[CANUFNET] Tree of Heaven

[Koskinen, Jennifer]

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
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        <BA3C6411452D9B438CBE2BB75C9C5F2624F2A0 at vsmailbox.city.kelowna.bc.ca>
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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