Species Action Framework: Management Guide

Lesser butterfly-orchid (Platanthera bifolia)

Scottish Natural Heritage

The Species Action Framework (SAF) programme ran between 2007 and 2012 to deliver targeted management action for 32 priority species in Scotland. Lesser butterfly-orchid was one of the species selected for conservation action having suffered a dramatic decline across Britain over the past five decades, leaving Scotland as its remaining stronghold.

This guide aims to summarise the knowledge gained on lesser butterfly-orchid over the 5 year SAF programme and provide guidelines for the successful future conservation management of this species and its habitats in Scotland.

Written by Liz Lavery and Andy Scobie, September 2013.

All images © Andy Scobie unless otherwise stated.

ISBN: 978-1-78391-479-1

FRAMEWORK

Contents

What is lesser butterfly-orchid? 2

How do you identify it? 3

Where does it occur in Scotland? 4

Why is it important? 6

What are the key threats to lesser butterfly-orchid? 8

Managing for lesser butterfly-orchid 10 What does it need? 10 Site specific management 12 Key steps to successful management for lesser butterfly-orchid 12 Unimproved lowland pasture and old hay meadows 13 Heathland and open hill ground 17 Road verges, golf courses and lawns 18 Restoration of neglected sites 19

How do you monitor it? 20 What to record 21 Survey and monitoring approaches 22

Further information 23

Acknowledgements 24

What is lesser butterfly-orchid?Lesser butterfly-orchid (Platanthera bifolia) is a long-lived perennial herb of grassland and heathland habitats. It flowers during June and early July when a loose spike of 5 to 30 striking-white flowers are produced at the top of the flowering stem 15 to 30 cm tall. The oval leaves occur in pairs at the base of the flowering stem, hence ‘bifolia’ which means ‘two leaves’.

Around dusk the flowers emit a strong, sweet scent attracting night-flying moths which pollinate them. The nectar is held at the end of a long, tube-like spur and can only be reached by certain species of moth. When a flower is successfully pollinated, a capsule is produced which slowly swells, then ripens, splitting down the sides to release several thousand dust-like seeds in August and September. The tiny seeds are dispersed by wind.

Each year, the orchid re-grows from a tuber below ground containing stored nutrients from the previous summer season. A second, new tuber forms beside it, equipped with a bud on the top, from which new growth will arise during the next season. The roots form a symbiotic relationship with mycorrhizal fungi which assist the orchid with uptake of water and nutrients from the soil.

Specific fungi are also required for seed germination and development, when the orchid may be entirely dependent upon the fungus for nutrition until the first leaf is produced. Initial growth and development takes place below ground, and can last for several years. It may take 3 or 4 years before the first flowering spike is produced.

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How do you identify it?Lesser butterfly-orchid can only be reliably identified when in flower. Flowering lasts for a short period, only 3 to 4 weeks during June and early July, presenting a narrow window of opportunity to look for and monitor this species. The green developing seed capsules, which remain after the flowers have gone, are inconspicuous and difficult to distinguish from those of other orchids.

Two species of butterfly-orchid occur in the UK: lesser butterfly-orchid (Platanthera bifolia) and greater butterfly-orchid (P. chlorantha). Butterfly-orchids can be distinguished from other orchid species by their loose spike of white flowers tinged with green which have a distinctive long, strap-shaped, undivided lower ‘lip’ and lateral ‘wings’ projecting from either side plus a long, narrow spur to the rear. The shiny, oval and unspotted leaves occur in pairs at the base of the flowering stem, with one to five small, narrow upper-leaves on the flowering stem.

Lesser butterfly-orchid looks very similar to greater butterfly-orchid, except that it is smaller in all of its parts. It is not uncommon for both species to occur at the same site. By far the most reliable way to tell them apart is to examine the angle and distance between the two club-shaped pollinia (pollen sacs) in the mouth of the flower. In lesser butterfly-orchid the pollinia lie close together (c. 1 mm apart) and parallel forming a ‘II’ shape. In greater butterfly-orchid they are widely-spaced at the base (c. 3-4 mm apart) forming an inverted ‘V’ shape (Fig. 1).

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Lesser butterfly-orchid

Greater butterfly-orchid

Figure 1. Position of pollinia (arrowed) in flowers of lesser butterfly-orchid and greater butterfly-orchid – the key character for telling them apart.

Where does it occur in Scotland? Lesser butterfly-orchid has a widespread distribution in Scotland but is most common in the northwest mainland and Hebrides (Fig. 2). It is a scarce plant in much of central, eastern and southern Scotland. It is found mostly in small numbers, often in widely scattered groups of a few flowering spikes. At the majority of Scottish sites less than 10 flowering spikes appear each year. Populations of more than 100 are unusual, and only a very few exceptional sites support 500 or more.

