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TreeSpecialist · 19th March 2008, 02:58 PM

Like all things, done well, crown reduction can and is very beneficial. Done poorly and you get Cass Turnbull (Plant Amnesty) on your case. It's all a matter of degree.

I face daily what is known around here as "lion tailing". A jack leg climbs a ladder, cuts off everything he can reach, and calls it pruned - skinning the interior of the tree, frequently done in the name of reducing the "wind sail." This actually causes the tree to be more likely to break during a storm or wind event.

Nearly all trees have interior branches - epicormic sprouts to be exact (trees don't have "suckers" or "water sprouts" - but that's another argument.) These interior sprouts are there because there is enough light to photosynthesize sunlight into food for the tree. The excess products of photosynthesis are stored and utilized within a few inches of the attachment points of those sprouts. The tree then uses these products to make the limbs larger in diameter, increasing the branch taper back towards the main trunk. (Research done by Dr. Bruce Fraedrich - Bartlett Lab.)

When a very thickly foliated tree is hit with wind loading, all of the leaves, twigs, branches and small sprouts along those stems absorb the wind energy resulting in less limb movement or sway.

A skinned tree with foliage only out at the tips of the branches will have more movement or sway frequently resulting in limb breakage. These trees are also especially susceptible to breakage with ice loading.

Crown reduction pruning forces new growth back towards the center of the tree, lowers the exposure of the tree to the prevailing wind and also lowers the tree's center of gravity.

Trees that have been constantly raised and thinned also are more likely to suffer "wind throw" or the complete failure of the tree as the wind is more likely to completely uproot the tree.

The same interior sprouts and interior foliage that the lion tailers strip from the trees would have helped to increase the root mass and therefore the "grip" the tree has on terra firma.

Dr. Gilman's work has shown that trees with tip reduction and or crown reduction does work.
"Thinning or reducing crowns significantly reduced upper trunk movement at all wind speeds, whereas raising did not. Lower trunk movement was not affected by pruning type. These data indicated that foliage and branches toward the top of tree crowns were largely responsible for trunk movement in straight-line wind with those toward the bottom less important. Trees that are reduced or thinned in the manner described could receive less damage in windstorms." Dr. Ed Gilman , Journal of Arboriculture.

Where tip or crown reduction can also really help is with any tree that produces fruit. Here in Central Texas, we reduce the crowns of 5 or 6 pecans a day starting each July lasting into October to keep the trees from buckling under the weight of the nuts only occurring at the branch tips because all of the interior branches were stripped out.

19th March 2008, 02:58 PM	#10 (permalink)
TreeSpecialist Semi-mature vigorous tree Join Date: Mar 2008 Location: Austin, Texas Posts: 201	Re: Altering climate affecting your pruning? Like all things, done well, crown reduction can and is very beneficial. Done poorly and you get Cass Turnbull (Plant Amnesty) on your case. It's all a matter of degree. I face daily what is known around here as "lion tailing". A jack leg climbs a ladder, cuts off everything he can reach, and calls it pruned - skinning the interior of the tree, frequently done in the name of reducing the "wind sail." This actually causes the tree to be more likely to break during a storm or wind event. Nearly all trees have interior branches - epicormic sprouts to be exact (trees don't have "suckers" or "water sprouts" - but that's another argument.) These interior sprouts are there because there is enough light to photosynthesize sunlight into food for the tree. The excess products of photosynthesis are stored and utilized within a few inches of the attachment points of those sprouts. The tree then uses these products to make the limbs larger in diameter, increasing the branch taper back towards the main trunk. (Research done by Dr. Bruce Fraedrich - Bartlett Lab.) When a very thickly foliated tree is hit with wind loading, all of the leaves, twigs, branches and small sprouts along those stems absorb the wind energy resulting in less limb movement or sway. A skinned tree with foliage only out at the tips of the branches will have more movement or sway frequently resulting in limb breakage. These trees are also especially susceptible to breakage with ice loading. Crown reduction pruning forces new growth back towards the center of the tree, lowers the exposure of the tree to the prevailing wind and also lowers the tree's center of gravity. Trees that have been constantly raised and thinned also are more likely to suffer "wind throw" or the complete failure of the tree as the wind is more likely to completely uproot the tree. The same interior sprouts and interior foliage that the lion tailers strip from the trees would have helped to increase the root mass and therefore the "grip" the tree has on terra firma. Dr. Gilman's work has shown that trees with tip reduction and or crown reduction does work. "Thinning or reducing crowns significantly reduced upper trunk movement at all wind speeds, whereas raising did not. Lower trunk movement was not affected by pruning type. These data indicated that foliage and branches toward the top of tree crowns were largely responsible for trunk movement in straight-line wind with those toward the bottom less important. Trees that are reduced or thinned in the manner described could receive less damage in windstorms." Dr. Ed Gilman , Journal of Arboriculture. Where tip or crown reduction can also really help is with any tree that produces fruit. Here in Central Texas, we reduce the crowns of 5 or 6 pecans a day starting each July lasting into October to keep the trees from buckling under the weight of the nuts only occurring at the branch tips because all of the interior branches were stripped out.