Posted by Kristyn Maslog-Levis on Wed, Apr 02, 2014 @ 8:44 PM
All images are from Greenleaf.
Greenleaf tests leaf fluorescence on urban trees in London:
Greenleaf has teamed up with Barcham Trees and Think Tree consultancy in a case study on trees planted in London using the company’s underground load-bearing systems.
According to an article by Keith Sacre and Dean Bowie, the team visited trees planted around nine to 12 years ago using Greeleaf products. “The purpose was to assess the health of the trees and the effectiveness of those products, which had been used in the last decade,” the report said.
Sacre and Melarange testing at Guidhall, London.
In September last year, Keith Sacre from Barcham Trees and Paul Melarange from Think Trees Arboricultural Consultancy teamed up to assess the trees in three difference sites in central London.
“The primary purpose of the day was to combine visual assessment of the selected trees’ condition with the use of leaf chlorophyll fluorescence testing, in order to ascertain whether the trees were under any latent stress, not visible to the naked eye.”
The report said that Barcham Trees has been using “leaf fluorescence to test the physiological condition of trees for four years”. Over the years, Barcham Trees built up a large bank of data on leaf testing on their nursery – over 600,000 leaf samples of over 300,000 species and cultivars.
Leaves being sampled.
“This has led to the production of a nursery benchmark system to evaluate the physiological health of trees post-transplanting against known criteria.” The tests were carried out by Barlett’s Research Laboratories.
The Multi-Function Plant Efficiency Analyser (M-PEA) “combines high quality, fast fluorescence, kinetic and P700+ absorbance studies with groundbreaking Delayed Fluorescence (DF) measurements, providing one of the most comprehensive systems for the investigation of plant photosynthetic efficiency available”.
Buttress root thickening as it begins to lift tree grille segment.
“Delayed fluorescence is light that is emitted from green plants, algae and photosynthesising bacteria for a short time after they have been exposed to light, but after the prompt fluorescence emission has delayed.”
In order to do the sample analysis on location, the team brought a portable PEA. The testing is an additional way for Greenleaf to assess trees’ health in different tree pit design scenarios.
Although the trees might look healthy from the outside, the test is able to back this up with real data. The report, however, said that the leaf testing is only one way to measure the tree’s health and does not give all the information.
“We are learning all the time, and as new methods and equipment are developed we will gain a greater insight to the different benchmarks and diagnostic methodologies to assess urban tree health in view of continuous improvement. This applies to tree pit design, appropriate species selection, treatment of different planting locations, product design and planting methodologies.”
The tree pits that were inspected were planted with Root Directors and ribbed ReRoot 600 barrier. The testing showed that there was no “root damage or trip hazards attributable to root growth on any of the locations”.
“However, on two sites, buttress root formation was beginning to lift the cast iron tree grille segments immediately next to the tree trunk. This kind of root formation often develops as the roots thicken to provide stability and is regarded as a ‘luxury problem’ in as much as it is associated with a successful tree.”
The first tree planting location in Guidhall, London.
The tests concluded that the trees are in excellence health.
“This is another step forward for urban tree pit design in the UK, in as much as we have trees planted using root management, in conjunction with load-bearing soil cells, for over 10 years now. This is the longest track record of load bearing soil cells globally, as we pioneered their use in the UK. This means, these tests have a special interest for us. Whilst we appreciate 12 years is not a huge percentage of a tree’s predicted life span, it is a good measure of how the trees can establish successfully in arboriculturaly speaking, very difficult conditions – without costly infrastructure damage,” said a Greenleaf spokesperson.
They are currently conducting further tests at other early RootCells projects in the UK.