Managing woodland for butterflies and

Why manage woodland at all? Surely a natural woodland, without (or with minimum) intervention would best supply sustainable habitat for butterflies and moths?

The answer lies in the processes cleared woodland habitats. The For many , the speed and that have formed our present natural processes that produce such extent of this change has made it landscape. Almost no woodland habitats within woodland (such as very difficult to adapt and landscape in Britain today can be considered fires, storms and the natural collapse changes have reduced opportunities wholly natural. We have inherited a of aging trees) typically occur too to relocate to suitable habitat long history of forestry use that has infrequently to provide the continuous elsewhere. substantially modified even our most cycle of clearings needed by these ancient woodlands. We have, and species. Woodlands would also have Overall objectives still are, continuously changing the been subject to regular, extensive This guide outlines specific woodland composition and structure of woods grazing and browsing by large management options designed to to meet our needs. The woodland herbivores which are now absent, benefit butterflies and moths. These wildlife we see today is a product of and these effects are not replicated options are designed to achieve the that history and many by the increasing number of deer following overall objectives: survive in woodland habitats only now browsing our woods. The small because of repeated human use of size and fragmentation of most • Structural complexity woodland resources. woods in the UK also prevent natural • Habitat diversity processes operating at a sufficient scale to conserve the full range of • Foodplant diversity woodland wildlife. Low-intervention • Management continuity management strategies can make • Landscape connectivity David Green a contribution to the mosaic of habitats within a landscape, but need The single most important factor to be complementary to an active that makes a woodland good for management process that maintains butterflies and moths is a diverse, and enhances the valuable habitat uneven structure. This should features found in our woods. include some mature or tall trees, Our current suite of woodland some dense regrowth, numerous species coexisted in the past sunny rides and glades (both large alongside often extensive active and small) and patches of recently management of woodlands. So cleared and regenerating open areas why is woodland management now with sparse ground vegetation and considered a conservation issue? The warm unshaded conditions. This diverse woodland structure creates a Sustainable removal of timber and reason lies in the extreme speed and firewood is an important part of woodland the huge scale of recent changes. variety of habitats necessary for the management The usage of woodland has always various life stages of Lepidoptera, changed over time, but change has including larval foodplants growing In Britain, applying a non- happened very rapidly in the last in appropriate conditions, a limiting intervention approach using only hundred years. This has occurred not factor for many species. natural processes within most of just within one type of woodland or Such a varied structure, with a diverse our woodlands will not create the one region of Britain, but across the range of tree and plant species, habitats needed by many of our whole landscape. At the same time not only provides good habitats for butterflies and moths. For example, urbanisation and intensive agriculture Lepidoptera, but also for a wealth many of our rarest butterflies are has removed or highly fragmented of other and forest wildlife. highly dependent on open, newly much of our woodland network.

14 | Woodland management for butterflies and moths Specific requirements for specialist Managing across patch is likely to undergo regular species requiring deadwood, lichens, local extinctions and regular re- mosses or wetland features can be the landscape colonisations. Problems arise when integrated with this overall aim. Looking beyond the survival of the breeding patches become species on single sites, conservation isolated, either by distance and/or Continuity of management is the must operate at the landscape scale because the intervening landscape is next vital factor to consider. Species to be effective in the long-term. There hostile. usually occur on a site because its is now considerable evidence that past use has created the habitat they the populations of many if not most Managing habitats at the landscape need, and periodically repeating that butterflies and moths function as scale is essential given the evidence management will be necessary for metapopulations. This is defined as a that some species are already them to persist. This is particularly collection of local populations which shifting their geographical range, important at sites with a long history occupy discrete habitat patches but their habitat use and the timing of of a specific management regime. which are connected by occasional their life cycles in response to climate Where woodland landscapes have dispersal of individuals. Each habitat change. Enabling species to move become fragmented management continuity is essential as it is harder for species to move to alternative habitats elsewhere. What butterflies and moths need

Continuity of management is also Indeed, adult butterflies may important because habitats are be encountered in parts of the dynamic: they will constantly change, woodland away from the vital often over very short time periods. breeding habitat, especially when Fundamentally, most woodland searching for nectar. In general, management for Lepidoptera is Lepidoptera require sheltered, about working within a cycle of warm sunny places as adults, often habitat succession rather than trying with a nectar source, as well as to maintain areas in a fixed state a suitable place to lay their eggs. over time. In particular, trying to hold The larvae will then require plentiful a permanent open area at an early foodplants, often growing in specific stage of woodland succession (such conditions, and will move to a as that used by Heath Fritillary) is sheltered or inconspicuous spot almost impossible. Regular cutting to pupate before emerging as an or grazing may keep the site open, Peter Eeles adult. For highly but will usually cause the woodland A Purple Emperor emerging from its in particular, understanding where ground flora to be replaced by a chrysalis on the underside of a sallow leaf they spend each of these stages, grassland community which may and at what time of year, can be the not support the target species. Understanding the life cycles of key to effective conservation. Land Most sites will require a shifting and butterflies and moths provides managers sometimes concentrate diverse habitat mosaic, created and an insight into what they need on providing the nectar-rich areas maintained by regular management from woodland habitats. All frequented by adult butterflies on different parts of the site to butterflies and moths go through (where they are most often seen) produce younger growth stages a complex lifecycle from egg to at the expense of other habitat (clearings or short, herb-rich swards) larva (caterpillar) and then pupa features. In fact it is rare that nectar which will in turn provide other (chrysalis) and adult. Some species is the factor limiting population habitats as they re-grow through spend much longer as an egg, growth, and suitable habitat for egg- woodland succession. Regular larva or pupa than as an adult, laying and larval development is management provides continuity of and the habitat requirements of usually crucial. Details of individual short-lived habitat conditions. each stage may be very different. species requirements are given in Section 4.

Woodland management for butterflies and moths | 15 Careful planning allows you to work out what is possible and to set Sam Ellis priorities. The stages are:

• Assess what you have (consider what habitats and species are represented, in a local and/or regional context) • Decide your objectives and priorities (incorporate the needs of butterflies and moths alongside other interests) • Decide how these objectives are to be achieved over time, given your resources and any legal requirements (including felling licences, site designations and protected species) • Monitor progress and examine how both vegetation and your target species respond to management (incorporating what you learn into future management) Once management is underway, be flexible and consider revising management prescriptions if they do not meet your objectives. It may be best to trial new management on only a proportion of the site, until monitoring results show that it does deliver the anticipated conservation Open space as part of the wooded landscape at Whitbarrow, Cumbria outcomes.

through the landscape and between Management planning Felling licences habitats gives them a better chance As part of the management plan it Management for butterflies and of adapting to future changes. must be noted that a felling licence moths often requires a long-term The aim should be to restore and from the Forestry Commission is commitment to produce a diversity construct landscape networks with generally required for the felling of habitats that will meet the interconnected, varied habitats. of trees, even if the work is part of requirements of a variety of species. Working at the landscape scale a grant scheme. Full details are It is essential to have clear priorities also helps share responsibility for included in the Forestry Commission and defined aims to ensure that the management, with each landowner booklet, Tree Felling – Getting main objectives are not lost in the day only needing to do a small amount Permission. to day practicalities of management. to contribute to the network. Coordinating management between multiple owners can be challenging, however, especially where woodlands

have been split into many small plots. Susan Clarke

The following sections detail management practices that can produce the diverse and dynamic woodland habitats that best support butterflies, moths and a variety of other wildlife. The options can be adapted to both small and large woodlands, and those with primarily conservation or commercial forestry objectives. While the suggested management has conservation aims, most will also produce commercial products such as coppice poles, timber, firewood and other wood Forestry operations provide a chance to improve habitat conditions whilst meeting other fuels. objectives

16 | Woodland management for butterflies and mothsmoths Woodland management relevant to woodland butterflies and moths of concern Dan Hoare Chequered Skipper Dingy Skipper Grizzled Skipper Wood White Brown Hairstreak White-letter Hairstreak Black Hairstreak Duke of Burgundy White Admiral Purple Emperor Small Pearl-bordered Fritillary Pearl-bordered Fritillary High Brown Fritillary Silver-washed Fritillary Heath Fritillary UK BAP Priority moths Other moths of concern

Promoting • • • • • • • • • • • • • • • • • diversity of age Using wood as fuel, in the form of logs, structure woodchip, pellets or charcoal, can Restoration and provide an economic basis for sustainable • • • • • • • • • • • • management of management coppice Managing for different Ride and glade • • • • • • • • • • • • species enhancement It may appear that many woodland Canopy thinning butterflies and moths of conservation • • • • • • • • • • • concern have incompatible requirements. Some species Woodland edge need regular woodland clearance, • • • • • • • • • • • • • • buffering while others depend upon closed canopy mature trees. This does not normally cause problems except Reinstating • • wetland features on very small sites. The following management techniques are all aimed at increasing the diversity of Increasing • woodland structure and the diversity deadwood resource of foodplants for Lepidoptera. Diverse woodlands will contain a wide variety Protection of • • of habitats that will be capable of veteran trees supporting a variety of species. The needs of closed canopy, high Restoration of • • • • forest species and those needing wood pasture early successional habitats should be seen as complementary rather Managing deer to • • • • • • • than mutually exclusive. Where reduce browsing requirements do appear to be in conflict, particularly on small Replacement of • • sites, it will be necessary to assess non-native trees conservation priorities in a local context. Conflicting priorities will also Improving • • • • • • • • • • • • • • • • • be more easily addressed within a connectivity landscape scale approach to habitat management.

