Scottish Natural HeritageCommissioned Report No. 558

Establishing trees without fences in Scotland

C O M M I S S I O N E D R E P O R T

Commissioned Report No. 558

Establishing trees without fences in

Scotland

For further information on this report please contact:

Jeanette Hall Scottish Natural Heritage Great Glen House INVERNESS IV3 8NW Telephone: 01463 725204 E-mail: jeanette.hall@snh.gov.uk

This report should be quoted as:

Armstrong, H.M. and Robertson, C.A. 2013. Establishing trees without fences in Scotland. Scottish Natural Heritage Commissioned Report No. 558.

This report, or any part of it, should not be reproduced without the permission of Scottish Natural Heritage. This permission will not be withheld unreasonably. The views expressed by the author(s) of this report should not be taken as the views and policies of Scottish Natural Heritage.

© Scottish Natural Heritage 2013.

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Establishing trees without fences in Scotland Commissioned Report No.: 558 Project no: 13513 Contractor: Broomhill Ecology and Carol Robertson, Native Woodland Adviser Year of publication: 2013 Background

Browsing by deer can detrimentally affect both planted and naturally regenerated young trees. Since deer move across land ownership boundaries, even heavy culling cannot always reduce browsing pressure on young trees to levels that will meet tree regeneration objectives. Additionally, many land owners want to maintain deer numbers higher than are compatible with successful tree regeneration. Fencing is not always an alternative due to practicality, cost and potentially negative impact on access, landscape and biodiversity. As a result, other means of protecting trees from deer are needed. This report reviews a range of different potential approaches, recommends those that are likely to be suitable for Scotland and provides an outline of trials that might be carried out at Creag Meagaidh and Beinn Eighe National Nature Reserves. Main findings

There are a number of no-fence methods of protecting young trees from deer browsing that have the potential to work in Scotland. These include:

o ‘Sabre’ planting i.e. planting trees of at least 1 m tall on slopes at right angles to the slope. This approach can work well in protecting trees from roe deer. It has not been tested in areas where red deer are present.

o ‘Natural’ protection using a range of native species (gorse, blackthorn, hawthorn, dog rose, holly, juniper, broom, bramble, raspberry and bracken), dead wood or clump planting with the outer trees being ‘sacrificial’. Gorse has the greatest potential as a protecting species.

o Diversionary feeding at some distance from where the tree regeneration is wanted, along with culling. Diversionary feeding can be done either directly or by increasing forage availability through habitat modification.

o Bud protection using sheep’s wool, plastic bud caps or plastic mesh nets that are stapled to the needles of conifers.

o Chemical repellents including calcium chloride solution (sold as the plant nutrient ‘Grazers’) and other chemical repellents that are registered in other European countries but not in the UK, e.g. TRICO. Experimental approval is needed to trial any of these.

All of these approaches need to be trialled in Scotland to test their effectiveness under different conditions.

They are all likely to work best where deer numbers are being kept well below carrying capacity by culling.

The most suitable approach for a particular situation will depend on the: o species of deer, and other herbivores, present,

COMMISSIONED REPORT

Summary

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o attractiveness and accessibility to deer of the areas where deer browsing is an issue,

o season of most intense browsing, o species and height of trees to be protected, o potential for habitat modification, o availability and type of planting stock, o available labour and financial resources, o accessibility to people of the areas where deer browsing is an issue

A combination of approaches may work best. All the approaches thought to be suitable for Scotland could be trialled at Beinn Eighe

and Creag Meagaidh National Nature Reserves.

For further information on this project contact:

Jeanette Hall, Scottish Natural Heritage, Great Glen House, Inverness, IV3 8NW. Tel: 01463 725204

For further information on the SNH Research & Technical Support Programme contact: Knowledge & Information Unit, Scottish Natural Heritage, Great Glen House, Inverness, IV3 8NW.

Tel: 01463 725000 or research@snh.gov.uk

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Table of Contents Page 1. INTRODUCTION 1

2. REVIEW OF TECHNIQUES 2 2.1 Sabre planting 2 2.2 ‘Natural’ protection 3 2.3 Habitat modification /diversionary feeding 17 2.4 Bud protectors 18 2.4.1 Sheep’s wool 18 2.4.2 Paper /tinfoil bud protectors 19 2.4.3 Plastic bud caps 20 2.4.4 Netting bud protectors 21 2.5 Chemical repellents 21 2.6 Summary of recommendations for Scotland 23

3. PRACTICAL TRIALS ON CREAG MEAGAIDH AND BEINN EIGHE NATIONAL NATURE RESERVES FROM 2012/13 TO 2014/15 26 3.1 Beinn Eighe 26 3.1.1 Plantations 26 3.1.2 Recent planting and areas for further woodland expansion 28 3.1.3 Ancient Woodland 30 3.2 Creag Meagaidh 32 3.2.1 Enhancing woodland expansion on areas currently with low or no

regeneration 32 3.2.2 Establishing a wider suite of native species in current areas of native

woodland 35 3.3 Work on Creag Meagaidh and Beinn Eighe NNR during winter 2012/13 36 3.4 Monitoring 42

4. CONCLUSIONS 43

5. REFERENCES 44

ANNEX 1: FURTHER INFORMATION ON THE USE OF GORSE FOR NATURAL PROTECTION 48

ANNEX 2: EFFECT OF SAMPLE SIZE ON CONFIDENCE LIMITS ASSOCIATED WITH CALCULATED PROPORTIONS OF TREES BROWSED 50

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Acknowledgements We are grateful to the following people who kindly contributed their knowledge and ideas: Bob Black (Argyll Woodlanders) Peter Duncan (Scottish Natural Heritage) Colin Edwards (Forest Research) Ian Fergusson (Forestry Commission Scotland) Wayne Fitter (Scottish Natural Heritage) Gordon French Jeanette Hall (Scottish Natural Heritage) Jens Haufe (Forestry Commission) Grant Holroyd (Knoydart Forest Trust) Douglas Howison (Forestry Commission England) Norman Healy (Forestry Commission England) Donald Kennedy (Organic Trees) Willie Lamont (Forestry Commission Scotland) Colin Lavin (Forestry Commission Scotland) Eoghain Maclean (Scottish Natural Heritage) Harry Pepper (Arboricultural Advisory and Information Service) Shaila Rao (National Trust for Scotland) Rory Richardson (Scottish Natural Heritage) Lorna Schofield (Knoydart Forest Trust) Ian Rowland (Chemicals Regulation Directorate) Richard Thompson (Forestry Commission Scotland) Andy Walker (Forestry Commission Scotland) Steve Watson (Bugailiad-y-Coed) In particular, we would like to thank Gordon French who provided the information in Annex 1 and Jeanette Hall who initiated the project and provided valuable information and advice.

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1 INTRODUCTION

There are a number of potential means of protecting young trees from deer without the use of fences. They rely on: planting so that the leading shoot is out of reach of deer (sabre planting). making the tree less visible, or less accessible, to deer (planting beside, or amongst,

other trees, shrubs, ground vegetation or dead wood). providing additional forage or modifying the habitat to attract deer away from areas

where trees are being browsed (diversionary feeding /habitat modification). physically protecting the leading shoot(s) from browsing (bud protectors). making the tree un-palatable to eat (chemical repellents). We review each of these in turn, suggesting which approaches are likely to be most suitable for Scottish conditions and which might be most appropriate for trials at Creag Meagaidh and Beinn Eighe National Nature Reserves.

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2 REVIEW OF TECHNIQUES

In this review we refer both to the published and ‘grey’ literature as well as to anecdotal information provided by a number of experts in the field. Sources of all information are provided. 2.1 Sabre planting

Sabre planting is a technique developed by Steve Watson in Wales to protect planted saplings from sheep (Ovis aries) browsing though, in some cases, he has also used the method to protect trees from goats (Capra aegagrus), cattle (Bos taurus) and /or a small roe deer (Capreolus capreolus) population. It involves planting saplings, with a minimum height of 1 – 1.2 m, on slopes of at least 30 – 40°, at right angles to the slope (Watson, 1998). The tree initially grows out from the slope thereby making the leading shoot less accessible to large herbivores than it would be if it grew vertically. Even if the buds on the up-side of the tree are browsed, those on the down-side are less likely to be and, over time, the tree will grow out and up, eventually becoming completely out of reach of large herbivores. At this stage the tree starts to grow vertically, producing a mature tree that has a trunk that is smoothly curved like a sabre (Watson, 1998). Over time, the sabre form may disappear, especially in the larger tree species (pedunculate oak, Quercus robur; sessile oak, Quercus petraea; ash, Fraxinus excelsior and beech, Fagus sylvatica), as wood is laid down on the upper side of the curve (Watson, 1998). On gentler slopes, small hillocks and hollows where the slope is steeper can often be found and trees can be planted on the uphill side of hillocks or the downhill side of hollows. Planting involves removing rocks and stones, digging a hole, putting aside the removed soil, planting potted trees more deeply than when they were in their pots and then replacing the soil. The tree should also have its side-shoots removed to discourage browsing. Watson (1998) provides more detailed information on recommended planting methods. Bare-rooted stock can be used in sites where there is enough soil but, where this is not the case, potted stock need to be used. These can be grown from locally-collected seedlings where these are abundant and are suppressed by shade or browsing (Watson, 1998). Oaks, however, need to be grown from seed as they do not transplant well (Watson, 1998). Willows can be grown from cuttings taken from the young stems of mature trees. When trees are large enough, spiral guards are fitted if necessary to prevent small mammal damage. Further details of methods of collecting and growing stock for planting can be found in Watson (1998), Thompson (2000) and Thompson & Watson (2011). Watson (1998) suggested that tree species that can survive in poor soils e.g. birch (Betula spp.) and willow (Salix spp.), can be planted first, followed by more demanding species once soil conditions have started to improve. It could be many years, however, before this occurs. This approach is usually not possible when planting inside a fence when all the trees usually need to be planted, and to have grown above deer height, within the lifespan of the fence. The presence of gorse (Ulex europeus), bracken (Pteridium aquilinum) or blackthorn (Prunus spinosa), where these are not so dense or tall that they shade out the sabre-planted trees, helps to protect trees and aids survival (Thompson, 2000). Where most of the browsing occurs in winter, however, bracken, being deciduous, will not provide protection. The only site in Scotland where sabre planting has been tested and monitored is near Traquair in the Scottish Borders (S. Watson & R. Thompson pers.com; Thompson & Watson, 2011). Thirty trees 1.1 to 1.4 m tall, growing in 17.5 cm pots, mostly ash and sessile oak, but also including a few downy birch (Betula pubescens) and alder (Alnus glutinosa) were planted in May 2010, mostly using the sabre method. Sheep and roe deer were present at all sites, horses (Equus ferus) at one site and sika deer (Cervus nippon) at the higher elevation sites (Thompson & Watson, 2011). At planting, the species, height and grid reference of each tree was recorded then, in April 2011, the presence or absence of browsing on each tree was recorded (R. Thompson, pers. com.). The trees will be checked again in the near future (R. Thompson, pers. com.). A few birch trees were sabre planted on

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Arran in 2010 (S. Watson, pers. com.) but these have not been monitored (A. Walker, pers. com.). Sabre planting, especially if combined with planting within a suitable density and height of protective vegetation, such as gorse, blackthorn or bracken, has considerable potential for some Scottish sites. The main difference between Welsh and Scottish conditions is the presence of red deer (Cervus elaphus) in large parts of Scotland. Given that red deer are taller than roe and sika deer, it will normally not be possible to plant trees that are tall enough to avoid browsing using the sabre planting technique described above. It is possible, however, to successfully establish trees, of any height, in micro-sites that have been carefully chosen to be relatively inaccessible to red deer e.g. the steep sides of gorges or amongst boulders. However such sites are often not easy for people to access and opportunities for such planting are likely to be limited in both scale and geographical coverage. In 2010, on the island of Rum, off the west coast of Scotland, at a site where red deer were the only large herbivores present, about 260 birch, rowan, willow and alder trees were planted in relatively inaccessible micro-sites (J. Hall, pers. com.). To date, these trees have not been monitored however, even if they had been, a low survival rate may have been due to the acknowledged poor quality of the planting stock rather than to browsing (J. Hall, pers. com.) At Glen Feshie, where red deer are the main large herbivore species, montane willows of various species have been planted on inaccessible ledges (Bodles & Duncan, 2012). The main limitation of the sabre planting technique is that it is largely confined to slopes of more than 30-40° although it may be possible to use the technique on less steep slopes where roe are the only deer species present if suitable micro-sites are present. Sabre planting using saplings and spiral guards has never been trialled in areas where red deer are present. 2.2 ‘Natural’ protection

