[CANUFNET] Tree Growth Factors Question

Mon Oct 15 10:28:29 EDT 2018

Thank you for your reply Naomi, much appreciated.

Cheers,

Darren Platakis
BSc., GIS(PG), FRCGS

On Wed, Oct 10, 2018 at 11:16 AM Naomi Zurcher via CANUFNET <
canufnet at list.web.net> wrote:

> This site-specific fact that Stephen refers to is even more evident in an
> urban setting, especially with trees planted curbside in pedestrian
> walkways. Same species planted along the same street will have very
> different growth rates, depending on light but more often based on the
> ability to break out of the limited volume of open accessible soil.
>
> You are much better off using other factors that can be more accurately
> determined - species (including cultivar if known), structural measurements
> plus a full condition assessment including annual shoot extension as well
> as details about the site in which the tree is growing.
>
> Naomi Zürcher
> Urban Forester, Consulting Arborist
>
> On Oct 6, 2018, at 12:13 PM, via CANUFNET <canufnet at list.web.net> wrote:
>
> In my experience there is no reliable rule of thumb for tree age vs
> diameter.  You can have two trees planted at the same time of the same
> species that have dramatically different DBH right beside each other, and
> this routinely happens with even-aged stands in the wild. If one is getting
> more sun and the other is suppressed there will be a large difference in
> diameter.
>
> In a even aged stand, say red oaks, you can have one dominant tree in the
> middle of the grove that is taller and thicker than all the others growing
> around it.  The others may all be growing sideways to try to get to the
> sunlight as the centre tree spreads it’s crown out to capture all of the
> sun above them and are a lot different in diameter but all close to the
> same age.  In a conifer plantation in the early stages there can be a
> narrow range of sizes so easier to make age estimates from size, but as the
> plantation ages the dominant trees grow much larger than the suppressed
> ones, which die out eventually.
>
> If you have some local data from core samples or counting rings of cut
> trees to compare with you could make up a rough table of age vs size that
> could be a fair estimate for each species most of the time.  It has to be
> local data – trees in Toronto or Niagara grow a lot faster than on the
> shield north of us.  You know that pines can be aged by counting the branch
> whorls eh?  There are also old MNRF publications that have age/height
> curves by species and site class that are based on good data and can be a
> good tool for estimating.
>
> You hear people all the time describing 60cm+ trees as ‘100 year old
> trees’ that are often silver maples or willows that can’t be more than 60
> years old since the area was developed then.
>
> Stephen Smith
> Urban Forester, ISA Certified Arborist
> Qualified Tree Risk Assessor
> Urban Forest Associates
> www.ufora.ca
> off 416-423-3387/cell 416-707-2164
>
> *From:* Andrew Almas via CANUFNET <canufnet at list.web.net>
> *Sent:* Wednesday, October 03, 2018 1:23 PM
> *To:* geospatialniagara at gmail.com ; canufnet at list.web.net
> *Subject:* Re: [CANUFNET] Tree Growth Factors Question
>
> Hi Darren,
>
> There is no extra mathematical step to applying the growth factor. It is
> just that trees grow differently in different settings. So in the case of
> the growth factor provide by the Morton Arboretum they are only considering
> trees that are "landscape specimens", these tend to grow in diameter far
> more quickly than trees in a forest setting that tend to grow taller. Most
> growth factors you will find are associated with that species growing in a
> forest setting. That is the source of the discrepancy. Another source of
> discrepancy could be locale - a red maple in Quebec will grow more slowly
> than a red maple in Georgia...
>
> Best,
>          Andrew
>
> On Wed, Oct 3, 2018 at 12:00 PM Darren Platakis via CANUFNET <
> canufnet at list.web.net> wrote:
>
>> Hello everyone,
>>
>> I was hoping to be enlightened with regards to tree growth factors and
>> estimated tree age. I am not a arborist by trade so be gentle with me.
>>
>> I'm trying to apply growth factors to an inventory of trees to estimate
>> age but some things do not make sense.
>>
>> By way of example, the growth factor for a Norway maple is noted as being
>> 4.5 so in essence, a Norway maple with a diameter of 20 inches is estimated
>> to be 90 yrs old - Diameter X Growth Factor (this number doesn't seem right
>> to me).
>>
>> However, there are several charts available that provide this
>> information, such as one released by The Morton Arboretum that state a
>> Norway maple of 20 inches in diameter is estimated to be 52 years old. This
>> would be a growth factor of 2.6 (Estimated age / diameter = Growth Factor).
>> My question is, why the big discrepancy? Am I missing a step somewhere?
>>
>> This is an exercise that I may like to take into a classroom but with the
>> wide chasm of results I'd be wary of doing so.
>>
>> Thanks in advance,
>>
>> Darren Platakis
>> BSC., GIS(PG), FRCGS
>>
>
>
> --
> *Andrew Almas*
> Lecturer
> University of Toronto, Mississauga
> Department of Geography and Programs in the Environment
> (647) 529-8867
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.web.net/pipermail/canufnet/attachments/20181015/ed54085b/attachment.html>