[ QUOTE ]
When I used the word 'steal,' I put it in quotes for lack of a better term. Yes, epicormic shoots add photosynthetic material, which is in essence a positive action, but healthy, successful trees don't have much epicormic growth, so let's start there... Epicormic growth is usually a reaction to loss of foliage or cambium somewhere, right? Loss of foliage or cambial material in the urban/built/residential environment is usually a reaction to human activity, not natural activity, or something that trees would experience in a forest.
[/ QUOTE ]
Generally, the human activity is us in trees with saws. There aren't many of us in forests with saws because no one will pay us. So, forests are generally well protected against the type of advantageous growth we're discussing here.
In the urban forests, and I still think it's oxymoronic, we saw away for reasons most kept to ourselves about the choice of what falls on the ground. I'm not complaining; it is what it is. I hope we most often prune for the health of the tree; but many times we prune to put enough wood on the ground so the customer feels he is getting that value to pay for our intervention.
Again, that is what it is; we have to feed our families, but subtly that begets more advantageous growth.
So, I think that our comments and dogma flow from the fact that this is very often what we see when we revisit our pruning.
A limb is there at one minute and then absolutely gone in the time it takes to saw through our unhappy selection. The wounding would appear to trigger both dormant and spontaneous attempts at re-creating the missing sugar supply. Dormant buds aren't necessarily in the right locations, so local "watersprout" growth is really the most successful substitute. Obviously it can't replace the volume of the missing supply, but as I pointed out before, it can help the local needs-and that's the best the tree can do at the time.
Epicormic growth is usually a reaction to loss of foliage or cambium somewhere, right?
At first glance, that seems true enough, but I think I don't ever remember seeing much of what I would call epicormic growth at a place where a dead limb joins the trunk. There certainly is a lack of foliage or cambium somewhere, but it really doesn't create the leafy response we're talking about. I suspect that the tree is surprised at a sudden loss and digs in its bag of tricks to come up with spontaneous substitution attempts--watersprouts.
A dying limb is no surprise to a tree; it has the time to become aware and plan for the future by providing the compartmentalization responses in another corner of its trick bag.
I "think" that the tree “knows” there is no point in providing a mass of leaves in response as if there were pruning unless it had some other problems in the local area. I don't know enough about trees to make that a dogmatic statement, but considering your own experience, is there a difference between the clustered response to wounding (pruning) and any other replacement foliage due to loss of leaves and cambium somewhere else?
[ QUOTE ]
Following that reasoning, the majority of the pruning that we do as residential arborists should not be viewed as silviculture, but as individual tree care, or arboriculture. If you take an arboricultural approach, you may find that definitions like 'aggressive shoots' and 'stealing nutrients' are real and relevant terms with regard to preserving individual trees that may be responding to human activity or natural competition from other trees.
[/ QUOTE ]
I'm trying to say that the “arboricultural approach” is much more filled with dogma, platitudes, and simple misunderstandings because there is money to puff it up and then convince us that there is value in some parts of the puffery. The ISA has a long history of dogma and pronouncements that have been quietly discarded over the years and replaced with new dogma. If you want to consider arboriculture as either science or craft, there is an inherent danger that we think we are now at the edge of total and final knowledge.
Docs do it all time. That lack of insight fills morgues and extends the length of illnesses. It is an understandingly human shortcoming and I suspect we can find it in all of us. So, I'm not being personally critical, just muttering that our feet are still made of clay in most everything we do.
[ QUOTE ]
So, simply put... "Train the plant that needs training." Many old specimen trees got to where they are both despite of and because of humans, which is the essence this whole argument, correct?
-Tom
[/ QUOTE ]
We probably should be careful about taking credit for the endurance, strength, or longevity of trees. I'm not sure that we can “Train the plant that needs training.” Like I said, trees of been around for a few hundred million years and our recent involvements began with the collection of deadwood at the base of these remarkable creatures.
Statistically, our interventions are tiny and are confined mostly to urban forests which already have surprising mortality rates for the things we plant. I believe that we see the bulk of advantageous growth in that small urban universe that is a result of us being in trees with saws.
I'm not saying don't prune, and I'm not saying you're wrong, I'm simply saying that we should expect to discover other things that will change our minds from what we thought before.
While I was writing this, it occurred to me that dealing with trees may be an awful lot like herding cats. You can think you're the boss, but cats know better.
Bob Squintalot
