Tree Safety Survey
All landowners are under a ‘common duty of care’ to people who may be damaged by their acts or omissions and must not expose visitors to their property or premises to unacceptable levels of risk. The Occupiers Liability Acts (1957 and 1984) refer to taking ‘reasonable care’ or ‘such care as in all the circumstances of the case is reasonable’. Trees have the ability to damage property and injure people and so they require attention as part of routine management and maintenance of a site.
Our consultants hold the professional tree inspection certificate and have considerable tree management experience. Treecall Consulting can carry out a range of tree surveys and provide appropriate management recommendations. The written reports are also valuable in demonstrating that a prudent approach to tree risk management is in force and can help to minimise liabilities, should an accident occur.
This is a basic level survey that we find is a cost-effective way of ensuring that problem trees are dealt with in an appropriate and timely manner. All trees within the site are inspected from ground level using the visual tree assessment method but only those that are identified as a hazard and require work for health and safety purposes are recorded. These trees are shown on a location plan to aid identification and all required work is listed in a schedule that includes a safety priority to indicate how soon it should be carried out.
This report can be submitted to the local planning authority in support of a tree work application if consent is needed for any of the recommended work.
Tree Condition Survey
A more detailed survey can provide a snapshot of the current condition of the trees on a site and serve as an inventory to inform and monitor progress towards management objectives. All trees are inspected from ground level using the visual tree assessment method and, in this case, all are recorded on the tree location plan and schedule. The information recorded includes the species, stem diameter, height, age class, physiological and structural condition and arboricultural observations. Recommendations are given for resolving any immediate problems – with a safety priority given, as above – and also to encourage future tree development.
This report can also be submitted to the local planning authority in support of a tree work application if consent is needed and has the additional benefit of demonstrating that the landowner is taking a proactive approach to tree management.
Treecall Consulting has permission for commercial operations (PfCO) from the Civil Aviation Authority (CAA) to fly our DJI Mavic 2 Zoom for the purposes of carrying out aerial tree inspections. Further details regarding the PfCO can be found here.
Using our drone we can safely inspect structural defects and the condition of the tree crown without needing to involve a professional climber.
High quality video footage can be recorded during the inspection and this can be used to inform the assessment of tree risk management, work recommendations, canopy cover assessments and identify future tree planting sites.
PiCUS Sonic Tomograph
Sometimes more information is needed about the internal condition of trees and Treecall Consulting has a range of equipment that can be used to carry out in-depth investigations to determine appropriate tree management.
The PiCUS Sonic Tomograph is an instrument for the detection of decay and cavities in standing trees.
Nails are driven through the bark around the circumference of the tree, to which sensors are attached. Each nail is struck in turn with a hammer and the sensors detect the resulting sound waves as they travel across the tree. The data received by the sensors is transmitted to a laptop and the software compares the speed of the sound waves. If the speed of travel is reduced in a particular area, this indicates that there may some decay, a cavity or an internal crack.
The results are shown as a cross section of the trunk showing the variations in speed of the sound waves in different colours. A brown or buff colour indicates good quality wood with insignificant strength loss. Purple, blue and white indicate progressively greater decay or dysfunction, white being the most significant and normally indicating hollows. The green colours indicate wood of intermediate characteristics, where there is likely to be some decay in its early stages.
The Resi-PD 500 is a microdrill that records the resistance of wood to the passage of its drill bit through a trunk or branch. Readings are taken just at the chosen points where information is needed about wood strength.
Regions of sound wood show high resistance to the forward motion of the drill bit, but as it enters a decayed region this resistance is reduced. The level of resistance along the path of the drill is displayed as a continuous trace and this enables the wood quality in different areas of the tree to be compared.
When light energy is absorbed by the chlorophyll in a leaf there are three processes at work: some of the energy is used to drive photosynthesis (photochemistry) and the excess can either be dissipated as heat or re‐emitted as light (chlorophyll fluorescence).
Current research suggests that chlorophyll fluorescence can be used to measure plant vitality and future growth potential. Values in the range 0.85-0.75 indicate a healthy plant and ‘normal’ growth, representative of the species, whereas lower values correlate with increasing levels of stress in the plant. In trees, a drop in values below 0.25 is often accompanied by signs of leaf drop and cessation of growth.
Treecall Consulting takes chlorophyll fluorescence readings using a small hand-held device called the ‘Pocket Pea’, produced by Hansatech. This instrument works by illuminating a dark-adapted leaf with a very bright red LED for around 1 second and recording the chlorophyll fluorescence signal that is emitted. The values obtained can help us to assess the overall health of the tree and where some intervention, such as soil decompaction or fertilisation, may be beneficial to improve vitality.
The air spade is a tool that enables the soil surrounding trees to be removed without damaging roots.
Compressed air is directed onto the soil which is blown away from the root surface. This method avoids inadvertent damage from spades or other hand tools and allows the tree root structure or decayed areas to be inspected or for underground services or foundations to be installed without the need for severing roots.
This method is also used where poor quality or contaminated soil is to be replaced with better quality material to encourage healthy tree growth.