The implementation of sympathetic management regimes aimed at butterflies will, on the whole, deliver Dan Hoare conservation for many moths. However, moths are a larger and more diverse group than butterflies. They exploit a far greater range of foodplants and habitats and additional features may need to be considered such as the availability of veteran trees, deadwood, fungi, lichens and wetland features. Butterfly habitats can be ideal for a range of other wildlife - reptiles are common on this Grizzled Skipper site on the edge of a young plantation

Woodland management for butterflies and moths | 17 Coppice An active coppice cycle provides a continuous succession of open space and a varied woodland structure that can create suitable habitats for a range of wildlife

Coppice and its history timber trees (standards). The habitats for woodland wildlife. It was underwood would be cut on every not until the late 1800s that markets Coppice is a system of producing rotation but the standards would for coppice products began to wood products that is based on the be left to grow for perhaps three disappear and commercial coppicing ability of trees to re-grow rapidly and rotations to produce larger timber. In diminished. This decline continued vigorously from their cut stumps simple coppice, only the underwood through the 20th century: in 1947, (stools). In coppice management, is present and it is all cut on every 142,000ha of actively managed trees and shrubs are cut to the rotation. In many areas it was coppiced woodland were reported, ground, allowed to re-grow, usually traditional for domestic to compared to just 23,000ha by 2000. with multiple stems, and then re-cut graze within the coupes once scrub on a set rotation. Coppicing appears growth was more than about 4 years By the end of the 20th century, to increase the life-span of trees, old, but nowadays this is rare. much coppiced woodland had indeed some of the oldest coppiced been grubbed out for farmland, stools have been estimated as more Coppicing was the main form of development, or converted to than 1,000 years old. woodland management over most conifer plantations. Other woods of lowland Britain until the end of were abandoned and reverted to Usually a coppice site will be divided the 19th century. Its purpose was closed canopy woodland dominated into many small areas (typically to produce a regular crop of small by mature trees. The resulting called coupes) and each will be cut timber and woodland products and, woodland structure was generally on rotation in such a way that at where standards were grown, to less diverse and more shaded and anytime the site will contain coupes supply a smaller amount of larger provided little habitat for species of of all stages of growth from newly timber. Only recently, in the last 30 open woodland. However, since the cut to mature. Coupes typically to 40 years, has it been viewed as 1970s, there has been some revival range in size from 0.5 to 3ha. The a specialist management aimed of coppice management, often but length of time between a cut on each at providing not exclusively as a tool to provide coupe will vary with the type of wood benefits. In particular, it has been specialist wildlife habitats. There product required and the rate of successfully utilised to provide the is still a small market for coppice growth, but can be anything between specialist open early successional products, together with a growing 3 and 50 years. woodland conditions required number of initiatives to promote and by some of our most threatened expand that market. butterflies such as Pearl-bordered Fritillary, Heath Fritillary and High The value of coppice for Brown Fritillary. It has also been butterflies and moths seen as an excellent management to Morag McCracken maintain habitat for other threatened The reduction of coppice wildlife such as helleborine plant management has been a major factor species, dormice and nightingales. in the decline of several butterfly and species, especially the The practice of managing woodland fritillaries. These species woodlands as coppice may go are dependent on the habitats found back into prehistory. Certainly, by only in the early stages of regrowth the time of the Domesday Book in after a coppice cut, but a full coppice 1086, coppicing was widespread cycle is needed to create these throughout lowland England. habitat conditions. A closed canopy Coppice systems have been stage with several years of dense Coppiced Sweet Chestnut in the Blean repeatedly modified throughout shade promotes shade tolerant Woods of Kent provides habitat for the history in response to changing woodland flora and suppresses Heath Fritillary markets. As timber uses changed, competitive plants. When the coppice this drove changes in species choice, is cut once more it will then provide rotation length, and in the proportion the open ground conditions and Traditionally in Britain, two of standards required. However, it foodplants needed, such as violets systems were used: coppice with seems probable that whatever the in the case of the Pearl-bordered standards and simple coppice. In system, coppicing took place on such Fritillary. Comparatively few butterfly coppice with standards the wood a wide scale that it created a dynamic species utilise the older stages of contains coppiced trees or shrubs mosaic of woodland, from open to coppice growth, but all stages of the (underwood) and also scattered closed canopy, providing a range of coppice cycle are of value to moths.

18 | Woodland management for butterflies and moths For many butterfly species, the To reduce shading yet retain the composition of tree species in the valuable mature tree habitat, there coppice is not particularly important are several options. Standards can because it is the ground flora that be grouped rather than scattered, supplies their larval foodplants. Amber Rosenthal individual standards can be situated However, the larvae of many moth at the corners of coupes (they make species do feed on shrub and good boundary markers) or small tree species. The presence of tall strips of un-cut woodland can be standard trees of different species left between coupes. These strips will provide additional habitat. should be carefully positioned to add shelter without excessive shading. When is coppicing a A balance between standard quality feasible option? and shading can be achieved by removing some older trees and It is probably not worth initiating allowing younger standards to grow coppicing within established on in their place. woodland that has no history of that management or on sites In the long-term, some standards where coppice has now developed should be left uncut to produce into high forest. The response to the veteran tree and deadwood coppice management is likely to Heath Fritillary nectaring on Bramble habitat required by many moths be poor and these sites may have and other wildlife. Allowing some developed fauna and flora associated Choosing simple coppice or short-lived trees such as and with mature woodland that will be coppice with standards? Unless willow to become standards can damaged by cutting. planting a new coppice, this decision produce deadwood habitat quickly in will probably depend upon the comparison to species such as oak. Coppicing is almost certainly history of the site. Generally when worthwhile on sites that have a recent managing for Lepidoptera the use Rotation length: Historically, the history of this management and that of a long rotation coppice with length of the coppice cycle and still have a good density of stools. standards is a good choice as it the size of coupes varied between Sites that have been extensively creates a diversity of habitats. different areas, between woods and cleared within the last 50 years also over time. For conservation are also likely to respond well to Number and rotation of standards: purposes, factors other than the size coppicing. The value of standards in coppice of the mature coppice stems usually can be enhanced by establishing a take priority. Nevertheless, if there Coppicing may not be the best mixture of tree species and ages. If, is a commercial product which can policy in very small woods. The area however, the aim is to create sunny make the conservation management of potential coppice must be large coupes with a varied ground flora more sustainable, then the desired enough to support the coupe sizes, for breeding butterflies and moths, crop size must be taken into account the rotation/s and also the layout then the number of standards when deciding both rotation lengths of age classes needed to meet the must be strictly limited. One of the and coupe size. management aims. For example commonest reasons why coppicing cutting a coupe size of at least 0.5ha fails to supply good butterfly habitat The value of mature coppice stages per year under a rotation of 7 or 8 is that too many standards are for moths must not be forgotten in years will require an overall coppice present producing too much shade. the effort to produce open sunny area of at least 4ha. This can be a Excessive shade will also reduce areas. If a site is large enough, problem when managing for some coppice growth and damage future then a solution can be to operate of the fritillary butterflies. Although coppice viability. It is most important predominantly short rotations of less the butterflies require a continuous that the total canopy cover of than 10 to 15 years but retain a series supply of newly cut areas, the standards is no more than about 10 of coupes that are cut on rotation of coppice must still go through a to 15% of the coupe area. 20 years or more. Sufficient young long enough rotation to shade out coppice can then be produced while vegetation as explained above. This The appropriate number of standards also ensuring that a certain amount problem can be overcome by cutting will depend on their canopy cover, of old coppice is always present. every other year, or by coordinating as each tree species produces a management across a group of different canopy area when mature. Ideally at least one coupe should be adjacent woods as one unit. It should also be noted that the cut every year, but if labour is short shade cast by trees in leaf is often or if the wood is too small to support Coppice structure and layout underestimated because most a full rotation, then a compromise is to cut a larger area every two or three Where coppicing is appropriate, management is carried out in the years. the following factors must be winter, and that young specimens considered to make it successful and will quickly expand their canopy size sustainable: once in an open situation. Generally

15 large standards per hectare should be the absolute maximum when managing for butterflies.