Figure 2. Distribution of lesser butterfly-orchid in Scotland showing hectad (10 km square) records made between 2000 and 2012. Data from national Species Action Framework survey, and the Botanical Society of Britain and Ireland.

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Lesser butterfly-orchid occurs in a broad range of heathland and grassland habitats in Scotland. Many sites can be described as ‘wet’ or ‘damp’. It is regularly found in wet heath, along the margins of boggy ground, on tussocks in marshy grassland, and at the edges of wet flushes in moorland. It also occurs on drier sites including dry grassy heathland and herb-rich grassland in unimproved pastures, old hay meadows, roadside verges and rough on golf courses.

It grows on mildly acidic through neutral to slightly calcareous soils overlying sands, gravels and clays. Lesser butterfly-orchid appears more tolerant of acid soils than greater butterfly-orchid, but its occurrence is often localised to areas where slight flushing reduces soil acidity.

Damp grassland habitat of lesser butterfly-orchid on South Uist, Outer Hebrides. © Stewart Taylor.

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Why is it important? Lesser butterfly-orchid is a widespread species which has undergone a dramatic decline in the UK. It is classified as ‘vulnerable to extinction’ on the Vascular Plant Red Data List for Great Britain (2005) and is a UK Biodiversity Action Plan priority species. It has no statutory conservation protection, except where its habitat is a notified feature within a Site of Special Scientific Interest (SSSI). The UK stronghold for lesser butterfly-orchid occurs within Scotland making this a highly important area for its future conservation.

Flower-rich grassland supporting lesser butterfly-orchid near Brora, Sutherland. © Robin Ward. 6

Lesser butterfly-orchid is an indicator of ecologically important sites, many of which are unimproved pastures and old meadows shaped by a long history of low-input grazing and/or cropping for hay. Here, lesser butterfly-orchid regularly occurs in the company of a rich diversity of wild flowers, often with several other orchid species, along with a wide range of associated biodiversity, including many insects and birds, both common and rare.

Once more commonplace across Britain and Ireland, these sites have suffered widespread losses since the mid-1900s mainly as a result of agricultural intensification. As a consequence, many species associated with these habitats have undergone dramatic declines as they have become increasingly confined to occasional corners of fields and road verges, which have escaped cultivation, and to areas of marginal land unsuitable for improvement.

It is vital, therefore, that remaining examples of these habitats are maintained and restored, not only to conserve lesser butterfly-orchid, but for the range of biodiversity they support.

Other orchid species, such as heath fragrant-orchid, often grow together with lesser butterfly-orchid. 7

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What are the key threats to lesser butterfly-orchid?

• Agricultural improvement of rough grassland and lowland heath The draining, ploughing and re-seeding of rough pasture and old meadows, along with applications of fertiliser and herbicide, to improve their productivity is a major cause of habitat loss. Lesser butterfly-orchid and many associated wild flowers are unable to persist amongst the dense, fast-growing swards resulting from these changes in management.

• Heavy grazing or cutting during late spring and early summer Orchid leaves and flowering spikes are susceptible to damage from heavy grazing or cutting too early in the season. When flowering spikes are lost, this limits seed production and potential for seedling recruitment and spread. Where heavy summer grazing is sustained year on year, orchids and other associated wild flowers can be completely ‘grazed-out’ over time.

Orchid leaves and flowering spikes are vulnerable to grazing, trampling and cutting from when they first appear in May through to seed set in August. 8

• Too little grazing or cutting Where there is too little grazing or cutting, or none at all, the development of dense tussocky vegetation and encroachment of scrub can lead to the gradual exclusion of lesser butterfly-orchid over time. Under-grazing of ‘species-rich’ grasslands is an increasingly common problem where sites are often stocked at insufficient levels, or not grazed for long enough, to eat down the sward in late summer/autumn.

• Woodland establishment Woodland regeneration or planting schemes can result in the loss of suitable grassland and heathland habitat for lesser butterfly-orchid which is excluded following the cessation of grazing and development of a woodland canopy.

• Damage from heavy poaching and nutrient enrichment Some light poaching can be beneficial, creating open sites for seedling recruitment amongst dense swards. However, the structure and composition of grasslands can be altered, and orchid tubers damaged, following heavy poaching and localised nutrient enrichment associated with overwintering and supplementary feeding of large numbers of livestock on small or wet sites.

