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

Wed Jan 15 12:25:24 EST 2020

 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 determiningthe proper way to look after one of our natural heritage assets.
It seems we look after our trees completely different from our otherassets. We inspect our roads, we inspect our play ground equipment, and weinspect our buildings and so on and make the necessary repairs or preventative maintenanceas 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 ourcrews have enough experience? If you use a contractor, we use the low bid. Willthese contractors send us their best to prune, highly unlikely? They send theircheapest crew so they can cover the low bid. 

Structural pruning is what I would call “subjective to the individualdoing the work”. Pruning a tree every 5, 7 years just because it is part of therotation can have devastating effects on trees. Remember “the best thing youcan 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, andpests. Salt, heat, vehicle damage, lack of habitat, lack of nutrients, lack ofsoils 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 surviveor at best be under constant stress.

Extensive structural pruning in warmer climates may be beneficial tosome trees. Longer growing seasons and better habitats will afford the treebetter 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 than50% 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 growingseason. Will 50% be too much for a tree to handle here and will it take longerto heal? This may leave it exposed to deceases and pests for a longer period oftime with wounds leading to cavities and weakened structures.

When we look at pruning schedules, what do we want? Structural pruning? 2.5to 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 trunkcuts? Do you thin out the Tree? Do you do reduction cuts? Do you have to climbeach tree? Is each cut made from the ground? What is your budget? How manytrees do you have to do?

What about basing the pruning on the type of tree? Does a Locust need asmuch pruning as a Linden, or vise versa? Locust are over used, as are Lindens alongour municipal street-scapes. Are they the best trees to be planting? Lindens arenotorious for over growing on the lower branches and will need to be drasticallyelevated once they have reached 10 to 15 years of age or older. This will encourageepicormic shoots to grow and now we are back removing these shoots in a fewshort years. Lindens often have the co-dominant leaders that will present aproblem when they are mature. Do you remove one whole leader all at once leavingthe tree looking lopsided with a large open wound, or do you remove one leaderslowly over a period of time.  Locusthave a bad habit of shutting down branches, which leaves deadwood throughoutthe tree. Locust too, can have long straggly branches, small leaves and insectinfestations that residents have trouble with leading to many visits forpruning. How do you manage this if you are on a 7 year pruning cycle? 

Trying to get developers, consultants, landscape architects, engineersand planners to diversify our tree canopy is a struggle, more like pullingteeth. Who doesn’t like the Freemanii Maple? They are planted everywhere. Howmuch pruning will these trees need? They have the structure and growth patternof a Silver Maple and it is the fall colour of the Red Maple that makes them soutilized. Usually multiple co-dominant stems and lateral branching wherever thesun seems to hit it the most. Locust, Lindens and some sort of Maple cultivaris the average species list that come with any sort of subdivision agreement.Trees are never planted correctly, so when municipalities assume boulevardtrees they are usually under stress from being dug in too deep, the worstnursery stalk and planted with ropes and burlap not completely removed. Weassume thousands of trees each year and may never get to see each tree untilyears later and then it will be some time after that before we can actually pruneall 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 thatmake sense?) Hopefully we are now looking at diversity for tree planting alongour boulevards. Pick species that will do well, show better structural growthpatterns, fit the habitat that they are growing and withstand the harsh growingmedium that they will be presented with. This may lead to a better option forpruning schedules. Training methods must be improved and staff must have thepassion for preserving our trees and doing what should be done, this includespruning practices. 

So as a summary to scheduled pruning??? Yes, if done properly! If a treedoes not need to be pruned, don’t prune it. I don’t think you can write atender that will cover proper pruning of a tree. Pruning is too subjective. No2 trees are ever alike, they never need the same type of pruning. Trainingmethods and opinions are too diverse. If we ever get to the point where we canactually engineer a tree that is the day when we can schedule pruning. We alsoneed to well staff Urban Forestry Departments. If we can fully train andcontrol pruning methods, that will help us with scheduling. Urban Forestry Departmentsare 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”. Howoften have you heard somebody say that they do not want a tree at or aroundtheir home? NIMBY!!! “Leaves get in my eaves trough, I have to rake too manyleaves, there is too much shade for my grass grow” etc. But that same personwill go to a park and sit under a tree to watch their family members play asport 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 havemore staff cutting grass, filling pot holes, doing snow removal, controlling water-wastewater, than looking after their trees. This thought may be changing since therehas been more concern for our natural environment all over the world. It willtake time and money to do the right thing for our trees. I hope I see it in mylife time.
I hope this helps with “Tree Pruning Scheduling”. Most likely not, but Ithought I would send my 2 cents worth anyways.

Mark Carroll ISACertified Arborist/Qualified Arborist Tech/Lead Hand |Public Works, Town of Whitchurch-Stouffville111 Sandiford Dr., Stouffville ON | L4A 0Z8905-640-1910 Ext. 4249| Cell; 416-791-1040 | mark.carroll at townofws.ca

    On Tuesday, January 14, 2020, 09:49:19 a.m. EST, Hettmann, Joerg via CANUFNET <canufnet at list.web.net> wrote:  

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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  Ijoerg.hettmann at vaughan.ca

City of Vaughan I Parks Forestry and Horticulture Operations

2141 Major mackenzie Dr., Vaughan, ON L6A 1T1

vaughan.ca

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