Woodland management for butterflies and moths | 19 Advantages and disadvantages of different rotations: Avoid creating narrow coupes, unless it is part of management along a ride edge. These are likely to have Short rotations the same problems with shading, encroachment and browsing damage Advantages Can maintain the supply of young growth areas, as small coupes. Aspect will affect often better for butterflies the amount of sunlight falling on Disadvantages Labour-intensive in large woods the coupe, and north or east-facing In some cases may be too short for the underwood coupes may need to be larger to to be of commercial value allow light to penetrate. May not supply habitat for species that require On a practical level, it is a good idea older coppice to mark out the corners of every Growth may not get dense enough to shade out coupe with permanent posts or by the ground flora pollarding trees, and to produce a map of the proposed coupe rotation. Medium to long rotations The length of most coppice rotations Advantages Longer rotations create a wider range of habitats means that the people doing the than short, often better for moths cutting will probably change from one cycle to the next, so markers and a Can make coppicing economically viable in map will be needed to guide future large woods management. Disadvantages In some cases may be too long for the underwood to be of commercial value Common failures Can be difficult to maintain the supply of young and problems growth areas • Initiating management without defining the aims and objectives Size of coupe: For the coppice- year, although a larger area is needed • Underestimating the resources dependent Lepidoptera, the advice for the habitat to be rotated through needed. Work is abandoned during is not to cut less than 0.5ha per year the full coppice cycle. the rotation because of labour per site. The main factor is to achieve shortages the minimum area of breeding habitat Layout: When selecting the coupe • Short-term planning. Rotational required to support a population areas, any special, legally protected coppice will not deliver of the target species. This will be or locally unique features and habitats conservation unless a long-term provided by the most recently cut that might be damaged or removed commitment is made to continue coupe together with a number of the by coppicing should be retained. For the management for many years example, stands of mature Aspen previously cut coupes depending • Isolation. Habitat created is too are uncommon and have high value on vegetation development. The distant for the target species to find for specialist invertebrate species, appropriate flora needed for a and colonise before the habitat is including moths. Retain any special species such as Pearl-bordered lost to succession Fritillary is very likely to exist only or uncommon trees, veteran trees or • Sites or coupes are too small to in small patches within any single old pollard specimens. provide a sufficient area of breeding coppice coupe and this must be Coupes are best situated next to habitat. Suitable ground flora fails taken into account. flower-rich sunny rides. These will to develop on otherwise suitable The total area cut each year can supply nectar, act as a seed reservoir, coupes be divided into as many coupes as provide flight paths between required, but single coupes of less coppice areas and also allow access than 0.5ha are usually too small to when cutting. For butterflies, it is best if coupes can be cut sequentially supply suitable unshaded, early Mark Parsons growth habitat. They are generally with areas cut in subsequent years shaded by adjacent woodland being no more than 300m away. This and are quickly encroached by the is essential for many of the butterfly established vegetation at the coupe species dependent on early stage edges. Small coupes are often heavily coppice as they are often poor at browsed by deer and rabbit, as these finding and colonising new areas. animals prefer not to venture far from Cutting slightly irregular coupe cover so avoid the open spaces of boundaries will increase the edge large cut areas. habitat and may be beneficial in Surprisingly, if the habitat is suitable adding another variation in structure then many butterfly species can have to the woodland landscape. For the viable populations within only 1 to same reason areas or small strips The Common Fan-foot is often associated with rotational coppice management, 2ha of coppice habitat within any one of uncut woodland can be retained between coupes, but avoid shading although it probably breeds on oak standards rather than the underwood the coppice. species

20 | Woodland management for butterflies and moths • Leaving too much shade. Typically too many standards are retained, or

coupes are too small Dan Hoare • Re-cutting before allowing the coppice to go through the full cycle. Re-coppicing part way through the cycle is sometimes attempted as part of emergency conservation measures for particularly threatened early succession species. This rarely has the desired result of restoring the early successional ground flora and tends to result in a uniform grassy sward of little value to the target species. The closed canopy stage is essential • Excessive deer or rabbit browsing. High levels will damage or prevent regrowth. Damage may be reduced by cutting large coupes, as deer and rabbits prefer to be close to cover. It may be necessary to protect individual stools or fence entire coupes through the stage of young growth (see “Managing deer” for a more detailed discussion) • Damaging the site during cutting and clearing. Use as few bonfire sites as possible. Locate them carefully where they will not A coppiced Sweet Chestnut stool showing vigorous regrowth two years after cutting damage stools or other habitats such as flower-rich grassland. Re-using previous burn sites is in most practical guides to coppicing. New coppice woodland recommended Low intervention: Neglected It is possible to create new coppice • Failure to monitor results and coppice could also be left to by planting or direct sowing, but incorporate successes or failures eventually take on the characteristics unless the area has been wooded into future management of a natural forest. In this case, it in the very recent past then creating might be worth thinning some of the suitable flora required by many Restoring neglected the coppice by singling, that is by of the woodland Lepidoptera may be removing all but the best stem on difficult. Many species of butterflies (over-grown) coppice each stool. This is generally used and moths will also have problems The choice of management in to try and produce good quality colonising a new coppice if it is neglected coppice (sometimes timber but in the context of habitat for any distance from their existing called stored coppice) is either Lepidoptera it is likely to speed up populations. to re-coppice, to manage as low the creation of large mature trees that If new coppice woodlands are intervention (leave to develop to will provide additional structure and to be created specifically for high forest) or to clearfell and then habitat. re-establish a new coppice or a new conservation then they are best broadleaved woodland. Clearfell and replant: Another sited next to existing semi-natural option is to clearfell the overgrown woods, otherwise it will be difficult Re-coppice: The choice to re- coppice and replant with native trees to establish the suitable woodland coppice will depend on the time at fairly broad spacing, allowing the flora and fauna required by the rarer since the last cut, the condition and underwood to regrow as shrub layer. Lepidoptera. density of the stools. Many sites with The site can then be managed as The creation of new, short rotation overgrown coppice have shown a either coppice with standards or left simple coppice for biofuels is now surprisingly good response to re- to develop as mature woodland. In being actively promoted (mainly cutting, although stool density may general, this option seems to carry willow or poplar species). It is not have to be increased by planting few benefits for conservation over yet clear if this process will hold or by encouraging vegetative re-cutting. It is expensive in cost any benefits for the conservation of propagation. Techniques for creating and labour and importantly unless Lepidoptera. new stools from the old stumps such small areas are clearfelled on a long as layering and stooling, as well as rotation the risk of damage to the re-spacing the stools, can be found existing flora and fauna is high.

Woodland management for butterflies and moths | 21 Rides A ride is any linear track or opening within the wood and includes the whole area between the mature trees on either side. That is the surface of the ride itself, any ditches and also the vegetation on the ride verges (grassland, scrub or coppice regrowth).

Most woods have at least some However, this limited amount of rides for access, shooting activities coppicing is usually not adequate on and increasingly for leisure activities its own to maintain the very specialist Dan Hoare such as walking, horse-riding and early-stage species such as the Heath cycling. In commercial forestry, rides Fritillary. do serve a purpose as fire breaks but are primarily to give access for Ride verges may have associated forestry operations, including timber ditches and these give not only extraction. As forestry machinery additional structural diversity, but also becomes larger, some of these can be a source of wetland or damp- rides have been surfaced to create loving plant species. The ditch banks woodland roads. are often particularly warm, sunny habitats. Why are rides important for Lepidoptera? Management of rides For butterflies and moths, the four In many modern woodlands key factors are the: (particularly in conifer plantations), Herb-rich vegetation in ride edges open areas are largely confined to provides nectar, roosting sites and larval • amount of shade foodplants rides and glades and these have • structure of the vegetation become a refuge for the butterflies than those orientated north to south. and moths that need open sunny • species composition of the ground- As a rough guide, ride width must conditions. Some of these species layer vegetation be 1.5 to two times the height of the are woodland or wood edge • species composition of the ride surrounding trees to provide good specialists, but many will also be edge trees and shrubs unshaded butterfly habitat (width is found in the wider countryside. Rides measured from the base of the crop also usually provide the best way of Although open sunny rides with less trees on either side). There can be connecting different habitats within than about 20% direct shade are scrub growth within this width as this woodlands, and prevent species required by many butterfly species, tends to have only a slight shading having to move through unfavourable other Lepidoptera (including some effect. conditions to reach the next habitat butterflies) prefer partially or even patch. Providing these areas can heavily shaded areas. Thus a variety Along some ride networks there may be suitably managed, their value for of shade conditions and similarly a be a constant mix of different tree Lepidoptera can be enormous. range of ride widths and orientations heights with many patches of low will need to be produced and growth and in such cases the width Rides potentially provide a large maintained. Even a single species and orientation will be less important. diversity in structure and vegetation will require a range of rides to meet within a small zone. They combine Practical methods for achieving the its requirements under different sheltered grassland with typical wood required ride structure are given conditions. For example, the Wood edge habitat and this can provide below. First the rides might need White tends to use areas with less diverse areas of nectaring and to be opened up or even created, than 20% shade, but one study breeding. On many sites they also then consideration must be given to suggests that it not only moves contain relics of habitat types that are ongoing management. between rides of different orientations now scarce in the wider countryside during the day following the sun, (for example; unimproved grassland, Widening existing rides but also on windy days it chooses wetland habitat, heathland) and so sheltered but slightly shady rides, Often the first priority in a wood is to can support the associated butterflies over the open sunny rides. increase ride width to reduce shade and moths. levels. However, this should target The amount of shade on a ride will be areas with simple structure and dense When rides are managed with a determined by its width, its orientation crops close to the ride, to avoid scrub-zone cut as coppice, then and the surrounding tree height. East damaging valuable semi-natural some of the species associated with to west orientated rides will receive woodland and the species using the coppice rotation will use this habitat. more sun during summer months current ride edges.

