Case Study

A large mature London Plane in a prominent London Park with advanced stem decay. A series of Picus tests were undertaken and as a result the tree was considered unsafe for retention and felled.

RESISTOGRAPH

The IML-RESI system is based on the measurement of drilling resistance.

The IML-RESI operates in a similar manner to a normal drill. A drilling needle with a diameter of 1.5mm is inserted into the wood under constant drive. While drilling, the resistance is measured as a function of the drilling depth of the needle. The data is printed and stored electronically at a scale of 1:1 simultaneously.

Although invasive the relatively small needle diameter causes very little damage, testing is normally only undertaken to confirm the remaining stem wall thickness in decaying trees.



Measurement result (internal cavity)

The graph profile records to a waxpaper strip and electronically for later printout

The waxpaper strip is water proof and records the measuring curve at a scale of 1:1. The resistance against the drilling needle is measured and automatically recorded on the strip. Due to the different mechanical resistance within a tree the graph profile represents the difference between sound wood and a cavity.

Measurement Result (Beech with decay)

The Resistograph has a number of uses, for Arborists it is used to determine the amount of decay in living trees or dead stems. We also use it in root assessment following Air-spade investigations and during climbing inspections. The Resistograph will provide you with measurable data which will determine to what extent a tree is at risk of failure. It is also invaluable for assessing structural roof beams, bridge timbers, wooden framed houses and playground furniture.

DYSFUNCTION

ESTIMATING TREE VITALITY:
CHLOROPHYLL FLUORESCENCE

DIAGNOSIS: Leaf samples are examined by the diagnostic staff at Tree Surveys. An initial inspection for insect, mite, fungal, bacterial or viral disease damage is undertaken on all foliage samples.

Chlorophyll fluorescence, this works on the principle that photosynthesis is one of the core functions in the physiology of plants. The functional state of photosynthesis has been considered an ideal physiological activity to monitor the health and vitality of plants (Clark A. J. et al (2000). Env. Pollution. 109: 501-507; Percival G.C. and Fraser G.A. (2001). J.Arb. 27(5): 233-245). Each leaf is clipped and prepared for assessment, the normal sample for any given plant is twenty leaves, each are measured using a portable fluorescence spectrometer and the response recorded, a range of 10 samples is displayed on Table 1.

TABLE 1.

TABLE 2.
USE OF CHLOROPHYLL FLUORESCENCE (CF) TO MEASURE PLANT VITALITY AND FUTURE GROWTH POTENTIAL

Chlorophyll fluorescence as a measure of the photochemical efficiency of plants is widely used in field studies as an early diagnostic measure of stress in plants caused by adverse environmental conditions. The process is none destructive if undertaken on site, alternatively samples may be collected and sent to us for analysis. From sample measurements we can assess stress levels and provide remedial advice.

For further information, costs or advice on sending samples for analysis please call us on 01189 762902 or e mail us at: info@tree-surveys.com

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