[CANUFNET] Canopy Cover

Wed Mar 25 15:01:26 EDT 2009

Thank you for the responses, most of which support the advice we have
been providing to the municipality.  Our process is unique in that it is
proceeding lock-step with a sustainability plan that allows us to
stipulate management requirements starting with sustainable planting and
management guidelines.  The key is that the approach is tied into
achieving economic and social objectives over the long term, therefore,
if the case can be made that the investment in sustainable soils and
increased density will pay off in health benefits, heat sink mitigation
and carbon sequestration/storage, the recommendation will be supported.
Oakville has gone a long way to demonstrating that, although I don't
know where they are in their process.  They have done such a good job
that I know of at least four other municipalities in southern Ontario
that are pursuing similar studies.

I also think that there is a difference between writing a plan that to
ensure that the tree canopy reaches a 40% target within a certain time
frame, and identifying a Vision for the purpose of writing policy that
provides a scientific justification for a requirement that any forested
area in a greenfield development site remain or be compensated for on a
two or three to one basis due to the importance of the ecosystem
services provided by the trees and/or forest.  Clearly forests provide
addition functions beyond street trees and many of those functions
cannot be quantified.  I am in no way saying that all of the services
provided can be quantified.  What we are looking for is a scientifically
justifiable threshold that says that you must aim for these big numbers
is you want to achieve sustainability.  So what can we use as an outcome
of an urban forest management policy?

American Forests have suggested the 40% for air quality improvement
(based on what research?) and clearly that has huge variability built
into it.  The question is how much variability?  Is it so great that I
will get laughed out of an Ontario Municipal Board hearing (because I
can see I'm going to end up there)?  Maybe.  That's why we have
reinforced the argument with research that indicates that water quality
impairment is detectable below 30% cover, and that you can't hope to
provide habitat for the bird species that should be breeding in the
forest at this location unless we achieve something in the order of 30%
cover - again, numbers with huge variability that are very site
dependant.  This target, which includes streetscapes and backyards, is
becoming more meaningful as some of the forest birds we once thought
were strictly rural are moving into the maturing city streetscapes and
backyards (e.g., Cooper's Hawk).

The other function of a threshold identified on the basis of identified
ecosystem services, is that there is more than one way to provide some
of these services.  Carbon storage may be provided through manipulation
of soils and drainage; green roofs and biowalls provide benefits as
well.  We have demonstrated what 40% looks like in Vaughan, and it is no
doubt ambitious.  But as properties come up for redevelopment, if we are
not trying to get as close to that number as possible on a City-wide
basis, then the policy to provide more trees, properly planted and
maintained is less compelling.

So if not these numbers, then what is defensible?  Can 40% be defended,
with all of its variability from urban to rural, if all of the
sustainable actions and inventory I've heard suggested are implemented?

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

________________________________

From: canufnet-bounces at list.web.net
[mailto:canufnet-bounces at list.web.net] On Behalf Of Andy Kenney
Sent: Thursday, March 19, 2009 10:02 AM
To: 'Canadian Urban Forest Network'
Subject: [CANUFNET] Canopy Cover

Hello CANUFNET,

I agree with Peter that the first step towards managing canopy cover is
to do some inventory work. There are many ways to go about this, and our
experience of late developing a canopy cover estimate for the City of
Thunder Bay might be of interest to all those concerned with urban
canopy cover inventory work.

1 - Imagery type and resolution: from satellite imagery to aerial
photography there are plenty of options. 

We found current year high res (i.e 50-80 c pixels) colour digital
aerial imagery acquired at a time of year when deciduous trees have
leaves the best for delineating the extent of individual tree canopies.
Coupled with high res imagery Cities typically have on hand collected
"leaf off" to view grey infrastructure to interpret any problem areas we
were confident that urban canopy cover exists where our interpreters
looked to classify points.  

2- Continuous versus point sample approaches to classification of ground
cover types. 

Continuous classification requires very high resolution images and lots
of $$. Does it provide better information remains a question. The key to
providing good estimates using point sampling is to have access to good
GIS data in order to provide stratification options that others in this
chat have alluded to - i.e. residential vs. commercial and industrial
land use types; Wards; Neighborhoods, etc.  Once strata of interest are
selected, one can measure precision of the estimates statistically and
ensure estimates fall within acceptable margins of error.

KBM can provide support for any of these approaches. We led all of the
study design, and flew our own aircraft and digital camera set-up for
Thunder Bay; and did all image processing and interpretation in house. I
don't know of any other Ontario forestry consulting service providers
that have/can do this. Most similar Ontario projects to date have relied
heavily on support from the US forest Service.

I invite anyone interested to contact me directly using the coordinates
listed in my e-signature below. Also, Thunder Bay City Forester Shelley
Vescio is open to discussing the Thunder Bay project. In fact, she and
City Planner Chris Doyle will be presenting the project methodologies
and outcomes at an upcoming ESRI user conference in Thunder Bay April
28-29 2009:

ESRI Regional User Conference - Thunder Bay 

Date : Apr 28, 09 ~ Apr 29, 09 
Venue : Valhalla Inn
Venue Address : 1 Valhalla Inn Road, Thunder Bay, ON P7E 6J1
Venue Telephone: 807-577-1121
Location : Thunder Bay, ON
Event Language : English

ESRI Regional User Conference - Thunder Bay
ESRI Canada is pleased to invite you to join other GIS professionals for
this exclusive opportunity to learn about the latest advances in GIS
technology and hear first hand how others in your community are using a
geographic approach in their work.

The main conference (plenary sessions, user presentations and technical
sessions) will be held on Wednesday, April 29, 2009.

Enhance your conference experience with a pre-conference workshop.
Workshops will be held on Tuesday, April 28, 2009.

Ben Kuttner, M.Sc.F., R.P.F.

Consulting Forester

General Manager - Toronto

KBM Forestry Consultants Inc.

www.kbm.on.ca <http://www.kbm.on.ca/> 

kuttner at kbm.on.ca <mailto:kuttner at kbm.on.ca> 

mobile: 647-273-4576

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