Why do trees lose their leaves?

Deciduous trees lose their leaves in autumn, the process takes place over four to six weeks as daylight hours shorten and temperatures decrease. This provokes the tree into the process known as abscission. The tree produces a cork like substance which slowly blocks the veins within the leaf and acts as a coagulant to ensure the tree doesn’t bleed to death once the leaf falls. At the same time the circulation of liquid around the leaf gradually lessens. Just before the leaf falls some useful nutrients are taken from the leaf and stored in the stem for later use. As water supply to the leaves lessens the chlorophyll is unable to keep the leaf green, this leads to the spectacular colours seen in different trees in autumn. Various shades of red,gold, orange and yellow can be seen dependent on the different levels of carotin and xanthophylls present in the leaves. Shade can also determine how well a tree will display its autumn colours.  When the process of abscission is complete the leaves simply  fall from the tree.

Leafy facts

A large oak tree has on average 700,000  leaves, a large apple tree only has 50,000!

Which tree can I plant for autumn colours ?

Small trees/shrubs include:

Amelanchier canadensis (snowy mespilus) white flowers and good autumn colours

Rhus typhina (stag’s horn sumach) large leaves and vivid colours

Medium trees (up to 8m tall)

Parrotia persica (persian ironwood) has red and yellow leaves .

Acer’s offer a great selection for autumn colour from the simple Acer campstre (field maple) which is our only native maple with its stunning gold to our personal favourite , Acer palmatum osakazuki which is a member of the Japanese acer family and shows amazing red and orange tints.

Others which have stunning colours and bark include Acer davidii,Acer forrestii and Acer pensylvanicum.

Larger trees (over 8m)

Prunus sargentii (Sargent’s cherry) has a red autumn colour.

Gingko Biloba (maidenhair tree) is another great tree with its yellow colour.

Taxodium ascendens (river cypress)

Should tree works be avoided during autumn?

Certain tree care practices should be avoided. Pruning should never be carried out during the abscission period. This excludes deadwooding of trees. Tree removals are unaffected as the tree is effectively being killed off.

Once felled the tree was sectioned and split using our 25 tonne log splitter. We produced over 12 cubic metres of firewood.

Trees are anchored into the soil by their roots.  The roots also take up water containing dissolved minerals, which then travels up the tree via special vessels called xylem within the wood of the tree. This upward passage of water and nutrients is caused by 2 phenomena; transpirational pull which is created by the evaporation of water from the surface of leaves which then pulls the sap up the xylem vessels and root pressure which is created by osmosis of water into the roots causing a positive pressure that forces water up the trunk of the tree.  Damage to roots or soil compaction above roots, such as from vehicles or construction traffic can therefore seriously affect the health of a tree.

The leaves of a tree are important in capturing sunlight energy which is converted into sugar by the process of photosynthesis. This chemical
reaction also uses carbon dioxide which is absorbed by the tree from the atmosphere and releases oxygen and so is a very important process to maintain a healthy balance of gases in our surroundings. This also explains how an unprofessional prune of a tree canopy can seriously damage the tree’s health.

 
The sugars that are created by photosynthesis are then transported around the tree in vessels called phloem. The sugars are either used to feed the cells of the tree or either stored for future use. The phloem vessels are found in the innermost layers of the bark, hence a tree will
normally die if a ring of bark is removed right around the tree.

 
During winter when deciduous trees lose their leaves, the tree survives on stored sugars produced earlier in the year.  The process of leaf drop conserves water and helps some trees better survive harsh winter conditions. The most stressful times in the tree’s yearly cycle are when it is coming into leaf and when it is shedding leaves. Pruning operations should not take place during these times.

The Arboricultural Association or Arb Association (AA) is the largest body in the UK for the tree care professional.  It was founded in 1964 by a group of government horticulturists and forestry officers who were concerned about the standards of tree care at that time.  Ten years later the AA merged with The Association of British Tree Surgeons and Arborists to form the Arb Association of today which currently has approximately 2000 members.  The aim of the organisation is to advance the science of arboriculture for the public benefit.  To that end the Association runs seminars, conferences and training courses on tree care and publishes The Arboricultural Journal, The ARB Magazine, and many other leaflets, booklets and guidance notes on all aspects of tree care.  In an industry unregulated by government, the Arb Association sets the standards for good practice and awards the status of Approved Contractor to those tree surgeons that meet the exacting standards in this difficult and dangerous profession.  It also awards the status of Registered Consultant to those individuals who have specialist knowledge on tree health, safety, preservation and issues concerning the law although these consultants do not undertake tree work themselves. The Directory of Registered Consultants and Approved Contractors is published each year and lists those consultants and companies who continue to meet the Association’s strict working standards on continual reassessment.  Anyone can contact the Arb Association to ask them for details of their local approved contractor or consultant.  This information can also be found on the Association’s website www.trees.org.uk.

