Since the start of the twentieth century it has been recognised that measures to protect ancient trees, woodlands and any tree that provides useful amenity within the urban area should be implemented. Since 1932 all Planning Acts have explicitly included the protection of trees within its legislative powers. Details of full TPO legislation is held under Part VII, Chapter 1, Town and Country Planning (Scotland) Act 1997.
The Secretary of State holds power to enforce litigation penalties on any persons in breach of the above legislation. It is the duty of the Planning Authority to make all documentation held on TPO’s available for public inspection, free of charge.
Conservation areas have been designated as areas for garden expert that hold special architectural or historic interest, the character or appearance of which it is desirable to preserve or enhance. Trees are recognised under this analogy and are therefore protected under guidelines set out in Part VII, Chapter 1, Section 172 of Town and Country Planning (Scotland) Act 1997 (Mynors, 2002).
Trees are protected in general terms under Conservation legislation.
High Hedges Act
Many of you will be familiar with the problems that boundary hedges can cause between neighbours. The primary element in most instances is sun light issues. The predominant offender in these cases tends to be Leylandii hedging. This species can reach heights of 90 feet, can have a large canopy spread and holds its foliage all year round (evergreen).
A High Hedges Bill has been passed and implemented throughout LPA’s in England and Wales. At the present time the Scottish Parliament has yet to pass the Scotland edition of this legislation.
In general terms this legislation would allow LPA’s, under Planning Law, to aid in cases of complaints between neighbours. Height restrictions would be implemented for Leylandii hedges, a height of 6 feet has been set in England.
The British Standards (BS) has numerous recommended guidelines for industry best practice techniques. The most commonly used Recommendations in the arboricultural industry are:
BS3998 Recommendations for Tree Works, 1989
BS5837 Trees in Relations to Construction, Recommendations, 2005
BS3936 Nursery Stock. Specifications for Trees and Shrubs, Part 1, 1992
Erskine Tree Surgeons Ltd works fully within these guidelines.
Correct Pruning Procedures
Trees as biological structures are not designed to be pruned however, in order to help insure their safe retention within the urban area, with maximum enjoyment, tree pruning exercises are often required.
Percentage (%) guidelines have been set out in British Standard 3998 with regards to maximum pruning thresholds. It is recommended that a maximum of 30% of the crown be removed on a single tree. This % may be increased upon site inspection or used to control the decline of a tree, but with it comes consequences.
In order to ensure damage limitation there are correct pruning cuts that should be adhered to, times of year to prune and long term tree management plans with regards to desired height, shape, density etc.
Every time a pruning cut is performed on a tree a small pocket of decay is implemented. Trees do not have immune systems like you or I, so what they aim to do is compartmentalise the wound. This means that the tree will put up a chemical barrier around the wound to reduce the spread of the decay and disconnect it from the living system of the tree. In effect the wound will never ‘heal’ and will always be present within the tree.
The reason why there are recognised proper pruning cuts (target pruning) is biological. Each branch contains a branch bark ridge that is situated where the branch is attached to the main trunk. If the cut is made correctly the tree can compartmentalise the wound and maintain a small decay pocket. If the cut is made too far away from the branch bark ridge (stub cut) or too near (flush cut) then decay spread will be larger.
Current research has constantly been proving and disproving correct times of year to prune. In general it is acknowledged that the best time to prune is when the tree is in a dormant state (winter months). We would advise that pruning be avoided in spring and autumn months due to the environmental cycles that trees go through at these times.
Pruning exercises can vary between species and age classifications of those species. It is advised that professional consultation be sought specific to your tree(s).
Trees and the Environment
Trees have the capacity to adjust rapidly to changes that threaten their survival. They regulate their growth within the limits of available energy, water, space and do not grow beyond their means. Although they are highly evolved structures, they are still subject to environmental changes.
One of the most common causes of decline in trees within the urban environment is compaction of the top soil. Due to the locations in which trees grow, high volumes of traffic are often noted in and around the rooting zones. Compaction causes the air to be pushed out of the soil, restricting water movement, making nutrients unavailable for plant uptake. Aeration of the top soil and the application of nitrogen are recommended in these circumstances.
Most of the problems encountered with regards to tree decline are often site specific. Erskine Tree Surgeons Ltd recommends that advise, from a person experienced in arbricultural, be sought when making changes to landscapes in and around the influencing distance of mature trees. Trees add great amenity value to the locales in which they are situated, care should be taken in preserving these values.