Natural’ protection, often referred to as ‘associative resistance’ in the scientific literature, refers to the protection afforded to palatable plants by being next to, or surrounded by, less desirable plants. The less desirable plants create a physical barrier and help to hide the more desirable ones. Physical protection can also be afforded to young trees by dead wood as well as by growing in clumps, where the outer trees are ‘sacrificial’ and protect the inner ones (Madsen et al., 2007). The outer trees can be of the same species, of a less palatable species or of a more palatable, but browsing resistant, species. Table 1 summarizes the results of 28 published studies on natural protection in a wide range of countries and habitats. In all but three of these studies, natural protection was found to assist the regeneration of young trees by reducing browsing pressure. In one study (Bobiec et al., 2011) natural regeneration was not limited by browsing, probably because there was enough alternative forage available that the large herbivores did not need to eat the young trees. In two studies (Kupferschmid & Bugmann, 2005; Pellerin et al., 2010) logs and woody debris were found to have no effect on rates of browsing on associated young trees. This contrasts with six studies (Morgan, 1991; Sanderson, 1996; Ripple & Larsen, 2001; Truscott et al., 2004; Casabon & Pothier, 2007; Smit et al., 2012) where coarse woody debris, fallen logs or brash did protect young trees from browsing. This difference perhaps reflects the need for dead wood to be of a type appropriate to the size of herbivore from which the young trees need to be protected. In the other 17 studies (and also as reported by Morgan, 1991), trees associated with shrubs, or other protective vegetation, were found to be protected from browsing to some degree. In three studies (Bakker et al., 2004; Van Uytvanck et al., 2007; G. French pers. com.), if rabbits (Oryctolagus cuniculus) were present, the protective effect of shrubs was lost. G. French (pers. com.) has suggested that, where rabbits are present, gorse branches can be cut and packed around the base of the young trees to protect them

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from both rabbits and voles, or spiral guards can be used. Rabbits may also prevent the expansion of patches of thorny shrubs such as blackthorn (Prunus spinosa; Smit et al., 2010) hence control of rabbits may, in some areas, be needed to allow thorny shrub species to expand and provide protection to young trees. Madsen et al. (2007) found that tree species that are highly preferred by deer such as silver fir (Abies alba), pedunculate oak, sessile oak and rowan (Sorbus aucuparia) have a better chance of avoiding browsing if they are growing in dense clusters than as single trees. There would, thus, seem to be considerable evidence that natural protection can be an effective means of reducing, if not eliminating, browsing by large herbivores. The effect would seem to be greatest when herbivore densities are low and /or alternative forage is available, since hungry deer are more likely to eat unpalatable forage. In some cases, although browsing rates were reduced, survival and growth of the saplings were adversely affected by the ‘protecting’ vegetation or the dead wood, probably through competition for light or nutrients or, in the case of dead wood, not allowing the roots of the young trees to get sufficient access to mineral soil. These potential effects may therefore need to be considered when designing tree regeneration schemes that use natural protection. In Scotland, the plant species that are likely to be most suited to providing natural protection to young trees are gorse, blackthorn, hawthorn (Crataegus monogyna), dog rose (Rosa canina), holly (Ilex aquifolium), juniper (Juniperus communis), broom (Cytisus scoparius), bramble (Rubus fruticosus), raspberry (Rubus idaeus) and bracken (Pteridium aquilinum, in summer only). Holly, juniper, broom, bramble and raspberry are all relatively palatable, despite there being thorns on all but broom, so they are less likely to protect young trees when deer browsing pressure is high. Bramble, raspberry and bracken grow quickly and are likely to shade out slower growing tree species if they form a dense stand before the trees have started to grow (Harmer et al., 2010). This is less likely to occur with bramble in Scotland than in lowland England since bramble growth rates in Scotland are usually lower (R. Thompson pers. com.). Of the species listed above, gorse has been most widely trialled (Watson, 1998; Thompson, 2000; Thompson & Watson, 2011; French, 2012) and is likely to provide the greatest protection since it is little browsed after its first two years of life (French, 2012). The branches can also be easily cut and packed around the base of young trees to provide protection from small mammals (G. French, pers. com.) or a spiral guard can be fitted to the young tree. Additionally, it grows quickly on a wide range of soil types and increases soil nitrogen levels by fixing atmospheric nitrogen (French, 2012). Gorse can reach a height where it can protect trees from roe deer within three years but, when the tree has reached maturity, the gorse will be shaded out (G. French, pers. com.). Although gorse can be established easily, it does not spread readily (G. French, pers. com.) unless the adjacent ground is disturbed (R. Thompson, pers. com.). Trees can be planted directly into existing gorse patches or a tree and gorse seedling can be planted alongside each other using gorse seedlings of 2-3 years old that have been pruned in the nursery to stimulate branching and spineyness. Gorse may mechanically damage some young trees when being blown in the wind (B. Black, pers. com.) but this can be reduced by pruning the gorse around the young tree (S. Watson, pers. com.). Of the common native trees species, rowan seems to be the most resistant to mechanical damage of this sort (B. Black, pers. com.). Further information on the use of gorse for natural protection can be found in Annex 1. At Mar Lodge, where browsing by red and roe deer has a damaging effect on tree regeneration, a trial started in April /May 2012 to investigate the potential protective effect of broom on birch trees planted in riparian areas (as well as on steep slopes and in different patch sizes; S. Rao, pers. com). Forty-nine trees of 40-60 cm tall were planted at two sites in each of a control (non-broom) area and within a stand of broom. The broom stands were open and about 60 cm in height. The planted birch trees will be monitored to find out

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whether the broom is having a significant effect on browsing rates or birch survival. R. Thompson (pers. com.) has planted ash amongst hawthorn. We are not aware of any other cases of the species listed above (other than gorse) having been used in the UK to protect planted trees however there are observations of all but dog rose providing protection from browsing (Table 1). Juniper and blackthorn grow slowly however (B. Black, pers. com.; G. French, pers. com.) and juniper is, itself, quite palatable. Gorse, where it is a feasible alternative, is therefore likely to be more suitable than juniper or blackthorn for establishing new patches of a potentially protective shrub. Gorse is, however, more likely to be killed during extreme winters (R. Thompson, pers. com.). Bracken occurs widely in Scotland, usually on relatively nutrient rich soils. It is probably not as good at protecting trees from browsing as the other species listed since it often grows in dense, tall stands that would shade out young trees. Humphrey & Swaine (1997) investigated the impact of bracken on the growth of young oak trees and concluded that ‘effective control of dense Pteridium stands is necessary to promote the successful regeneration of oak’. Its deciduous habit also leaves trees exposed over winter so it is only likely to protect trees from summer browsing. Dead bracken can also smother young trees (B. Black, pers. com.). Ash is probably the most resilient native tree species to bracken since it is shade tolerant, then hazel and oak (B. Black, pers. com.). Birch needs too much light to be able to survive amongst bracken (B. Black, pers. com.). Only very open stands of bracken are likely to allow young trees to survive and grow but the most open will not provide protection from browsing. However, J.Hall (pers. com.) has observed ‘a lot of rowan getting away within fairly dense stands of bracken at the Moy end of Creag Meagaidh National Nature Reserve, whilst trees outside of the bracken were being kept back by browsing’. The apparent effect of the bracken on browsing rates may, however, have been confounded by a soil effect since the bracken is likely to have been growing on patches of richer soil. In some situations, it may be feasible to break up bracken stands using cattle or pigs. Where dead wood is available, for example from felling, or thinning, of plantations, it can be used to protect naturally regenerated, or planted, young trees. It is clear from the relevant studies listed in Table 1, however, that the nature and height of the protecting dead wood needs careful consideration. Brash can protect young trees from browsing but it may also not allow them sufficient access to the soil and they may be subject to dessication (Truscott et al., 2004). Careful planting to ensure that roots have good access to soil, or planting on mounds, should overcome this problem (B. Black, pers. com.). Brash can also harbour the beetle Hylobius abietis, which can kill planted conifer, and sometimes also, broadleaved, trees (R. Thompson, pers. com.). Branches and logs can be used but their size will need to be appropriate to the type of deer present since larger deer are likely to be able to negotiate larger obstacles. Deer can also lean over obstacles to browse trees so the dead wood needs to extend to a sufficient distance away from the trees. At Balachuan, a nature reserve owned by the Scottish Wildlife Trust on Seil Island, near Oban, when Donald McVean was the manager 20 years ago, they coppiced hazel then used the wood to build 5 foot high, and very wide, brash barricades around about eight stools (B. Black, pers. com.). There were about fifteen roe deer present in 27 ha of hazel wood at the time. The brash rotted down and reduced in height quite quickly. The unprotected stools did not regenerate and the most heavily protected ones regenerated very well. The less protection there was, the less good was the re-growth but they did get away (B. Black pers. com.). We are not aware of clump planting having been trialled in the UK. This approach has the obvious disadvantage of having a high wastage of trees however relatively cheap, fast-growing species, such as willows, that can be easily grown from cuttings, could be planted on the outside of clumps (R. Thompson, pers. com.) protecting a less browsing resistant species of tree in the centre. Oak is sometimes found growing within birch thickets (B. Black, pers. com.). Since birch is relatively fast growing, and regenerates prolifically in some

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situations, it may be practical in some cases to use clumps of birch to protect planted trees of other species. The palatability of the protecting species in relation to that of the protected species is probably not important since the protecting trees are ‘sacrificial’ and are acting as a physical barrier. The protecting species does, however, need to be sufficiently unpalatable, or resilient, to browsing that it can maintain enough height growth to ‘keep up’ with the protected species (see http://www.forestry.gov.uk/forestry/INFD-8R9DG5 for detailed information on the relative palatability and resilience to browsing of Scottish native tree seedlings and saplings). Since this approach has not been trialled in the UK it is difficult to recommend clump sizes, spacings between clumps or spacings between trees within clumps. However, a suitable ‘clump’ might consist of up to 40 protecting trees planted about 20 cm apart around each protected tree (R. Thompson pers. com.). A space might be left around the protected tree to reduce the risk of it being out-competed by the protecting trees. Depending on planting objectives, clumps could be anything from contiguous, forming a large patch of protecting trees interspersed with protected trees, to very widely spaced. This approach depends on deer either not being able, or not trying, to reach the ‘protected’ trees. It is therefore likely that larger clumps of taller trees will be needed to protect trees from red deer than from the smaller roe deer.

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Table 1. Summary of published results and observations on the effectiveness of ‘natural protection’ for protecting young trees from browsing by large herbivores. Comments on the Conclusions are contained within square brackets.

Reference Location Browsing

animals Protecting species /feature

Protected tree species

Conclusions Did it work?

Bakker et al. (2004)

Three floodplain sites in the Netherlands, one in Germany and one in England (the New Forest)

Cattle, Horses

Blackthorn (Prunus spinosa)

Pedunculate Oak (Quercus robur)

Palatable, light-demanding pedunculate oak seedlings can successfully regenerate in the presence of large herbivores shrubs. This process does not offer protection from abundant small herbivores, such as rabbits.

Yes (not if rabbits present)

Bobiec et al. (2011)

Białowieża National Park, Poland

Red deer, European bison, Roe deer, Moose, Wild boar

Raspberry (Rubus idaeus), Aspen (Populus tremula), Hornbeam (Carpinus betulus)

Pedunculate Oak Most 0-5 m tall oaks (62%) grew without another woody plant species within 1 m radius. The remaining oaks (38%) were associated mainly with raspberry and saplings of hornbeam and aspen - all highly ungulate-preferred species. Associational resistance from unpalatable plants was not necessary to secure successful oak regeneration in woodlands subject to browsing by wild ungulates. This might be because of the abundance of highly attractive vegetation making oak relatively un-preferred by ungulates.

