Friday, July 10, 2009

ISA HK/China --- 2009 Research in Tree Transplant Shock

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Dear Station Members,

Attached is the 2009 research of ISA on the common problem of 'Transplant Shock' in landscape tree planting. The contents are comprehensive & should be noted by anyone in the field to acknowledge the issue. Please ignore the funny underlining as the Station Manager was making notes of it while traveling on a bus for himself.

In our territory of HK, Macau, Taiwan & China, Transplant Shock in Tree Planting is disliked by landscapers because it does not provide the so-called 'Instant Effect' to show developers & clients. The solution was thought to be by using 'Containerized Trees' usually 'root bound' (roots completely circling & filling the container) in a bag or pot so that little root disturbance would occur during the transplanting process. This concept appeared to derive from Greenhouse Production in which Plugs (seedlings planted in seed beds) would need to be root bound before transplanting to a bigger container. This method works well for short-lived & smaller plants like annuals & shrubs, but not for trees which will grow for dozens of years in urban landscape to massive sizes to cause excessive damage if failed.

Although without the apparent Transplant Shock after installation, root bound trees would develop Girdling Roots to strangle xylems & problems to gradually kill a tree in time. The process would take 3 - 7 years after installation depending on the species & once contracted, there is nothing that can be done to revert it. Also, trees with Girdling Roots will be much more receptive to Wind Failure by having a massive crown but a circling & tiny spread of roots to anchor the tree against wind. Tree Failure by Girdling Roots is a common phenomenon in many parts of the world, & one acceleration is by planting fast growing trees like Ficus in a small Tree Pit.

Girdling Roots may be just one area that the Tree Management Office (TMO) in HK would look into in future to minimize potential Tree Failure in just HK alone. The general Tree Planting Specification may also need to be revised to follow international experience to install safer & healthier trees to provide assets to our community instead of Time Bombs. Trees must not be selected for flowering & scent alone without regard to public safety.

The TMO in HK will have a long way to go if it is to provide genuine benefits to our community by overhauling what's not been done scientifically correct in the past.

May we all support the TMO to let it go in the right direction.

best regards,

Sammy Au
Station Manager

"If a tree is not designed, installed, maintained & inspected properly, it is likely to become a liability rather than an asset."

"Trees are good for the community. Trees need care like human beings. Arborists are the Tree Care Professionals."