Tree protection

In most areas of Britain, newly planted trees and natural regeneration will require protection against damage by wild animals, domestic stock or people. Tree protection can be provided by fitting individual shelters or guards around each tree, or by fencing the entire area, or by a combination of the two methods.

Damaging agents

Wild animals

Obtain advice locally about the likely incidence of damage to young trees by deer, rabbits and voles. Deer are now present in nearly all rural areas, and increasingly in urban fringe areas. The likelihood of rabbit damage can be found out by looking for burrows nearby. Rabbits rarely move more than 200m from their burrows to graze. Voles are present in most areas, and populations will increase rapidly in some years where grass is left to grow long. Weed control measures using herbicide reduce vole damage, because voles are reluctant to cross bare ground.

Domestic stock

In pastures or on grazed commons, newly planted trees must be thoroughly protected against all domestic grazing animals likely to have access to the land. Grazing animals are usually curious and hungry, and will browse on any foliage they can reach. They can also physically damage young trees by rubbing against them, or by damaging the bark. Horses may strip the bark of trees if they get bored or hungry.

People

In areas of public access, local consultation should ensure that new planting is done in accordance with the wishes of the local community. Planting that blocks access, restricts the use of open spaces for informal games, or restricts views may attract adverse attention.

Accidental damage can be avoided by careful design, so that local users are not tempted to take short-cuts through planted areas, or operators of mowing machinery are less likely to damage young trees accidentally.

Targeted vandalism is more difficult to prevent. Measures may include:

• Unobtrusive planting in long grass or scrubby vegetation.
• Planting young, small trees amongst thorny shrubs such as gorse, hawthorn, bramble or berberis.
• Fencing. Most fencing can be vandalised by cutting with wire cutters, but fencing which is difficult to climb will deter casual vandalism. Chestnut paling, strained wire fencing or barbed wire fencing may be suitable.

Individual protection

The cost of perimeter fencing needs to be compared with the cost of individual protection. The following factors should be considered:

• The cost of individual protection (expressed as £/tree), and the cost of fencing (expressed as £/metre).
• The size of the area to be planted.
• The shape of the area to be planted.
• The planting density.
• The public use of the area and the likelihood of vandalism.
• The effect of fencing on movement of non-damaging wildlife such as badgers and game birds.

An example, for roe deer, is shown in the graph below.

Both the graph and table are from the Forestry Commission Practice Note 3 The Prevention of Mammal Damage to Trees in Woodland (Forestry Commission, 1998) which should be consulted for further details.

There may be other factors to consider for small planting schemes. It may be possible to re-use fencing or individual protection products. The role of fencing to prevent mower damage may be important. The method of weed control is also significant, as weeds growing up within shelters and guards can be difficult to deal with. For small planting schemes, a perimeter fence to protect against damage by animals or people, combined with total weed control within, can lead to very rapid establishment.

There is a large and potentially confusing range of tree protection products on the market, with new products coming available each year.

Shelters or guards must be carefully chosen to suit the size, species and form of planting stock, the damaging animals present, and to combine efficiently with the chosen method of weed control. Nearly all shelters, guards or spirals for small transplants will need a stake or bamboo for support. For mixed species planting, different types of shelters or guards will normally be necessary.

A ‘shelter’ normally refers to a solid, twin-walled, transparent tube. A ‘guard’ normally refers to a mesh product. Hybrid products are also available. Some guards have solid walls for the lower 300mm or so, to protect against herbicide damage, or for extra rabbit protection. Shelterguards are of mesh with a transparent film that disintegrates before the mesh.

Spirals are mainly used for rabbit protection in areas fenced against other animals. The vole/strimmer guard can be useful for fitting to newly established trees as necessary when shelters, guards or spirals are outgrown.

Consult suppliers’ current catalogues or websites for detailed advice on products.

Advantages

• Properly used, shelters or guards provide reliable protection against target species of animals.
• Shelters with solid walls can provide protection against damage from herbicides used for weed control.
• For most tree species, treeshelters enhance growth by raising humidity. Mesh guards can enhance growth by protecting against wind damage.
• Treeshelters or guards act as markers, to reduce the chance of trees getting trampled, and aid relocation during weeding operations. They can help protect against damage by mowers or strimmers.

Disadvantages

• Shelters and guards may be seen as an alternative to weed control, which they are not. Shelters and guards are expensive, and are a waste of money if effective weed control is lacking.
• Shelters and guards must be checked periodically to make sure they are secure in the ground, and that weeds have not taken hold inside. Solid-walled shelters should have releasable ties or a sliding attachment, so they can be lifted up for hand weeding or application of herbicide. With careful hand spraying, it is possible to spray through the mesh of some guards, but this must only be done before the trees come into leaf. It is not a suitable method for multi-stemmed shrubs in shrub shelters.
• Shelters and guards can draw unwelcome attention to trees in areas where vandalism may be a problem.
• Shelters may result in tall, spindly growth which cannot support itself (see below).
• Although most types are designed to degrade after use, this may not occur, so removal and clearing up may be necessary.
• Beech is not suitable for growing in solid walled or fine mesh shelters, as woolly aphids are a problem. Beech greater than 40cm in height at planting should be resistant if planted in fine mesh guards.

