7.7 Protection and establishment of trees

Trees should have an appropriate level of protection for their environment. Bark protection is essential for a tree’s survival, especially for younger trees with thinner bark.

Trees in publicly accessible areas must therefore have temporary light protection at their base. This includes hessian wrapping, bamboo wrapping or light duty mesh cages. Any light mesh guard must be removed once the tree is established and this programme of aftercare must be scheduled in, whilst the tree is in its infancy.

In the permanent case, the primary method of protection should be through planting in appropriate locations and using an appropriate size of tree. The use of larger tree pits with low level planting offers an effective method of protection while bringing additional biodiversity benefits.

In busier areas street furniture such as seating or raised planters should be used to provide a space efficient method of protecting trees.

Where no other methods of protection are feasible, and the tree is at risk from vehicle strikes, metal tree guards could be used. Consideration should be given in the budget to the maintenance and eventual removal of these, as the guard must be removed as the tree grows.

Figure 7-2a: Trees and greening can soften streets and parking courts. Watercolour, Redhill, Surrey. (Credit - Create Streets)

Figure 7-2b: Trees and greening can soften streets and parking courts. Upland Road, Guildford, Surrey (Credit - Create Streets)

Street trees must be supported by stakes in the first few years of growth while root systems establish to protect them from strong winds and accidentally damage. The stakes must be embedded at least 60cm into the ground and secured to the tree.

Plastic or rubber ties must be avoided as they need to be removed manually and can throttle the tree if left in place. Biodegradable ties, such as jute, should instead be used. The stakes and ties must be removed after 18 to 24 months.

Root anchor systems could be used as an alternative to staking. These permanent support without the visual impact of stakes and do not need to be removed. However, they must be specified and installed by a specialist and can only be used on larger root balls.

Consideration should be given to irrigation of the trees. Irrigation rings, root drenchers or other suitable systems should be installed on trees in hard landscapes. These will allow effective irrigation of the root ball which is essential in the first few years after planting. Notices should be affixed to new street trees encouraging residents to water new trees with clear guidance on how to do so (including the use of grey water which is clean waste water from baths, sinks, washing machines, and other kitchen appliances).

Figure 7-3a: Street trees, Poundbury, Dorset (Credit - Create Streets)

Figure 7-3b: Street trees, Poundbury, Dorset (Credit - Create Streets)

Street trees are at particular risk of damage from continued use of salt as a de-icing agent which can damage soil quality and can cause management problems by encouraging the establishment of salt tolerant weeds.

To reduce risk for de-icing salts, the following recommendations should be followed:

• Salt bins and salt dumps should be placed away from trees and shrub beds.
• The amount of de-icing salt used by maintenance teams should be kept to a minimum. Salt tolerant species can be selected if this cannot be avoided. Evergreen species and in particular conifers are especially susceptible to salt damage and grasses can be affected in the same way.
• Provide information to other parties who are likely to use salt (shop owners, local residents) and use of alternative materials such as calcium magnesium acetate (CMA), urea, and salt/grit mixes in pedestrian areas.
• There should be provision of slush disposal zones adjacent to planted areas with efficient drainage to remove salt laden water.
• Ensure soil cover in planting areas is of good quality and free draining to avoid water logging. This is particularly important where the planter is receiving surface run off as part of a SuDS scheme. If the tree pit is receiving runoff from the highway, this could be diluted with other runoff to provide dilution and reduce salt concentrations.