Discussion in 'General Discussion' started by tom_otto, May 4, 2008.
I agree with what Guymayor has said.
The following post turned out to be much longer than intended. The short version is that this month's (February 2018) Arborist News magazine had two separate, independent articles that touched on whether or not removing deadwood is beneficial to the health of a tree. One stated that it was (p.30-31), the other stated that it was not (p. 14). Although both provided a reference for their statement, neither gave any substantive, material evidence. Both acknowledged and discussed various environmental and ecological reasons for leaving deadwood.
A third article (p. 26) mentions the importance of "...dead, dying and decaying trees and branches" for wildlife habitat, but gives no opinion either way about how dead branches affect the health of an individual tree.
In an article that appears in this months Arborist News magazine (Arborists and Wildlife: Retaining Trees for Wildlife Habitat, Arborist News Volume 27 Number 1, February 2018:12-19) Brian French (p. 14) states
According to Dr. Edward Gilman, author of An Illustrated Guide to Pruning (2002), there is no evidence at this time that supports the statement "Removing deadwood improves tree health".
The quotes are French's, but he gives no reference for that specific statement by, nor the general opinion of Dr. Gilman.
In a different article in that same issue of Arborist News (Deadwooding Tree Canopies: Cosmetic or safety surgery? Arborist News Volume 27 Number 1, February 2018:30-33), G.M. Moore (p. 30) states
The biological advantages of deadwooding not only relate to the development of a sound canopy, but also to compartmentalization, wound closure, and the minimization of pest and disease attack.
That paragraph goes on in more detail and then provides a reference, of which Moore is the co-author: Ryder, C., and G.M. Moore. 2013. The aboricultural and economic benefits of formative pruning street trees. Arboriculture and Urban Forestry 39(1):17-24.
But this reference is both irrelevant and misleading as support for any biological advantages of the removal of deadwood. The AUF article states that
Research was undertaken to determine the need for, and costs of, formative pruning recently planted street trees.
...Health was similar for all species, but form and structure varied. Data showed that
codominant stems (68%) and included bark (40%) in the canopy or trunk were by far the most common structural defects.
...The pruning required
to rectify these structural defects was recorded and then multiplied by a time factor for pruning with secateurs (hand pruners),
a handsaw, or a pole pruner. Total time was then converted to an economic cost using current labor market prices. (Abstract, p. 17)
The purpose of this study was to look not only at how formative
pruning can improve a tree’s structure, but to quantify the financial benefits of removing structural defects early in a tree’s life. (p. 17)
The trees selected were young (3–5 years of age) and under
6.5 m in height. (p. 17)
Structural defects on which data were collected (Table 3) were
co-dominant stems, included bark, decay, deadwood and crossing
or rubbing branches...(p. 18)
...epicormic shoots, broken stems, and deadwood occurred at low levels. The low value [i.e. low incidence] of deadwood is a reflection that the street trees were young and in good health. (p. 19)
Analysis of data indicates there is a strong rationale for pruning
when trees are young. (Discussion, p. 21)
Formative pruning is a cost effective way of reducing structural
defects in trees and improving the quality of the structure
of street tree populations. Overwhelmingly, the major structural
fault recorded was the presence of codominant stems
in the canopy or trunk, often exacerbated by the presence
of included bark. All other structural defects recorded were
in much smaller numbers. (Conclusion, p. 23)
The article by Ryder and Moore focuses on a study that investigated the time and cost benefits of doing structural pruning on young street trees, and the article itself states that deadwood was a very small part of that pruning. There is no research or discussion on any possible biological advantages of removing deadwood. Additionally, the AUM study looks only at young (3-5 year old) trees, not at established or older or mature trees, which is the focus of the AN article.
In the AN article Moore also states (p. 31)
...the removal of deadwood may reduce available habitat for wildlife and for beneficial organisms that deadwood and hollows in trees provide. There is an important balance to be maintained between removing deadwood and preserving important wildlife habitat within the urban forest. deadwooding should be done with a clear purpose rather than as a matter of habit, and other environmental values must be considered.
