Altering climate affecting your pruning?

blair duncanson

All,
The number of times folk are mentioning extremes of weather. Regardless whether you think climate change is a reality or not, i certainly feel that there are bigger extremes in the weather. Thing is, do any of you international arborists consider this when offering clients advise, tree spp, crown reduction etc, etc. Kinda feel we have a certain responsibility? In area of Scotland i remember recently reading that some orginations were considering serious crown reductions on Fagus sylvatica, shallow rooted, prone to windthrow and they wanted to preserve the population of Beeches?What do you think and have you altered you're mind set when offering advise??

Eric Frei

Well, here I can say we haven't had any storms more fierce than those of 2004 and 1999/2000 region.

I changed the title of the thread to something a little more arb focused as many might skim it thinking that it's another one of those save the planet threads.

Pruning in anticipation of weather extremes is common. Local knowledge of species performance is the key ... what is likely to happen if the tree is left alone?

At the same time it opens a can of worms that all trees stability is improved if reduced, so we prune them all, whether or not they really did need it.

Then you stop and think, hang on, what about the ions of time before man was here with his ingenious chainsaw, the trees coped then and grew mighty and large?

Oh, however they were likely in groups or forests not isolated fringe specimens. Also if a forest or low target tree was damaged in a storm ... frankly so what, it would get some shoots and continue or become habitat or mulch.

I would say that consideration be given to each individual trees location and form. Over here I have spotted many eucs where I have said the tree branches would likely fail ... and many did.

Good question, local knowledge and assessing each tree on it's own merits is the key IMHO.

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TreeSpecialist

I always take the exposure to prevailing winds into consideration when advising different types of pruning jobs.

Dr. Ed Gilman has done some good work with crown reduction pruning of trees exposed to hurricane force winds (http://www.isa-arbor.com/related/ re...ePaper2007.pdf -)

Trees have been evolving over millions of years. They generally prefer keeping their low branches keeping their center of gravity low. Raising low limbs, changing wind patterns around trees, cutting roots, over irrigating, etc. all become problems in the long run that can cause the tree to fail.

Mechanically balancing the tree should always be a part of a good pruning job.

A live oak we recently worked on with 70% root loss was cabled to the ground to prevent wind throw. The cables were installed 2 days prior to 75 mph wind gusts experienced during a spring storm. The tree is still standing 2 years later. (Photo shows only one side cabled to ground - a similar arrangement was installed on the opposite side of the tree.)

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Eric Frei

The link is dead, is that a link you get when logged in or something from ISA, I tried many configurations but not happening.

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blair duncanson

Aye, cannot see that link. Would be very interested in seeing it though.

blair duncanson

Cheers for the response and appreciate what your both saying, i hope it doesn't workout though that we reach the stage of, extreme pruning cause of extreme weather but always the optimist that willnae happin'!

TreeSpecialist

The ISA has all of these articles online but its for members only so I guess
that's why the link is "dead."

Check out the pdf file below for the full article.

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Pruning Effects: Ed Gilman.pdf (457.9 KB, 1459 views)

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gump

hey blair, i think it is important that an arborist is based in their area for a substantial amount of time, or if moving to a new area they should research, ask local arborists about the local species and reactions to extreme weather. i have travelled and worked around a bit now, and always try to achieve the local knowledge, where possible.

im currently working in a hard wood belt in the mid west, america, and recently have had to some reductions/tip pruning on silver maples ,hackberrys and elms. these species tend to have "over extension" in limbs throughout the canopy. in ice storms, or high winds, tornados/hurricanes these snap of, in turn creating a smaller canopy.
i have had to climb and reduce these over extensions, to help to prevent these "over extended"(a term of a local arborist) limbs from snapping under there own weight or excessive weather conditions.
i can see how this type of pruning can work,
but i have seen trees that have had similar pruning done, about 5 or so years ago, and the tips become far denser than it would normally appear.

so, i think that this new denser tip canopy would be more susceptible to wind damage because the wind cant pass through the canopy as easily,( like wind hitting a solid wall, apposed to wind hitting a wall with gaps in it ,ya see what im getting at?) and this could possibly cause larger limb?or whole tree failure, im still yet to witness a major wind storm here, and probably wont be around long enough to see one.

i dont agree with crown reductions unless it absolutely nessacery to preserve a trees health.

anybody else got any experience with exterme weather conditions and prevention pruning?

p.s, where in scotland are ya ill be heading those ways in may.

scott forrest.

blair duncanson

Cheers for that. Travelling definately broadens the knowledge with regards to tree care, if only i was fluent in French, i could ask them why they pollard, everything!? Travellin' just now myself. Won't be back in Haggis Heaven for a while. Check out the central and west coast. Mind the midges and watch out for those pesky beasties- the haggis! How long are you in Scotland for, are you looking for work?