No (protection not needed)

Brooker et al. (2006)

Scotland Red deer Heather (Calluna vulgaris)

Scots pine (Pinus sylvestris)

Planting within heather reduced browsing rates. This effect was strongest at intermediate browsing intensities. There were no longer-term biomass gains for trees planted within heather so competition from heather out-weighed reduced browsing. [The trees in this study were below the height of the heather (R. Brooker pers. com.). Trees growing

Yes

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amongst heather are often protected until they emerge above the heather canopy at which point they are browsed (J. Hall, pers. com.)]

Casabon & Pothier (2007)

Anticosti island, Quebec, Canada

White-tailed deer

Woody debris Balsam fir (Abies balsamea)

Woody debris seemed to protect balsam fir seedlings from browsing 8 years after clear-cutting. This protection was likely to last until the seedlings grew taller than the woody debris.

Yes

French (2012) Rahoy hills, Morvern, Scotland

Deer, Sheep, Cattle

Gorse (Ulex europaeus)

Birch (Betula spp.) Other preferred tree species.

Gorse is useful for protecting young, broadleaved trees from browsing. It gets browsed in its first year but, thereafter, although it gets browsed in spring, it rarely succumbs. Young plants can be planted with young birch trees or seedlings can be planted within open birch stands. [If rabbits or voles are present, saplings can be protected with cut gorse branches put around the base of the sapling (G. French, pers. com.)].

Yes (need extra protection if rabbits present)

Garcia et al. (2000)

Sierra Nevada, Southern Spain

Chamois, Goats, Sheep

Shrubs Yew (Taxus baccata)

The estimated density of the yew in the study plot was 287.9 individuals ha-1, more than 90% being juveniles (seedlings and saplings), which were mostly located under fleshy-fruited shrubs. Saplings suffered serious herbivore damage when unprotected by shrubs.

Yes

Gómez et al. (2001)

Sierra Nevada, Sierra de Baza, Spain.

Goats, Ibex, Sheep

Spiny shrubs Scots pine The pines only regenerated successfully when surrounded completely by shrubs. This was an arid area so the shrubs were the main forage source. Saplings growing next to shrubs, but not surrounded by them, were browsed more than those further away from shrubs but the ones in open areas tended to die from drought.

Yes

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The saplings adjacent to shrubs were just as likely to be browsed if the shrub they were growing next to was spiny than if it was not.

Graham et al. (2010)

North America Deer Woody debris Various species Leaving 10–15 metric tons of large (>8 cm diameter) woody debris ha-1 has been shown to decrease forage utilization and, in turn, decrease damage to planted seedlings. Creating heterogeneous forest floor, tree, woody debris and ground-level vegetation complexes will also minimize animal concentrations and subsequent seedling damage.

Yes

Hamard & Ballon (1998)

Nogent-sur-Vernisson, France

Roe deer Woody climbing plants

Red oak (Quercus rubra)

Planting and maintaining accompanying woody climbers appears to be an efficient means of preventing browsing. ‘Protected’ trees are thinner and more elongated than non-protected trees.

Yes

Harmer et al. (2010)

Beech woodland, central-southern England

Roe deer (75%) Muntjac (10%) deer Fallow deer (15%)

Bramble (Rubus fruticosus)

Birch, Willow (Salix spp.) Oak

For birch and willow, there were significant positive relationships between seedling height and diameter and bramble cover and heights, indicating that bramble facilitates the establishment of both species. Bramble reduced the incidence of browsing. Both the proportion of birch browsed and seedling mortality were lower than for willow, which was browsed even in a dense bramble thicket >60 cm tall with a cover of c. 60 per cent. If a bramble thicket or other shrubs develop before young oaks have established, then new oak seedlings are unlikely to establish from acorns due to the adverse effects of small mammals.

Yes

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However, plants may grow and establish if they are transplanted into areas with bramble or they occur at the advancing edge of a thicket. If seedlings had not grown in the first year after thinning, then the failure of willow and birch to regenerate in the later years would lead to the conclusion that bramble does not facilitate their regeneration. Within woodlands, the tree species most likely to benefit from any protective effect that bramble may have against browsing animals are those that are fast growing (such as birch, willow and ash) and begin their establishment either before or at the same time as the thicket. In contrast, oak and beech are less likely to establish: these species grow slowly and are unable to compete with the growth of the bramble and their seeds are a favoured food of small mammals which can thrive in bramble thickets. [In Scotland, bramble generally grows more slowly than in lowland England and, since it is very palatable to deer, it is rare to find bramble thickets (R. Thompson, pers. com.)]

Jensen et al. (2012)

Southern Sweden

Large ungulates

Shrubs Pedunculate oak The probability of a seedling being browsed (browsing frequency) was approximately 20% lower for individuals growing among shrubs than for individuals growing in the absence of shrubs. When browsing did occur, the intensity (measured as a reduction in height growth) was significantly lower for

Yes

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seedlings in shrubs. Browsing intensity decreased if the seedling grew in tall and dense shrubs. Browsing frequency and intensity increased on oak seedlings that over topped the shrub canopy. Increased abundance of the spiny raspberry and bramble in plots with shrubs did not affect browsing frequency and intensity. Two and a half years after planting, oak seedling mortality was increased by the presence of shrubs. Although shrubs restricted oak seedling growth, we conclude that shrubs initially facilitated oak regeneration by concealment, and subsequently by numeric dilution i.e. the presence of a high number of neighbouring plants. Shrubs may be used to reduce browsing damage if long-term evaluation indicates a net positive outcome for oak survival and growth.

Kuiters & Slim (2003)

Dutch-Belgian border

Icelandic ponies

Bramble

Pedunculate oak Alder buckthorn (Frangula alnus)

Woody regeneration was encountered at several places on the former arable fields. Highest densities were found within patches of bramble, heather or soft-rush. Bramble especially was found to facilitate the regeneration of browse-sensitive species, i.e. pedunculate oak and alder buckthorn. All saplings taller than 100 cm (oak) or 200 cm (buckthorn) were associated with bramble shrub. Rabbits were at very low densities (<1 animal per ha).

Yes

Kupferschmid & Bugmann (2005)

Swiss Alps Chamois, Roe deer Red deer

Logs Norway spruce (Picea abies)

Shrubs and logs did not reduce the browsing intensity. In contrast, more Norway spruce saplings were browsed

No

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close or under logs than far away from logs at the montane level. Hence, logs cannot be considered as obstacles for chamois in these snag stands.

Madsen et al. (2007)

Denmark Red deer Roe deer, Fallow deer, Sika deer

High density of saplings

Silver fir (Abies alba), Pedunculate oak Sessile oak, Rowan (Sorbus aucuparia)

Both the literature and practical experience show that densely stocked regenerations are more robust against deer browse than sparsely stocked regenerations (Reimoser & Gossow, 1996). Species that are highly preferred by the deer like silver fir, oak (pedunculate and sessile) and rowan have a better chance of avoiding browsing if growing in dense clusters than as single trees.

Yes

Miller et al. (2006)

Australia Native marsupial herbivores

Thistles Blue gum (Eucalyptus globulus)

Repellent-treated seedlings received less browsing than those without repellent; and browsing decreased with increasing thistle cover. The presence of thistles also increased the time it took for browsers to find seedlings. Results are consistent with the associational plant refuge hypothesis, and vegetation effects may be manifested via an alteration in plant apparency. They demonstrate the principle that the use of less palatable seedlings combined with tall, unpalatable vegetation can reduce browsing on plantation seedlings in the short-term, and that the effects are additive. [Note that this is also relevant to repellents and to the argument that it pays to combine approaches.]

Yes

Morgan (1987) New Forest, Hampshire, England

Various large herbivores

Holly (Ilex aquifolium)

Various broadleaf species

Regeneration rates are low throughout the woodlands but appear to match broadly with the principal variations in the light regime of the woodland floor. This is

Yes

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reflected in the spatial distribution of seedlings of the different species. Other influences are also apparent, in particular that of holly understoreys. In some instances the understorey constributes to the shade pressure on seedlings, whilst in others it appears to act as a nursery for certain species, probably by protecting against browsing.

Morgan (1991) New Forest, Hampshire, England

Various large herbivores

Holly, Fallen branches, Logs

Beech (Fagus sylvatica) Pedunculate oak Sessile oak

Older seedlings appeared to be located in or near areas of young holly understorey, or near fallen branches, logs, etc.

Yes

Pellerin et al. (2010)

Eastern France Roe deer Red deer

Woody debris Silver fir Oak spp.

The use of woody debris as protection against browsing by deer did not limit damage to seedlings and saplings of the main commercially valuable species, silver fir and oak. Instead of limiting deer impact, use of woody debris seemed to increase the negative effect of deer browsing on regeneration relative to those without protection.

No

Pietrzykowski (2003)

South-eastern Australia

Red-bellied pademelon, Bennett’s wallaby, Brushtail possum

Bracken (Pteridium aquilinum), Shrub

Radiata pine (Pinus radiata)

Browsing of radiata pine was higher in palatable short vegetation (grass), intermediate in high-quality tall vegetation (perennial herb: Lomandra longifolia) and least in low-quality, tall vegetation (bracken and shrub).

Yes

Ripple & Larsen (2001)

Yellowstone National Park, USA.

Red deer (elk)

Coarse woody debris

Aspen (Populus tremuloides)

Aspen suckers protected from elk by fallen conifer barriers were on average over twice the height of adjacent unprotected suckers (subjected to elk browsing). These results illustrated the role that fallen conifers can play in aspen regeneration.

Yes

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Rousset & Lepart (1999)

Calcareous grassland, Southern France

Cattle Box (Buxus sempervirens), Juniper (Juniperus communis)

Pubescent oak (Quercus humilis)

The shrubs improved pubescent oak regeneration by protecting individuals from grazing.

Yes

Sanderson (1996)

New Forest, England

Various large herbivores

Fallen trees Various broadleaf species

Some trees will regenerate even under quite heavy grazing if there is cover from e.g. fallen trees.

Yes

Smit et al. (2006)

Wooded pasture, Switzerland

Cows, Horses

Great yellow gentian (Gentiana lutea), Dwarf thistle (Cirsium acaule)

Norway spruce Great yellow gentian is chemically defended, dwarf thistle is mechanically defended. 5 and 10 cm tall Norway spruce trees were used. Sapling survival was significantly higher near unpalatable plants where grazing intensity was significantly lower. The thistle provided more protection than did the gentian. Protection against cattle is particularly important for small saplings. Transplanting tree saplings near unpalatable plants could be an alternative reforestation technique in intensively grazed wooded pastures.

Yes

Smit et al. (2012) Białowieża National Park, Poland

Red deer, European bison, Roe deer, Moose, Wild boar

Coarse woody debris

Pedunculate oak Coarse woody debris plays an essential role for the recruitment of oaks in old-growth temperate forest systems, predominantly via protection against ungulate browsing.

Truscott et al. (2004)

Clear-felled plantation on Atlantic oakwood site, Glen Nant, Scotland.

Deer, Sheep

Brash Sessile oak Brash left in lines after felling protected seedlings against browsing by herbivores, with the depth of brash affecting the probability of browsing. Browsing rates on seedlings planted in brash were about half those on seedlings not planted in brash six

Yes

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months after planting. However, survivorship and performance over two years was lower for seedlings planted in the brash than for seedlings planted in the clear area between brash lines. Probable causes were water and nutrient limitation, the acidity of the brash, and shading. It may be that seedlings planted in the brash suffered because of inadequate root penetration. If brash is to be left, consideration needs to be made of the optimum depth and width of the brash lines to be left, and how this is affected by the size of the branches and trunks constituting the brash.

Van Uytvanck et al. (2007)

Wood pasture, south Flanders, north Belgium

Cattle, Horses, Rabbits

Bramble thickets, Tall sedges (Carex spp.), Soft rush (Juncus effusus) tussocks, ruderal vegetation with unpalatable or spiny species

Pedunculate oak, Ash (Fraxinus excelsior)

Bramble thickets were suitable safe sites for survival and growth of seedlings of both species, however rabbits may undo the nursing effects of bramble thickets. Tall sedges, soft rush tussocks and ruderal vegetation with unpalatable or spiny species provided temporal protection, allowing seedlings to survive.

