[CANUFNET] tree canopy target

Wed Jun 22 14:22:06 EDT 2016

Merci! Je n'avais jamais vu ce document!
" Le couvert forestier devrait représenter au moins 30 % du bassin
hydrographique. C'est une approche très risquée permettant d'abriter
seulement moins de la moitié de la richesse potentielle des espèces et des
systèmes aquatiques à peine viables;"

Louis-Marie Poissant
Le 2016-06-22 13:01, "Margot Ursic" <mursic at beaconenviro.com> a écrit :

> Another source of the "40% urban forest cover target" that is sometimes
> cited in eastern Canada is Environment Canada's How Much Habitat is Enough?
> Guidelines, last revised in 2013.
>
> These guidelines put forward 30% forest cover at the watershed scale as a
> generalized minimum to sustain certain ecological functions (described as
> "high-risk"), 40% as a "medium-risk" level, and 50% as a "low-risk" level
> for sustaining potential species and healthy aquatic systems in a given
> watershed. These guidelines are intended for the Mixedwoods Plains zone,
> and while they are science based, the document acknowledges that there are
> many gaps in the available science on this topic.
>
> These guidelines also notably apply to natural or semi-natural forest
> cover, so would exclude canopy from street trees and the like.
>
>
> Margot Ursic, M.Sc. / Planning Ecologist, Facilitator
> BEACON ENVIRONMENTAL
> 373 Woolwich Street, Guelph, ON  N1H 3W4
> T) 519.826.0419 x21  F) 519.826.9306  C) 519.803.8101
> www.beaconenviro.com
>
>
> -----Original Message-----
> From: CANUFNET [mailto:canufnet-bounces at list.web.net] On Behalf Of Brian
> Geerts
> Sent: Wednesday, June 22, 2016 10:28 AM
> To: 'Canadian Urban Forest Network' <canufnet at list.web.net>
> Subject: Re: [CANUFNET] tree canopy target
>
> ‎I believe the 40% number came from  studies of the Chesapeake Bay area
> geared towards watershed water quality - from "Urban Tree Canopy Goal
> Setting: A Guide for Chesapeake Bay Communities"
>
> Brian Geerts
> Manager of Forestry and Horticulture
> City of Cambridge
> Dickson Centre
> 30 Parkhill Road W. ON N1R 5W8
>
> geertsb at cambridge.ca
>
> Tel:519.740.4681 x4558
> Fax: 519.624.6975
>
> From: Alex Satel
> Sent: Wednesday, June 22, 2016 10:20
> To: 'Canadian Urban Forest Network'
> Reply To: Canadian Urban Forest Network
> Subject: Re: [CANUFNET] tree canopy target
>
>
> Hi Alan (and all),
>
> I think the very fact that we aren’t able to jump forward with a quick
> reference to why 30% is “good” but, say, 25% isn’t, supports what Dr.
> Duinker has already said – these targets are rarely based on science or
> even high-level assessments of what is possible or reasonable.
>
> The 40% canopy cover target that’s been adopted by many communities seems
> to go back to a publication by American Forests, which set that level as
> “optimal” for US cities east of the Mississippi. I can’t dig up the
> publication as the link I had to it on AF’s website is broken. That same
> publication set lower targets for western regions (somewhere in the order
> of 20-30%, I believe). I honestly can’t recall the basis behind those
> figures.
>
> It seems that urban forest managers and decision makers have decided to
> run with targets within that range for any number of reasons, not the least
> of which is that they probably just ‘seem’ reasonable and achievable. I
> think a lot of it also has to do with what Dr. Duinker said – peer
> behaviour. Communities are constantly benchmarking against each other – it
> wouldn’t look good for community X to set a target of 24% if neighbouring
> community Y has a target of 35%, even if community X had done an exhaustive
> potential canopy cover study and found 24% to be a realistic target based
> on its potential carrying capacity. I’ve even heard of one community that
> set its target because “30 by 2030” (or was it 40 by 2040? I can’t recall)
> had a nice ring to it and was sellable.
>
> Your question again raises valid issues with these high-level canopy cover
> targets:
>
>
> ·         are they achievable (how much canopy can we actually cram into
> this urban area)?
>
> ·         Would they actually translate to tangible increases in benefits
> (and therefore, should we even be trying to achieve them)?
>
> ·         When we say 30% or 40%, what do we really mean (is that 30%
> averaged across the entire area, where forest stands can be 95% canopy but
> neighbourhoods where people actually live only 10%)?
>
> ·         Does focusing on increasing canopy detract resources and
> attention from other important urban forest management activities (risk
> management, protecting existing trees, etc. etc.)?
>
> ·         and on and on…
>
> Cheers,
>
> Alex
>
> Alex Satel, MFC
> ISA Certified Arborist ON-1353A
> Urban Forest Innovations, Inc.
> 1248 Minnewaska Trail
