Anyone who knows JP Associates knows that we have a fascination for the latest developments in arboricultural techniques and thinking. Most of these remain in the realms of researchers or major corporations with deep pockets, and are inaccessible for the average arboriculturist.

However, the new, handheld Arborcheck system has given us the opportunity to apply one exciting and proven scientific method to our client work: chlorophyll fluorescence.

How does it work?

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).

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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.

How JPA will be using Arborcheck

One doesn’t often get to claim a world-first, but to our delight it appears we’re the first commercial arboricultural consultants to have ordered the new Arborcheck system.

By comparing readings from our clients’ trees with the optimum readings in the Nursery Benchmark Database, we will be able to make a quick, non-invasive physiological assessment of their health.

What we really like about it is that it will enable us to make early detection of severely damaging stress factors well before visible symptoms are apparent.

It will also help us to judge when a tree that looks visibly poor actually has a sound physiological framework – which means we’ll be able to take action to alleviate the cause of the stress and help a tree recover when it might otherwise have been felled.

In short, the Arborcheck system will enable JP Associates to provide the most sophisticated assessment of tree health in our field.

Even more excitingly, it will give us an opportunity to participate in our own little piece of research.

Too little is as yet understood about how trees cope with the stress imposed on them by a development project.  So far, all the benchmark readings are from nursery trees that are given the best chance to thrive. We’re hoping to develop a parallel baseline of measurements from mature and semi-mature trees in the real world, with readings taken before, during and some time after construction works occur. By comparing the two sets of data, we hope to advance our knowledge of how different trees are affected by development, which protection methods are most effective, and any factors that contribute to, or undermine, recovery.  

It’ll be interesting to see where this takes us...