22 | Woodland management for butterflies and moths If left to themselves, rides will quickly revert to high forest. In order to create and maintain diversity active management will be required. Several cutting regimes have been developed to specifically meet the needs of butterflies and moths: -

Alan Reid / Forestry Commission Two zone system: This is similar to the rideside management used in commercial forestry. It is low cost, low maintenance, but also comparatively low in structural diversity. It does not produce the good scrubby margin needed by many moth species, although under some rotations, patchy scrub is likely to develop. It can provide good open grassland habitat for butterflies. Ride widening for Wood Whites at Bury Ditches, The central ride zone is cut once or twice a year (unless it is surfaced) to In conifer plantations, often the only Creating new rides maintain it as an access route. remaining deciduous trees and In semi-natural woodland with no shrubs are located in a thin margin pre-existing rides it is suggested A zone (2 to 5m wide on each side) along the crop edge, and this will that a most careful examination of either side of the central zone is cut be removed by widening. Potential the site is required before creating on 4 to 7 year rotation, but this is damage can be reduced if only ride habitat. If the site is an actively carried out in sections so that only a short areas are done at a time and managed (or recently managed) portion is cut each year. Importantly, substantial lengths of the original pasture woodland or if it has a rich the whole ride, or even all of one ride edge habitat are left between or uncommon ground flora, then side of a ride should not be cut in the widened sections. ride creation may not be suitable. same year. Retain specimens or groups of As always, consider the aim of the management and examine any Further habitat variety can be created locally uncommon trees (uncommon by simply introducing two different in terms of either species or age). A conflicts that the new management might produce. cutting rotations, cut some margins patch of Aspen for example, may be on a short rotation (4 years) and the only breeding area on the site Try to create wide, gently curving some on a long rotation (7 years). for several species of moth. Sallows rides with varying orientations along provide an important nectar source their length. Plan the routes of new Three zone system with coppice: for many insects in spring and may rides carefully to avoid conflict with This is a more complex regime that provide breeding sites for Purple existing features. Any special, legally can provide an excellent mosaic of Emperor and many moths, and protected or locally unique features habitat for both butterflies and moths, should be retained where possible. and habitats must be protected. including habitat for some of the canopy-living species. An often-stated objection to ride Retain any special or uncommon widening is the wind tunnel effect trees, veteran trees or old pollard The central ride zone is cut once or - the channelling of wind between specimens. twice a year (unless it is surfaced) to stands of tall trees. This can have After clearing, the stumps in the maintain it as an access route. an impact on a timber crop and may centre which will become the grass/ reduce the sheltered conditions A zone of tall grassland vegetation is herb zones can be removed, ground favoured by many Lepidoptera. created either side of the central zone down or treated with herbicide. Ride layouts with curves rather than (2 to 5m on each side). This zone Stumps along the margin should not straight lines will not suffer from this is cut, in sections, on a 3 to 4 year be treated but allowed to re-grow and effect, but many woods have straight rotation with opposite sides being then managed as coppice. line, grid system rides. Wind damage cut in different years. As with the two

can also occur after ride widening, as zone system, it is important that the wind-hardened trees on the edge are Creating and maintaining whole, or even one side of a ride is removed, exposing weaker trees that verge habitat not cut in the same year. are then damaged or blown down. These issues can be minimised by The best ride edges graduate from A mixed species scrub zone (5 widening using scalloped edges so tall trees, to a variety of shrubs, to tall to 10m on each side) is created that the ride is not uniformly wide and herb-layer vegetation then grassland between the tall grassland zone it remains sheltered. An alternative flora. It will also include some bare and the woodland. This is managed is to leave “squeeze-points” along ground and ideally there will be rather like coppice to provide mixed a ride, retaining occasional mature canopy gaps and height variation ages of woodland succession. A trees which break up the exposed within the scrub zone. rotation of 8 to 20 years is suggested profile. and as with the adjacent zone, it is

Woodland management for butterflies and moths | 23 cut piecemeal. A three zone ride edge As with coppice, the length of rotation Dan Hoare must be balanced between providing sufficient open newly-cut woodland habitat and allowing the regrowth to shade out the ground vegetation so that sparse vegetation/bare ground conditions are produced after each cut. The ideal cutting rotation will depend on the growth and density of the scrub. If scrub density or species variety is poor then the zone can be planted, or temporary fencing can be used for protection while tree seedlings establish naturally.

Each section can be 50-100m in length dependent on the size of the woodland, and both section length The three zones of a south-facing ride edge in a woodland. The central ride zone (at right in this image), cut once a year, is grassy but holds plenty of herbs and and cutting rotations can be varied bare ground, supporting Grizzled Skipper. The tall grassland zone, cut every 3 years, across a woodland. has a mixture of bracken, herbs and grasses, and at this site supports Pearl-bordered Fritillary. The mixed scrub zone at the back, cut as coppice, is predominantly birch and Further enhancements to provides breeding sites for Argent & Sable. basic ride management The following can be used along or to produce patches of early rides and forest roads in combination Including rideside native trees: successional vegetation. Varying with the two and three zone cutting Native broadleaved trees can be a sizes of patches could be selected systems described above, or as rare habitat in coniferous plantations. on rotation and mechanically scraped stand-alone management: Even within mixed or deciduous free of all vegetation, making sure woodland older trees may be that a degree of soil disturbance also Scalloped edges: A series of uncommon. Many Lepidoptera seem occurs. Allowing scuffing or scraping rideside bays, often called “scallops” to require mature trees that are by ride-cutting machinery can also are created along the ride verge/ slightly separate from woodland and create bare ground habitat on a tree boundary. These not only widen that have ground-vegetation around small scale. Small scrapes along the the ride to reduce shading but also their trunks rather than underwood. top of roadside banks are effective provide shelter and increase the at establishing the low growing length of edge habitat. A few, mixed species deciduous foodplants of the Grizzled Skipper, standard trees can be planted or left and more extensive scarification and A suitable size, as a very rough guide, to grow in the ride margins (making rotovation techniques have been is approximately 30 to 50m long by sure the canopy cover along a used to improve floral diversity in the 10 to 20m deep. If the scallops are rideside or within a scallop is less Brecks of and Suffolk. cut opposite each other then they than 10 to 15%).These trees can provide a maximum open area, be in small groups or as scattered The timing of verge cutting: The essentially widening the ride. They individuals. time of year and frequency of cutting can also be staggered, alternatively plays a key role in determining the or randomly along a ride. Bare ground areas: Many composition and structure of ride Lepidoptera require some bare vegetation, but this is also affected They can be managed to produce ground patches to provide the by soil type so the effect will vary one of two habitats, scrub or suitable hot-spot microhabitat around between sites. Cutting at any time of grassland, the difference is in the their foodplant or for basking. It also year, whatever method is used to cut frequency of cutting. A scrub scallop provides structural diversity as well as and remove material, is very likely is managed on a coppice-style floral diversity by encouraging seed to affect or destroy some life stages. rotation in the same way as a scrub germination. Several larval foodplants It is therefore important to only cut zone in the three zone system. A for scarce Lepidoptera are associated part of the verge in any one year and grassland scallop is managed on the with regular ground disturbance, such to monitor the impact on any target same system as the tall grassland as Wood Spurge which supports species. If the only breeding area zone in the three zone system. the Drab Looper moth. Activities or for a species is in the portion due to managements that regularly result Scallops can be used as a be cut that year, consider whether in areas of bare ground can be most management in its own right or cutting can be delayed to allow useful, as long as they only affect a incorporated to add extra diversity colonisation of nearby habitat. part of the habitat in any given year. within a three zone system (see case study “Chiddingfold Forest”). It can sometimes be useful to create areas of bare ground under controlled conditions, to perhaps encourage seed germination

24 | Woodland management for butterflies and moths General recommendations are as Combining conservation will regularly remove all breeding follows: habitat along the road edge. Timing management with forestry forestry operations to the needs Cutting grassland vegetation: operations of Lepidoptera is also not usually Cutting during the autumn is usually Forest roads are maintained to allow possible, although often some recommended, to avoid damage good access for forestry machinery compromise can be reached. It is while insects are most active in so they are usually wide and kept therefore vital that similar habitat summer, and to allow plants to set clear of overhanging canopy. This is available within a more secure seed. In the past, however, most also means that they can have high location. If there are no refuge rides would have been maintained potential as Lepidoptera habitat. habitats nearby to provide continuity, either by grazing or by cutting for However, a forest road with its then local extinction of species is hay in July or August. On particularly verge is a working environment and highly probable. fertile sites with strong ground-flora conservation management needs growth then some cutting during to take this into account. If forest Features such as turning circles July or August could be considered, roads and associated features are and loading bays can, like the road as there is evidence that this not maintained efficiently, then their edge habitat described above, encourages a broader range of flora. maintenance incurs extra cost. provide good breeding habitat for Alternatively, some cutting during the species requiring sparse vegetation spring or very early summer would Many are managed on a similar and bare ground, but this habitat remove early grass growth yet still cutting regime to the two zone will be damaged or destroyed at allow many species to flower later. system. The alternative three zone intervals. This is also the case for system can result in vegetation most roadside ditches, created to Spring or summer cutting may be encroaching on the road surface take the run-off from the surfaced beneficial in the long-term but will as might occur on a 3 or 4 year roads. These ditches, their banks and temporarily remove some breeding rotational cut. In this case a slightly associated vegetation can provide habitats and nectar sources. This modified three zones can be used habitat for species such as Wood issue can be limited by only cutting a whereby the central zone is moved to White, but they will be regularly re- small proportion of the site each year. a narrow strip (1 to 2m on each side) dug, with spoil removed to the ditch Whatever cutting period is decided, it along either side of the road surface. banks or verge edge. is worth building a degree of variation This strip can then be maintained into the management because by annual or more frequent cutting. Forestry activities can have an impact different plant species will respond For ease of mowing, this strip can on verge habitats, for example where to different regimes. Deciding the additionally be cut whenever the vehicles use the verge during timber timing, frequency and rotation of adjacent zone of tall grassland flora extraction or where wood is stacked cutting, together with an aim of what is cut. on the ride edge. Minimise impacts structure you are trying to create, is by: more important than defining precise Essential forestry operations may cutting heights. have significant adverse impacts on • Ensuring that the entire ride Lepidoptera breeding areas along network is not managed uniformly It is best to remove the cut material rides. The road/verge edge tends in any one year if at all possible (some forage to receive regular disturbance as • Providing refuge breeding areas for harvesters can cut and gather the all operational forest roads have the species that may be affected vegetation in one pass). Cuttings or a periodic maintenance (grading) • Monitoring breeding areas used mulch can smother the remaining during which this zone is scraped by susceptible species so that vegetation and increase nutrient back to bare ground. This regular potential problems can be avoided build-up which will reduce floral ground disturbance often provides or mitigated richness. Cuttings can be raked into good breeding habitat for species • Protecting sensitive areas with heaps, but these must be carefully such as Grizzled and Dingy Skipper temporary fencing during forestry sited to minimise the effect on the but road grading cannot usually work rideside vegetation. Blowing or be carried out piecemeal and raking the material into the adjacent crop can be considered in coniferous woodland, but within deciduous

woodland (or where there is a Dan Hoare managed rideside scrub zone) this would cause damage to the ground flora under the canopy.