Blocking light or space and overhanging branches

There is no absolute right to light or to a view, therefore you would normally need to negotiate with your neighbour about managing their trees. In extreme cases it is possible to apply to a magistrates court for an injunction to control or restrict the growth of trees however this requires specialist legal advice and only applies in limited circumstances – there is also no specific law on how tall trees are allowed to grow and cases for loss of light normally only apply to windows in buildings not gardens.

You have a general right to prune overhanging branches back to your property boundary, however the owner of the tree is not usually obliged to cut them back. They must not be cut beyond the boundary and you cannot remove the top of someone else’s trees without their consent. You must ensure the trees are not subject to a tree preservation order or in a conservation area otherwise you are commiting an offence. If in doubt ask your local council’s tree officer first. It is normal to offer the removed branches back to the owner as they are their property, unless you have mutually agreed beforehand to dispose of the arisings for them.

Falling leaves, fruit, flowers or debris

Although these can cause a lot of inconvenience particularly if over your drive for example, falling leaves and debris are not regarded as a ‘nuisance’ in the legal sense and a tree owner has no obligation to clear them. It is normally the responsibility of all landowners to undertake their own ‘property maintenance’ if for example, they need to clear paths or gutters.

High hedges and conifers (Cypress leylandii)

This relates to evergreen or semi evergreen hedges only, not ordinary deciduous trees. It is sometimes possible to apply for enforcement action from your local council to restrict the growth of a neighbour’s hedge if it exceeds a certain height in relation to its distance from a property. There are specific criteria for doing this and also a cost element. Your council’s planning enforcement section manage this function and can give further guidance.

Dangerous trees

Every tree owner has a general duty of care to ensure their trees do not pose an unacceptable risk to other people on or adjacent to their land – you will however only be liable for injury or damage caused by trees if you are found to be negligent in some way e.g. by not taking reasonable care to inspect them or undertake essential work such as removing deadwood that could easily be seen to be hazardous etc. This is an area where it is advisable to take the advice of a qualified tree surgeon.

Tree roots and damage to property

If a tree is found to be causing damage to a neighbouring property it is classed as a legal nuisance and the tree owner would normally be liable for the associated costs of any loss or damage. In the event of any form of damage it is advised that you notify your neighbour and also contact your property insurers for further advice.They can often investigate and deal with the issue on your behalf.

TV & Satellite reception

TV interference can be caused by trees however there is no legal right to TV reception. We recommend you consult a television engineer to assess your aerial and signal.

DISCLAIMER

PLEASE BE AWARE THAT THIS IS INTENDED AS A USEFUL GUIDELINE. IF IN DOUBT PLEASE CONTACT YOUR LOCAL COUNCIL PLANNING DEPARTMENT. HAWKES TREE SERVICES LTD  WILL NOT BE HELD RESPONSIBLE FOR ANY ACTION RESULTING IN PROSECUTION

It causes white-rot in the tree leading to cavity formation. As the fungi is perennial we were able to ascertain that it had been infected for at least three years as there were three layers of fungus. The tree was encrusted with ivy,  however a further inspection revealed a cavity at 3m high. When we climbed the tree using a ladder to look at the cavity it was over a metre deep and the infection had eaten the heartwood of the tree.

We assessed the tree as potentially dangerous. The growth above the cavity was estimated to weigh at least two tonnes and was leaning towards the road. Due to the state of decay it would have been impossible to climb. Felling was out of the question due to the proximity of the road. A short phone call to our local District Council planning office confirmed that the tree was protected under a Tree Preservation Order. We therefore prepared an application to remove the tree on the grounds that it was dead and infected with a decaying fungus.

After a site visit from our local tree officer and a short wait, permission was granted to remove the tree. The land owner loaned us his rough terrain access platform to carry out the works safely which greatly reduced costs. Operated by one of our three qualified personnel, the tree was removed safely in one day. The trunk weighed an estimated 4 tonnes.