Yes (not if rabbits present)

Vandenberghe et al. (2009)

Jura mountains, Switzerland

Cattle Sweet briar (Rosa rubiginosa)

White pine (Abies alba), Norway spruce, Sycamore (Acer pseudoplatanus), Ash

1.5 m tall sweet briar was planted. Saplings were planted next to a sweet briar or 1.5 m away. All species of sapling benefited in terms of sapling growth and browsing frequency from the nurse species. The less resistant coniferous saplings benefited significantly more from nurse shrubs than the more resistant

Yes

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deciduous species in terms of growth of the surviving saplings, but not in terms of overall survival. At high grazing intensity facilitative effects of the nurse shrubs decreased, especially for the coniferous species.

Watt (1919) New Forest, Petworth Park, sourthern England

Deer Ponies, Cattle

Holly, Blackthorn, Hawthorn (Crataegus monogyna), Gorse

Pedunculate oak Sessile oak

In the New Forest, saplings were found growing up among the protecting branches, usually near the periphery of clumps of holly, blackthorn and hawthorn. It was not uncommon to find a large oak standing in the centre of such a clump. This phenomenon has been recorded by numerous observers for trees in general. At Petworth, a few oaks were coming up amongst gorse.

Yes

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2.3 Habitat modification /diversionary feeding

Deer make choices about what to eat at the landscape and at the patch scale. At the landscape scale they choose patches that provide them with the best quality and quantity of forage, with the best shelter in poor weather conditions or with the best hiding conditions if they feel threatened. At the within-patch scale, they choose to eat plants that provide them with the highest intake of digestible energy or with particular nutrients that they need. At the landscape scale deer can be attracted to particular patches, hence away from other patches, by increasing the attractiveness a patch. If forage is the main attractant for deer e.g. in mild weather conditions, when they do not need to seek shelter, and when their behaviour is not being affected by culling, increasing the provision of forage in one patch can divert them away from another. Miles & Kinnaird (1979) commented:

Suggestions have been made for the use of diversionary feeding e.g. sowing and fertilising patches of grass, and winter feeding, as a means of controlling grazing. Kinnaird (unpublished) has recorded negligible browsing of Betula pubescens saplings at Inverpolly National Nature Reserve during a year when weather encouraged vigorous and sustained growth of herbaceous vegetation compared to that found in both earlier and later years. This suggests that in most years supplementary winter feeding might reduce browsing damage. Red deer are often fed with artificial foods in winter, and large reductions in damage to trees have been reported (Ueckermann, 1960; Strandgaard, 1967; König, 1970). However, several instances are known of severe browsing by red deer even when feed was given.

Additional forage can be provided directly or through habitat modification. A number of ways of achieving this are possible e.g.: Providing glades within woodlands on good soils that support high quality ground

vegetation. This can not only provide additional forage but also facilitate culling, and increase biodiversity. This approach is routinely used by Forestry Commission England to achieve all three objectives (N. Healy, pers. com.). Forestry Commission Scotland routinely create glades in areas with high quality vegetation, largely to facilitate culling. In some cases this may also assist with diverting deer from the crops /habitats requiring protection (I. Fergusson, W. Lamont & C. Lavin, pers. com.). This approach will probably only work where the glade is on good soils and the young trees to be protected are on relatively poor soils where only relatively poor quality forage is available.

Thinning plantations to encourage ground vegetation growth. Grazing cattle on areas dominated by rough grasses, such as matgrass (Nardus stricta)

or purple moor grass (Molinia caerulea). Through their grazing and trampling of these grasses, the cattle will open up the vegetation and encourage the growth of more nutritious and palatable plant species (Grant et al., 1996a; Grant et al., 1996b; Common et al., 1998; Wright et al., 2006). Trampling by cattle can also reduce the cover of bracken. This can be encouraged by placing feed, or nutrient, blocks in areas of dense bracken (H. Armstrong pers. obs. ). Pigs, at low density, or for a short period of time, might achieve a similar effect.

There are, however, several reasons why supplying extra forage in one area may not deflect deer from regenerating trees in another area: The extra forage is located too close to the young trees so the browsing pressure is

increased by attracting more deer to the area. The extra forage must therefore be located well away from the regenerating trees.

The provision of extra forage increases the carrying capacity of the landscape so a higher density of deer can be supported. Culling of deer is thus essential if diversionary feeding is being attempted.

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Even with the extra forage the deer are still hungry enough to search all patches for food and to eat young trees. This might occur, for example, where ground vegetation is sparse or of poor forage quality, or during a hard winter when snow covers the ground vegetation for long periods and the leaders of young trees are above snow height. Additional habitat modification /diversionary feeding may help in this case.

The deer are drawn to the patches where the young trees are located for other reasons than hunger i.e. shelter, hiding or particular nutrients. If, for example, trees are regenerating in the only patch of woodland in an otherwise open landscape then it is likely that deer will spend considerable amounts of time sheltering in the woodland regardless of the amount of forage on offer elsewhere. In this case diversionary feeding by any means is not appropriate.

At the within-patch scale a high availability of alternative, palatable forage can also deflect deer from young trees (Ward et al., 2008) as long as it does not attract deer to the patch thereby increasing the overall browsing pressure to the point where the deer are hungry enough to eat both the trees and the alternative forage. Leaving clearcut areas fallow for a few years to allow re-vegetation before planting is a strategy used by Forestry Commission England (N. Healy, pers. com.). The competitive effect of the additional ground vegetation may, however, have a detrimental effect on the regenerating trees. Forestry Commission England have also tried planting, or leaving, sacrificial trees around the edges of clearcut blocks. In Kielder forest district, however, when they tried sacrificial planting of Douglas fir (Pseudotsuga menziesii), both the Douglas fir and the crop trees were ‘hammered’ (D. Howison, pers. com.). The soils in Kielder district tend to be acidic, supporting a ground vegetation of low nutritional value to deer (Ward et al., 2008) hence the sacrificial Douglas fir did not protect the crop species presumably because the deer were still short of food, even with the provision of the extra forage. In Scotland, diversionary feeding either directly, or through habitat modification, has the potential to reduce deer browsing on trees at both the landscape and patch level as long as the conditions are suitable (see above). However, it may not always be possible to determine the suitability of the conditions before applying the approach so it may not always be successful. 2.4 Bud protectors

Bud protectors are materials that are attached to the leading shoot (and possibly other shoots) of a tree that deter deer from browsing on the shoot. They come in a variety of types and materials. Although one type of bud cap is designed to move up with the shoot as it grows (Terminalschutzkappe, see 2.4.3), all other types have to be replaced at the end of each growing season. 2.4.1 Sheep’s wool

Raw sheep’s wool is used in Germany to protect shoots of conifers and broadleaves (Fig 1). A small amount of wool is attached to the shoot. Whether it will work or not with broadleaves depends on how well it can be attached to the shoot. FCH 2010(ME) is a product sold by the German company, Grube (http://www.grube-shop.at/de/fch_2010_me), specifically as an adhesive to attach sheep’s wool to tree shoots to protect them from browsing (J. Haufe, pers. com.). Since FCH 2010(ME) is not a pesticide, it will not need to be registered as such nor will experimental approval be needed for it to be used in the UK. Nevertheless, before trialling it in the UK, it will be essential to confirm that, were it to be ingested by a deer, it would not affect venison quality or saleability. We are not aware of sheep’s wool being trialled in the UK. Raw wool is cheap and light and, as such, if it works in the UK, it could potentially be a very useful tool where labour is available to place the wool on the shoots once per year until the trees have grown above deer height. The wool is attached to the

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leading shoot at the end of the growing season and protects it from browsing over winter. To protect a growing shoot during summer wool would have to be re-applied at regular intervals making summer protection impractical in most circumstances.

Figure 1. Wool placed on Norway spruce (left) and on beech (right) shoots to protect them from deer browsing).

2.4.2 Paper /tinfoil bud protectors

U.S.D.A. (2007) documents how to make, and deploy, bud protectors:

The bud cap itself is a simple device consisting of a piece of paper wrapped around the leader, covering the terminal buds. Covering about ⅓ to ½ of the plants is usually as effective as covering every single plant. Put more around edge rows than middle rows to keep deer from entering the planting [if being applied to a block planting]. Use lightweight paper such as computer or typing paper cut into 4" x 6" pieces (quarters) so the caps are light enough that they do not cause the leader to bend over due to the weight of the bud cap. Other bud capping materials include: office paper, computer paper, old forms printed on card stock, index cards, envelopes, waterproof paper, tin foil, and plastic mesh or netting [see below] among other materials. The bud cap should be stapled in at least 3 places forming a tube. The staples should catch some needles to hold it in place. Trees should be at least 1½ feet tall or have a sturdy leader if shorter, before bud caps are applied. A strong leader is important or the weight of the cap, particularly when wet, may cause the leader to droop thereby deforming the tree. Terminal buds should be about ½ inch below the top of the bud cap. Ideally this protects the terminal bud while still allowing the tree to grow through the paper during the next growing season.

U.S.D.A. (2007) also reports:

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Other than deer learning to pull them off and being limited to conifer plantings; disadvantages include premature deterioration of the paper type bud caps from excessive moisture, bending or disfigurement of the terminal leader, regular or annual reapplication, aesthetics and incompatibility with some land uses.

Given Scotland’s high rainfall, bud protectors made from paper, even if waterproof, are likely to deteriorate quickly so may not be suitable for Scotland. A trial with waterproof paper bud protectors may, however, be warranted. 2.4.3 Plastic bud caps

The German company PlantaGard produces two types of plastic bud protector: The Terminalschutzkappe. This is a small, red, plastic cap with four legs that cling to

conifer shoots (Fig 2). The top of the cap has a hole in it to facilitate air flow. The cost is €85.5 for 1,000. (http://www.grube-shop.at/de/Fachkatalog/Forstschutz/Pflanzenschutzmittel/Mechanischer-Pflanzenschutz/PlantaGard-Terminalschutzkappe).

The CactusPro. This is a blue plastic clip with three 20 cm long ‘whiskers’ at the top (Fig 2). The clip is attached to the needles of a conifer shoot. The cost is €199 for 1,000. (http://www.grube-shop.at/de/PlantaGard-Cactus-Pro)

Figure 2. The Terminalschutzkappe (left and centre) and the CactusPro (right).

The Terminalschutzkappe is designed for conifers with ‘hard’ shoots, such as spruce trees, and is meant to move up with the shoot as it grows. Four of these caps were put onto Norway spruce saplings in the Forest Research nursery near Roslin in summer 2011 (C. Edwards, pers. com.). All four came off (probably blown off) as the shoot extended and the cap became less securely attached (C. Edwards, pers. com.). A larger, and more controlled, trial would be needed to be test this bud cap properly under Scottish conditions. It is not likely to work for Scots pine saplings, however, since Scots pine buds are more pointed than those of spruces or firs and the needles are longer. A similar bud cap could potentially be designed that would work for Scots pine but the development and testing of such a bud cap would entail considerable time and resources. The CactusPro has to be moved up the shoot at the end of of each growing season until the tree is above browsing height. The blue colour apparently deters deer more than do other colours. There is no obvious reason why it would not work for Scots pine. As such, it has potential for use in Scotland, although its ability to withstand Scottish weather conditions would need to be tested.

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2.4.4 Netting bud protectors

There are various companies in the USA that make plastic mesh bud protectors including: Pacforest supply company who market the ‘Breathe Easy’ bud cap (Fig 3;

http://www.pacforestsupply.com/index.php?cPath=4_18). Itasca Greenhouse Inc. sells both stretch (Tiller stretch net) and non-stretch (bud cap

net) netting from which bud protectors can be made. (http://www.itascagreenhouse.com/page21.html)

Figure 3. The ‘Breathe easy’ bud cap at installation (left) and in the second season (right).