Insufficient grazing can result in development of dense ground vegetation, scrub and woodland leading to the exclusion of lesser butterfly-orchid over time. 9

Managing for lesser butterfly-orchid

What does it need? 1. The opportunity to grow, flower and set seed – promoting persistence

and spread to new areas. Orchid leaves and flowering spikes are most susceptible to damage from grazing and cutting during mid-May to mid-July, but seed capsules can take a further six to eight weeks beyond this to mature and shed their seed.

2. Short and open vegetation – seedlings and adult plants are susceptible to shading from dense vegetation or scrub and can be suppressed by a build-up of dead plant litter or ‘thatch’ if excess growth is not removed each year by grazing or cutting at appropriate times.

3. Bare or disturbed ground – seeds need to come into contact with the soil to germinate. Light poaching from animal hooves and recently disturbed ground, such as spoil from ditch-clearing, can help to provide suitable open ‘micro-sites’ for seedling establishment.

4. Maintenance of existing drainage patterns and flushing – where orchids grow in damp or wet areas it is important not to alter the water table as this can cause changes to soil and surrounding vegetation creating conditions less favourable for the orchid.

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Lesser butterfly-orchid thrives at sites where a well-timed grazing regime maintains a short and open sward, with a sufficient summer grazing break to permit growth, flowering and seed production.

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Key steps to successful management for lesser

butterfly-orchid 1. Identify the location and full extent of the orchid population and the

vegetation in which it occurs. This will help to target effective management to the right areas or fields.

2. Protect sites from agricultural improvement (including drainage of wet areas and applications of fertiliser, herbicide, lime, slurry and farmyard manure) and woodland regeneration schemes which cause unfavourable changes to the habitat of the orchid.

3. Establish and maintain a well-timed grazing and/or cutting regime permitting orchids to grow, flower and set seed whilst removing the growth of vegetation each year to maintain a favourable open sward and prevent litter build-up (see detailed guidance below).

4. Monitor the site and orchid population, adapt the grazing or cutting regime where fine-tuning of sward conditions is required and manage orchid areas to keep them free of bracken and scrub.

5. Avoid overwintering large numbers of livestock on small or wet sites where this may lead to excessive poaching. Where supplementary feeding is required to extend periods of grazing through autumn and winter, site feeding stations well away from orchid areas.

Site specific management Lesser butterfly-orchid occurs in a variety of habitats in Scotland under a diverse range of management regimes. Some sites receive very little management whilst others are regularly grazed or cut. As a consequence, a single approach to managing for lesser butterfly-orchid is both difficult to describe and unlikely to be successful. Instead, some key principles can be applied to help tailor appropriate management regimes to individual sites. If the orchid is already present at a site in high numbers then it is likely that the existing management regime is already favourable. In these situations, the best possible course of action is to ensure that a similar pattern of management is continued in the long term.

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Unimproved lowland pasture and old hay meadows Many lesser butterfly-orchid sites fall within this category which includes damp acid grassland, dry herb-rich grassland, and rush pasture, where regular grazing and, occasionally, hay cropping are the key management tools. The timing and intensity of the grazing or cutting regime is important to the survival of lesser butterfly-orchid at these sites. Grazing management:

• Release sites from heavy grazing pressure between mid-May and mid-July allowing orchids to grow and flower. A ‘shut-up’ or exclusion period may be required on smaller sites, whilst reducing stocking to low levels is sufficient on extensive sites where animals are free to roam in and out of areas with orchids.

• There is a delicate balance to be struck between allowing enough time for the orchid to set seed, which can take until late August, and reinstating sufficient grazing to control the sward before vegetation starts to die-back and become less palatable to livestock in late summer.

• On larger sites, moderate stocking from mid to late July onwards, especially with cattle, can be effective at controlling the sward whilst still permitting a proportion of orchid fruiting spikes to survive and shed their seed.

• On smaller sites, where there is a greater risk that all fruiting spikes will be grazed-off, limit grazing until late August then stock to graze down summer growth.

• As a general rule, all sites should receive a significant period of grazing between the end of August and November taking the sward down to a max height of 5-10 cm over much of the site. This can be achieved by stocking heavily for 3-4 weeks or with lower stocking for a longer period.

• Spring grazing can be beneficial to control fresh growth, especially on more productive sites. Remove or reduce stocking by mid-May at the very latest.

• Where desirable to stock sites heavily throughout summer, electric fencing can be used to protect orchid areas. Remove to permit grazing from late August.

• Cattle are especially good for removing large quantities of grass in late summer. Periodic light poaching by cattle can also open up seedling recruitment sites amongst dense swards.

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• Sheep tend to target flowering spikes in summer but are good for close-cropping a sward over autumn/winter and can be effective at controlling regenerating scrub and tree seedlings.

