[CANUFNET] Tree Maintenance Cycles and the Effect on Growth and Rotation

[Naomi Zurcher]

Dear Mark:

Thank you, thank you, thank you.

It is not often that one hears the truth about pruning and its ability to solve ALL the problems. All too often, it creates more problems than it solves when it’s too much and too often and it has nothing to do with the architecture of the species being pruned. In addition, if one thinks about what a tree is being asked to forfeit for every branch we decide it doesn’t need - all those nutrients that are stored in that branch - this fact should give pause to anyone associated with this work as all to often the tree would disagree with your  branch-removal decisions

I would like to suggest that if we need today much more attention to all the things that need to be thought about and initiated before we plant a tree, driven by the understanding that most of our urban trees come from forests somewhere in the world and that, while you can take a tree out of the forest, you can never take the forest out of the tree. Such an understanding should inform planning for a tree, preparing the site to accommodate a tree’s needs for the long term, selecting a healthy tree that’s true to species specific architecture and is the correct tree for what the planting sire can accommodate - if we did all these things for every tree we plant, we might not have to do so much after care, including pruning and we might see a lot less failure.

As with most things that fall into the “long term” category, accommodating trees is front-loaded but, as you have stated so well, trees are often a total after thought and that’s when the problems begin.

I hope this additional comment helps with the “tree pruning schedule” question.

Naomi Zürcher’

