ISA HK/China --- Root disturbance in the name of 'Cultivation'

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Dear Station Members,

Just one more Station Mail before Hawaii.

The Station Manager drove passed this site yesterday & saw a bunch of landscaping workers busy digging with hand tools & excavator to churn the 1 ft. topsoil upside down, & raked anything in the way for collection as garbage in storage bags for disposal.

Upon asking what they were doing, the workers replied that they were told to carry out 'Cultivation' as required in their landscape contract. It was said that the 'Cultivation' was absolutely necessary to loosen & aerate the soil to avoid 'compaction'. When it was examined what kind of debris would be removed from the 'compacted' soil in the storage bags, over 90% of them were tree roots. The roots of the mature trees underneath were matting to form an extensive network at the 1 ft. topsoil for water & nutrients absorption, & they were treated as debris during the so-called 'Cultivation' process. They were cut, grabbed & pulled out in a genocide fashion for the purpose of 'Aeration'.

It is known to Arborists all around the world that the Absorbing Roots of a mature tree would grow & mat the 1 ft. topsoil in most places. Absorbing roots are also Primary Growth which would not regenerate upon damage & would simply die. If a mature tree would lose too many absorbing roots for water & nutrient uptake, being senile, it would lose vigour quickly & may not be able to generate new roots quick enough to support all the living functions of the canopy above. What the mature tree may do is to divert energy reserves within cells to compensate root loss, at the expense of the defence mechanism. If pathogens nearby could take this opportunity to invade the weakened tree at the many wounds inflicted during 'Cultivation', depending on its energy reserve & vigour, the mature tree may not be able to compartmentalize adequately & would be attacked by pathogens.

When so happened, dieback & internal decay may happen. Internal cracks & cankers may develop. The tree may try to fight back by adding more compartmentalization, burning up remaining energy reserves up to a point. Then if incorrect pruning like Lion-Tailing or Topping would happen at the same time during 'Cultivation', the tree may not be able to replace its energy loss & may decide to give up of some of its boundaries to pathogens for co-existence. This compromise may persist for a few years. Then a storm may come & break off the tree at its weakest parts, & perhaps hit somebody or a car passing by.

Then can we call this Tree Failure an 'Act of God' ?

The Certified Arborist acting as Expert Witness in Court certainly would not. If a tree within a managed domain has been tampered with horticultural practice, the Tree Failure would not be regarded as an 'Act of God' in most Western Courts. It would simply be a Civil Negligence or a Tort. The tree owner may be responsible for the action.

Somehow our territory has mixed up practices of Horticulture with that of Arboriculture. Some horticultural experts would regard their practices on shrubs & herbs would be equally applicable to trees. If they were right, ISA would not need to start in 1924 & the 20,000 Certified Arborists around the world would be out of a job. The hundreds of Govt bodies, Universities & Research Institutes around the world would be wasting time & money to study trees & tree care. Our Station would simply pack up & go home, & would not grow to the size of today. Tree Care is a specialist subject.

Trees are the tallest & longest living creatures in this planet. They were there long before humans learned to walk (for 200 million years) & modern civilization could not exist without trees. Trees dominate the forests & would determine the smaller plants underneath to survive or not. Tree Care can not be compared with that of the smaller plants.

Knowing all these, do we reckon we would need Arborists to look after our trees? Or would we prefer to see Veterinary Surgeons operate on humans in our hospital ?

best regards,

Sammy Au
Station Manager