Tree 'Reduction Via Thinning". Holistic and sympathetic tree management. By David Lloyd-Jones.
The full specification and a detailed explanation of the innovative theories behind it are now available in a book that you can find on www.TreeMorphogenesis.com
The Tree Morphogenesis project has been developed from the earlier practitioners versions which I used as a training guide for arborists working for Cheshire Tree Surgeons.
On all quotations for Reduction Via Thinning we include a brief summary of the technique which reads:-
"RVT - the removal of a small portion of primary foliage bearing branches back to naturally occurring pruning points within the canopy to subtly reduce and thin the canopy. This reduces wind resistance giving the roots, trunk and structural branches a mechanical advantage while sympathetically retaining the shape, biological functionality and most importantly the character of the tree.
This method concentrates on the removal of small percentages of the foliage bearing branches which are pruned back to the best, naturally occurring pruning points within the canopy. We usually limit this to a small percentage of the foliage, typically between 5 and 20%. This represents a subtle and progressive tree management method, which is sympathetic to the trees health and growth requirements." It also closely resembles the tree's own naturally evolved strategy of progressive branch loss in high winds and this naturalistic ageing is what Reduction Via Thinning approximates so closely. As a conceptual model it passes the common sense test.
Tree Morphogenesis book 1, Reduction Via Thinning" describes the theory, science, research and practice behind the evolution of this holistic pruning and management regime. As such it explains the various issues including "morphological pathology without dissection", "resonance frequencies in organic structures", "age classification related morphology and its implications for sympathetic tree management based on milestones that are significant to the development of the tree.
Understanding all of the influences will give the reader greater insight into how trees have evolved and especially the strange phenomenon of the "evolved weakness" that is the weakly attached and even acute angled fork. If you have never wondered why after 700 million years of evolution most families of trees still have a genetically preserved "weakness" throughout their structures, then its high time you did.
Pruning induced stress. - The stress imposed on the trees biological systems by significant reduction of the leaf (photosynthesizing) area should be avoided if the health, vitality and disease resistance of the tree is important. Large leaf loss tends to force a tree to replace lost leaf using stored reserves of carbohydrates and sugars. In extreme cases the tree will adopt a juvenile tree's strategy of growth characterised by vigorous growth, apical dominance, large leaves with high stomatal density and little reproductive activity.
Aesthetics - Most people seem to have a built in capacity to appreciate natural beauty and conversely also recognise unnatural shapes and forms, this recognition is almost subliminal. It is difficult to describe what is inherently right or wrong about a trees shape and form, but poor pruning is usually recognisable as such with little or no arboricultural training. We call this a snap assessment but it is really a natural skill called by neuro scientists who study such phenomenon "saccading". Understanding how the human eye "saccades" a subject can give the arborist interested in aesthetics at a cognitive and even a subliminal level, a tool of significant importance
These issues are covered in more detail in the practitioners version which is in peer review and should be published in the summer of 2002.
I would like to see more research on many aspects of tree structure, physiology and especially tree resonance frequencies because, if trees gain a significant measurable mechanical advantage by the removal of only a small amount of the peripheral mass (which is what my research, measurements and observations suggest), changing the way that the tree reacts to strong or successive wind loadings then a lot of work undertaken to "stabilise" and manage the risks associated with retaining large trees may well be overdone. unnecessarily.
If the client wants to see that his tree is safe then the arboriculturist advising him has to change his clients perception if only because tree work that is obvious to a casual observation usually guarantees the need for more tree work in the future!
As a simple rule, if you can tell at a glance that it has been pruned at all - then its over pruned!
Copyright © David Lloyd-Jones
original article extracted from : VOLUME 1 - ISSUE 2 of "Treeswork" 1996