Urban Forester /. Consulting Arborist
ISA CA #NY 0604A



> On Jan 15, 2020, at 12:25 PM, Mark Carroll via CANUFNET <canufnet at list.web.net> wrote:
> 
> To All,
> Thought I would send a couple thoughts for scheduled tree pruning to the forum,
> This may not help but here it is...
> 
> In regards to tree pruning, is a schedule an accurate way of determining the proper way to look after one of our natural heritage assets.
> It seems we look after our trees completely different from our other assets. We inspect our roads, we inspect our play ground equipment, and we inspect our buildings and so on and make the necessary repairs or preventative maintenance as needed. With trees we seem to have the need to just send crews out to prune. Do our crews have the knowledge, do our crews care enough, and do our crews have enough experience? If you use a contractor, we use the low bid. Will these contractors send us their best to prune, highly unlikely? They send their cheapest crew so they can cover the low bid. 
> 
> Structural pruning is what I would call “subjective to the individual doing the work”. Pruning a tree every 5, 7 years just because it is part of the rotation can have devastating effects on trees. Remember “the best thing you can do to a tree is prune it, the worst thing you can do to a tree is prune it”.
> 
> Boulevard trees are subjected to a multitude of deceases, hardships, and pests. Salt, heat, vehicle damage, lack of habitat, lack of nutrients, lack of soils and the list can go on. It’s a wonder we have trees at all these days. Add to this the unnecessary pruning and you now have a tree that may not survive or at best be under constant stress.
> 
> Extensive structural pruning in warmer climates may be beneficial to some trees. Longer growing seasons and better habitats will afford the tree better conditions to heal quicker without putting stress on the tree. Ed Gilman, a well known expert in structural pruning will not hesitate to remove more than 50% of a tree to prune it for proper structure. My opinion is that this may be ok for a tree in Florida where the growing season is almost 12 months of the year, but will it work in Ontario where we only have 6 to 7 months of a growing season. Will 50% be too much for a tree to handle here and will it take longer to heal? This may leave it exposed to deceases and pests for a longer period of time with wounds leading to cavities and weakened structures.
> 
> When we look at pruning schedules, what do we want? Structural pruning? 2.5 to 3 meters over the sidewalk? 4 to 6 meters over the road for safe vehicle passage? How big will branches be when removed? No larger than 8 to 10 cm? No main trunk cuts? Do you thin out the Tree? Do you do reduction cuts? Do you have to climb each tree? Is each cut made from the ground? What is your budget? How many trees do you have to do?
> 
> What about basing the pruning on the type of tree? Does a Locust need as much pruning as a Linden, or vise versa? Locust are over used, as are Lindens along our municipal street-scapes. Are they the best trees to be planting? Lindens are notorious for over growing on the lower branches and will need to be drastically elevated once they have reached 10 to 15 years of age or older. This will encourage epicormic shoots to grow and now we are back removing these shoots in a few short years. Lindens often have the co-dominant leaders that will present a problem when they are mature. Do you remove one whole leader all at once leaving the tree looking lopsided with a large open wound, or do you remove one leader slowly over a period of time.  Locust have a bad habit of shutting down branches, which leaves deadwood throughout the tree. Locust too, can have long straggly branches, small leaves and insect infestations that residents have trouble with leading to many visits for pruning. How do you manage this if you are on a 7 year pruning cycle? 
> 
> Trying to get developers, consultants, landscape architects, engineers and planners to diversify our tree canopy is a struggle, more like pulling teeth. Who doesn’t like the Freemanii Maple? They are planted everywhere. How much pruning will these trees need? They have the structure and growth pattern of a Silver Maple and it is the fall colour of the Red Maple that makes them so utilized. Usually multiple co-dominant stems and lateral branching wherever the sun seems to hit it the most. Locust, Lindens and some sort of Maple cultivar is the average species list that come with any sort of subdivision agreement. Trees are never planted correctly, so when municipalities assume boulevard trees they are usually under stress from being dug in too deep, the worst nursery stalk and planted with ropes and burlap not completely removed. We assume thousands of trees each year and may never get to see each tree until years later and then it will be some time after that before we can actually prune all of them. By this time it may be too late to properly prune a tree.
> 
> I would recommend a species determined schedule for pruning. (Does that make sense?) Hopefully we are now looking at diversity for tree planting along our boulevards. Pick species that will do well, show better structural growth patterns, fit the habitat that they are growing and withstand the harsh growing medium that they will be presented with. This may lead to a better option for pruning schedules. Training methods must be improved and staff must have the passion for preserving our trees and doing what should be done, this includes pruning practices. 
> 
> So as a summary to scheduled pruning??? Yes, if done properly! If a tree does not need to be pruned, don’t prune it. I don’t think you can write a tender that will cover proper pruning of a tree. Pruning is too subjective. No 2 trees are ever alike, they never need the same type of pruning. Training methods and opinions are too diverse. If we ever get to the point where we can actually engineer a tree that is the day when we can schedule pruning. We also need to well staff Urban Forestry Departments. If we can fully train and control pruning methods, that will help us with scheduling. Urban Forestry Departments are always under funded and under staffed. We rely on the “Request for Tender” for outside crews to the majority of work. Do we get the best? Again “maybe” most likely not. 
> 
> I always say” we all know we need trees, we just don’t want trees”. How often have you heard somebody say that they do not want a tree at or around their home? NIMBY!!! “Leaves get in my eaves trough, I have to rake too many leaves, there is too much shade for my grass grow” etc. But that same person will go to a park and sit under a tree to watch their family members play a sport or go to the playground and splash pad. Trees are often an after thought. Not really looked upon as an essential asset. Municipalities will often have more staff cutting grass, filling pot holes, doing snow removal, controlling water-waste water, than looking after their trees. This thought may be changing since there has been more concern for our natural environment all over the world. It will take time and money to do the right thing for our trees. I hope I see it in my life time.
> 
> I hope this helps with “Tree Pruning Scheduling”. Most likely not, but I thought I would send my 2 cents worth anyways.
> 
> 
> 
> Mark Carroll ISA Certified Arborist/Qualified Arborist Tech/Lead Hand | Public Works, Town of Whitchurch-Stouffville
> 111 Sandiford Dr., Stouffville ON | L4A 0Z8
> 905-640-1910 Ext. 4249| Cell; 416-791-1040 | mark.carroll at townofws.ca <http://www.townofws.ca/>
> 
> 
> 
> 
> 
> 
> 
> On Tuesday, January 14, 2020, 09:49:19 a.m. EST, Hettmann, Joerg via CANUFNET <canufnet at list.web.net <mailto:canufnet at list.web.net>> wrote:
> 
> 
> Hello All;
> 
> We are in the process of developing a long-term tree maintenance strategy for the City of Vaughan, including a tree pruning rotation.  While we preliminarily have considered a seven year cycle, we would appreciate any information from other municipalities on their strategies. 
> 
> We are also looking for information to what degree proper tree pruning enhances tree growth(yield), resistance, and age.  This information would be very helpful in our valuation of the investment into tree maintenance.
> 
>  
> Thank you for any information you may be able to share.
> 
>  
>  
> Joerg Hettmann, R.P.F.
> 
> Manager of Forestry and Horticulture
> 
> 905-832-8577 ext. 6139  I joerg.hettmann at vaughan.ca <mailto:joerg.hettmann at vaughan.ca>
>  
> City of Vaughan I Parks Forestry and Horticulture Operations
> 
> 2141 Major mackenzie Dr., Vaughan, ON L6A 1T1
> 
> vaughan.ca <http://vaughan.ca/>
>  
>  
> 
> 
>  
>  
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