> Mississauga, ON L5G 3S5
> P: (905) 274-1022
> asatel at ufis.ca<mailto:asatel at ufis.ca>
> urbanforestinnovations.com<http://www.urbanforestinnovations.com/>
> [UFI new logo very small]
>
>
>
>
> From: CANUFNET [mailto:canufnet-bounces at list.web.net] On Behalf Of Andres
> Olaya
> Sent: June-22-16 8:00 AM
> To: Canadian Urban Forest Network
> Subject: Re: [CANUFNET] tree canopy target
>
> Good morning colleges:
> I’ve found this interesting article (World Health Organization web site)
> that might give us some answers:
>
>
> http://apps.who.int/iris/bitstream/10665/174012/1/9789241508537_eng.pdf?ua=1
>
> Have a great day.
>
>
>
> Andres Olaya
> Forestry Information Analyst, Central Operations Parks & Open Space Town
> of Oakville | 905-845-6601, ext.2900 | www.oakville.ca<
> http://www.oakville.ca/>
>
> Vision: To be the most livable town in Canada Please consider the
> environment before printing this email.
> http://www.oakville.ca/privacy.html
> From: CANUFNET [mailto:canufnet-bounces at list.web.net] On Behalf Of Peter
> Duinker
> Sent: Tuesday, June 21, 2016 2:05 PM
> To: Canadian Urban Forest Network
> Subject: Re: [CANUFNET] tree canopy target
>
> Greetings Alan:
>
> Canopy targets for a city or town are, in my view, fairly arbitrary and
> definitely not generalizable.  I hold the view that targets are never
> scientifically based because they depend on people to express preferences
> and are therefore value-based.  The target-setting exercise can be
> scientifically informed, of course.  In the case of urban-forest canopy,
> one might expect an analysis of current canopy coverage and its benefits,
> as well as a range of forecasts detailing how many more trees it would take
> to get to a specific canopy coverage, and what would be the benefit stream
> associated with each scenario of canopy coverage.  I have never seen this
> done.
>
> One could look at the question this way: what factors influence the
> setting of a canopy target?  Factors might include: (a) the current canopy,
> which is presumably lower than the target; (b) the cost, in terms of new
> trees established, to get to a specific canopy target at a particular
> future year; (c) the prospects that the cost predicted can be covered from
> the various budgets available; (d) the increase in benefits associated with
> the targeted canopy cover; and (e) what other cities and towns are doing in
> this respect.  While (a) through (d) are sensible factors, (e) is less so,
> but I’ll bet that many urban-forest strategies are based on peer behaviour
> when it comes to canopy targets.  Perhaps it boils down to this: how much
> canopy cover would we ideally want?  Probably much, much more than we have
> today.  But how much canopy cover can we realistically hope to achieve in
> the next decades?  Probably some smallish fraction of the ideal.  So let’s
> pick a number that seems achievable and gets us substantially more canopy
> than we have today.
>
> I would be most interested to know if anyone is using a more sophisticated
> approach than this.
>
> Best wishes, Peter Duinker
>
> Peter N. Duinker, PhD, P.Ag.
> Professor
> School for Resource and Environmental Studies Faculty of Management
> Dalhousie University
> 6100 University Ave.
> Halifax, Nova Scotia, Canada
> B3H 4R2
> Phone: 902-494-7100
> Cell: 902-229-5141
> Fax: 902-494-3728
> Email: peter.duinker at dal.ca<mailto:peter.duinker at dal.ca>
>
> http://www.dal.ca/faculty/management/sres/faculty-staff/our-faculty/peter-duinker.html
>
> From: CANUFNET [mailto:canufnet-bounces at list.web.net] On Behalf Of Alan
> Kemp
> Sent: June 21, 2016 1:11 PM
> To: 'Canadian Urban Forest Network' <canufnet at list.web.net<mailto:
> canufnet at list.web.net>>
> Subject: [CANUFNET] tree canopy target
>
> The City of Nanaimo has an Urban Forest Management Strategy. In that
> Strategy we have a target of increasing our forest canopy to over 30% in
> the next decade. Of course this is difficult in the urban setting. Our
> Management and Protection of Trees Bylaw supports this document by
> requiring tree replacement plans for development, which in general terms
> works. However, I was asked why 30% or even 35%? What is the scientific
> reasoning behind that. Although I can explain all the benefits of an urban
> forest, I could not really give a good science based answer. I have looked
> through a lot of literature, but don’t seem to be able to give a reasonable
> answer.
>
> Any suggestions?
>
> Alan Kemp
> Urban Forestry Coordinator
> Certified Arborist, Certified Tree Risk Assessor Community Development
> City of Nanaimo
> 250 755 4460 (local 4357)
> alan.kemp at nanaimo.ca<mailto:alan.kemp at nanaimo.ca>
> www.nanaimo.ca/goto/urbantrees<http://www.nanaimo.ca/goto/urbantrees>
>
>
>
>
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