Openplants: Dead branch on the tree! Cut it down right now before it drops on someone!

A slightly over-dramatic exclamation whenever an enthusiatic manager/member-of-public/person-with-nervous-energy spots a dead branch on a tree. This post would be based on Arborist News, the February 2018 edition.

Removal of dead and diseased branches that are attached and have broken off from tree is called deadwooding. Crown cleaning is not widely used in arboriculture outside of North America. It is done for safety, aesthetic, and biological: for compartmentalisation and wound closure to occur, and reduce incidence by pest and disease attack. Clearing of deadwood after storm events could be more expensive than scheduled deadwooding due to reduced economies of scale and crown thinning due to repairing branch attachment points. However when left uncleared, deadwood could provide a habitat for wildlife, and nutrient resource for insects, fungi and other organisms.

This branch was topped and resulted in a dead stub that is blocking wound closure. Note the wound wood surrounding the base of the dead stub.

Acacia and Eucalypts usually have a lot of relatively small deadwood. As the deadwood would be constantly present in such species and give a messy look too the surroundings and the tree crown, it would not be practicable and economic to remove them all the time. Parks and estate management should be aware of this characteristic instead of yelling for the arboriculture team to turn up every other week.

Two Eucalyptus deglupta with quadpod staking at the entrance of a condo estate at Pasir Ris. At first I thought they were Hopea odorata.

A row of Eucalyptus deglupta along the periphery of another condo estate at Pasir Ris. The crowns were overhanging a cycling/jogging path and it does not seem to be littered with deadwood. Perhaps due to the trees' relatively young age. Wait till they get to 50 years old and things may be different.

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Branches on trees act as coupled masses and in winds develop a mass damping effect which helps distribute, reduce and dissipate the wind energy. (James and Haritos 2014)

Source: James KR and Haritos K 2014 Branches and Damping on Trees in Winds

23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23), 9-12 December 2014, S.T. Smith (Ed.)

Mass damping is part of the tree's response to strong winds (Moore 2014), reducing the impact of dynamic forces on the branches and minimising the occurence of harmonic waves in branches on windy days.

Source: Moore GM 2014, Wind-thrown tree: Storms or management? Arboriculture & Urban Forestry 40(2):53-69

Dynamic loads can be defined simply as time-varying (Clough and Penzien 1993) and may vary with magnitude, direction and/or position with time. The responses of tree structures also vary with time (Coutts and Grace 1995).

Source: James KR 2010, A dynamic structural analysis of trees subject to wind loading. Doctoral thesis, School of Land and Environment, University of Melbourne.