Plastic mesh bud protectors are put over, or around, the leading shoot of conifers and can also be stapled to themselves at the base (Fig. 3) and to the needles to hold them on more securely. The ‘Breathe Easy’ bud cap is UV-degradable so will fall apart by the time that new growth starts the following summer. At this point the new shoots push through the top, and out of the sides, of the bud protector. Bud protectors of this sort can be applied before, at the time of, or after planting or to naturally regenerated trees. This type of bud protector has the potential to be used in Scotland to protect trees from winter browsing where the labour is available to apply new bud protectors after every growing season until the trees are above deer height. They are probably not suitable for broadleaved trees although it may be worth trialling their use if a way can be found to securely attach them to the leading shoot without harming the tree. 2.5 Chemical repellents

Repellents work by having a scent or a taste that deters deer. Repellents can either remain on the surface of the plant or be taken up by the plant to become systemic. Some repellents, such as capsaicin (derived from chilli), are also irritants. Repellents, both non-systemic and systemic, have to be re-applied to protect new growth. U.S.D.A (2007) summarizes the factors affecting the efficacy of repellents:

The efficacy depends on the intrinsic palatability of the crop plant compared to the desirability or availability of any alternative forage plants. If a plant is particularly desirable to deer, it may be consumed regardless of the repellent. Chemical repellent effectiveness depends on:

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palatability of the protected plant, population density and number of animals, mobility of the problem animals, availability and palatability of alternate forage, weather, amount, concentration [and effectiveness] of the repellent. Chemical repellents work best when palatable alternate forage is

available or is made available nearby. U.S.D.A. (2007) reported that, in published studies, no repellent completely prevented browsing by deer. They also found that it was very important for there to be alternative palatable forage available to the deer since hungry deer were much more likely to feed on repellent-treated plants. They reported that chemical repellents are more effective on less palatable plants than on highly palatable plants. Repellents are therefore more likely to work on relatively less palatable tree species such as Scots pine, juniper, birch, hawthorn, beech and alder than on more palatable species such as aspen, willow, ash, rowan, hazel or oak (see http://www.forestry.gov.uk/forestry/INFD-8R9DG5 for more detailed information on the relative palatability and resilience to browsing of Scottish native tree seedlings and saplings). Trials of a wide range of repellents carried out by Harry Pepper at Forest Research between 1965 and 1998 gave the following results: Scent aversion tends to be ineffective; taste aversion works better. Irritants are the best deterrents but tend not to get approval under the Chemicals

Regulation Directorate (CRD). If systemic repellents did not change the appearance of a plant, then deer would eat

some of the plant before being deterred. Nearly all the repellents tested did not live up to manufacturers’ claims. Repellents have to be extremely good to prevent deer browsing trees when ground

vegetation is covered with snow. None of the four repellents currently approved for use in the UK was very effective. The

four approved repellents are: Curb Crop Spray powder, Liquid Curb Crop Spray, Rezist and Sphere ASBO. All are based on aluminium ammonium sulphate.

Cervacol Extra is used on the Continent. It is very thick and goes hard once it has been applied so it often pulls the leading shoot down. In Germany and Austria hunters are responsible for deer damage. Since fences restrict the deer range they are more willing to use repellents than are deer managers in the UK.

Getting approval for use in the UK entails carrying out very expensive, large scale trials. Since the potential market in the UK is not very large, there are only the four approved repellents mentioned above. To become registered, not only does the repellent have to be shown to be ‘safe’ it also has to be shown to be effective if it is to be sold as a repellent. If a chemical is registered in another EU country, especially if it is in the same zone (the UK, Germany and Austria are all in the central zone) then, under ‘mutual recognition’ rules, getting a chemical registered in the UK will probably be an administrative task rather than requiring new trials (I. Rowland pers. com.). The applicant would, however, need to address whether there is a difference in the circumstances of use between the country in which it is registered and the UK. Anyone wanting to trial a repellent that is registered in another EU country, but not in the UK can, however, apply for experimental approval (see www.pesticides.gov.uk for further information on applying experimental approval). This is a relatively inexpensive, administrative, task. The repellent can then be trialled over a limited area (5 – 10 ha). A new repellent (TRICO) is currently listed in the catalogue of the German forestry equipment company Grube (http://www.grube-shop.at/de/TRICO-der-natuerliche-Verbiss-

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Schutz-fuer-Sommer-und-Winter). TRICO presumably came on the market after the Forest Research work was completed. The makers claim that it offers all-year browsing protection for broadleaves and conifers alike, is based on sheep fat, is Forestry Stewardship Council certified, and is approved in Germany and Austria until 2020 (this is beyond the approval period of most other products; J. Haufe, pers. com.). Since TRICO is based on sheep fat, it is probably safe to enter the food chain and is therefore unlikely to affect the saleability of venison. TRICO is potentially a repellent that would be worth trialling in Scotland with experimental approval from the CRD but confirmation would first need to be obtained from the makers that, should it be ingested by a deer, it would not affect the quality or saleability of the venison. Plant nutrients do not need approval by the CRD. ‘Grazers’ is a plant nutrient (calcium chloride solution), developed and sold by a British company, that is also reputed to repel vertebrate herbivores (http://www.grazers.co.uk/). It does not taint the meat of animals that eat it and is, in fact, safe to spray directly onto human food crops. CRD are aware of Grazers and accept that, since it is marketed as a plant nutrient, it is outside the scope of pesticide regulations and therefore does not require registration. Grazers is applied by spraying onto the plant during the growing season. It is then taken up into the plant becoming systemic. The effects last about 6 weeks during which time it protects the tree. If sprayed monthly throughout the growing season it will build up and remain in the plant. Heavy rain will dilute it in the plant which may then require extra applications. Trees would need to be monitored regularly, especially during times of heavy rainfall, to determine if re-applications would be necessary. It is used routinely on conifers in Christmas tree and forestry plantations and commercial nurseries. Conifers sprayed monthly during the growing season are likely to remain protected during the winter because the chemical will remain in the needles. In broadleaved trees, Grazers would also need to be applied monthly and is likely to only protect trees during the growing season. Given the lack of approved repellents available in the UK and the relative ineffectiveness of the four that are approved, it appears that Grazers is the only substance obtainable in the UK that is likely to be of use in assisting in getting trees established in Scotland without fences. However, Grazers is not registered as a repellent and can only be trialled as such after experimental approval has been obtained from the CRD. It will only be of use: where it can be applied monthly during the growing season on broadleaves where most of the browsing by deer is in summer on conifers where browsing is in summer and/or in winter although its effectiveness over

winter needs to be tested As such, it is likely to be useful only over small areas and where significant staff resources are available. If the makers of TRICO can supply information to support its likely effectiveness in Scottish conditions and to confirm that it does not affect the saleability of venison from deer that have ingested it, then it, too, may warrant being trialled in Scotland with experimental approval. 2.6 Summary of recommendations for Scotland

Sabre planting, especially if combined with planting within protective vegetation, such as gorse, blackthorn or bracken (but see the bullet point below for the limitations of using bracken), has potential for Scottish conditions. The main limitations of the technique are that trees of at least 1 m tall are needed to ensure that leading shoots cannot be browsed by roe deer and that it can only be used on slopes of more than 30-40°, although, where roe are the only deer species present, careful inspection can reveal suitable micro-sites for sabre tree planting on less steep slopes. To date, the method has not been trialled in areas with red deer present. In such areas, it will not normally be

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possible to plant trees tall enough to avoid browsing, even if sabre planted. Instead planting will need to be in micro-sites that are relatively inaccessible to deer.

The plant species that are likely to be most suited to providing natural protection to young trees in Scotland are gorse, blackthorn, hawthorn, dog rose, holly, juniper, broom, bramble and raspberry. Of these, gorse is probably the least palatable and the fastest growing and has been most widely trialled. Gorse grows well on a wide variety of sites and fixes nitrogen. Young gorse plants can be planted alongside young trees or trees can be planted into gorse stands (packed around the base with cut gorse stems in areas with rabbits). At sites where gorse is not a suitable species, other species can be used but there will be a degree of trial-and-error involved given that their use has not been trialled in Scotland (although there is evidence of them allowing the establishment of naturally regenerated trees). Bracken can provide protection to young trees but is only likely to do so successfully where most of the browsing occurs in summer, the bracken stand is short and open and the tree species is shade tolerant and has a robust shoot.

Dead wood can be used to protect young trees from browsing but the type of dead wood used needs to be suited to the herbivore(s) present and care needs to be taken that the trees have adequate access to the soil.

Clump planting has the potential to work in Scotland. This approach might involve using fast growing, relatively easily established species that are also relatively unpalatable, e.g. alder, or browsing resilient, e.g. willows, planted on the outside of clumps to protect more palatable, less resilient, or hard to establish, species in the centre of the clumps. A space should be left around the protected trees to reduce the risk of them being out-competed by a faster-growing protecting tree. Alternatively, more sensitive tree species could be planted amongst trees that have naturally regenerated in dense thickets, as is often found with birch.

Diversionary feeding either directly, or through habitat modification, and in combination with culling to control deer numbers, has the potential to reduce deer browsing on trees at both the landscape and patch level as long as the conditions are suitable. However, this approach is only likely to work if: o Sufficient culling is undertaken to ensure that deer numbers do not increase as a

result of any increase in deer recruitment or survival rates that result from the provision of additional feed.

o The divisionary feeding takes place some distance from where tree regeneration is wanted.

o There is sufficient forage available, whether diversionary or otherwise, when the young trees are likely to be browsed, to deflect the deer from the trees.

o The area where tree regeneration is wanted is not an area that deer use for shelter in winter.

Bud protectors have the potential to be used in Scotland where the labour is available to replace them on the leading shoot once per year. They have not been trialled in the UK and, as such, any use in Scotland would have an element of trial and error. The bud protectors most suited to Scottish conditions are likely to be: o Sheep’s wool, which can be used to protect conifers, and potentially also

broadleaved trees, over winter. o The CactusPro plastic bud cap, which can be clipped onto conifer leaders at the end

of the growing season to protect them over winter. It has to be moved up once per year at the end of each growing season.

o Plastic mesh bud protectors that are stapled to the needles of the leading shoot of conifers at the end of each growing season. It may be possible to find a way of attaching these to broadleaved trees as well as to conifers.

The only substance available in the UK that is currently likely to be worth trialling in Scotland as a repellent is calcium chloride solution (Grazers). Since it is designated a plant nutrient and is non-toxic, it does not need CRD approval but does need experimental approval to be trialled as a repellent. It is systemic so has to be applied

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during the growing season but, if applied monthly during summer, has the potential to protect conifers over winter and broadleaves during summer. TRICO is a repellent based on sheep fat that is available from, and registered in, Germany, It may also be suitable for trials in Scotland once experimental approval has been obtained.

In many cases, the effects of different approaches are additive and combining them may provide the best results (Miller et al., 2006; U.S.D.A., 2007). Given the lack of trialling of any of these approaches in Scotland, however, trials using just one approach at a time would be worthwhile initially so that the efficacy of each approach, under different conditions, can be judged.

The most suitable approach for a particular situation will depend on the: o species of deer, and other herbivores, present, o attractiveness and accessibility to deer of the areas where deer browsing is an issue, o season of most intense browsing, o species and height of trees to be protected, o potential for habitat modification, o availability and type of planting stock, o available labour and financial resources, o accessibility to people of the areas where deer browsing is an issue

Non-fence tree protection is most likely to be successful where deer browsing pressure is not at its most intense (U.S.D.A., 2007) hence sites where deer are being heavily culled are likely to be the most suitable.

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3 PRACTICAL TRIALS ON CREAG MEAGAIDH AND BEINN EIGHE NATIONAL NATURE RESERVES FROM 2012/13 TO 2014/15

3.1 Beinn Eighe

The Beinn Eighe Habitat Management Plan (S.N.H., 2009) focuses on key elements and management requirements to enhance the designated features, including the Caledonian Forest, that are currently in unfavourable condition. In the Plan, the woodlands have been zoned according to type and their associated management requirements to achieve the long-term priorities of:

Increased woodland connectivity from the north east to the south west end of the reserve.

Enhanced “natural” woodland structure including increased: tree species diversity, tree regeneration, deadwood, understorey and ground flora diversity and integral open space.

The woodland management zones listed below have the potential to be used for trials of no-fence tree regeneration techniques. All the zones are located within the High Priority Zone for deer. Note that the authors have not visited the sites and the information below comes from discussions with SNH site managers (P. Duncan and E. Maclean). 3.1.1 Plantations

Compartment 8 (12.2 ha) (Figure 4) was planted between 1960 and 1969 and thinned during the early 1990s. It has reasonable numbers of relic veteran trees, and some standing deadwood but very little fallen deadwood (S.N.H., 2009). Management objectives for this area include: Increasing the amount of deadwood, both standing and fallen, with the latter left as large

lengths in the wood. Enhancing tree species diversity through a combination of releasing areas of

regeneration as well as planting (especially juniper, aspen and oak) in appropriate areas. The development of a shrubby understorey in areas of the plantations which are

sufficiently open for holly and rowan. Detailed techniques listed by Clifford & Clifford (2012) for creating fallen deadwood in this compartment over the next 5 years have the potential to create areas of natural protection by:

Felling whole trees in a triangular shape to create corrals to facilitate and protect regeneration from browsing.

