old rides which have become overgrown with shrubs or trees will normally benefit from clearance, both to bring them back into use, and to increase their value as a habitat. Where rides remain only as a route on a map or from some indication on the ground, the potential loss of woodland habitat may make clearance inadvisable.
Management of rides
In commercial coniferous woodlands also managed for wildlife and amenity, priority is being given to thinning and felling the zones along roads and other access routes, which ‘opens up’ the forest for recreation. Oppressive shaded tracks through coniferous woodland are not attractive for recreation in Britain where sunshine is valued, and shade is rarely sought. Invertebrates, birds and other wildlife also seek out the sunny sheltered woodland edges where there is shelter, warmth and food. These felled areas can then either be left unplanted and mown, or planted with the smaller species of native trees and shrubs to create woodland edges attractive for wildlife and amenity.
In woods of mainly broadleaved species, clearance and ride widening may involve losses of mature trees. However, this can be balanced by the introduction of coppicing regimes, where possible from the existing stumps, which will provide valuable alternative habitats, whilst at the same time reducing shading of the ride. Sufficient width needs to be cleared to create an area large enough to support strong coppice growth, which itself will be poor if heavily shaded. A strip 5-10m (16-32’) wide is the minimum, with wider strips or blocks of 10-20m (32-65’) width preferable. Follow normal coppicing procedure (Chapter 9 – Coppicing).
Various mowing regimes can be used, according to local conditions and the type of vegetation community which you wish to create. The requirement for management must be planned for at the outset, because in the absence of grazing, at least annual mowing will be required to maintain open, grassy habitats.
The diagrams above indicate various regimes which can be used for the management of rides. An overall ride width of 20-30m (65-100’) is suggested, including grass, scrub and coppice zones, to retain sunny conditions where surrounded by mature woodland. The lower diagram is a simpler regime, with no coppicing required. Scrub of bramble, shrubs and small trees can be self-maintaining, but any potentially large trees which grow up through the scrub should be cut down to maintain the open conditions. Rides can be wider or narrower as circumstances permit. In Britain (excluding the far north), rides which run east-west receive more summer sunshine than rides which run north-south.
To provide visual variation, and to avoid wind-tunnel effects in long straight rides, the shrubby margins can be varied, or mature trees retained, to create a varied edge. Retain any sheltering growth at entrances to rides, or rises or other points where the wind is funnelled. This growth is important in sheltering the ride and the woodland within. Once removed, it may also be difficult to re-establish woody growth at particular locations exposed to the wind.
In small areas of woodland, the ride edge zone will be limited to 5m width or less. Make the most of sunny, sheltered aspects, points where rides meet or areas where ground conditions prevent tree growth.
Bare ground on sunny, south facing slopes are valuable basking areas for reptiles, and can be created by removing the soil at suitable points, or by frequent cultivation to maintain bare soil. Where natural sites already exist, or where rubble, gravel or other inert material has created suitable conditions, these should be maintained by removing encroaching vegetation as necessary.
For information on mowing regimes for glades and rides see here. With time, some stability should develop which makes the system partly or wholly self maintaining. Grazing by rabbits or deer, and frequent trampling by walkers, will keep grass short. Established bramble patches and other shrubby growth can be remarkably consistent in height and width over many years if their spread is checked by grazing.
For further details see Managing Rides, Roadsides and Edge Habitats in Lowland Forests (Forestry Commission, 2000).