• Orchid populations on sites managed as part of extensive, low-input grazing systems are by far the most successful.

• Supplementary feeding to support grazing through autumn/winter should not be ruled out where this could help to achieve favourable sward conditions. Stocking at appropriate levels for the site and locating feeding stations well away from orchid areas can reduce undesirable impacts of heavy poaching and nutrient enrichment.

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Take care to site feeding stations well away from areas with orchids. © Glyn Satterley/SNH.

One of the largest populations of lesser butterfly-orchid in Scotland occurs in short-cropped (5-10 cm) dry heathland and species-rich grassland at a 5 ha site in Stathspey in the Cairngorms National Park.

The site is managed as part of a single larger 16 ha grazing unit stocked with around 40 cows and followers in periods from early summer through to winter. Cattle are free to roam between the unimproved orchid meadow and improved pasture within the wider grazing unit. They typically don’t visit and graze the orchid meadow until mid-August, providing the orchids with an opportunity to flower and set seed.

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Cutting management:

• Lesser butterfly-orchid also persists on a few croft sites in the north of Scotland managed for a late hay crop cut in late July/August. The process of turning and drying the hay over several days allows seed capsules to ripen and seeds to be shaken out before bailing. Cutting earlier risks removing fruiting spikes before the seeds have matured.

• This management is most successful where hay cropping is followed by a period of ‘aftermath grazing’ in late summer/ autumn and preceded by light grazing in spring.

• Early cutting for silage production and associated sward improvements is detrimental to orchids and other wild flowers and are therefore not recommended.

• At sites where it is proving problematic to graze at sufficient levels to remove the build-up of vegetation each year, cutting can provide an alternative. It is essential that cuttings are collected and removed. Cut as late as possible, preferably before late September, to allow orchid seed capsules to mature.

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Cutting sites too early in the summer can remove orchid seed capsules before they are ripe.

Heathland and open hill ground At these sites lesser butterfly-orchid usually occurs in naturally open areas of vegetation in wet heath and mire, on the edges of wet flushes, or on slopes over thin gravelly soils. Management input is typically very limited, or none at all. However, extensive grazing by livestock or red deer can be important for keeping sites open and preventing scrub from invading. Here, it is important to:

• Graze orchid sites to maintain a diverse mosaic of short, open grassy areas and taller areas of heather, and keep flushes open, whilst preventing scrub and bracken from invading.

• Protect sites from heavy grazing between mid-May and mid-July, especially by sheep, to permit flowering.

• The importance of red deer as winter grazers should not be overlooked.

• Take care if burning heather. Evidence suggests that lesser butterfly-orchid can withstand light burning, but high intensity fires are likely to be damaging.

17© Ian Strachan.

Road verges, golf courses and lawns Small strips of grassland and heathland on road verges and golf courses, and occasionally in lawns, can provide an important refuge for lesser butterfly-orchid and a range of associated wild flowers. Cutting is the key management tool though some unfenced verges are grazed by livestock and deer.

Here, it is important to:

• Cut the site each year to remove the build-up of vegetation after the growing season.

• Collect and remove cuttings, if left they can enrich the soil and create a build-up of thatch unsuitable for the orchid.

• Delay cutting until autumn, preferably not before late September, to allow plants to flower, set and shed their seeds.

• Inform local authorities of sections of road verge with orchids and request that cutting is postponed until late September and cuttings raked and removed (where possible).

• Permit grazing by livestock or deer where this is likely to be a key factor in maintaining suitable open vegetation.

Specialist tractor-mounted flail collector mowers can be useful for managing small sites such as rough on golf courses where grazing is impractical.

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Restoration of neglected sites At sites which haven’t received sufficient management for a long period, actions to restore favourable conditions for the orchid include:

• Clearing and removal of scrub to create open areas for grazing or cutting.

• Cutting the site each year in autumn (late September onwards) and removing cuttings. Additional raking can also help to remove thatch and open up the sward.

• A combination of late cutting followed by a period of grazing over autumn and winter can be effective for restoring a favourable open sward.

• Where appropriate, cutting can be substituted by a suitable grazing regime in the long-term once favourable sward conditions have been restored.

Heath fragrant-orchid with six-spot burnet moth. Restoring sites for lesser butterfly-orchid can help a large number of other species. 19

How do you monitor it?Monitoring is an important means of tracking long-term changes in orchid populations in response to management. This can be done very simply by counting the number of flowering spikes each year. It is typical for the number of orchid flowering spikes at a site to fluctuate naturally from year to year, sometimes quite dramatically (Fig. 3), so it is important to make counts over several successive years in order to detect a general upward or downward trend.

