[CANUFNET] Tree of Heaven

[stephen at ufora.ca]

Actually non-natives often don't do well either.  They just tolerate the 
crappy conditions we put some of them in.  If we do a decent job of 
preparing the site and caring for them during the establishment period then 
both do much better. I don't even mind a few invasives like black locust and 
Siberian elm on some hostile sites.  But tree of Heaven seeds too much.

Nurseries producing trees with circling roots or buried root collars is a 
huge problem and it's getting worse as they switch to potted stock to grow 
up to larger sizes. I get really mad when I see the landscaper left the wire 
basket and ties on the ball, or planted too deep. I see this every day.

My pet peve though is how many good planting sites are wasted on small 
stature trees and common tough species when we could plant much more 
interesting ones.  How many times have you seen a serviceberry (non-native 
by the way) planted on a big lawn that had enough space to support a white 
oak?  Just because the owner doesn't want a big tree, or there's a wire 
somewhere nearby. Blanket rules like no trees that grow more than 10m tall 
within 6m of hydro wastes a lot of good sites that could accommodate an oak 
with a little pruning. Or planting species that only tolerate 'hostile' 
urban sites like silver maple or honeylocust on a lawn with great soil and 
lots of space because some designer plants those on every site they work on 
(because they always survive). Every site in the city is not hostile, many 
are very productive if you bother to check the soil.

Stephen Smith
Urban Forest Associates Inc.
Urban Forestry and Ecological Restoration
www.ufora.ca
-----Original Message----- 
From: Koskinen, Jennifer
Sent: Monday, June 18, 2012 4:15 PM
To: canufnet at list.web.net
Subject: Re: [CANUFNET] Tree of Heaven

Tree of  hea- LL, lol.

Trees are better than no trees.  But I thought that we were on the road to 
planting local genetic stock -  planting trees  that came from seeds in that 
seed zone - increase the planting of native tree species, changing 
development design so that trees we recommend to be planted can survive?

Yes,  we are faced with providing planting plans for clay filled 
subdivisions, and parking lot islands etc.  Native species don't do well 
here.  So we plant non-native.  But planting invasive species - wrong 
direction.  Hey, remember the time Norway Maple was the #1 fav street tree? 
Oh wait, and remember the time we are finding it in our ESPA (enviro sens 
protection area) forests?

Tree of Heaven can be a large beautiful tree, fast growing.  But even if it 
doesn't produce seed, what about the suckering, the production of trees 
vegetatively.  Also just finished reading that the Tree of Heaven produce a 
chemical that inhibits growth of some types of vegetation; and that the male 
flower has a god aweful smell that people can't stand.  Sounds like the most 
not-perfect invasive tree to be planting in our developments that may be 
close to our woodlands.

Cities like Kitchener are currently developing new design guidelines that 
include better development requirements for street trees so that they can 
survive because they have not been.  I like the idea of the developments 
catering to trees instead of trees catering to developments.  As for 
Alberta, you can't grow many trees there not just because of the 
developments, but because of the soil and warm/freeze  changes, just keep 
planting poplars as street trees, poplars aren't so bad just don't park 
under them - i'm from thunder bay, we don't have that many tree species 
either.

Don't plant invasives. (i should make t-shirts)

jennifer koskinen

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Message: 1
Date: Mon, 18 Jun 2012 15:13:35 +0000
From: Ian Wilson <IWilson at kelowna.ca>
To: 'Canadian Urban Forest Network' <canufnet at list.web.net>
Subject: Re: [CANUFNET] Tree of Heaven RE: CANUFNET Digest, Vol 89,
        Issue 5
Message-ID:
        <BA3C6411452D9B438CBE2BB75C9C5F2624F2A0 at vsmailbox.city.kelowna.bc.ca>
Content-Type: text/plain; charset="us-ascii"

I agree with both of you - native species SHOULD be the ultimate goal.  But 
it's not about being "lazy", the fact is that we are dealing with extremely 
harsh urban conditions, hardscape, lack of water, highly modified soils, 
lack of space, pollution, vandalism - you name it, it's a tree's worst 
nightmare.  Many of us are trying to improve things by using new 
technologies, and fighting to preserve the little bit of space that we can 
get, to fit in the trees among all of the other competing interests.  The 
theory is good but it's very difficult to achieve in practice.

The alternative is "zeroscape" with no trees at all and yes the exotics do 
provide many environmental benefits as well as benefits to wildlife.  In our 
city we quantified them with the UFORE model and it's millions of dollars in 
benefits, in addition to all of the benefits that can't be quantified.  In 
southern Ontario I could see there may be some concerns about gene flow from 
certain exotic species into native communities because your native forests 
are more diverse.  In my area it is semi-arid and we have three native 
trees:  ponderosa pine, Douglas-fir and cottonwood.  London plane is not 
going to cause any gene flow into our local native forests, but they will 
actually produce many benefits if planted in the right place.

The other big unknown is climate change - will today's native species be 
mal-adapted in the future, due to changing climates?  Some have suggested 
that if we want to know what is going to be native in the future, we will 
have to look to more southerly forests.

Ian Wilson