[CANUFNET] Canopy Cover

Wed Mar 18 12:45:28 EDT 2009

A point to consider in this 40% discussion is how much vegetation canopy
will ultimately be required for the future of a community? Consideration
should be given to vegetative canopy depletion through urbanization (we
all know too well what happens when development occurs) and possibly
climate changes that can be quantified today. Decision makers understand
both things. 

If our climate is changing, locally or globally, what would be the
ramifications to your own local community based on environmental
predictions put forth by local experts with the information available
today? Would 40% be enough, or not enough, to offset the effects of
climate change?  Consider predictions which include increased
rainfall/erosion, drought conditions, hotter days, colder days or more
violent wind event days.

A while back I did a satellite based data analysis of Winnipeg's tree
canopy cover (aka total vegetative cover above ground level) and
computer model of same. Canopy cover ranged between <5% to just over 80%
with an average of around 20%. The latter figure means absolutely
nothing! In the minimal canopy area I feel the heat and the cold wind. I
would like to see more trees planted for those neighbourhoods. In the
maximum canopy areas I feel cool in summer and warmer in winter (I want
to live there) but it means major landscape maintenance costs!  

Municipally initiated and planned tree plantings on boulevards and in
parks started in Winnipeg in the 1920's but I doubt that any more than
the shade value and gothic arch look were considered. Today, through
education, knowledge sharing and lots hard dedicated work, planting is
seen as a valuable worthwhile effort that most citizens can agree on.
Our Urban Forestry Branch has gained the respectful ear of decision
makers and our citizens (that took about 35 years). I feel it is now up
to us to put forward the best urban forest plan for the future because
that is what our staff does for a living!

-gerry

________________________________

From: canufnet-bounces at list.web.net
[mailto:canufnet-bounces at list.web.net] On Behalf Of Andy Kenney
Sent: March 17, 2009 8:14 PM
To: 'Canadian Urban Forest Network'
Subject: [CANUFNET] Canopy Cover

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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