Cutting scrub vegetation: Ride edge scrub zones should be treated like coppice and are best cut during the winter. The section on coppice includes advice on the disposal and burning of cut material.

A wide sunny ride provides ideal breeding conditions for Pearl-bordered Fritillaries at a Forestry Commission site in Sussex

Woodland management for butterflies and moths | 25 Glades Woodland glades are permanent or semi-permanent areas that contain few or no trees but are surrounded by woodland. They are usually non-linear, in contrast to rides and wayleaves, and are distinct from young plantations or clearings containing young woodland.

Why are glades important for suitable ground flora and also the Lepidoptera? movement of Lepidoptera into these new habitats. Dan Hoare Glades provide a larger area of open habitat than is found in rides, which Management of glades may be important for the colony Glades can be treated in the same structure of some butterflies. Several way as rides to provide a range species can reach high population of vegetation types, from open densities in glades but will only grassland through to scrub. A scatter ever occur in rides in low numbers. of tall trees can also add diversity, but The Marsh Fritillary, for example, restrict canopy cover to less than 10% rarely breeds on rides even when its of the glade area. foodplant is abundant, but will use damp grassy woodland glades of at The specific management will depend least 1ha, and does best when there on the permanency of the glade. are a series of such glades. A glade can be a temporary open space, that is cut and then allowed Creation of glades to re-grow, or a more permanent Glades can be created either linked opening where regrowth is controlled to the ride complex, or separate and or suppressed. Scrub cut on rotation within a permanent glade provides a varied age structure and located within the mature or semi- sheltered conditions mature woodland. Overall the same If the glade is to be managed as a temporary open space then the principles of width, shading and crop also as small patches scattered habitat produced is similar to that height apply as discussed for rides, across the glade. This can be created under coppice. Open bare also the same concerns for cutting enhanced using irregular, piecemeal ground conditions will dominate at new glades within natural or semi- cutting of the patches of scrub on first, regrowth then produces scrub natural woodland. Glades linked to anything between an 8 to 20 year and finally mature woodland. Such ride systems are better connected to rotation, depending on the rate of a light to shade cycle will maintain the wider habitat network, whereas growth at the site. glades within mature woodland may the typical woodland flora and will be more isolated and difficult for prevent the vegetation becoming On a box junction, each corner some species to locate. grass dominated. section could receive a different cutting regime. Some cut every 1 Management of true permanent open As part of the ride complex: With to 4 years to create grass and herb space in woodland has much in minimal tree removal a good sized dominated vegetation. Others cut common with unimproved grassland. glade can be created by simply on a rotation longer than 4 years to Repeated cutting, mowing or grazing enlarging the intersection of two allow the development of scrub. If will be needed to prevent scrub rides to produce a “box junction” the rotation is long enough to allow growth and without a period under or “corner glade”. Usually all four the scrub to shade out the ground dense canopy shade the vegetation corners of the junction are removed, vegetation, then after re-cutting, usually becomes grass dominated. but sometimes only two and the valuable early successional woodland different segments to the glade do If large enough, then a mixture of habitat can be created for species like not have to be the same size. permanent and temporary open Pearl-bordered Fritillary. space can be created across the Separate from the ride complex: On some sites there may also be glade. Such a mosaic habitat It can involve a considerable felling an option of using domestic grazing structure is highly attractive to many of timber to create a suitably sized animals within enclosures. Grazing Lepidoptera and mimics that found glade. Generally glades should be creates a very different type of along a natural wood edge. The at least 0.25ha and preferably 0.5 to vegetation from cutting, so adding grassland areas could be cut on short 2ha in size. Grouping glades within diversity. Grazing is more practical in rotations (1 to 4 years) and some the same area and providing some woodland glades than rides and was scrub could be allowed to develop connectivity with an existing open often the traditional management. not only along the wood edge, but feature will aid the establishment of The aim would be to create diverse

26 | Woodland management for butterflies and moths Susan Clarke

A large permanent glade among planted conifers vegetation, while preventing or To save expense, often only the south-facing edges and rotational reducing the growth of scrub and tallest scrub (that which will breach cutting of sections rather than trees. Rotational grazing can give a clearance thresholds) is cut at any uniform management. An alternative high level of control because stock one time. This can create a mosaic is to cut and treat stumps to create can be moved periodically around a of small scrub of various ages more permanent open areas, single large glade or from glade to together with open, cleared areas. although this will require similar glade. Grazing is discussed in more It is often the only habitat of its type management to a ride or glade to detail in the following pages. within the woodland and can be maintain floral diversity. excellent habitat for Lepidoptera. In Wayleaves Scotland, for example, wayleaves are Wayleaves are the areas beneath extremely important as habitat for power lines, and within woodlands the Chequered Skipper and Pearl- these areas are regularly cut to keep bordered Fritillary in otherwise dense scrub/tree growth away from the plantations or regenerating native Rob Petley-Jones cables. This effectively means that woodland. wayleaves within woodlands are The management of wayleaves linear glades managed on a short is often outside the control of coppice rotation, which can provide woodland managers, but if scarce important wildlife habitat and improve butterflies or moths are known to connectivity between other open be using the site it is worth passing areas. Widths vary, but most are on specific recommendations to the 10 to 20m wide. They are typically power company. Where pipelines managed by the power company are buried beneath the surface the or a contractor, whose objective is area above may also be kept clear to keep any vegetation a minimum to allow access and prevent root distance away from cables and other damage, providing very similar equipment. This means that rotation The moth funebris breeds on habitat opportunities. Best practice Goldenrod in glades, rides and wayleaves lengths are not set, but depend on wayleave management is similar to the height of the cables and the ride management and includes the growth rate of the scrub. creation of scalloped edges along

Woodland management for butterflies and moths | 27 Open Bracken habitats in woodland Bracken dominated areas are a key habitat for four species of violet-feeding fritillaries including two of the UK’s most threatened butterflies, the High Brown and the Pearl-bordered Fritillary.

less than a third grass cover and at the other end, a grassy Bracken mosaic with a light cover of litter and Susan Clarke approximately two thirds grass. Grazing and trampling by cattle and ponies, especially in winter and early spring, is an excellent way of producing the required variation in Bracken structure, but this is not often an option within woodlands. For most woodland rides, a standard 3 to 4 year rotation of verge cutting in autumn/winter combined with longer cutting rotations on the scrub- layer will provide adequate habitat where Bracken is present. If glades are to be managed to provide good Bracken habitat then a slightly longer cutting rotation of 3 to 4 years will be required on the grassy areas, rather than the suggested 1 to 4 year rotation used to produce grassland habitat. Where High Brown Fritillary or Pearl- bordered Fritillary are present, more Violets growing amid light bracken litter are essential for several of the rarer fritillaries specialist management may be needed to maintain the necessary Violet-rich Bracken habitats are and indeed seems to be critical in the violet density and depth of Bracken typically found in grassland areas survival of some fritillary species on litter. Cutting Bracken areas during outside woodland, they can also many woodland sites. late May or early June on a 3 to 10 occur in rides, glades, young year rotation has been found to be Each of the violet-feeding fritillary plantations or woodland edges. This useful for these species, but this species has a very distinct is an often overlooked habitat, but should only be carried out on patches microhabitat within the Bracken, these areas can be highly important where there is currently no potential some requiring a strong layer of for both these butterflies and for other breeding habitat. dead litter and avoiding any grassy wildlife. patches, others needing moist If the Bracken structure becomes too In early summer, the developing conditions with violets growing in uniform under the usual cutting then green fronds of Bracken act like a mosaic of Bracken and grass. there are several options aimed at a low growing tree canopy and It is certainly possible to meet the creating variation: suppress the ground layer vegetation, requirements of all four fritillary Cutting pathways of 0.5m to 1m particularly coarse grasses, providing species at a single site by providing a width through Bracken in June. This ideal conditions for many shade- varied structure. encourages violet growth along path tolerant woodland plants such as The main objective in managing edges and is particularly suitable for violets. In the autumn, the Bracken Bracken is to prevent it becoming High Brown Fritillary. dies, but because the fronds and too dominant, by reducing its vigour stems take some years to decay, a and density, without eradicating it. Removing Bracken litter by layer of litter and standing trash is This maintains a mosaic of herb- raking in autumn or winter, even formed (litter is the semi-degraded, rich grassland interspersed with on a small scale, can encourage dead fragments and standing growing Bracken and dead litter. violet growth and maintain litter in trash refers to intact dead Bracken, Aim to create and maintain a varied suitable conditions. This is a useful either standing or fallen). This dead Bracken structure that at one end of option between the rows of young Bracken can provide an ideal warm the spectrum has up to approximately plantations to keep them suitable for microclimate and shelter for insects 15cm depth of Bracken litter and longer.