Winching whole trees over to mimic windthrow. The deadwood could be used to protect both existing native regeneration, including Scots pine, birch, willow and holly, as well as enrichment planting of species more susceptible, or less resilient, to browsing, for example, oak, aspen and rowan. These species could be planted along with juniper, gorse and eared willow to provide continued natural protection as the deadwood decays. Possible areas to trial deadwood as a natural protector include: densely stocked areas (sub-compartments 1E, 1G & 2D) where the management

recommendation is the creation of 2 to 4 m³ year-1 of dead wood, utilising trees with a minimum dbh of 15 to 20 cm.

sub-compartments 1B, 1F & 2B where the recommendation is to bring in deadwood logs (Clifford & Clifford, 2012).

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There is potential to combine the natural protection approach with the following techniques: Bud protectors - both sheep’s wool, with and without adhesive (FCH 2010 ME), and

plastic caps (CactusPro) could be trialled both within and outwith these natural protection corrals.

Sabre planting by utilising suitable planting micro-sites within areas of natural protection e.g. on the sides of hummocks (see section 2.1).

Figure 4. Beinn Eighe NNR – proposed locations for trialling establishment of trees without fences (north section).

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3.1.2 Recent planting and areas for further woodland expansion

Previously a commercial forestry plantation, Compartment 2 (Figure 5) was felled in the 1990’s and replanted in 2004 using local provenance Scots pine with birch, alder and juniper. Over the years naturally regenerated birch has established in the restock resulting in an almost equal mix of birch and Scots pine (E. Maclean pers. com.). The top edge is straight and further work is needed to improve it visually by expanding the woodland up the hillside; this will include planting some of the knolls with Scots pine and planting alder and willow in the wetter areas, to give it a natural appearance (S.N.H., 2009). At the west end of Compartment 2 (NH003584) to the edge of Compartment 16 (NG980578), the Coulin link (Figure 5) has been identified as one of the areas to plant to enhance woodland connectivity from the south west to the north east of the reserve (S.N.H., 2009). A vegetation survey has recently been completed for this area (E. Maclean pers. com.). The application of Grazers as a chemical repellent, sprayed on the Scots pine plants monthly during their second summer in the tree nursery, could afford some individual protection as a result of a build up of the active ingredient in the needles when planted out the following spring. The use of Grazers as a repellent could be combined with bud protection, using both sheep’s wool (Scots pine and broadleaves) and the CactusPro plastic bud cap (Scots pine only), as individual plant protection in the first or the following years. The review has highlighted other chemical repellents currently approved for use in other EU countries, e.g TRICO, which may also be informative to trial. However more detailed research is required into these products before further recommendations on their potential use can be made. Grazers is sold as a plant nutrient and is currently not registered for use as a repellent. SNH would therefore need to obtain experimental approval (www.pesticides.gov.uk) to trial Grazers as a repellent. SNH would not then need to report the results but would be limited to using it in a 5 or 10 ha area. The same experimental approval would also allow SNH to trial other repellents that are registered in other EU countries but not in the UK e.g. TRICO. Since gorse occurs naturally in Glen Torridon, the use of planted gorse to protect tree seedlings is acceptable. Two year old plants could be planted within a few centimetres of small broadleaf transplants, e.g. birch a few centimetres tall, to form natural protection as they grow. French (2012) recommends clipping gorse plants prior to planting out to stimulate branching and thereby enhance the degree of protection. A site visit by Gordon French may prove valuable in providing detailed instruction on this technique. Areas of fast growing and relatively browsing resilient species, such as willows, alder or birch, planted in individual or a series of clumps (with a minimum of 40 trees planted with about 20 cm between the trees in each clump), could enhance the establishment of more palatable, or less resilient, species planted in the centre of each clump. There is the potential to combine the above techniques with sabre planting (in suitable local planting niches; see section 2.1) of potted (pots ideally 15 cm deep and 10 cm wide) broadleaf whips. Within Compartment 2, the Scots pine is approximately 4-5 ft in height. At the northern end of the compartment, there is around 10 ha of dense birch of 12-15 ft in height. A small patch of gorse (0.5 ha), which is dense in places, is located in the centre of the compartment (E. Maclean pers. com.).

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The existing gorse, as well as the birch thicket, have the potential to form natural protection and camouflage for highly palatable species, such as aspen (Populus tremula), planted through these areas.

Figure 5. Beinn Eighe NNR – proposed locations for trialling establishment of trees without fences (south section).

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The Taagan link (Figure 4), the area between compartments 8 and 9 (NH009641 to NH012636), has been identified as an area for woodland expansion to enhance connectivity between the south west and north east ends of the reserve. Rocky knolls and broad open habitat types have been mapped by volunteers to inform planning of work (S.N.H., 2009). Deer control measures are resulting in tree regeneration, mainly of Scots pine (E. Maclean pers. com.). Within this area are steep-sided gullies with bracken that is dense in places, pockets of birch and dog rose as well as rocky knolls. These gullies are one of the few areas suitable for the planting of oak on the reserve (E. Maclean pers. com.). The gullies have a number of attributes, e.g. steepness of slope, uneven ground, dense bracken and richness of the soil, that could favour sabre planting. Pot-grown oak (minimum 1-1.2m high whips, recommended pot size 15 cm deep and 10 cm wide), could be planted at right angles to the slope within, or on the edge of, patches of bracken or dog rose. Key to the success of sabre planting is finding suitable micro-sites (see section 2.1). A site visit from Steve Watson may prove valuable in identifying such micro-sites. There is potential to combine sabre planting with the following techniques: Bud protectors - both sheep’s wool, with and without adhesive, and plastic caps (Cactus

Pro) could be trialled over the wider area. Areas of fast growing and relatively browsing resilient species, such as willows, alder or

birch, planted in individual or a series of clumps (with a minimum of 40 trees planted with about 20 cm between the trees in each clump), could enhance the establishment of more palatable, or less resilient, species planted in the centre of each clump e.g. aspen.

3.1.3 Ancient Woodland

The former Compartment 1 (Figure 4, centred on NG988658) largely comprises semi-natural woodland, with a lot of open space. Within the older woodland, the main species are Scots pine and birch, with a few holly and juniper (S.N.H., 2009). Compartment 1, and the area to the north west at Grudaidh (Figure 4), is used by the deer, and naturally regenerated trees, mainly Scots pine, are scattered and browsed (E. Maclean pers. com.). The use of bud protection, both sheep’s wool, with and without adhesive, (see section 2.4.1) and the CactusPro bud cap (see section 2.4.3) on the naturally regenerated Scots pine trees would provide an informative trial. The site is exposed to the north westerly prevailing wind and is near the march with the neighbouring estate. A trial of bud protection under these challenging Scottish conditions will have value in informing the suitability of this technique in many other locations in the Highlands. Table 2. Beinn Eighe: Summary of trial areas and recommended techniques 2012-2015. Dark blue shading = primary technique. Light blue shading = secondary technique that can potentially be combined with the primary technique.

Location Sabre Planting

Natural Protection

Bud Protection

Habitat Modification/ Diversionary Feeding

*Chemical Repellents

Cpt 8 Potential sub-cpts 1E, 1G & 2D as well as possibly 1B, 1F & 2B.

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Cpt 2 Expansion Coulin link and softening top straight edge Cpt 2.

Cpt 2 Enrichment planting within woodland

Taagan link, the area between compartments 8 and 9

Cpt 1 & Grudaidh (area to the north west)

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3.2 Creag Meagaidh

Priorities for woodland management on the reserve include enhancing woodland expansion on areas currently with low or no tree regeneration and introducing a wider suite of native tree species into sites that already have tree cover (R. Richardson and W. Fitter pers. com.). Note that the authors have not visited the sites and the following recommendations are based on discussions with SNH site managers. 3.2.1 Enhancing woodland expansion on areas currently with low or no regeneration

Near the reserve office at Aberarder, is a stock fenced field (NN481876, Figures 6 and 7) which has the potential for woodland creation. The field is approximately 75% heather and dense bracken with litter accumulation, and 25% lower lying and wet. SNH staff are keen to encourage tree regeneration on this site by using pigs for initial ground preparation to open up the dense bracken sward and expose the mineral soil. The intention is also to plant tree species currently absent or under represented on the National Nature Reserve. Potential species identified for planting include Scots pine, oak, hazel, holly and aspen. Due to the accessibility of the site, the use of bud protection on the growing shoots of planted trees, using both sheep’s wool with and without adhesive (FCH 2010 ME) (on Scots pine and broadleaves), the CactusPro plastic bud cap (on Scots pine only) and the plastic mesh nets (on Scots pine and potentially also broadleaves) could be trialled. The use of bud protection could be combined with trialling Grazers as a chemical repellent. Spraying Scots pine plants monthly, during their second summer growing in the tree nursery, could afford some individual protection as a result of a build up of the active ingredient in the needles when planted out the following spring The main period of damage by deer is during late October to May (R. Richardson pers. com.) and therefore the use of bracken for natural protection is not appropriate. Whilst gorse does occur in small areas on the reserve, it could also be planted (using two year old plants clipped prior to planting out to stimulate branching) within a few centimetres of small broadleaf transplants (e.g. birch a few centimetres tall) to form natural protection as they grow (French, 2012). A site visit by Gordon French may prove valuable in providing detailed instruction on this technique. In addition, areas of fast growing and relatively browsing resilient species, such as willows, alder or birch, planted in individual or a series of clumps (a minimum of 40 trees planted with about 20 cm between the trees in each clump), could enhance the establishment of more palatable, or less resilient, species planted in the centre of each clump. Located within 400 m of this field is an area of arable ground which is sown with wild bird cover, including a mix of kale and turnips, as part of a Field Bird Project. By coincidence, this sown mixture, by providing additional forage, has attracted deer into this area where they are culled (Richardson pers. com.). This provides an interesting trial of the potential of diversionary feeding on the adjacent regeneration/ planting area.

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Figure 6. Creag Meagaidh NNR – proposed locations for trialling establishment of trees without fences.

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Figure 7. Aberarder: proposed locations for trialling establishment of trees without fences.

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Scattered regeneration of rowan and birch occurs at the west end of the reserve on the slope above the plantation north of Moy Lodge (centred at NN435840, figure 6). The ground vegetation is wet heath and Molina grassland (R. Richardson pers. com.). To augment the regeneration, SNH are interested in planting trees, including juniper and Scots pine, in part of this area. The use of Grazers sprayed monthly on a minimum of 50 Scots pine and 50 juniper trees during their final summer in the tree nursery, could afford some individual protection as a result of a build-up of the active ingredient in the needles by the time they are planted out the following spring. Depending on the accessibility of the site, and the availability of labour, some of the planted trees could be re-sprayed monthly each summer with ‘Grazers’ to provide additional protection. Monitoring of re-sprayed and non re-sprayed trees should be undertaken to determine the effectiveness of re-spraying. The review has highlighted other chemical repellents currently approved for use in other EU countries, e.g TRICO, and it may be informative to trial these in future years. However more detailed research into these products is required before further recommendations on their potential use can be made. Grazers is sold as a plant nutrient and is currently not registered for use as a repellent. SNH would therefore need to obtain experimental approval (www.pesticides.gov.uk) to trial Grazers as a repellent. SNH would then not need to report the results but would be limited to using it in a 5 or 10 ha area. The same experimental approval would also allow SNH to trial other repellents that are registered in other EU countries but not in the UK e.g. TRICO. In other areas of planting, the use of ‘Grazers’ could be combined with bud protection, using both sheep’s wool with and without adhesive (on Scots pine, juniper and broadleaves) and the CactusPro plastic bud cap (on Scots pine only) on individual trees in the first or in following years. At least 50 trees of each species should be given each type of bud protection. Areas of fast growing and relatively browsing resilient species, such as willows, alder or birch, planted in individual or a series of clumps (a minimum of 40 trees planted with about 20 cm between the trees in each clump), could enhance the establishment of more palatable, or less resilient, species planted in the centre of each clump. There is the potential to combine the above techniques with sabre planting of potted broadleaf whips in suitable microsites (see section 2.1). In discussion with SNH staff the boulder slope near Creag Tarsuinn (centred on NN450858, Figure 6), was identified as a potential area where sabre planting could be trialled as a means of achieving woodland expansion. A number of attributes of this area e.g. steepness (ideally 30-40°) and unevenness of slope, could favour sabre planting in suitable local planting niches (see section 2.1) using potted broadleaf whips (minimum 1-1.2m high whips, recommended pot size 15 cm deep and 10 cm wide). A site visit from Steve Watson may prove valuable in identifying suitable micro-sites. The potential of the technique could be further enhanced by sabre planting within protective vegetation such as gorse or perhaps by close planting of individual or a series of clumps (a minimum of 40 trees planted with about 20 cm between the trees in each clump) of eared willow around the sabre planted trees. The outcome of any trials of this technique would help inform its potential as a method to establish native woodland in the more inaccessible, deep corries on the reserve, many of which are currently used by deer for shelter and have no seed source. 3.2.2 Establishing a wider suite of native species in current areas of native woodland The native woodland on the reserve is dominated by birch and rowan with willow and alder (R. Richardson pers. com.). In a number of these woodlands there is potential to undertake enrichment planting with key native species such Scots pine, oak, holly and aspen. This will