TreeSpecialist

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.

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blair duncanson

Thankyou, that article could be of benefit to many. I certainly have made a point of watching tree movement in heavy winds. Kinda thought that the more flex in a tree the less chance of damage, apart from in strong gusts? More to learn. Perhaps i should make more of a point of digitally photographing individual trees, so i have something to relate to, if and when they get damaged?
Cheers again.

gump

in mid to late may, 2 weeks, and work yeah maybe!

Treelore

Agree with most of the comments other than yet to hear answers to, have the Fagus sylavatica always grown in that region ie. the particular one u speak of and not had many trees removed around from them that may make them susceptible to windthrow. And what if any advantages are gained from pruning Fagus sylvatica extensively. It is a diffuse porous tree and doesn't lend itself to pruning well.

blair duncanson

The Fagus in question is in a category where many folk say that it is not native to Scotland. Certain orginisations actually authorised the removal of some massive specimens, purely on their beleif that it was not native It is non invasive and creates cracking singles or small woodlands, not to mention habitat. I never pursued this consideration of severe crown reduction and unfortunately do not know the outcome. Hoping an arborist was called upon to consult.? They are very shallow rooted and yes, do not lend themselves to pruning. Think i was trying to workout, with all this wind about, how extreme would you prune to preserve the tree, albeit it would lose all dignity and form and continual management would be required, and perhaps the tree would just become a stumped, knarley habitat but are you not in essence preserving the tree?? Unsure if i'm wording this correctly? Sure, some species would perhaps die from such drastic pruning but many would not.

blair duncanson

Bye the bye, i'm not talking about a particular tree.

TreeSpecialist

I would never severely reduce a tree to preserve it - you might as well cut it down completely.

I would try to reduce it 10 to 20% at a time with 3 to 5 years between pruning.

Severe crown reduction might as well be topping. Cutting back to codominant unions has the same effect (in some trees) as topping. Severe reductions are the beginning of the end of most trees.

Here in Central Texas 99% of our trees are shallow rooted (soils very shallow and those that aren't are very heavy clays.) We only 5 trees commonly found which will put down a tap root.

I wouldn't worry so much about a "shallow rooted" tree falling over as I would be more focused on what I could do to make the ground beneath the tree a more favorable place for roots to develop - reduce soil compaction, fertilize, aerate, etc. Combined with crown reduction done well, most trees will be "safer."

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blair duncanson

Agreeing with most points made. With reference to never severely reducing a tree to preserve it, i must question what values you award to a tree?
Any trained Arborist, at some point will hopefully have been taught the, 'evils', of ,'topping' and rightly so. However i do think that the constant emphasis on such practise is partially due to the rage caused by the undermining of the trained Arborist, by so called, 'cowboys'. I to get the same rage but on a couple of occassions i have been pleasantly surprised of the sound thought processes which equated to the , topping or partial topping of trees.
Ancient trees; Partially topped, to delay iminent crumbling of stem, to retain and inhance exceptionally species- rich communities, associated with wood decay, (crown and tare cuts were used). Retaining, landscape, cultural and wildlife value.
Incorporating this approach more frequently into an urban environment is a positive step. With all safety issues considerd, diversity would be allowed to thrive where normally there would be a sterile clean environment.
Within areas of France a great many trees are in some form, pollarded. Percentage have had there first cuts from a young age-(recommended).Spp observed, Morus, Castanea, Tilia, Robinia, Juglans and Aesculus. Many have received their first pollard at a much later stage and in some cases at a height of 60-70 ft,(topping). Spp observed, Platanus, Tilia and Quercus. Yes, these trees had lost there text book form for ever, and yes evidence was there of decay on pruning cuts. However the individual trees showed vigorous, positive, response, with reference to reaction wood, callusing and overall wellbeing, ( perhaps timing was of the essence?).There seemed to be a form of management in place, thinning the new colomnur crowns, presuming inspection would be carried out also. Unsure of management schedule, would like to know more but these trees were aesthetically awesome, sitting well within, tall sided, straight, bright streets, dating back to Roman times(not the trees, aye).
Arcing back it is evident that consideration is made to climate when assessing clients trees and with regards to extreme wind conditions the ISA document was very informative, yet not conclusive.
If world climate predictions are correct and so far i have no reason to disbeleive, previous coscepts of making trees relativley safe will surely require adjustment? Techniques will need to be more immediately effective and worked in conjunction with current work practises.
I do not wish to sound full of doom and gloom and i as much as any of you would prefer to enjoy trees untouched. It all started with just a thought and hopefully the discussion allows further ideas to unfold.