He provided no specific reference for the statement above. He ends the article with a balanced assessment:
Because deadwood has environmental value in terms of the provision of habitat for wildlife and microorganisms, such as fungi, unnecessary removal of deadwood should be avoided. However, there are many good reasons for implementing a deadwooding program as part of urban tree management. (Conclusion, p. 32
There were a total of 12 references for Moore's AN article, but the only one I looked at was by Ryder and Moore, discussed above.
In yet a third article (Practical Advice for Wildlife Protection During Tree Care Operations, Arborist News Volume 27 Number 1, February 2018:326-28), Ryan Gilpin mentions the importance of "...dead, dying and decaying trees and branches" for wildlife habitat, but gives no opinion either way about how dead branches affect the health of an individual tree.
It's good to see discussion on the importance of wildlife, ecology, and the environment.
Great information. Its always good to keep an open mind about everything. Perspectives change. Thanks for bringing this to our attention.
John Kesslick used to urge me not to use the term "dead tree", because the tree was full of bacteria and fungus and could be considered more alive than when it was "alive"...
SO what should I call them I asked.....
symplastless.... OK how's that going to sound on a proposal.
While it would be good to know if removing deadwood is actually good for a tree, I don't imagine that changing much in the "real" world... Customers are going to want to get the trees "cleaned up" and tree guys are going to sell it cause it pays the bills... I don;t know too many people that are going to get upset by the loss of habitat for fungi, but I can think of one that might.... He talks to the trees... goes by "the tree whisperer".. I try to go to any workshop he gives... Did I mention its always good to keep an open mind...
Science is only one way of accessing knowledge, and while its treated as a modern religion, its application in tree work is extremely limited.. Understanding the limitations of science can lead to a major breakthrough in thinking and awareness. Paradigms come and go .. what was once considered unquestionable truth, soon becomes laughable. Yet so many hold onto the truth of the day as if it has to be the only way. Common sense trumps science for most of what I do. I trust my own ability to observe how trees respond to pruning and what types of decay or structural defects cause failure and how effective cabling is some 30 years later etc over what most any PhD is writing. Of course its good to study their "Science" to learn basic biology and help speed up the learning from real world observations...
And of course when you are swinging from a rope at 70 feet, rigging out big wood, common sense will prove far more practical than science... From my perspective, science is given too much credibility. Common sense trumps science.
Um... yeah. We simplify "science" There's scientific theory and then there's scientific law. Understanding when something is a theory we can then recognize it's still not fully developed nor irrefutably proven. Thus the "theory of relativity" and not the theory of gravity. Common sense, though not commonly found, is rooted in the understanding of the fundamental laws. To say common sense trumps science is nonsensical. It maybe that in your observations you're learning new aspects of that can build onto a theory and help refine the concepts such that they better reflect observation.
That rope you're swinging from at 70' is backed by that science you say you're trumping.
Science depends on observation when it comes to observing trees to do real science for example on what type of pruning causes tree failure would take 50 to 100 years or more now shigo in particular used discoloration as a marker for the type of decay that occurs after pruning. And the assumption was made that discoloration was a good predictor for decay, in particular the type oofdecay that causes tree failure.
so shigo said make all your pruning cuts exactly at the target. not outside the target , and not inside the target but exactly at the target.
this is been a disservice to the tree industry because in the real world finding that exact target cut is not that easy as it appears in the book.
not every cut is a textbook cut so the scientist say do it this way but, common sense will tell you you should make any questionable cut outside the target to make sure you're not violating the protection zone
Is it starting to make sense that common sense Trumps science?
and it particular the scientist that haven't been out there doing tree work for 30 years seeing everything that happens when improper pruning cuts are made.
in the fantasy world of a scientist he can tell you to make a perfect pony cut but in the real world where there's a bunch of guys, that are actually doing the work, of questionable skill, experience and diligence pruning cut should be made outside the target
Anyone who's been looking at trees for 30 years should recognize do the decay that occur from improper pruning. its pretty easy to see because it's all over the place in my market.
