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The Approach

Basic tree safety surveys are undertaken to assess the potential hazard trees can pose to people or structures. This guidance is aimed at providing volunteers with a basic knowledge and understanding of the processes involved when conducting tree surveys on or near waterways and to identify tree’s which could pose a danger to the community. For larger areas or woodland a more in depth safety survey should be undertaken by an arboriculturalist.  

Surveys should be undertaken in the following order:

  1. Preliminaries and consultation
  2. Scope of the survey
  3. Planning and preparation
  4. Tree risk management
  5. Tree Assessment
  6. Reporting

Preliminaries and Consultation

Prior to undertaking the tree survey, discussions should be held with the client from the relevant group, e.g. land management agent, project planner or restoration manager, to determine the expectations and criteria for assessment. A summary and explanation of the survey process and personal capabilities of the surveyor’s should be outlined to the client. Surveys can range from identifying individual trees that are an immediate threat to people, or they can encompass an assessment of every tree within a target area and their potential hazards. Clear and specific requirements should be agreed. Surveys completed by unqualified individuals are an advisory assessment in lieu of a fully qualified surveyor; it should be discussed with the client that the surveyor cannot be held responsible for sudden tree failures.

Scoping and Planning

Scoping

Scoping the site should ascertain the timing, planning requirements and the cost involved, as well as determining the suitability of the surveyor’s ability to meet the client’s expectations. The surveyor needs to take into consideration their own personal safety when assessing the site. Construction sites carry their own associated risks and will differ from site to site. All surveyors need to be diligent when entering an active construction site. A risk assessment will need to be completed for each site.

Understanding that a tree is a living organism is paramount in assessing trees. Attributing factors such as condition, size, and relationship to buildings can alter greatly over a period of a few years or even months. A survey should state a period of time that should be expected for a tree to maintain its current condition and requirements for future monitoring. Once confirmed by both parties, a written confirmation should be written to state that everyone understands the instructions and expectations agreed, as well as other necessary documents including risk assessments and access.

Planning and Preparation

Landowner permission should be agreed in writing before undertaking any survey.  When lone working, ensure that contact is maintained with a responsible person throughout the day.

 Tree Risk Management

Site context and the location in which the trees are surveyed should be addressed prior to assessment.  It is important to understand the site’s use and the frequency of visitors within fall distances of the trees in question. Some areas may require more detailed and in depth surveys and/or take priority over other parts of the site.

What to look out for:

  •       Buildings, sheds, storage areas
  •       Site boundaries and fences
  •       Recreational areas and pathways

These areas may have a greater footfall or falling trees could damage structures not owned by the landowner. These areas can be recorded as a ‘Target Zone’. Personal safety should also be taken into account, the condition in which the tree(s) are situated could pose other risks to the surveyor, such as slope, tree lean, tree density and weather, etc.  Appropriate PPE should be worn and adherence to the particular sites specific risk assessment.

Tree Assessment

The assessment itself will be a ‘visual inspection’ looking into the physical signs of failure and making observations in the context of the local environment.  The local environment can play an important part in the trees’ current condition. An idea of historical site use, soil conditions, local climate, previous tree works or previous constructions and any land use change can lend a hand in accurately assessing the potential failures on a site. To assess a tree’s overall condition, signs and features associated to tree failure are inspected, as well as an assessment of the risks made, from ground level, noting variations against what would be expected from a healthy tree. The assessment utilises the surveyor’s knowledge and experience of tree biology and structure to assess the overall condition of the tree. 

Reporting

Data collected should be filled into the appropriate areas in a Basic Tree Safety Survey Form during the survey of each tree; ensuring notes are easy to follow and are written in laymen terms for those who may have less knowledge concerning tree surveys. Once a report has been written and digitised, the original copy should be stored in a safe location. A PDF document should be sent to the client outlining your observations and possible recommendations, dependent on arboricultural knowledge.  Copies of this should also be sent to the client and stored for a minimum of five years.

Basic Tree Survey Methodology

Hazardous Trees

This section will help identify hazardous features on 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 should be referred to an appropriately qualified person.

Methodology

Where possible individual tress should be assessed from all sides, though this can be difficult when working along a towpaths or in areas of dense vegetation. Descriptions and the locations of each surveyed 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 (if known)
  • Position of tree e.g. coordinates, map locations or a description of its location, where possible all three should be completed.
  • Comments (i.e. distinctive attributes and features)
  • 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. Note 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 weight in the canopy
  6. Is the tree leaning?  Particularly over 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 usage, 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 and relevant contacts.

Further training can be arranged through the Restoration Hub’s Environmental Support Officer.

Disclaimer: This guidance note is intended to offer volunteers the basic knowledge of how to undertake a tree survey to identify potentially hazardous trees and report to the relevant person(s). Support should be sought from an appropriately qualified Arboriculturalist, if unsure whether a tree poses a risk. 

Download these documents to help with your survey

Tree Survey Form – word doc.

(69.47KB)

Download

Tree Survey risk Assessment – word doc

(198KB)

Download

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