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not only enhance diversity within these woodlands but will also establish seed sources for future expansion on the reserve. Two areas of native woodland were identified by SNH staff, above and below the A86 road from the SNH office entrance to the west end of the reserve (Figure 6). The dense birch/ rowan regenerated woodland on the loch edge would require some thinning to open up areas to allow enrichment planting of oak (R. Richardson pers. com.). Individuals, and small groups of highly palatable species, such as oak and aspen, could be planted within patches of dense birch regeneration to provide protection. Opening up the predominantly birch thicket will provide additional light to oak, aspen and rowan seedlings. Thinning operations may assist in deflecting deer from the planted trees or alternatively deer could be attracted into this area and browse the trees as a result of the additional forage created. Careful planning and monitoring of these operations is thus required. Table 3. Creag Meagaidh: summary of trial areas and recommended techniques 2012-2015. Dark blue shading = primary technique. Light blue shading = secondary technique that can potentially be combined with the primary technique.

Location Sabre Planting

Natural Protection

Bud Protection

Habitat Modification/ Diversionary Feeding

*Chemical Repellents

Field, stock fenced

Slope west end of the reserve

Creag Tarsuinn

Native Woodland along the A86 road

3.3 Work on Creag Meagaidh and Beinn Eighe NNR during winter 2012/13

Work recommended for Creag Meagaidh and Beinn Eighe during winter 2012/13 is summarized in Tables 4 and 5 respectively.

The minimum number of trees of each species that we recommend should be used to trial each technique is 50. Annex 2 provides details of how the confidence limits associated with the calculated proportion of trees browsed changes with sample size. If smaller confidence limits are required then a larger sample size is needed. It is very important that a similar number of un-protected ‘control’ trees are identified and monitored so that the impact of the treatment can be accurately gauged.

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Table 4. Beinn Eighe: summary of work recommended for winter 2012/13. Dark blue shading = primary technique. Light blue shading = secondary technique that can potentially be combined with the primary technique.

Location Sabre Planting Natural Protection Bud Protection Cpt 1 & Grudaidh (area to the north west)

Bud protection must be applied securely as deer can learn to pull them off. Apply at the end of the growing season. 1. Sheep's wool - identify at least 50 Scots pine and 50 birch/ rowan trees that are currently browsed. Apply wool by: winding around leading shoot to

create a matted effect. Applying damp wool may help the wool to mat together. Needs to be replaced every year until the tree is above deer height.

applying wool using the adhesive (FCH 2010 ME) onto 50 broadleaf trees to compare the persistence of the material on the plants. The wool may require replacement each year.

2. CactusPro plastic bud cap - identify at least 50 Scots pine trees that are currently browsed. The cap clips around the leader and onto the conifer needles. Needs to be moved up the shoot every year until the tree is above deer height.

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3. Identify 50 Scots pine and 50 broadleaf trees without any protection to act as a control when comparing the effectiveness of the above techniques. The unprotected trees should, preferably, be paired with protected trees.

Cpt 8 Potential sub-cpts 1E, 1G & 2D as well as possibly 1B, 1F & 2B.

A suitable slope can be within a micro-site (e.g. a mound created by an old ant hill). Utilising these planting micro-sites within areas of deadwood, natural protection could afford extra protection to palatable species such as aspen. See more detailed guidance below. At least 50 sabre trees should be planted and a similar number of accessible trees should be planted to act as controls.

The material felled to created deadwood habitat must be large enough (at least 15 cm dbh) and of sufficient quantity, to provide an effective barrier. Create variable sized deadwood corrals around pockets of vulnerable regeneration as well as enrichment plantings. Undertake enrichment planting of groups of shrubs, such as juniper, gorse and eared willow, within these deadwood corrals to establish future natural protection thickets as the deadwood decays. Identify 50 broadleaf saplings outside the corrals to act as a control.

See more detailed guidance above. Suggest use of both sheep’s wool with and without adhesive and CactusPro plastic bud caps to be trialled within and out with these deadwood corrals. At least 50 trees should be protected using each method. Fifty ‘control’ trees should also be identified.

Taagan link, the area between compartments 8 and 9

The identification of suitable planting micro-sites within the gullies is crucial. Factors to consider are: Steepness of slope. Ideally a 30-

40° slope is needed. Where the slope angle is less than this, taller sturdier trees are needed.

Roughness of slope. Rougher slopes are more likely to deter deer movement but it must still be suitable for planting.

Density of bracken. High density deters deer but shades trees.

Richness and quantity of the soil

Variable sized patches of fast growing, relatively browsing resilient and easily established species, such as eared willow, alder or birch, planted in individual or a series of dispersed clumps (a minimum of 40 plants with about 20 cm between the trees within each clump), with a more palatable, or less resilient, species (aspen) planted in the centre of each clump. Suggested planting material is 18" transplants. At least 50 clumps should be planted and the same number of un-protected trees identified to act as controls.

See more detailed guidance above. Suggest both sheep's wool with and without adhesive and CactusPro plastic bud caps to be trialled over the wider area. At least 50 trees should be protected using each method. Fifty ‘control’ trees should also be identified.

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at the site. There must be enough soil to cover the roots.

Location of other potential protective vegetation e.g. dog rose.

Planting stock recommended is pot grown whips (minimum 1-1.2m high whips, recommended pot size 15 cm deep and 10 cm wide). The importance of careful planting of the root ball is stressed. The tree is planted at right angles to the slope, any side branches within reach of the grazing animal should be pruned off. When trees develop a 7.5-10 cm root collar, spiral guards can be fitted. Potential trial species: oak and possibly hawthorn. At least 50 sabre trees should be planted and a similar number of accessible trees should be planted to act as controls.

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Table 5. Creag Meagaidh: summary of worked recommended in winter 2012/13. Dark blue shading = primary technique. Light blue shading = secondary technique that can potentially be combined with the primary technique.

Location Natural Protection Bud Protection Habitat Modification/ Diversionary Feeding

Field, stock fenced

Variable sized patches of fast growing, relatively browsing resilient and easily established species, such as willows (eared willow), alder or birch, planted in individual or a series of dispersed clumps (a minimum of 40 plants with about 20 cm between the trees within each clump), with a more palatable, or less resilient, species (aspen) planted in the centre of each clump. Suggested planting material is 18" transplants. Within the planted areas create patches of very close planting (only a few centimetres apart) of gorse (two year old plants, clipped to stimulate branching) with native broadleaves (young birch transplants a few centimetres tall) to form natural protection as they grow. This latter technique is dependent on the availability of suitable planting material. At least 50 clumps should be planted and the same number of un-protected trees identified to act as controls.

Bud protection must be applied securely as deer can learn to pull them off. Apply at the end of the growing season. 1. Sheep's wool - secure to at least 50 trees of Scots pine and 50 broadleaves (birch/ rowan/ aspen) transplants prior to planting. Apply wool by: winding around leading shoot to

create a matted effect. Applying damp wool may help the wool to mat together. Needs to be replaced every year until the tree is above deer height.

applying wool using the adhesive (FCH 2010 ME) onto 50 broadleaf trees to compare the persistence of the material on the plants. The wool may require replacement each year.

2. CactusPro plastic bud cap - secure to at least 50 Scots pine transplants prior to planting. The cap clips around the leader and onto the conifer needles. Needs to be moved up the shoot every year until the tree is above deer height. 3. Plastic mesh nets - secure to at least 50 Scots pine transplants prior to planting. Staple the mesh nets at the

Potential impact of wild bird cover sown on adjacent arable area as alternative forage should be monitored by noting any changes in deer use of this area following scarification and tree planting in the field (NN481876).

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base, enclosing the stem, as well as to the needles of the leading shoot of conifers at the end of each growing season. 4. Identify 50 Scots pine and 50 broadleaf trees without any protection to act as a control when comparing the effectiveness of the above techniques.

Native Woodland along the A86 road

Plant individual and small groups of highly palatable species such as oak and aspen through existing areas of birch regeneration. Suggested planting material 18" transplants.

Oak and aspen require sufficient light to establish. Restructuring of the predominantly birch thicket to increase light could also assist with culling and either deflect deer from vulnerable plantings or encourage the animals into the area. Consideration should be given to this in planning & monitoring thinning operations through this area.

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3.4 Monitoring

It is recommended that SNH monitor the trials at both Beinn Eighe and Creag Meagaidh National Nature Reserves. In developing a monitoring plan the following elements should be considered:

There should be clear aims and objectives for monitoring The methodology used should ensure that monitoring can be repeated over several

years, potentially by different surveyors, and without the need for specialist skills or equipment.

Data collected should be safely stored, readily retrievable and easily interpreted. It is unknown what resources could be available to undertake monitoring at each Reserve or the level of detail required, however some suggestions for parameters that might usefully be recorded, on both treatment and control trees, are presented below. Year 1 (baseline): For each trial area:

type of treatment, altitude, aspect, soil type, habitat information (cover, height and species composition of the ground layer plant

species, shrub cover, canopy tree species and cover, woodland structure), For each tree (control and treated) within each trial:

tree species, GPS location,, digital photograph, planting method (if relevant) type (naturally regenerated or planted and, if the latter, bare rooted or potted) height,; presence /absence, type and cause of damage to the leading shoot, presence /absence, type, and cause of damage to other parts of the tree

Following years: For each trial area: update habitat information if necessary For each tree (control and treated) within each trial:

digital photograph, type, (naturally regenerated or planted and, if the latter, bare rooted or potted) height, presence /absence, type and cause of damage to the leading shoot, presence /absence, type, and cause of damage to other parts of the tree

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4 CONCLUSIONS

All the ways of protecting trees from deer that we have reviewed here have the potential to be used in Scotland, however only sabre planting, protection of young trees with gorse and the Terminalschutzkappe bud cap have been tried in Scotland and, even for these, no formally monitored trials have been carried out. Our conclusions regarding the suitability of the different approaches therefore need to be tested. Different methods will be suited to different situations depending on a range of factors (see Recommendations). No-fence tree protection is likely to be most effective where different approaches are combined, where deer densities are low and where deer are not short of forage. There is the potential to trial the complete range of no-fence tree regeneration techniques at Beinn Eighe and Creag Meagaidh National Nature Reserves.