Height

Table 6d gives a guide to the height of treeshelter or guard required against the wild animals listed. Treeshelters or guards are not sufficiently robust to protect against domestic stock including cattle, horses and sheep, which will rub against or trample the shelter.

Treeshelters

Treeshelters were originally designed as mini-greenhouses, to increase survival and growth rates on young, newly planted trees. Growth can be from two to five times the normal rate in the first few years. Treeshelters should only be used with small bare-root transplants or cell-grown stock, which should be considerably shorter than the height of the shelter at the time of planting. There is no point in using a shelter on a tall whip which is as tall or taller than the shelter at the time of planting. For taller whips, use an open mesh tree protector as necessary to give protection against browsing wild animals.

Although treeshelters are a proven aid to tree planting, there are problems associated with their use:

• On windy, exposed sites, the leading shoots may get damaged as they emerge from the top of the shelter. Roadside plantings can suffer similar damage from the slipstream of passing lorries.
• Treeshelters accelerate early height growth, but stem diameter and root growth do not increase proportionally because of the lack of wind movement, which in open conditions stimulates root and basal stem growth. If shelters are removed too early, the young tree will not be able to support itself.
• Treeshelters are not recommended for protecting beech, as this can be badly damaged by the beech woolly aphid, which thrives in the humid conditions inside the shelter. Some shelter designs have holes in the lower portion, to increase air movement whilst retaining some microclimatic advantages.
• As the base of the tree stem thickens it can fill the shelter, trapping rainwater which then kills a strip of bark, so killing the tree.
• Weed growth inside the shelter will also be enhanced, and can swamp the tree.
• Treeshelters are not an alternative to weeding, but must only be used with thorough weed control measures.
• Small birds can get trapped inside shelters, and cannot clamber up the smooth walls.

To fit a treeshelter:

1. When planting in grass, it’s normally easier to remove a turf first. This acts as an initial weeding, so that grass does not grow up inside the shelter, and makes it possible to push the shelter down into the soil to deter voles. Plant the tree, using the notch-planting technique. If the roots are too big to be planted this way, the tree is probably too big to require a shelter.
2. Position the shelter temporarily over the tree, to give the exact position of the stake, which should be placed on the windward side of the tree. A flat face of the stake should be flush against the shelter.
3. Remove the shelter (or a second person can lean it to one side) and knock the stake at least 300mm into the ground, finishing with the top of the stake 50-100mm above the height of the upper tie. A pre-emergent herbicide can be applied at this point, to prevent weed growth within the shelter.
4. Push the base of the shelter down into the ground to deter access by voles. Attach the ties.
5. Use weed control techniques to prevent weed growth for a 1m diameter spot or band around the tree.

The shelter must be checked at least twice a year. These checks can be combined with weed control measures, and should include at least one visit during the growing season.

• Make sure that the shelter is still upright, firmly attached and with no gap at the bottom. Remove and replace any shelters badly damaged by wind or vandalism.
• Remove any weeds that have become established inside the shelter. This will require loosening the ties, sliding the shelter up and pulling away the weeds or using a herbicide.
• During the summer, check all shelters for trees which have failed to come into leaf. Leave the shelters in position, marked with coloured tape or similar so that they can be relocated and replanted. Any replanting must be done in the following winter, so the new plants have a chance to catch up the original planting.
• Shelters are designed to split down a ‘laserline’ or down the fold as the tree stem swells, but shelters need checking to make sure this happens. Most shelters are also designed to biodegrade, but again this may not occur due to low light levels or other reasons, and the shelters may need removing.

Tree protectors and guards

There is a large range of products made from plastic mesh of various gauges, available as pre-formed tubes, in rolls or pre-cut in various heights and diameters. All give protection against rabbits, and those over 1.2m height protect against deer (see Table 6d, above). Unlike shelters they do not increase temperature or humidity, but give protection from wind damage, whilst allowing more natural ‘unforced’ growth. Fine mesh guards are claimed to give some microclimatic benefits, without the problems of high humidity and moisture build-up associated with solid wall shelters. As guards offer less wind resistance, they are also less likely than shelters to get blown over. Mesh guards do not give protection for foliage against herbicide spray drift, but conversely can be useful for hand-applied herbicide which can be used through the mesh to kill grass within the guard. Guards are less of a danger to small birds than are shelters, as any birds that fall in can clamber up by gripping on the mesh. Birds play a useful role in eating aphids, caterpillars and other damaging insects within the guard.

