Canary: Coal Mine = Sugar Maple: Urban Health (Or why I advocate for native street trees that die)

Acer saccharum in fall color represents the dominant forest type in much of western MA (and other parts of the eastern deciduous forest))

Species sugar maple (Acer saccharum) is a huge part of the regional forest composition here in western MA.  At this very moment it is also a big part of our regional economy…the maple syrup production season is upon us.  But you will not see these contributing to our ‘sense of place’ along any urban street.  As one website describes it, “Sensitivity to compaction, heat, drought and road salt limit usage of Sugar Maple for urban street plantings…”

Your town may have a list of approved street trees that are “adaptable to urban conditions…handles our heat well. “  Or list a species that should be chosen because it “tolerates extremes of soil, heat and pollution; is very adaptable to soils and tolerant of salt, drought, and soil compaction; is tolerant of adverse environmental conditions.”

There are other reasons for selecting street trees…so they won’t interfere with utility lines or break up the sidewalks or drop messy twigs or fruit, or have an unpredictable branching habit that might not match one tree to the next along the street. But the one desirable characteristic common to all the lists on my internet search is the ability to tough it out in bad air, bad soil, excessive heat, and salt-contaminated water (at least in regions with winter conditions).

Such street tree lists often include a native genus, but the highway departments and homeowners are not just advised, but are required, to “Select resistant cultivars, tolerant of drought, salt, air pollution.” (As an aside, if you care about “reading the landscape,” the species list often becomes a roster of plants from other continents that, if planted along your street, would cause you to wonder where in the world you were standing.)

Here’s what I would like to know: why do we want urban plants that do not give us fair warning that environmental conditions are becoming bad for the health of living beings?  Why do we want plants that show no sign that conditions are not suitable for habitation? Is it a good idea that, similar to Acer saccharum ‘Green Mountain’ and ‘Legacy’ with “thicker, waxier leaves, better to withstand heat and drought”, our lungs, skin, mucous membranes, and eyes might have to adapt to these conditions?  Is it a good idea that specialized trees can thrive in these intolerable habitats, but we might get sick.

I can’t speak for everyone, but personally, I would like to see trees dying when the air and water are bad…as a clue that we should do something about the conditions.


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  1. says

    What a great point Ruth…we should use the cues form our environment…..but why change the things we do that add to the bad air and water….that will cost too much money…cheaper to replace the tree and not say a word about the air and water…sad.
    Donna@ Gardens Eye View recently posted..Viewing Violets

    • Ruth Parnall says

      Ellen and Donna – Happy to hear that I’m not the only one who thinks this way….thanks for the comments.

    • Ruth Parnall says

      Yes, sense of place is another huge concept…maybe another blog post about it to add to the recent ones.

  2. Vicky says

    Even if the streets were landscaped with native trees that would act as canaries, there is absolutely no guarantee that the public would make the connection. They’d probably just grumble, “Government can’t do anything right. Not even keep trees alive.” I believe your idea has merit, but most people have no idea what trees line our streets, and without that awareness and knowledge, it would be a wasted exercise.

    It’d never happen, but a city government could plant some trees in a well traveled public place and label them, “These are your lungs” and when the trees are dead label them, “These are your lungs on pollution.”

    • Ruth Parnall says

      Phil – I just read of a California town planting using food-bearing trees, shrubs, etc. throughout a park…free fruits and nuts for anyone who passed by and wanted to nibble. I guess in our hypothetical plans for a habitat-intense new town, it would have wide “tree lawns” so falling fruit wouldn’t mess up sidewalks or road edges…

  3. says

    Ruth, I can’t agree with you more! I am in the process of trying to convince my Town Board of Selectman to establish a “native” street tree bylaw (it will be on our April ballot) and I continue to be amazed at the general public’s resistance to change and what sometimes almost seems like an innate desire to remain “uninformed.” I have to keep reminding myself “slow and steady wins the race.” Thanks for making such a great point!
    Cori Rose recently posted..Spring Has Sprung!

    • Ruth Parnall says

      Cori – Persist if you can… By the way, I heard a red-wing and a mourning dove this past week, myself.

  4. says

    Ruth, this is EXCELLENT Food for thought. The Canary/Coal Mine reference puts a real face on what you are trying to say. Maybe people will “get it” using that association! Great article….I’m certainly thinking about it now!
    Loret recently posted..Crap!


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