28 | Woodland management for butterflies and moths Bracken bruising can be useful within dense Bracken where violets to reduce the density of growing have become scarce. Only spray Bracken and is often used on rough part of the Bracken area, avoiding Caution terrain where cutting is difficult. currently good breeding habitat. Any management of Bracken Rollers with bruising bars are used to Target the denser areas and avoid between March and August must be damage, but not to sever the stems, spraying near water courses. Within carried out with great care and only often pulled behind a quad bike or young plantations, occasional spot- within small areas at any one time, tractor. This is best carried out when spraying around the trees can not because Bracken is well used at this fronds are fully open between June only benefit the tree growth, but can time of year by ground-nesting birds and August, in patches or strips so create variable structure and bare and reptiles (particularly adders). It as to vary the Bracken mosaic across ground patches for violet germination. is important to only cut, roll or bruise a site. Bracken whipping is similar to Bracken when conditions are warm bruising but is done by hand using a Although burning is a useful enough for reptiles to move out of the stick or light aluminium rod. management technique for way. For this reason, avoid managing Bracken in open habitats it is Bracken early or late in the day. Spraying patches or strips of not a management option within Bracken with a selective herbicide woodlands. (such as Asulox) can be beneficial Woodland edges Developing boundary habitat as a buffer strip along the woodland edge can greatly increase the potential habitat for Lepidoptera and will also protect the woodland from the effects of intensive agriculture.

Importantly, this can also integrate Grassland and tall-herb buffer strip: woodland habitat within the Establish a grassy strip either by surrounding landscape, rather than sowing (native grass or wild flower Dan Hoare leaving it as an isolated feature. Buffer mixes) or natural regeneration along strips can even be used to connect the wood edge. Do not fertilise or use nearby woods separated by intensive manure and avoid using herbicide farming. The wider the buffer strip (except to spot-treat specific injurious the greater its impact, but they are or alien weeds). Cut buffer strips on a usually between 2 and 15m. Strips 2 or 3 year rotation to control woody wider than 15m would provide far growth (see under Ride Cutting for greater benefits. timing).

Three basic structures of buffer strips Scrub and grassland mosaic buffer are suitable for Lepidoptera. Agri- strip: This type of buffer strip will environment schemes can provide need to be more than 5m in width funding for similar buffer strips if it is to provide a suitable habitat Complex structure at the woodland edge through a variety of options: structure. It is established as for the provides habitat opportunities for a range grassland and tall-herb buffer strip of wildlife • Grassland and tall-herb buffer strip above, but then left uncut for a period • Scrub and grassland mosaic buffer to allow scrub to develop. The scrub Scrub buffer strip: This type of strip can then be cut to produce a 50:50 buffer strip will need to be more than 5m in width if it is to provide a • Scrub buffer strip mix of scrub and grassland, within irregular patches along the strip. suitable habitat structure. It is left to The choice of basic structure and develop scrub and then managed of subsequent management may Cut the scrub piecemeal, on anything like coppice, cutting during autumn be influenced by the presence of between a 4 and 20 year rotation or winter on a rotation of 8 to 20 woodland Lepidoptera of concern depending on the rate of scrub years depending on the rate of scrub either within the wood itself or within growth and the habitat structure growth and the habitat structure the landscape area. For example, if required. Cut the grassland patches required. the wood is in an area supporting on a 2 or 3 year rotation (see under Black Hairstreak, then the scrub Ride Cutting for timing). If possible, In some locations, a narrow strip option may be the preferred choice. during the rotation allow some scrub of regularly cut grassland may be For Duke of Burgundy, the choice patches to develop on the grassland needed alongside the scrub zone for would be for the scrub and grassland and balance this by reverting some ease of access. mosaic. cut scrub areas back to grassland.

Woodland management for butterflies and moths | 29 Grazed woodland: pasture woodland and parkland management Grazing is beneficial in maintaining specific woodland types such as wood pasture, particularly in the upland/Atlantic oakwoods in the north and west of Britain.

the livestock become less selective in their feeding. Heavy grazing will keep the vegetation short, suppress many larval foodplants, and so limit the potential to support Lepidoptera.

Grazing animals will consume seedling trees, and as with the ground flora, the more palatable species will be removed at low Mark Monk-Terry ©Sussex Wildlife Trust stocking densities. Where grazing levels are intense only the most inedible tree and shrub species will survive. Over time, this has implications for the species composition of the wood, and for its diversity. Elms and limes are usually absent from woodlands with a long history of grazing. Thorny species are avoided and will develop thickets beneath gaps in the canopy or on the woodland edge. However, the hardier breeds of livestock adopt more browse in their diet and some, particularly old pony breeds are even Cattle grazing a Sussex Wildlife Trust site in the Western Weald adept at taking Holly and gorse.

It can also be used within woodland from hill land to seek shelter and It is important to note that wild deer to produce an open structure, or at protected forage. This contributes to grazing is very different to domestic low intensity to maintain a healthy the development of closed canopy livestock grazing, as deer are more shrub layer. However, without woodland with a sparse shrub selective, and their impacts are more control, it is easy for grazing and layer, which is important for several unpredictable and difficult to control. browsing pressure to cause damage moths associated with the lichens to the woodland structure and its and rich ground flora. The livestock regenerative capacity. suppress sapling growth, often prevent regeneration and also the David Green For woodlands with a historical development of a dense shrub layer tradition of grazing the aims should and mid-strata. Elsewhere woodland be: grazing has largely died out, other than on some wooded commons and • To restore grazing where this no wood pastures. longer occurs • To link appropriate grazing animals Relatively light grazing pressure will and grazing levels with conservation maintain the ground layer, and will objectives enhance variations in its structure. • Give support to commoners and Livestock preferentially take the other graziers most palatable species and the degree to which the ground layer is altered or enhanced will depend Grazing of the ground layer of on the relative proportions of the woodlands is traditional in many parts palatable to non-palatable plants. of Britain, particularly western oak Higher livestock densities cause woods, where sheep, and to a lesser more intensive grazing, which will Distinct browse lines where low vegetation extent cattle, are still given access compromise structural diversity as has been removed can indicate grazing is too intense

30 | Woodland management for butterflies and moths Impacts of different livestock at low stocking levels

Cattle are unselective grazers, random, although concentrations Goats will eat virtually anything particularly more traditional breeds develop where night gatherings and they browse more than other which will also browse. They tend occur. Some older breeds readily livestock, which means they can to leave a tussocky structure across browse on woody growth. cause damage to saplings and a wide area. They dung randomly, shrubs even in low numbers. which is then avoided when grazing, Ponies are selective and graze increasing the variation in ground palatable vegetation tightly. Local Pigs mainly root in the soil vegetation. alteration of fertility and vegetation surface, eating roots and rhizomes can occur around dung sites. including Bracken, but will also Sheep are selective grazers, and Certain breeds such as New Forest take grasses and stems. Rooting will tend to produce a tight sward and Exmoor, have a high propensity behaviour creates seed beds for in patches by favouring the most for browsing. plants that otherwise are vulnerable palatable species. Dunging is largely to competition, but can suppress sapling development. High forest High forest is a loosely-used term. In Britain, it usually refers to mature woodland which has the appearance of a natural structure. The trees may be of mixed age when a product of natural regeneration, or even-aged as in a plantation.

Single tree selection: Single trees extremes associated with clearfelling. are felled as they reach the height However, it remains unclear whether required. They are replaced by these systems will provide habitat David Green natural regeneration or by planting. suitable for many of our most threatened woodland species, Group selection: A small area is particularly those with a strong felled (maximum about 0.5ha) and requirement for open space. replaced usually by planting. Conservation management Shelterwood: The stand is partially felled, but a scatter of mature trees for high forest is retained, often spaced by leaving Conservation management for approximately 6 to 10m gap between Lepidoptera in high forest should the remaining canopies. Usually the attempt to introduce the features seed from the mature trees is left to covered under glades and rides Well-developed high forest habitats can be regenerate in the canopy gaps, but whilst paying particular attention particularly important for woodland moths sometimes the gaps are planted. to the requirements of species Once either regeneration or the associated with the canopy layer of growth of the planted trees is strong, mature trees. Management should Until recently most high forest was then the remaining mature trees are focus upon: managed by clear-felling, in which felled. a whole stand is felled at once. The • Introducing greater structural open area is then usually replanted or Neither clearfell nor continuous diversity and uneven age of trees allowed to regenerate naturally. cover systems are specifically • Introducing glades and enhancing aimed at delivering conservation for ride features Continuous cover systems Lepidoptera. However, both systems • Improving tree species diversity In recent years various systems of have the potential to provide some continuous cover forestry have been benefits for woodland butterflies • Protecting veteran trees, which may proposed and tested in the UK. and moths if they produce open involve removing competing trees These systems use small-scale felling areas within formerly closed canopy • Restoring hydrology within a stand and allow much of the monocultures, even temporarily. • Retaining and promoting deadwood woodland cover to be retained at all Continuous cover systems could features times, with the intended result being also improve landscape connectivity • Reinstating grazing where a mosaic of age-structures. The most by providing a more varied mosaic appropriate common continuous cover systems of open and closed canopy habitats are: across the woodland rather than the

Woodland management for butterflies and moths | 31 Wet woods and wetland features Many specialised and uncommon moths rely on these features, which have been lost from many woodlands through a combination of management neglect and changes in hydrology.