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5 REFERENCES

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Harmer, R., Kiewitt, A., Morgan, G. & Gill, R. 2010. Does the development of bramble (Rubus fruticosus L. agg.) facilitate the growth and establishment of tree seedlings in woodlands by reducing deer browsing damage? Forestry, 83, 93-102. Humphrey, J.W. & Swaine, M.D. 1997. Factors affecting the natural regeneration of Quercus in Scottish oakwoods. I. Competition from Pteridium aquilinum. Journal of Applied Ecology, 34, 577-584. Jensen, A.M., Götmark, F. & Löf, M. 2012. Shrubs protect oak seedlings against ungulate browsing in temperate broadleaved forests of conservation interest: A field experiment. Forest Ecology and Management, 266, 187-193. König, E. 1970. Effects of fresh food on the prevention of peeling damage by red deer. . Proceedings of the International Congress of Game Biologists, 9, 176-181. Kuiters, A.T. & Slim, P.A. 2003. Tree colonisation of abandoned arable land after 27 years of horse-grazing: the role of bramble as a facilitator of oak wood regeneration. Forest Ecology and Management, 181, 239-251. Kupferschmid, A.D. & Bugmann, H. 2005. Effect of microsites, logs and ungulate browsing on Picea abies regeneration in a mountain forest. Forest Ecology and Management, 205, 251-265. Madsen, P., Buttenschøn, R.M., Madsen, T.L. & Olesen, C.R. 2007. Restoring a mixed species forest landscape on privately owned land under heavy deer browse pressure. Unpublished. Miles, J. & Kinnaird, J.W. 1979. Grazing: with particular reference to birch, juniper and Scots pine in the Scottish Highlands. Scottish Forestry, 33, 280-289. Miller, A.M., Mcarthur, C. & Smethurst, P.J. 2006. Characteristics of tree seedlings and neighbouring vegetation have an additive influence on browsing by generalist herbivores. Forest Ecology and Management, 228, 197-205. Morgan, R.K. 1987. Composition, structure and regeneration characteristics of the open woodlands of the New Forest, Hampshire. Journal of Biogeography, 14, 423-438. Morgan, R.K. 1991. The role of a protective understorey in the regeneration system of a heavily browsed woodland. Vegetatio, 92, 119-132. Pellerin, M., Saïd, S., Richard, E., Hamann, J.-L., Dubois-Coli, C. & Hum, P. 2010. Impact of deer on temperate forest vegetation and woody debris as protection of forest regeneration against browsing. Forest Ecology and Management, 260, 429-437. Pietrzykowski, E., Mcarthur, C., Fitzgerald, H. & Goodwin, A. N. 2003. Influence of patch characteristics on browsing of tree seedlings by mammalian herbivores. Journal of Applied Ecology, 40, 458-469. Reimoser, F. & Gossow, H. 1996. Impact of ungulates on forest vegetation and its dependence on the silvicultural system. Forest Ecology and Management, 88, 107-119. Ripple, W.J. & Larsen, E.J. 2001. The role of postfire coarse woody debris in aspen regeneration. Western Journal of Applied Forestry, 16, 61-64.

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Rousset, O. & Lepart, J. 1999. Shrub facilitation of Quercus humilis regeneration in succession on calcareous grasslands. Journal of Vegetation Science, 10, 493-502. S.N.H. 2009. Beinn Eighe National Nature Reserve habitat management plan 2009-2015. Scottish Natural Heritage. Sanderson, N.A. 1996. The role of grazing in the ecology of lowland pasture woodlands with special reference to the New Forest. In: Read, H.J. (ed.) Pollard and veteran tree management II. Corporation of London. Smit, C., Bakker, E.S., Apol, M.E.F. & Olff, H. 2010. Effects of cattle and rabbit grazing on clonal expansion of spiny shrubs in wood-pastures. Basic and Applied Ecology, 11, 685-692. Smit, C., Den Ouden, J. & Müller-Schärer, H. 2006. Unpalatable plants facilitate tree sapling survival in wooded pastures. Journal of Applied Ecology, 43, 305-312. Smit, C., Kuiper, D.P.J., Prentice, D., Wassen, M.J. & Cromsigt, J. 2012. Coarse woody debris facilitates oak recruitment in Białovieża primeval forest, Poland. Forest Ecology and Management, 284, 133-141. Strandgaard, H. 1967. En undersøgelse over Kronvildtets tilpasning til det danske kulturlandskab. Dansk Viltunders, 13, 9-75. Thompson, R. & Watson, S. 2011. No fence planting. In: Martynoga, F. (ed.) A Handbook of Scotland's Trees. Perseus Books Group. Thompson, R.N. 2000. No-fence planting - Bugeiliaid-y-Coed. Roslin: Forest Research. Truscott, A.-M., Mitchell, R.J., Palmer, S.C.F. & Welch, D. 2004. The expansion of native oakwoods into conifer cleared areas through planting. Forest Ecology and Management, 193, 335-343. U.S.D.A. 2007. Reducing deer browse damage. Forestry Technical Note no. 44. Minnesota Natural Resources Conservation Service. Ueckermann, E. 1960. Wildstandsbewirtschaftung und Wilschadenverhiltung beim Rotwild, Berlin, Paul Parcy. Van Uytvanck, J., Maes, D., Vandenhaute, D. & Hoffmann, M. 2007. Restoration of woodpasture on former agricultural land: The importance of safe sites and time gaps before grazing for tree seedlings. Biological Conservation, 141, 78-88. Vandenberghe, C., Smit, C., Pohl, M., Buttler, A. & Freléchoux, F. 2009. Does the strength of facilitation by nurse shrubs depend on grazing resistance of tree saplings? Basic and Applied Ecology, 10, 427-436. Ward, A.I., White, P.C.L., Walker, N.J. & Critchley, C.H. 2008. Conifer leader browsing by roe deer in English upland forests: Effects of deer density and understorey vegetation. Forest Ecology and Management, 256, 1333-1338. Watson, S. 1998. Sabres in the hills. Tree News, Spring, 14-15. Watt, A.S. 1919. On the causes of failure of regeneration of British oakwoods. Journal of Ecology, 7, 173-203.

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Wright, I.A., Pakeman, R.J., Dennis, P., Dalziel, A.J. & Milne, J.A. 2006. The effects of cattle on the natural heritage of Scotland. Scottish Natural Heritage commissioned report no. 203.

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ANNEX 1: FURTHER INFORMATION ON THE USE OF GORSE FOR NATURAL PROTECTION

The following information was provided by Gordon French. I was warden of Selkirk Hill in the Scottish Borders from 1988-95. Much of the Hill was covered by old and expanding blocks of gorse. These were regularly burnt leading to boom and bust re. habitat potential. Using loppers and trampling I set about fragmenting these blocks to remove the fire risk and develop ‘age’ structure through re-growth. As I went I planted native trees, these being oak, ash, Scots pine, birch, rowan, holly, hazel, bird cherry, gean, aspen, alder, hawthorn, yew, blackthorn and willows. These were planted in the presence of voles, rabbits, brown hares, roe deer and sheep. Gorse was the only protection the trees had. I visited the hill in May 2012. Nearly all the trees, with the exception of ash (?), had not only survived but thrived. Some of the pine trees were not far short of 2 ft (60 cm) in diameter in 23 years!! The gorse below was gone. In complete contrast, again in the late 1980’s, and by whom I don’t know, a tree planting scheme had been undertaken using tubes as protection on the open ground. By the end of my tenure, in spite of attempts to maintain the guards, nearly all of the trees were dead. One of my main sources of litter was in gathering these tubes. None of the trees was alive in 2012. Gorse is great for protecting native trees from browsing:

It is native. Trees that happen to be growing amongst it are often the only specimens emerging

where large herbivores occur (even choice browse such as rowan). Also they are usually far more robust than any growing in the open. This is due to the physical protection provided, nitrogen enhancement, the decomposition of needle litter and shaded ground vegetation. Mycorrhizal associations may also be influential.

Trees growing amongst gorse have a far greater chance of reaching maturity (bearing fruit).

Extant gorse patches are excellent planting sites, needing little alteration of structure. Gorse seedlings in their first year or two of life are fatally vulnerable to grazing so

rapid spread is unusual, except where grazing pressure fluctuates precipitously. Gorse will grow on poor ground, if not too constantly wet. While soft growing tips will be browsed, seldom is more than one third of new growth

taken annually. As gorse matures, growth slows and browsing diminishes. Gorse provides vital habitat for a whole spectrum of native species. Gorse creates ‘puddles’ of fertility and protection that lend themselves to planting Gorse dies when shaded by trees. Gorse is easily killed using lever and mulch techniques. The only threat to gorse is stags wrecking them in autumn [during the rut].

Thus, [it can be useful to] introduce gorse in places where trees are desirable. To this end gorse is again perfect:

The seed is not difficult to collect or in short supply most years and will remain viable in dry, cool, dark conditions for decades.

Plants are not difficult to grow. They transplant well (few die) as long as the planting spot is properly cultivated: a

spade width /half depth cube inverted and chopped. A slot stabbed into the ground and the plant stuffed in won’t do.

They can be transplanted small, often in their first year. Pinch out the tip during their first year of growth (a pre-emptive nibble). This causes the plant to grow out lateral

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stems and become spiny quickly. The more prostrate the form of such plants as they grow increases their planting potential most rapidly. In this form some ‘wrecking’ is less of a problem.

Tiny birch, again often in their first year, can be planted concurrently in the same spot. These small, light plants allow planters to carry several hundred with ease and, as such, widespread planting is simplified.

Testing /monitoring All the ingredients of rolling out projects to test the worth of gorse or gorse /birch planting are straightforward and cheap e.g. an individual, in something like a third of their working year (the bulk of this being from autumn to spring) could collect 10,000 seeds each of gorse and birch, grow on 50-60 m2 of seedbed and plant out in their final locations. The only problem arises in difficulties of monitoring dispersed planting without reams of GPS co-ordinates.

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ANNEX 2: EFFECT OF SAMPLE SIZE ON CONFIDENCE LIMITS ASSOCIATED WITH CALCULATED PROPORTIONS OF TREES BROWSED

The best estimate of the proportion of trees that would be browsed in a trial with an infinite number of trees (the ‘true’ proportion), is the estimate from the sample of trees used in the trial. There is a 95% chance that the ‘true’ browsing rate lies between the proportion of browsed trees in the trial plus or minus the 95% confidence limit. The confidence limit changes with sample size and with the ‘true’ browsing rate (Table 6; Fig 6)). It is at its highest, for a given sample size when the browsing rate is 0.5 (half of trees browsed; Table 6; Fig. 6)) Number of trees sampled (n) Browsing

rate (p) 10 20 30 40 50 60 70 80 90 100 200 300 400 500 600 700 800 900 1000 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

0.1 0.19 0.13 0.11 0.09 0.08 0.08 0.07 0.07 0.06 0.06 0.04 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.2 0.25 0.18 0.14 0.12 0.11 0.10 0.09 0.09 0.08 0.08 0.06 0.05 0.04 0.04 0.03 0.03 0.03 0.03 0.02 0.3 0.28 0.20 0.16 0.14 0.13 0.12 0.11 0.10 0.09 0.09 0.06 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.4 0.30 0.21 0.18 0.15 0.14 0.12 0.11 0.11 0.10 0.10 0.07 0.06 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.5 0.31 0.22 0.18 0.15 0.14 0.13 0.12 0.11 0.10 0.10 0.07 0.06 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.6 0.30 0.21 0.18 0.15 0.14 0.12 0.11 0.11 0.10 0.10 0.07 0.06 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.7 0.28 0.20 0.16 0.14 0.13 0.12 0.11 0.10 0.09 0.09 0.06 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.8 0.25 0.18 0.14 0.12 0.11 0.10 0.09 0.09 0.08 0.08 0.06 0.05 0.04 0.04 0.03 0.03 0.03 0.03 0.02 0.9 0.19 0.13 0.11 0.09 0.08 0.08 0.07 0.07 0.06 0.06 0.04 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.02

1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Table 6. 95% confidence limit associated with different ‘true’ browsing rates (p) and sample sizes (n). The 95% confidence limit =

/np1p *0.96 . For example, if the true browsing rate is 0.5 (50% of trees browsed), and 50 trees are sampled, the true browsing rate is

estimated, with 95% confidence, to lie between the estimate of browsing rate calculated from the sample, plus or minus 0.14 (see yellow cells). So if the estimate is 0.5 there is a 95% chance that the’ true’ value lies between 0.36 and 0.64. To improve on this level of precision, a larger sample is needed. With 100 trees sampled, and an estimate of 0.5, there is a 95% chance that the true value lies between 0.4 and 0.6 (see blue cells). Note that the gains in precision reduce as sample size increases. Most benefit comes from increasing sample size at low sample size.

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0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0 100 200 300 400 500 600 700 800 900 1000

Number of samples

Co

nfi

de

nc

e li

mit

p = 0.1 or 0.9 p = 0.5

Figure 7. Effect of sample size on browsing rate 95% confidence limit.

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