[CANUFNET] CANUFNET Digest, Vol 52, Issue 7 - 1. Canopy Cover

Tue Mar 17 21:33:12 EDT 2009

I also wanted to weigh in re: the 40% canopy cover.
Is some canopy more valuable than others?

The three main values of the canopy are:
1. Reducing the heat island effect by providing shade
2. The interdicting and evapotranspiration of rainwater
3. Sequestering carbon and pollutants

A tree in the park only helps with #3

However, a tree in a hardscape area provides all three values.

So the 5% canopy that the street trees provide in Brampton is the most important canopy. 
So the target for canopy is not the only question but where you add canopy as well.

Michael James
DeepRoot Canada Corp.
800 561 3883
604 687 0899(o)
604 220 9521(c)
604 684 6744(f)

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Today's Topics:

   1. Canopy Cover (Andy Kenney)

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Message: 1
Date: Tue, 17 Mar 2009 21:14:14 -0400
From: "Andy Kenney" <a.kenney at utoronto.ca>
Subject: [CANUFNET] Canopy Cover
To: "'Canadian Urban Forest Network'" <canufnet at list.web.net>
Message-ID: <004901c9a766$da826050$8f8720f0$@kenney at utoronto.ca>
Content-Type: text/plain; charset="us-ascii"

I think this question of "where did the 40% canopy cover" value come from,
as raised by Dale, is an very important one.  My guess is that it has been
passed along from an estimate that American Forests came up with.  However,
when pressed, even AF admits that "one size doesn't fit all".  I am
concerned that this new-found interest in increasing canopy cover to some
magic number is, in fact, setting urban forest management back! 

Some food for thought:

1)      Such numbers are seldom based on an understanding of what the
community's carrying capacity is, so we assume there is room to achieve 40%.
Perhaps this might be theoretically possible in many communities but WHERE
is the 40% (what land-use type, what ownership, is it strategically located,
etc.)?

2)      Since most of our urban forest is on private property, reaching
meaningful canopy cover targets means that we will have to rely heavily on
the private sector not only to establish trees but to TAKE CARE OF THEM for
many decades.  Do the communities proposing dramatic increases in canopy
cover have well-developed community engagement programmes to deliver on
this?  I have yet to see one even getting close.

3)      Expansion of canopy cover is highly sensitive to mortality rates.
What is the mortality rate in your municipality?  If we are to increase
canopy cover (often by breathtaking amounts) we surely must have some idea
of how quickly we are LOSING cover?  I often hear communities state that
they have planted X number of trees this year, how often is that number
accompanied by the number of trees removed.  Oh, and remember, planting a 60
mm B&B doesn't account for removing a 900 mm veteran. We don't have any
meaningful estimates of mortality rates that I am familiar with.  Numbers
can be picked out of thin air or educated guesses can be made, but do we
have any scientifically-based mortality rates?  That is just mortality given
the usual rigors of city life for trees.  When we factor in climate change,
invasive insects, infill development, etc. ..

4)      Planting may cost $600 per tree but that isn't the cost of the tree.
Perhaps we should be suggesting that no tree be planted on city property
unless there is a long-term commitment from council to provide the resources
needed AT LEAST to ensure that the tree lives long enough to contribute to
the environmental, social and economic well-being of the community.
Clearly, that takes some time.

But surely proposing expanding canopy cover can't be a bad thing for our
urban forests!  I'm not so sure. I believe we are in a serious dilemma.  It
seems that politicians and others are finally recognizing that urban forests
are important and need support.  But the "40%" solution or the "expand
canopy cover" approach is a painful oversimplification of what is needed!
The trees that already exist, especially the large ones, are the ones that
are contributing to the social, economic and environmental quality of our
communities.  (On that note, does the community even have a tree inventory
to indicate the current status of the urban forest - not the municipal
forest but the entire urban forest?). There seems to be an ever-increasing
head-long rush to increase canopy cover with, what appears to be little
regard for the issues I raised above. Remember, canopy cover alone tells us
very little about the state of our urban forests (nothing about species
diversity, size class distribution, tree condition, etc.).  This
simplistically appealing approach, I fear, will shift any focus from
meaningful urban forest management/stewardship to a programme of tree
planting.  

If your council wants to dramatically increase canopy cover I suggest you
first ask them why. Then, if you are convinced they really know, insist that
this programme to theoretically increase canopy cover is funded only after
your budgets to sustain the existing canopy are secure.  Then ask them to
guarantee that resources will be available to sustain the trees to be
planted in this expansion programme not for a few years after the guarantee
but right up to and including the removal of the big stump that will be left
after a BIG tree finally must come down.

Of course we must plant trees and yes canopy cover is one convenient but
simplistic measure of the extent of our urban forests, but it is incumbent
upon us as urban forestry professionals and stewards to make sure that
policy makers don't  dumb-down the issues to such a degree that the real
tasks are left floundering and, after all the money is spent and the
silver-plated shovels have been put away, the urban forest is less well-off.

Sorry for frothing at the mouth and the run -on sentences, but I was on a
roll!

Andy

From: canufnet-bounces at list.web.net [mailto:canufnet-bounces at list.web.net]
On Behalf Of Leadbeater, Dale
Sent: March 17, 2009 6:33 PM
To: canufnet at list.web.net
Subject: Re: [CANUFNET] CANUFNET Digest, Vol 52, Issue 6

Hello:

I am working on a plan for the City of Vaughan that is targeting 40% canopy
cover, including urban street trees as well as forest within the core
natural heritage network.  We have prepared a draft document that provides
the justification for an outcomes based approach to planning and are in the
initial stages of developing policy.  I expect that models like the City of
Toronto Ravine By-Law will be most helpful in pushing the envelope to
greater forest cover.  We are linking forest cover to ecosystem services in
order to increase value to the developer.

Do you have a justification for the 40%?  How did the recommendation come
about?  

Dale Leadbeater, B.Sc., B.Ed.

Senior Biologist

AECOM

300 Town Centre Blvd., Suite 300

Markham, ON L3R 5Z6

(905) 477 8400 ext. 229

dale.leadbeater at aecom.com

Does anyone have a comprehensive plan developed for their city to increase 

the canopy cover? The Brantford City Council has directed us to develop a 

plan to get to 40% canopy cover for the entire city.  We have begun to 

assess canopy cover and we conclude that our blvd trees contribute 5% to 

the canopy cover of Brantford.  Is anyone else working on a similar 

project? 

________________________

Brian Geerts 

Urban Forestry Technician

City of Brantford 

Parks & Recreation Department

1 Sherwood Drive

Brantford, ON     N3T 1N3

519.756.1500 x5511

Fax 519.756.4893 

bgeerts at brantford.ca

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