Basic Tree Survey Methodology

Hazardous Trees

This section will help you identify hazardous trees and help you decide upon the urgency of the required actions. At this point the preliminary planning and scoping should have identified ‘Target Zones’ and the trees within them, as well as the agreed upon parameters set out by the surveyor and client. In the case  that the surveyor believes they have not got the appropriate knowledge to fully assess whether a certain tree is hazardous, the decision/survey will be referred to an appropriately qualified person.

Methodology

It is essential to ensure tree safety surveys are carried out in a methodical and consistent manner. Where possible it is beneficial to be able to assess individual trees from all sides, though this can be difficult when working along a towpath.  Descriptions and the locations of each survyed tree requiring work must be noted to ensure the correct tree is monitored and processed. Prior to the hazard assessment the following details will assist future arborists find and work on the tree:

  • Tree Species
  • Position of tree e.g. coordinates, map locations or a description of its location (i.e. opposite mooring 21) where possible all three would be beneficial
  • Comments (i.e. distinctive attributes)
  • Rough age of the tree (Newly Planted, Young, Middle Aged, Mature, Over Mature)

Now the tree can be assessed, it is recommended to start from the top of the tree and work your way down in the following order:

1. Inspect the crown, checking for gaps in the canopy (summer only), colour of the leaves and whether deadwood is present.

2. Look for the presence of deadwood, hanging or broken branches within the canopy.

3. Scan through the canopy keep an eye out for cracks, splits and clearly damaged branches, where the wind can take it off or it can simply rot away. 

4. Moving down the look for abnormal features within the tree such as swellings, bark damage, fungus, splits and cracks and hollows.

5. Not the presence of Ivy and the extent of the spread. Ivy can make it difficult to fully inspect a tree for defects and hazards as well as potentially add excess wieght in the canopy

6. Is the tree leaning?  Particularly towards a ‘Target Zone’.

7. Are there any signs of fungi or decay within the main trunk, at the base of the tree or surrounding the trees base?

8. Looking at the ground are there any obvious

signs that there may be damage to the roots such as digging and track marks? Are any of the roots exposed?

9. Finally look at the soil surrounding the tree and are there any noticeable cracks in the ground or uplifting of a towpath/concrete structure?

The overall physical condition of the tree to then be classified:

Good-  Healthy, full crown, long life expectancy, no obvious signs of failure.

Fair- Generally healthy, some thinning of crown, some defects of low significance.

Poor – Lacking vigour, short life expectancy, poor leaf cover, major defects.

Dangerous/Dead- Urgent removal required depending on the trees location.

You should then be able to classify the priority of the works based on the information gathered such as useage, location and  physical condition. Then being able to place a time frame in which the trees should be dealt with, along with recommendations if suitably qualified.

Fill in your Basic Tree Survey Form and provide a copy of your findings to the client, canal camp leader and IWA head office.

WRG's Forestry Team Felling

Photo: WRG Forestry clearing trees

Further Guidance

More information regarding the necessity of tree safety can be found from the Forestry Commission's National Tree Safety Group

Advice

For advice on hazardous trees on your restoration site contact Alex Melson at alex.melson@waterways.org.uk

Resources

Tree Survey Form

Example Risk Assessment

OPAL Tree Identification Guides