Pre-formed tree protectors and guards are fitted in a similar way to treeshelters. Rolls or pre-cut lengths, supplied flat, must be formed into a roll, attached with ratchet or similar ties and then stapled to the stake. Further details are available from suppliers.

Spirals

Transparent spiral guards, supported by a cane, are a cheap method of protecting small hedging plants or other small transplants against rabbits, hares and voles. The outer end of the spiral should always be at the base, as shown, so that it is free to expand as the stem expands. If fitted the wrong way up, the bottom end gets trapped, and constricts the growth of the stem. To fit to small transplants, plant first, slip the spiral over without unwinding, and then insert the cane through the spiral.

Spirals can also be wrapped around the stems of larger, clear stemmed stock. To fit, hold the spiral the correct way up, and then wrap it around the stem starting at the bottom. Then hold the bottom and the top, give the top a sharp tug, and the spiral should spring into its correct form with the bottom end to the outside.

Other methods of tree protection

Standard fencing materials can be used to construct tree guards. These may be useful for protecting individual trees against damage from grazing domestic stock or deer, for which tree shelters and plastic mesh guards are not sufficiently robust. Applications include individual trees in fields, pastures, grazed commons and wood-pastures, and individual trees in woodlands with a high deer population. Such guards are mostly expensive in materials and time-consuming to build.

Against domestic stock, four posts and rails will be needed for each tree. To be proof against deer and rabbits, the 1.8m height guard, with 8 rails, will be necessary. Leave one end of the upper netting detachable, to give access to the tree for aftercare.

A less robust guard is sufficient to protect plantings or natural regeneration in woodlands, where cattle and sheep are excluded. Use a 3.6m (12’) length of wire deer netting, joined back on itself to form a ring, and secured to the ground with 1.8m (6’) stakes. Where rabbit protection is necessary, use a plastic mesh or spiral guard around the stem of the tree.

Various products are available to protect individual trees in parklands and orchards:

• Plastic mesh tree guards (Netlon) for sheep protection in orchards.
• Heavy grade fine plastic mesh for protection against deer and other animals.
• Weldmesh guards in a variety of height and diameters.

For suppliers see here.

Fencing

Fencing will be needed to protect new planting or natural regeneration in the following circumstances:

• To keep out cattle, horses, sheep or other domestic stock.
• To prevent people from accidentally or purposely damaging young trees. Damage may be caused by trampling, vandalism or by mowing machinery.
• As an alternative to individual protection, to protect against damage by rabbits and deer. No fences are proof against voles, for which vole guards are necessary.

Careful costings will be needed to choose the most cost-effective solution for each planting site. Sometimes a combination of fencing and individual protection may be used, for example a stock fence against cattle, and spiral guards around each tree against rabbits. For details see Fencing – Tree protection.

There are disadvantages to fencing new woodlands, blocks within existing woodlands or to encourage natural regeneration:

• Fencing can hinder the natural movements of non-target species, including badgers, foxes and game birds. In coniferous woodlands in Scotland, fencing can have damaging effects on capercaillie and black grouse populations.
• Browsing and grazing has value in keeping woodland glades and rides open, and in controlling undergrowth. If all deer and rabbits are fenced out, it may be necessary to increase mowing and hand clearance to keep areas open, and to control undergrowth. A balanced woodland ecosystem requires some grazing, and is an argument for the need to bring deer populations into a sustainable balance with the woodland habitat.
• Unwanted species can be fenced in, as well as fenced out. It is essential that rabbits are eliminated before any area is fenced. Fenced areas must include a gate to give access for woodland management, as well as to allow out any deer or stock which get into the area. Alternatively site the fence near a bank or rocky outcrop, or build a ramp, so that deer or sheep which get in can leap out. Once the woodland is established, the fence can be used to enclose a sustainable population of grazing animals.
• Fences require regular maintenance, and if breached repair is essential, or the protection for the whole area is lost. Redundant fences are an eyesore and a danger, and can take as long to remove as they did to erect.

Deer fencing

This is the highest specification fence for protecting tree planting, and is also proof against domestic stock and people. Against rabbits, hexagonal mesh should be fitted to the lower section, and turned out at the base in the direction of rabbit attack. Badgers are strong enough to push their way through which then gives access to rabbits, hares and small deer. Fit badger gates on established runs, to allow badgers but no other animals through.

Rabbit fencing

This is proof against rabbits and sheep. For cattle and horses, extra line wires should be fitted mid way and at the top. Where there is heavy pressure from domestic stock, an electric line wire to keep stock away from the fence may also be advisable. This fence is not proof against deer, although muntjac and roe may be discouraged from jumping it. Where areas of tree planting are below about one hectare, most species of deer will tend to go around the fence rather than jump it, unless the fence crosses a path which the deer have traditionally used.

