[CANUFNET] tree canopy target
Amelia Needoba
amelia at diamondheadconsulting.com
Wed Jun 22 13:00:36 EDT 2016
Hi Alan and all,
This is a great discussion. We have worked with several municipalities in
BC to develop canopy targets and have used a range of approaches. There was
a time when the 40% ‘benchmark’ from American Forests was widely used. The
original blogpost that published that benchmark has completely disappeared
leaving us with nothing to support it and demonstrating the lack of science
behind it. There is a void in canopy benchmarking and it would be a really
useful tool. The question of ‘what is the optimal canopy cover we should be
targeting to maximize urban forest benefits’ is often asked and it would be
great to have a study similar in scope to that described by Peter Duinker
and with the addition of using zoning/land use to break down the benchmarks
further.
When working with municipalities to develop targets, we have relied a
mixture of art and science:
- The nation-wide US study of urban forest canopy cover that
reports canopy cover as being primarily explained by ecoregion type,
population density and land use - the average cover in forested ecoregions
was 34% (Nowak, D.; M.H. Noble; S.M. Sisinni; J. F. Dwyer. 2001. Assessing
the US Urban Forest Resource. Journal of Forestry, 99 (3), 37-42);
- The municipality’s existing canopy cover by land use type, its
underlying ecology, population density, anticipated future growth and
plantable areas;
- The municipality’s aspirations/values drawn from community
engagement (i.e., a municipality that wants to be a leader in the field may
choose a more aggressive target for communication even if it will be
difficult to achieve);
- We project canopy loss and gain forward for the entire study
area using averages from the municipality’s existing resource to set
achievable targets (and planting rates) by land use/zoning;
- In small cities in forested ecoregions, ‘vacant land’ tends to
be forested leading to higher canopy cover baselines than in prairie
regions. However, that land is likely to be developed in the future, which
is why it’s so important to set targets by land use so that the strategy
anticipates those losses with replacement planting in new development
areas, roads etc.
As some interesting examples for setting aspirational but achievable
targets in grassland ecoregions:
- City of Melbourne set a target to double its canopy cover from
20% to 40% by 2040. This is aspirational but likely achievable because it
is a target for public realm only (i.e., their target only applies to the
land they have control over – citywide canopy cover is actually closer to
10%)
- City of Calgary has a target to increase canopy cover to 20%
(currently 8%) but it is to be achieved at a rate of 1% per decade increase
(their well-treed, established communities do sit around 20%).
It would be great to have more research work done on this topic for Canada
regionally.
*Amelia Needoba | Senior Urban Forester, PMP, ISA Cert. Arb*
3551 Commercial Street | Vancouver | V5N 4E8
Diamond Head Consulting <http://www.diamondheadconsulting.com/>
<http://www.diamondheadconsulting.com/> P *604.733.4886 <604.733.4886>** ext.
33* F *604.733.4879 <604.733.4879>*
On Wed, Jun 22, 2016 at 8:44 AM, Charlotte Young <
charlotte at envision-synergy.net> wrote:
> Greetings everyone,
>
>
>
> I was the facilitator for several workshops on Toronto’s “canopy study”
> several years ago. While I can’t comment on the decision to work towards
> 40% coverage (I suspect, as the threads have said, it was somewhat
> arbitrary), participants did identify the land uses they thought were most
> suitable for increasing coverage to get to the 40%. I recall especially
> “commercial” and “industrial” lands holding the highest potential. Have we
> made progress here? I would love to know.
>
>
>
> Charlotte Young
>
>
>
> Charlotte Young, Ph.D.; Facilitator/Graphic Recorder/Evaluator
>
> envision…SYNERGY/PICTURE your Thoughts
>
> 120 Dewhurst Blvd.
>
> Toronto ON M4J 3J6 Canada
>
> www.envision-synergy.net; www.pictureyourthoughts.com
>
> phone: 416-778-4713; fax:416-778-1956
>
> charlotte at envision-synergy.net
>
>
>
>
>
>
>
> *From:* CANUFNET [mailto:canufnet-bounces at list.web.net] *On Behalf Of *Alex
> Satel
> *Sent:* June 22, 2016 10:16 AM
> *To:* 'Canadian Urban Forest Network' <canufnet at list.web.net>
> *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
>
> urbanforestinnovations.com <http://www.urbanforestinnovations.com/>
>
> [image: UFI new logo very small]
>
>
>
>
>
>
>
>
>
>
>
> *From:* CANUFNET [mailto:canufnet-bounces at list.web.net
> <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
>
> 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
> <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
>
>
> http://www.dal.ca/faculty/management/sres/faculty-staff/our-faculty/peter-duinker.html
>
>
>
> *From:* CANUFNET [mailto:canufnet-bounces at list.web.net
> <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>
> *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
>
> www.nanaimo.ca/goto/urbantrees
>
>
>
>
>
>
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