[CANUFNET] Canopy Cover continued
Rike Burkhardt
rburkha at toronto.ca
Wed Mar 18 09:07:53 EDT 2009
Hello all:
As regards the magic 40% number, I explored that somewhat further in
the background for Toronto's UFORE report. I came up with the following
points, including the American Forests reference (see below). I'm sure
there are more. Please feel free to correct me if I am wrong on any of
the references to specific municipalities.
Incidentally, one of the most challenging aspects of Toronto's
UFORE/canopy work is answering the commonly-asked question - are our
treeplanting programs effective in helping the City reach its canopy
goals?
As Andy also points out, there are no reliable numbers for mortality
and as such, it is almost impossible to predict ("Grow-Out" models
notwithstanding) what the long-term outlook for canopy is in the face of
balancing new gains from tree establishment with continuing loss of
mature canopy.
I would recommend to any City that a specific exploration of this issue
is key to understanding the long-term outlook.
Why 40%?
"Toronto*s tree cover targets are based in part on American Forest
(www.americanforests.org ( http://www.americanforests.org/ ))
recommendations of an average 40% canopy cover (the equivalent of
approximately 20 large trees per acre) to ensure the sustainability of
the urban forest. American Forests arrived at that figure after
analyzing the tree canopy in dozens of cities over the last five years
and working closely with the research community. Urban areas most likely
to achieve that 40 percent figure would have an ideal mix of central
business district, urban residential, and suburban property (cited from
AF source).
Furthermore, a systems approach to protecting natural heritage has been
incorporated into official plans of municipalities in Toronto and Region
as a Natural Heritage System (City of Toronto), a Greenlands System
(Regions of Peel, York) or an Open Space System (Region of Durham), with
similar systems being incorporated into local municipal official
plans[1] ( about:blank#_ftn1 ).
The concept of identifying a minimum target amount of natural heritage
lands to be restored and included in the system is also emerging as
follows: The Great Lakes Remedial Action Plan work coordinated by
Environment Canada has suggested that to achieve and maintain healthy
watersheds, at least 30% of a watershed should be in forest cover and
10% of the watershed should be wetlands
The Oak Ridges Moraine Conservation Plan recommends that municipalities
assess the desirability of achieving 30% of a subwatershed in
self-sustaining vegetative cover
etc.
Rike Burkhardt, Planner
Urban Forestry
18 Dyas Road
Toronto, ON M3B 1V5
Tel: 416-392-7305
Fax:416-392-1915
>>> <BGeerts at brantford.ca> 3/18/2009 8:44 AM >>>
Excellent points Andy,
That is exactly where our research is coming from. Our initial Council
direction came from a concerned member of the public that had found the
American Forests guidelines on the web. The citizen made a presentation
to City Council and they latched on to the idea. Now our main task is
to back the whole train up to a point we can start from. The carrying
capacity is a point that especially concerns me. In Brantford, our
historical canopy cover has never been that high; there were large
woodlands, but also large expanses of prairie and oak savanna. These
ecosystems have important ecological services and value too.
We have recently completed the first stage of canopy research for
Brantford where we overlayed a 100m square grid over the entire city and
estimated canopy cover for each cell. This has given us an excellent
coarse detail map of where the canopy is high and low. It is easy to
overlay with land use, property boundaries, zoning, etc to see how tree
canopy relates to each of these current land uses. This gives us a much
better start than a random sample system that gives over all averages.
Once the ground truthing is complete, we will be able to report how many
hectares has 0%, 1%, 5%, 10% cover etc.
A key component of our initial presentation to City council will be
where the onus for canopy improvement lies. We have current
measurements using our tree inventory that City of Brantford street
trees contribute 5% to the total, but now we will be able to present the
large component that lies on private property. Our 60,000 street trees
provide 900 acres of canopy cover. It's interesting to note that we
have enough street tree canopy cover to shade all the street pavement in
the City. That's not a bad ratio.
We will use the political momentum to improve our management of the
urban forest, but the size, shape, and location of how that is to be
done is yet unclear. So far we've been told where to go, but without
detailed information on where we are and where we've been, it's not much
use.
________________________
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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Today's Topics:
1. Canopy Cover (Andy Kenney)
----------------------------------------------------------------------
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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