Temporary fencing

Temporary fencing may be appropriate to give protection for a minimum of three years, which is long enough for fast-growing newly planted species to grow beyond the reach of deer. Physical damage by cattle, sheep and horses is likely to be a problem for up to 10 years or more after planting, so temporary fencing is not normally suitable against stock. Light grazing by sheep may be possible.

Temporary fencing is appropriate for protecting newly-cut coppice coupes from deer. Lightweight plastic netting, dead hedging or electric fencing may be suitable.

Protecting natural regeneration

Areas within or on the edges of woodland can be fenced against deer and rabbits, to protect any natural regeneration of trees from being browsed.

In many woodlands there is ample regeneration, but all apart from the unpalatable species are browsed away within a few months of the seedlings emerging. However, in spite of its name, natural regeneration may not happen without intervention in managed woodlands, as there may be insufficient seed trees, not enough light or other reasons. Woodland succession may mean that the species mix changes as the woodland ages.

Natural regeneration ensures the survival of local genotypes of tree, and saves the cost of purchase and planting. Natural seedlings usually establish more quickly than transplants due to the lack of root disturbance, and because they are adapted to local conditions.

Some species such as ash, sycamore, birch, rowan and aspen produce seed virtually every year. Others, notably beech and oak, only produce seed in ‘mast’ years, which may occur at intervals from 3-5 years for oak, and 5-15 years for beech. Most species of trees will require ground that is free of other growth, although oak germinates through a grass sward. Oak, hazel and other species do not regenerate under a closed canopy, because it is too shady. The seedlings germinate, but wither away after a few years unless the canopy is opened up. Oak is spread by jays to woodland edge and grassy habitats, where it’s thought that seedlings which grow up in the protection of thorny bushes are the main method of spread in grazed semi-natural habitats. Germination and survival is normally best on soil which is well-drained at the surface, with plenty of leaf mould to suppress other growth and provide the mycorrhizal associations which most species of tree require.

For further details on natural regeneration, see here.

There are two approaches to protecting natural regeneration. You can either fence an area and wait for regeneration to occur, or you can protect regeneration after it has occurred. Because protection has to be put in place quickly after a successful season for regeneration, it’s not normally feasible to fence a large area. One method is to use portable ‘cages’ (for example Gengards) or build tree guards from standard fencing materials to protect small patches of regeneration. Cages can be erected very quickly in response to regeneration, and have few of the disadvantages of large fenced areas listed above. Costs of later thinning are greatly reduced, as it’s only necessary to thin the protected regeneration. Gengards are 2.4m x 2.4m x 1.2m. For suppliers, see here.

The progress of regeneration should be checked at intervals during the first year, as later-germinating tree species may appear through the season. A typical pattern of emergence in a mixed broadleaved woodland is firstly sycamore, followed by beech, ash, oak and lastly sweet chestnut. Weed out any unwanted species. Seedlings can also be removed and relocated as desired.

It is estimated that 5 Gengards or similar per hectare are sufficient to ensure establishment of regeneration for a single tree selection system. The Gengards can be repositioned after about five years. For group felling, 16 are needed per 0.25 hectare. Provided the guards are not damaged, making re-use possible, they represent the best-value method of ensuring natural regeneration. See Enact Vol. 8 No. 4 for full details.

Allternatively, a ring of deer netting as described here can be used. Rabbit netting (1050mm height, 31mm mesh, 18 gauge) can be fitted around the lower half, and lapped outwards 150mm. Secure with two stakes. Re-use is possible with careful handling.

Another method is to use coppice poles or other untreated wood of suitable size, and build a guard of the type shown here. Leave one top section of fence temporarily fastened, so it can be rolled back to give access for weeding and thinning. It should be possible to detach and re-use the netting if done with care, and attach to fresh poles in a new position.

Individual seedlings can also be protected with shelters or guards.

As can be seen on abandoned railway lines, undisturbed gravel heaps and other barren areas, tree seedlings can thrive on apparently inhospitable ground where they are free of competition from grasses and other plants. In places where there is a seed source nearby, the simple procedure of applying herbicide to an area of grass, and then protecting it against trampling, grazing and mowing as necessary, can result in a crop of tree seedlings. These are most likely to be pioneer species such as birch, sycamore, ash or oak, or suckers of nearby trees such as elm, aspen, cherry or blackthorn. Similar regeneration can occur along fencelines, in ‘dead hedges’ or piles of brash, or other places where weeds, browsing, grazing or mowing are absent.

Oak regeneration, through dispersal by jays, tends to occur in rough grass at woodland edges, roadsides, along hedgerows and in grassy areas. Where such regeneration is desirable, protect the seedlings in early summer from browsing or mowing, and use mulch or herbicide to reduce competition from weeds. Seedlings can be transplanted in the late autumn as required.