TreeSpecialist

Severe crown reduction (in my part of the world) always results in large codominant stems being removed.

Any student of Shigo knows that large codominant stem removals do not compartmentalize well resulting in large areas of decay forming. Also, when large portions of a crown are reduced, a corresponding portion of the root system that it was supporting dies. Besides supporting the crown biologically, it mechanically holds the tree up. As this portion of the root system rots away, it may undermine the stability of the tree.

Frequently large strips of necrotic tissue result along the main trunk or stem from which the codominant was removed as well.

Being more pragmatic than poetic, I encourage replanting with the right tree in the right place. Early in my career, I fought to save every tree I could only to have some of them fail later on. Trees are a renewable resource and we need more new trees to be planted. We also need to know when to give up on those in the wrong place, or the wrong species, or those in poor condition.

Pollarding is very labor intensive and while Dr. Shigo studied them closely, he never really agreed with the practice. Pollarding is not something one can do once in a while - to work it needs to be performed every year.

Crown reduction done well can rejuvenate a tree and give it many more decades of useful life. Done poorly, it dooms the tree to a premature death.

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blair duncanson

Aye, agree with all points made. Do still think though that in some cases a retained , topped tree, can and will contribute many assets to a clients garden, if continually managed. Many trees we work on are in some form Severely damaged, whether by man, nature, mechanical, etc and not text book specimens. On most occasions complete removal will have a huge effect on the ecosystem of the garden. People whom are passionate and knowledgeable about their gardens do often insist on as much of the tree being retained as possible, albeit a 20ft severley topped tree. I think certain circumstances allow for that.
Will readup more on Shigo's finds with ref to pollarding.
Cheers for the input all.

TreeSpecialist

A couple of references to start.

Al Shigo's " New Tree Biology" and "Modern Arboriculture" are two books every arborist should have, read, and understand. If you don't own them, get them. Also Shigo's dictionary that accompanies the New Tree Biology and his book simply called "Pruning.


Tree Pruning


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I can understand people's reluctance to loose trees though severely damaged. I've even had clients have me leave a dead standing trunk cut just above the edge of the roof because, from inside the house, it still resembled a tree (until you looked up the trunk...)

I caution clients about rapid advancing decay in the roots holding the thing up and leave it up to them as to their comfort level of liability. (We have subterranean termites here that help things along..) I even get them to sign off of some trees so that I don't get sued as the last person to have worked on or consulted on a dying tree that should have been removed.

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blair duncanson

Cheers for that. I do have both those books, full understanding of all, perhaps not. Bugger when travelling, you can'"t carry your books with you, compiling a web data base justnow though all about the individual trees i meet on the way. Thankfully Scotland is way behind with the sueing culture but will bare that, signing off , in mind.
All the best and cheers for the discussion.
Do you know of an individual continuing Shigo''s work?

TreeSpecialist

Although some may disagree, Shigo took his work about as far as one can from a biology/ anatomy/ compartmentalization stand point. There is always more to learn, but Shigo brought arboriculture out of the dark ages in such a "quantum leap" that it will be hard to eclipse his work.

Check out his web site for all of his publicatons:

Shigo and Trees > Home ( DNN 3.3.7 )


His daughter is running the show now. It's still very much a family business.


Areas Al was interested in and fascinated by but didn't have time to pursue like he would have liked was where Claus Mattheck has gone - tree structure. If you've never heard him speak or bought his books, you need to get "The Body Language of Trees" to start with.....

Ed Gilman is another one to watch for practical applications of arboriculture. Ed's really great.

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blair duncanson

Cheers again, Claus, the one that looks like Ozzi Osbourne. The theory of helical growth. Closest i have seen to that is on Castanea sativa back home.
Think i might have exhausted this thread?