Although these habitats do not support any UK BAP Priority butterflies or moths they are vital for many other invertebrates. The overall David Green aim should be to restore degraded or destroyed wetland features and to maintain hydrology within woods. Managing wet woods Maintain structural diversity: Wet woodland is often a transient successional stage between open wetland areas and drier woodland. Maintain as diverse a habitat as possible and maintain any transitions with other semi-natural habitats. There should also be a good age structure of trees.

Maintain hydrology: It is crucial that appropriate water levels of wet woodland areas are maintained. A draw down of groundwater levels tends to result in an invasion of Common Nettle and Bramble and Wet woodlands such as this Alder carr provide a range of damp habitats for invertebrates with it the potential loss of the Lepidoptera. If the woodland is Managing specific wet Water-filled ditches. Ditches are of prone to flooding, then ensure the particular value where light penetrates maintenance of the natural flood habitat features to allow herbs or aquatic plants to regime and, if necessary, dam The following features are likely to be grow, and support a range of moths existing drains to restore water levels an integral part of a wet woodland and other invertebrates. if a site is beginning to dry out. site, but also can often be found as more isolated features within other Woodland ponds. Ponds can Maintain open areas and edge woodland types: support many specialised moth habitat: Edge habitat is of great value species. Retain and manage by to insects and so clearings and rides Reed and sedge beds. An important rotation to ensure all successional should be kept open. Rotational habitat for many scarce moths. Water stages (open water to dense marginal coppicing of Alder or sallow can levels need to be high enough to plant cover) are present every year. create temporary glades, but this ensure their continuity and dead plant Also, do not cut all marginal or should not be done at the expense of matter should be allowed to form a bankside vegetation in any one year. stands of mature trees. layer of deep litter. Avoid excessive Always provide both shaded and cutting or tidying and use rotational unshaded pond habitat if possible. Grazing management: Extensive, management. low-level grazing to maintain open areas can be beneficial, but boggy Streams and seepages. Avoid habitats can be fragile and easily channelling or piping. Seepages damaged by trampling. Excessive may appear to be a minor feature, grazing by deer or stock will inhibit but should always be incorporated tree regeneration and may have a into any woodland evaluation and detrimental effect on the ground flora. management plan.

32 | Woodland management for butterflies and moths Deadwood management Deadwood habitats support a number of moths and many other invertebrates.

Dead fallen wood should ideally be very damaging. Trees with top-heavy left where it falls or stacked in piles, limbs should be pruned rather than preferably in shaded locations, removed and any -infected

Susan Clarke although a range of both shaded trees or those with sap runs should and unshaded deadwood should be be retained. Rot-holes should not be encouraged. drained or filled. In areas where there is little deadwood it may be beneficial Pollarding can be a good to increase this by ring barking limbs. management for extending the lifespan of old trees and their associated deadwood features, but some forms of tree surgery such as the unnecessary felling of limbs are Deadwood can support lichens and fungi that in turn support moths and other invertebrates Veteran trees Living veteran trees typically contain a valuable deadwood resource and are also of conservation value in their own right. Some Lepidoptera have a strong association with mature or over-mature trees.

The priority is to conserve all existing Of equal importance is to plan mature and ancient trees and their ahead and ensure that as the older associated deadwood niches. trees die, there will be an adequate Tidiness and over-zealous removal number reaching post maturity to David Greene of deadwood and felling of trees on ensure continuity. A problem at many the grounds of a perceived threat to sites, including such key areas as public safety are the greatest threats the New Forest, is gaps in the age to the survival of species associated structure of trees. Recruitment of with these trees. new pollards and large trees is vital if the specialist invertebrate fauna is to Management regimes that will ensure survive. As discussed for standards the persistence of old trees should be within coppice, it could be useful to adopted including: also select a few short-lived trees to become future veterans (birch • Use traditional tree management and willow) as these will mature and techniques such as pollarding, to produce deadwood habitat quickly in prevent trees becoming top-heavy comparison to species such as oak. and collapsing • Protect veteran trees and in Tree Preservation Orders can be a Veteran are important for a number particular the tree roots from valuable tool for protecting old trees of moths including Welsh Clearwing damage including soil compaction and the Ancient Tree Forum and local and erosion caused by factors tree officers can provide advice and including; livestock trampling, car support. parking, the application of fertilizers/ pesticide, ploughing and changes in ground-water levels.

Woodland management for butterflies and moths | 33 Managing deer Deer influence Lepidoptera and other woodland wildlife by altering both the structure and the species composition of woodland. Within coppice, high levels of browsing can damage or even prevent regrowth and can reduce the quality of the resulting poles.

At low densities and in areas managed for conservation, the presence of deer can have some Dan Hoare beneficial effects. Browsing can reduce dense scrub, maintain grassy open glades and add a diversity of habitat structure. Studies examining the use of coppice as butterfly habitat suggest that a low level of deer browsing can sometimes be useful. If the resulting crop does not need to be of high quality, and if browsing merely reduces the initial growth rate but does not kill the stools, then the delayed growth can allow a longer period of open conditions suitable for coppice butterflies. However, these effects need to be monitored closely, as floral diversity may also decline as grasses and sedges increase. Deer can also delay natural regeneration on clear-felled areas, an effect that is particularly striking in Scotland, where areas that are fenced to exclude deer rapidly become rank or Deer browsing on a one-year-old Sweet Chestnut coppice stool: regrowth is limited and heavily scrubbed and lose their value will be of low quality even if it survives. for butterflies. Assessing the absolute number • Fencing of coupes or woodland At high densities, deer impacts can of deer on a site is less important areas. There are various options of include severely reduced woodland than understanding whether they temporary or permanent fencing, regeneration, altered tree species are having a negative impact on the but these are generally expensive, composition, removal of the shrub woodland and your management often need maintaining and may layer and reduced floral diversity. objectives. Where deer impacts are only be effective at excluding some There is increasing evidence of the apparent a range of methods can species of deer. Expert advice ecological impact of deer on breeding reduce the damage, although none on fencing should be sought as birds, small mammals and plants, seem universally successful: this will save costly mistakes. In and there may also be direct negative addition, excluding deer from one • The simplest is to cut coppice in effects on butterflies. For example, area will simply shift the pressure to large coupes as deer prefer to be deer grazing of Honeysuckle can another part of the woodland. close to cover, which will tend to greatly reduce potential egg sites for • Where deer impacts are severe, limit damage to the edges of the the White Admiral. Changes to the a coordinated approach by coupe. This may work best where shrub layer can include reducing the neighbouring landowners may be deer densities are low. amount of Bramble, a key resource necessary, perhaps combining both for butterflies, moths and other • Protecting individual stools with fencing and deer culling. The wide invertebrates both as a foodplant and brush is sometimes effective woodland rides and open glades a nectar source. against larger deer species, but that suit butterflies also provide can encourage Muntjac and rabbits useful features when culling deer. by providing protective cover beneath which they can browse the regrowth. Dense layers of brush may also have an adverse effect on both the development of ground flora and the quality of coppice regrowth.

34 | Woodland management for butterflies and moths Dan Hoare David Green

Fallow deer feeding on young vegetation in a woodland clearing Rides are often good sites for pheasant feeders, but they need careful placement to avoid damaging valuable habitats Game management and woodland Lepidoptera The use and management of woodland for game such as pheasants is largely compatible with the needs of woodland Lepidoptera. Pheasants are birds of the woodland edge, requiring scrubby growth and open glades, the same habitats favoured by some woodland butterflies and moths.

Woodland management for game Predation of butterfly or moth • Non-native species planted often aims to produce habitat caterpillars by game birds has as game cover, such as features that are similar to those not been shown to be significant, Rhododendron, cotoneaster or recommended to encourage even close to release pens. High Snowberry, can out-compete and Lepidoptera. For example, wide rides bird densities may still be cause overwhelm native shrubs and young and glades are needed to provide for concern, however, if they are trees. Plant only native shrubs in access, positions for the guns, released or fed in an area with limited woods of conservation importance, flushing points and suitable feeding breeding habitat for a threatened and avoid planting invasive species sites for the birds. A study by the species. In general, managing semi- on all sites Game & Trust natural woodlands for game interests • Avoid locating release pens on or found that coppicing was used by supplies more benefits than conflicts near habitat features of conservation many site managers, although due for Lepidoptera. importance, as soil enrichment and to the labour required, they did not changes in ground vegetation can Although game management can be usually reinstate a full rotation cycle occur, especially where game bird complementary to conservation, care and often managed only small areas densities are high of a wood. is needed to integrate the two and a • Feed from hoppers, rather than on number of potential issues should be considered: straw, as it can suppress natural vegetation in rides and glades and cause long-term degradation of flora. Where straw is used, minimise the area covered and avoid features of conservation importance

Woodland management for butterflies and moths | 35 Connectivity and landscape scale conservation Effective conservation of threatened Lepidoptera can only be achieved if measures on individual sites are combined with actions at the landscape scale.

