Measuring the Health of Your Trees

Is My Tree Healthy and Safe?

This is one of the commonly asked questions when we attend a client’s address to assess a tree that is experiencing problems. There are two elements to a tree’s health that we look at, physiological health and structural stability. Physiological health incorporates the vascular system’s flow from root to shoot providing the canopy and its leafage with the nutrient when harnessed with sunlight to photosynthesize, produces carbohydrates and starches for energy needed to sustain its structure. Structural stability is the ability of the tree to maintain its position in achieving its primary goal of light capture. That stability is created through the integrity of woody fibers laid down in previous years that provided vascular conduits no longer used but now performing both rigidity and flexibility.

We have two methods by which each of these vital components of the tree’s health can be measured. Physiological health is measured by assessing the tree’s effectiveness in using red light during the photosynthetic process and is called chlorophyll fluorescence testing. The structural stability of the tree is measured by performing a scan through the relevant cross-section using soundwave technology known as sonic tomography.

​To perform a chlorophyll fluorescence test on a tree, a sample of twenty leaves anywhere within the canopy will give us the physiological efficiency of the tree’s photosynthetic process. The measurement involves light darkening a small area of the leaf’s surface for approximately 45 minutes after which the aperture is opened, and a one-second burst of red light is passed into the photosynthetic cell. This measures the efficiency by which red light is used within the photosynthetic process before any signs are outwardly shown by the tree. This process will alert us to the direct physiological condition of the tree and how efficiently it is able to photosynthesize and create energy for its system. This is an extremely efficient way in which we can tell whether the tree is suffering from stress prior to pruning or any major work that may need to be carried out.

To perform a tree scan, soundwaves are sent from sensors positioned around the tree’s circumference with an electronic hammer tapping each sensor point in succession. Any pathogen that has entered the woody structure and started to cause fiber separation during the process of rot will produce air pockets between these fibers through which the soundwave has to travel. The soundwave speed will alter depending on the extent of fiber separation and the gap through which the soundwave now must travel, relevant speed is color-coded and sent back to the computer. The tree can be mapped to show the different degrees of fiber separation and where the potential areas of pathogenic rot are located. The scan enables us to carry out either structural reductions or general pruning to make sure that high-loading areas, where there is evidence of fiber degradation, are lessened and the chances of failure are mitigated substantially. 
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