0

30

60

90

120

150

2012201120102009200820072006

Num

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of fl

ower

ing

spik

es

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Figure. 3. Annual variation in flowering population size at three Scottish lesser butterfly-orchid sites. Data from Plantlife Flora Guardian volunteers.

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Wester Balgair

Glen Luss

Flanders Moss

What to record

1. Recorder – the name of the person who did the survey;

2. Date – when the survey was done;

3. Location – note the grid reference of the site (from GPS unit or 6-figure from map) and/or make a sketch map showing the position of groups of plants at the site;

4. Count – the total number of flowering spikes in the population;

5. Extent – approximate area (length x breadth) covered by the population.

Monitoring of lesser butterfly-orchid by a team of volunteers at Loch Leven. © Ian Borland. 21

Survey and monitoring approaches

1. Small and discrete populations – re-visit the same area each year to make a count of flowering spikes then search out from this point in concentric circles across the site (Fig. 4A) to detect new groups or outlying plants.

2. Large and extensive populations – these can be very difficult to count all at once. Walking transect lines spaced at intervals across the site is an effective way of managing the task (Fig. 4B). Space transects closer together (e.g. 2 m apart) where orchids occur at high density, and further apart (e.g. 5 m apart) where they are at lower density. Bamboo canes are useful for marking the ends of transects.

3. Searching for new populations – new discoveries await those willing to search through suitable looking areas, especially those near to existing sites. Walking across the site in a zigzag pattern (Fig. 4C) is the most efficient way of covering the ground, searching more intensively in areas where you encounter orchids.

Figure 4. Survey and monitoring approaches for lesser butterfly-orchid:

A. small and discrete populations – concentric circles;

B. large and extensive populations – parallel transects;

C. searching for new populations – zigzag across the site.

Please submit your monitoring data to: Plantife Flora Guardians, Plantlife Scotland, Balallan House, Allan Park, Stirling, FK8 2QG. scotland@plantlife.org.uk or to the Botanical Society of Britain and Ireland.

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A B C

Further informationRecommended stocking levels for grassland and heathland habitats: Chapman, P. 2003. Conservation grazing of semi-natural habitats. SAC Technical Note: TN586. www.sruc.ac.uk/downloads/file/1128/tn586_conservation_grazing_of_semi-natural_habitats Grasslands and their management: Hall, C. 2010. Management of species rich grasslands. SAC Technical Note: TN629. www.sruc.ac.uk/downloads/file/749/tn629_management_of_species_rich_grasslands

Scottish Natural Heritage. 2010. Guide to types of species-rich grassland. SNH Publications, Battleby, Perth. www.snh.gov.uk/publications-data-and-research/publications/search-the-catalogue/publication-detail/?id=1734

Ward, S. & MacKintosh, J. 2001. Grasslands: Scotland’s living landscapes. SNH Publications Battleby, Perth. www.snh.gov.uk/publications-data-and-research/publications/search-the-catalogue/publication-detail/?id=39

Additional information on managing grassland sites for lesser butterfly-orchid and other plant species can be found on the Plantlife Magnificent Meadows web pages. For further information please contact:Plantlife Scotland, Ballallan House, Allan Park, Stirling, FK8 2QGscotland@plantlife.org.uk, www.plantlife.org.uk

Further information on the lesser butterfly-orchid carried out during the Species Action Framework can be found at Lavery, E.L.D. 2016. Lesser butterfly-orchid. Version 1.0. In The Species Action Framework Handbook, Gaywood M.J., Boon P.J., Thompson D.B.A., Strachan I.M. (eds). Scottish Natural Heritage, Battleby, Perth. www.snh.gov.uk/speciesactionframework

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Acknowledgements

This guidance was based on a wealth of information contributed to the Species Action Framework national lesser butterfly-orchid survey by volunteers, botanists, land managers and conservation partners from across Scotland, without whom the production of this document would not have been possible.

This document was produced as an output of the Cairngorms Rare Plants Project with funding and support from the Esmée Fairbairn Foundation, the Cairngorms National Park Authority, the University of Aberdeen, and Scottish Natural Heritage.

About the authors

Liz Lavery is a freelance ecological consultant who worked on the SAF lesser butterfly-orchid project between 2007 and 2012, and is an expert on the orchid and its habitats in Scotland. Liz continues to manage annual surveys of lesser butterfly-orchid by the Plantlife Flora Guardian volunteers.

Andy Scobie is a conservation ecologist and botanist. As Project Officer for the Cairngorms Rare Plants Project, which ran between 2010 and 2013, Andy worked on the conservation management of lesser butterfly-orchid and a selection of other rare Scottish plants in the Cairngorms National Park. 24