Colonies of butterflies and moths If the intervening landscape between • A varied habitat mosaic including surviving in small, isolated woodlands patches of breeding habitat can be successional stages from open remain highly vulnerable to extinction made more favourable for butterflies space to closed canopy woodland however successfully the individual and moths it will greatly enhance makes it easier for species to move woods are managed. This can even dispersal opportunities, although between suitable habitats be a problem if a species becomes this will vary considerably between • Boundary margins around restricted to a small patch of suitable species. woodlands can encourage habitat within a single large woodland movement around the site complex. Connectivity within Increasing the ability of species to woodlands Connectivity between move between habitat patches can A number of features can encourage woodlands have major and long-lasting benefits dispersal between patches of on butterfly and moth populations, possible breeding habitat within The following can improve the ability enabling metapopulations to function the same woodland or woodland of species to move between separate more effectively and persist for complex: woodland blocks which contain longer. This can be achieved by possible breeding areas: • Wide interconnecting rides with increasing the area or quality of • Hedgerows/walls/ditches with habitat at occupied sites (which good nectar sources. These increase movement through the boundary strips/verges connecting increases core populations and woodland blocks thus the probability that they will wood and increase the chances of disperse outside the habitat patch). insects finding new open areas • Unsprayed and uncultivated margins on fields in the surrounding landscape • A graded woodland edge containing scrub and a wide flower- rich margin • Small habitat patches, such as a field corner with abundant nectar plants Individual site managers can

Rich Howorth / ©Sussex Wildlife Trust make a significant contribution to landscape condition by improving the habitats on their own site and coordinating management work with neighbours. Effective landscape scale conservation is best delivered through schemes where agencies, organisations and land owners work together towards shared objectives. Additional support through targeted woodland grants or agri-environment schemes can greatly increase management activity and encourage the coordinated habitat improvements that are necessary to improve the fortunes of our most threatened butterflies and moths.

Connections between woodland blocks, and the habitat quality of the intervening landscape, are important features in the wooded landscape, as shown here in the West Weald

36 | Woodland management for butterflies and moths Case studies – conservation management in practice

Ride management for a range of species at Chiddingfold Forest

temporary habitat that develops on the verges as a result of regular clearance now becomes a valuable David Green bonus rather than the most important habitat in the wood. Management Existing verges are cut on a short rotation (c. 2 years), scallop areas on a longer rotation (c. 5 to 10 years). One or two deciduous trees are left in each scallop to provide leaf-litter and some shelter. Ditches at the edge of the graded road provide a well- drained sunny bank which can supply further valuable habitat. The results have been monitored each year and in 2010 the scallops were assessed as providing potential breeding habitat for 12 of the target Lepidoptera species including 8 UK A scallop cut into the ride edge during forestry operations provides temporary open BAP Priority species. In total, 84% space of the surveyed scallops produced Chiddingfold Forest is a large early successional, open woodland potential habitat for at least one of complex of woodlands managed habitats across the landscape. The the target Lepidoptera, including by the Forestry Commission. This scallops will supply secure refuges Wood White, Grizzled Skipper, Purple landscape has long been important compensating for any losses on the Emperor and Drab Looper. Due to for Lepidoptera, and holds a ride edges and with this network in slow regrowth in the scallops the nationally important population of place the value of the ride verges is cutting rotation has been increased to Wood Whites, but the key breeding also increased. The opportunistic, 7-10 years. areas often tend to be isolated and concentrated along ride verges. The periodic clearance and maintenance of road verges during necessary

forestry operations can have Jessica Pelling significant adverse impacts on this important habitat, although this is also the very process that creates floral diversity and increases the conservation value in the long-term. The main risk in such operations is that if there are no refuge habitats nearby from which species can repopulate the ride verges, local extinction of some of these threatened species is highly likely.

In response, in 2006 the Forestry Commission planned 63 rideside scallops, each at least 30m x 10m, cut on rotation over five years, to The Drab Looper is dependent upon Wood Spurge which typically flourishes following provide a continuous supply of woodland management

Woodland management for butterflies and moths | 37 Blean Woods, Kent: coppice management for the Heath Fritillary

Fritillary in the UK. A rapid decline in suitable habitat only produced the butterfly across the complex was sufficient foodplant in about a third shown to be due to a reduction in of clearings. Adult Heath Fritillaries David Green overall coppicing activity, an increase were shown to be very sedentary in the length of the coppice cycle and only colonised new clearings if and the planting of conifers over they were within 200 to 300 metres significant areas. A huge conservation of an existing colony. Many isolated effort was carried out over many clearings were never colonised in years to examine how the butterfly the four years that they remained used the woods and to improve suitable. management. It was concluded that continuous, Research confirmed that Heath carefully targeted coppice Fritillary colonies in the different management was the only way to management units of the Blean support the Heath Fritillary in the Sweet Chestnut coppice in East Blean were not independent, and that Blean. A 25-year programme of The Heath Fritillary has been found instead each cluster formed part of coppicing, with each cut in close to be highly dependent on coppice a large metapopulation, exchanging proximity to previous colonies, management and is an extreme individuals as the butterflies moved to combined with ride widening to example of a species that needs a find freshly cut coppice coupes. improve connectivity, has saved the targeted and continuous supply of Heath Fritillary population here and The majority of coupes in the Blean newly cut coppice. allowed it to expand throughout the were found to be suitable for the complex. This programme has of The Blean Woods are a large butterfly for only two to four years course provided benefits to other complex of woodlands north of after clearance. The main larval wildlife including the Goldenrod Canterbury with a number of different foodplant, Common Cow-wheat, is feeding micro-moth Anania funebris owners, and hold one of the few erratic in distribution and abundance and Nightingales. remaining populations of the Heath and management of potentially

Rewell Wood, West Sussex: coppice stages and their value for moths

Rewell Wood is an actively coppiced scrub habitats and most utilised tree Sweet Chestnut woodland well known species as larval foodplants. Within for its coppice butterflies including a the mature coppice coupes the moths

David Green large population of Pearl-bordered were species typically associated with Fritillary. The use of the coppice closed canopy woodland and some blocks by moths was less well were specialists whose larval food understood. To assess whether the comprised of material such as lichen coppice was providing benefits for and decaying leaves. All coppice the scarce Waved Carpet and other stages including the mature closed- moths, coppice coupes at this site (of canopy coupes supported species of between one and 20 years of coppice listed . regrowth) were systematically sampled for night-flying moths with The study showed that active the cooperation of the woodland coppicing supports a variety of managers, the Forestry Commission. moth assemblages, with the species composition changing as coppice The moths found in newly cut regenerates, and that closed-canopy coppice areas were typically stages are as valuable to moths as associated with open habitats. The the open, newly-cut areas. Thus Scarce Merveille du Jour was associated with areas of coppice regrowth of 5 years moths recorded within the middle moth diversity can be promoted by and older coppice stages were species typically providing a range of coppice growth associated with open woodland and stages.

38 | Woodland management for butterflies and moths Scarce and threatened moths associated with Sweet Chestnut coppice of different ages at Rewell Wood (Source: Butterfly Conservation/Forest Research)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Clay Fan-foot Paracolax tristalis Rosy Marbled venustula Anania verbascalis

Capperia britanniodactyla

Teleiodes wagae Great Oak Beauty Hypomecis roboraria Scarce Merveille du Jour White-line Snout Schrankia taenialis Waved Carpet The Festoon Apoda limacodes Spatalistis bifasciana

Oecophora bractella

Cattle grazing of woodland: conserving the Netted Carpet moth

is vulnerable to local extinctions. The have continued to increase. successful conservation of the Netted Carpet relies on a year-on-year In the seven years since the initiative began, the number of Netted Carpet

Graham Jones supply of abundant Touch-me-not Balsam. larvae has risen from twelve, found on 400 balsam plants, to over 1,500 Cattle were first introduced to found on 25,000 plants. National Trust woodlands near Coniston Water during 2002/2003. Since the successful introduction of This has continued annually, with a cattle in 2002/2003, this woodland small herd of traditional Blue-Grey management approach has cattle spending each winter and early been extended to additional sites spring moving round the various sites around Coniston Water. Controlled with the objective of lightly poaching winter cattle grazing is now a key the ground. The cattle move balsam management tool in Lake District Cattle grazing at Coniston Water, woodlands, providing suitable Lake District seeds around on their hooves, thus spreading the plant widely. They conditions for the Netted Carpet to Touch-me-not Balsam is a nationally also locally enrich the soil through thrive. scarce plant occurring as a native dunging which encourages vigorous primarily in the Lake District, but also balsam germination and growth. The in north Lancashire, Shropshire and cattle are removed before the balsam North Wales. Larvae of the Red Data germinates in the spring. Book Netted Carpet moth can be Graham Jones found feeding on the seed-pods of The effect of the introduction of cattle Touch-me-not Balsam in the Lake on both the plants and the Netted District and north Lancashire. Carpet has been closely monitored. The results show a rapid increase in Touch-me-not Balsam is an annual abundance of Touch-me-not Balsam species of moist, nutrient-rich to a level never previously seen. By soils, usually occurring in damp 2007 the balsam population had woodlands. It can quickly colonise multiplied by 3,400%, and the Netted newly disturbed areas but is intolerant Carpet larval count had increased by of competition with perennial a similar proportion. Since the 2007 plants; key to its persistence is an balsam peak, the plants numbers element of bare soil creation. It has a have stablised at around half the Netted Carpet, a UK BAP Priority species shortlived seed bank which means it peak level, however, larval numbers

Woodland management for butterflies and moths | 39