However my market is mostly hardwoods , Eastern hardwoods. someone out west pruning conifer might come up with a different conclusion
I've been dictating this is the my phone so hopefully came out well this is what I'm talking about when I say comment sense Trumps science. and if you would open your eyes look around you from outside the box its amazing what type of insides can be gleaned
Daniel...could you go back and...I don't know...throw a little punctuation in that glorious diatribe for us?
Reads like Beat stream of consciousness or something.
Or how do you do science on how wind effects with your trees how can you measure that last I heard they were taking small trees driving them around in the back of pickup truck and extra plating from that data
So tell me what scientist are advocating for reduction pruning on large horizontal limbs?
no there saying reduction pruning is bad because it doesn't compartmentize. That's only because they don't have the common sense to see that the tree doesn't need to compartmentalize decay after reduction cut because there's nothing it has to hold up much.
all the new wood growth is going to be plenty the support the weight on the branch tips.
Then take a look at what the scientist do when they actually try to get out there and do real tree work.
how well do they fare with that.
Do they have the common sense to use the rope that has stretch in it when rigging out big pieces?
Do they have the common sense not the side load a tree when rigging out big pieces?
Do they have the common sense to not use a new piece of equipment until they have been properly trained how to use it?
Last I heard reduction of over-extended limbs can very much be a best management practice and that smaller wounds (that also expose less heartwood) kept far away from main stems and branches will compartmentalize well on many species.
But, not all species are created equal and individuals within a given species may react to this type of pruning differently depending on site conditions, recent/current vitality, and past management history.
Most people have no scientific training beyond high school science, if that.
That's part of why people make irrational statements about science.
Same reason I make irrational trouble- shooting statements about mechanics. I'm really not a trained mechanic so I am half--ssing stuff sometimes, sometimes throwing parts at it A lot of time it works.
I'm still a half-ss, compared to real mechanics, but seem skilled to the mechanically-incompetent.
Sometimes, even a blind squirrel finds a nut.
You guys are kind of making my point that science has become the new religion and no one wants to question it. But do you really understand the mechanics of how science is done and how the limitations of actually measuring data in Realtree situations is so difficult
Last I heard the people making the decisions about best management practices refused to include overextended limbs as a tree defect
Taking science and understanding science are two different things I never understood science until I took a course in college called the philosophy of science that was a real eye-opener
That is because they are not, though they can be. You want to make a rule about that?
I think you are making a good motion here Daniel. scientist's concepts should not dictate our pruning prescriptions. We should follow our observations of an indivudual tree and our mentors who practice. we should use scientists teachings as perspective and basics. but who is a scientist and who is a practitioner? sometimes there is a grey area, no? we all take observations as practitioners, and as such we are amateur scientists. the biggest problem is perhaps that we don't take measurements. it seems to me we can all take observations on trees but no one has been able to take measurements that really matter. it's very challenging with trees and that may be causing this inability for a scientist to look at trees as individuals which have an immeasurable problem with an immeasurable solution. and great point Daniel on the reasons for deadwooding. most tree care is not for trees it is for people. it is for safety and aesthetics. it makes sense to make it look good and it makes sense to make it safe. it also makes sense not to waste time on small or out of site, non risk deadwood. the small difference it makes on tree health or not is non applicable. fine, frequent, reduction work will be better for tree longevity anyway, when it is affordable and practical. Science and practice should go hand in hand. Shigo was great at that. perhaps practitioners should be doing more science and vice versa? or do we just need better collaboration?
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Retrenchment pruning and crown reduction are mentioned in the new ansi.
BMP needs to be updated but Gilman has been lecturing on the subject last few times I saw him.
Daniel I just read your post 313. I think we were typing 'measure' at the same time. this is a big problem. we can't measure in a relative way. I know guys have measured a lot but a good reduction is really just a guess not an answer from a calculator.
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The last time I saw Gilman he told me ahead of time he was going to cover reduction pruney but said about two words about it in an hour and a half lecture
Separate names with a comma.