JPA was delighted to have the opportunity to demonstrate its Arborcheck tree health diagnostic system to the ranger team at the National Trust's Knightshayes estate.

Although it was a little late in the season to gather readings, consultants Chris Hawley and Dan Vickridge were able to test two trees - one oak in fine fettle and a beech with a small patch of meripilus at its base - and explain the findings to head ranger Raef Johnson and some of his team. They saw how the system gives an accurate picture of a tree's immediate health and its longer-term vitality, before any physical signs of deterioration appear. Both trees were given a clean bill of health, although the beech was showing some signs of stress, most likely due to the presence of the fungus.

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How it works

We all know the main principle of photosynthesis: a plant’s leaves will take energy from the sun and convert it into complex carbohydrates that it can use for nutrition.

Normally a healthy tree will use about 80-84% of the sunlight it receives at the leaf surface for this process. It needs to disperse the rest in a different way. It will do this by non-photochemical processes: re-emitting in the form of infra-red radiation (heat) or far-red radiation (chlorophyll fluorescence).

However, when a tree is not at optimum health, this balance changes. After a period of drought, for example, the rate of photosynthesis will be reduced, and a tree will have to increase its dissipation of energy by chlorophyll fluorescence. Other environmental issues will have a similar impact on the plants management of solar energy, such as a development project.

Further, stress in a tree reduces the amount of carbohydrates available for growth and therefore nutrient uptake. This results in leaf chlorosis and necrosis.

By reading the intensity and nature of a tree’s fluorescence, and also by measuring the foliar chlorophyll concentrations in a leaf (leaf greenness), an arborist is able to make a judgement on the tree’s health - even before there are the usual visible signs of stress.

That’s where the new Arborcheck system comes in.

What is the Arborcheck system?

The system comprises two instruments: 

  • The ArbFl-01 Chlorophyll Fluorescence System (Chlorophyll fluorimeter) provides calculations of the photosynthetic efficiency and vitality of an individual tree via 10 simple one-second measurements from 10 individual leaves.
  • The ArbCm-01 Chlorophyll Content Meter can be purchased with the fluorimeter or separately. This measures the foliar chlorophyll concentrations of a leaf (leaf greenness).

The values measured by the ArbFl-01 chlorophyll fluorimeter are downloaded to the Arborcheck Data Analysis app, and the operator can add the chlorophyll content values if also collected.

These readings are then compared to a species-specific Nursery Benchmark Database. This database has been independently compiled and verified by the team at  Bartlett Tree Research Laboratories and is based on identical measurements of 600,000 individual leaf samples from 350 species made annually since 2009 on trees grown in optimum conditions at the Barcham Trees nursery in the UK.