Unsuitable tree species

Sean Freeman · 5th January 2008, 04:54 PM

As we move into the proper wet season and the first of the real winds arrive here's something that perhaps will provoke thought and comment. As Arborists we should be giving our local authorities more direction in relation to the more reliable trees to selct for planting in street scapes.

Ok there are no species able to reverse the impacts of poor and damaging practices, but all of us are well aware of particular species that seem dangerously vulnerable in specific conditions..ie shallow clay soils etc...

Khaya senegalensis African mahogany was a species heavily promoted by local authorities in Darwin after TC Tracy, and we have known for a long time sicne that as a species it is not suited to shallow clay soils, it develops such a massive canopy that it requires an extensive root system.

This morning in Darwin
Damaging winds, floods forecast for NT - ABC News (Australian Broadcasting Corporation)

Ekka · 9th January 2008, 01:53 AM

That would have been really bad if there were cars parked out front.

Shallow clay soils on top of some shaley rock, lots of rain, some wind.

I'm not familiar with those trees at all, they dont have roots like a ficus then I take it. More suited to sandier soils well draining then Sean?

The ground is real soft here now, rained out this morning, more rain coming, windy again ... unreal, nothing catastophic yet but the way it's been brewing since Christmas I reckon this years going to be full of surprises.

philinsydney · 10th January 2008, 03:01 AM

For some reason Sydney is full of Lophostemon confertus planted under street wires. They are always chopped off at about half height, and look absolutely awful.

JayD · 10th January 2008, 03:23 AM

Hi Phill,
They plant Lophostemon confertus ( brush box) here in Sydney as they adapt well to pruning needed around power lines. My favorite tree, They have some grand old girls in Gore Hill Cemetary,Which I and a few others deadwooded last year,It was a challeging job as we had to be extreemely carefull of the old headstones as they are very brittle.

JohN Dee · 10th January 2008, 03:26 AM

The brushbox/london plane's wern't chosen to be the predominant street trees. They just survived the most out of all the trees originally planted.

Brush boxes adhear to the harsh pruning that goes on around the wires really well.

Ekka · 10th January 2008, 06:02 AM

Here's a pic of a mature brushbox, most suitable for under wire planting.

TreeDimensional · 10th January 2008, 06:32 AM

Sean, its very interesting to read of tree failures in other regions of the world. A few years back a group of Arborists in the US started collecting data on different types of failures. Apparantley not just anyone can contribute to the database, you are required to take a course. With the regulatory system in Australia, could it be to everyone advantage to have a component on tree failures as part of the educational training. This would allow a a list of tree failure traits to be developed for each region?

It is really interesting to note that in Canada, we use hardiness zones that take into account the lowest temperature a species of tree can handle. Do you folks down there use a sytem that takes into account, say, drought?

The picture of the tree that failed in your original post appears to be windthrown, and I would concur that there doesn't appear to be a lot of major anchoring roots outside the root plate, they may have broken when the tree fell. But the thing that first came to mind was, whow there are a lot of trees nearby. I was at a workshop in which Dr. Kim Coder reminded us that the best thing that you could do for a tree was to give it room. It appears that the tree in the pic had a very dense canopy, that didn't allow the extra wind through. There are so many factors to consider when looking at a tree failure, but a lot of the failures might be prevented IF the people planting new trees knew of the traits of partiular trees to fail in particular enviornments. Proper tree in the right place. (Site appropriate trees)

I am also glad to here that its not just Canadians that put 60' trees under 30' power lines. I figured we were a little shy on the learnig curve.

It doesn't appear that we are alone. While it was interesting to read that you folks have a few species that tolerate harsh crown reduction pruning, wouldn't it be better to control what may be planted under the overhead infrastructure?

Just a few thoughts, carry on!

Ekka · 10th January 2008, 06:49 AM

Here's a link to the Australian Tree Failure database.

Australian tree Failure Database

With all due respect to the producers of such and their intentional goodwill it's a chronic dead duck. Try get some data out of it? It's now 2008 and it was last updated 2004. Hmmm, maybe I should take it off their hands and fix it... but knowing how much effort it is for people to post I can see why they'd shun at filling that out.

Here's who needs to be completing that info, insurance companies and councils predominantly, I would say the bulk of failures would fall into those 2 buckets.

TreeDimensional · 10th January 2008, 07:21 AM

Ekka, from what I've seen, it appears that if they asked you to fix it, I'm bettin' on you.

I must admit though, at least you can get in to see the form, the US people won't even let you do that. I whole heartedly agree that the departments you mentioned SHOULD be doing the reporting. If your property tax system is like ours, the greenspace aorund your home will dictate property values. Who Benefits from increased property values, the councils. Here its not that the greenspace is taxed in the value of the home, but the resale of a nice yard supercedes one thats not.

If mother nature decides to teach us a lesson, she will always win. I personally like to see trees used to keep the revenue to the "man" in check.
If we reduce the wind off the heated buildings in the winter and can shade the house in the summer, utility consumption is dramatically reduced. Of coarse tree perform much more than wind and sun abatement, noise reduction is the one thing that trees perform well. We have a 2 row shelterbelt between the house and the highway (1/4 mile away). There is a dramatic differance between summer and winter tire whine from highway tractor trailers.

Its nice to have silence after hearing chainsaws and chippers all day.

philinsydney · 11th January 2008, 03:14 PM

Has anyone noticed the jacarandas at Circular Quay West? They are threadbare on their water-facing side; presumably they hate the sea breezes carying salt on to their leaves.
Is Sydney City Council so determined to have jacaranda flowers that it will allow the trees to suffer to this extent?

Ekka · 11th January 2008, 09:45 PM

What, no picture?

9th January 2008, 01:53 AM	#2 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 6,846	Re: Unsuitable tree species That would have been really bad if there were cars parked out front. Shallow clay soils on top of some shaley rock, lots of rain, some wind. I'm not familiar with those trees at all, they dont have roots like a ficus then I take it. More suited to sandier soils well draining then Sean? The ground is real soft here now, rained out this morning, more rain coming, windy again ... unreal, nothing catastophic yet but the way it's been brewing since Christmas I reckon this years going to be full of surprises. __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping Brisbane Tree Care, Consultations and Arborist Reports Forum Sponsors

10th January 2008, 03:01 AM	#3 (permalink)
philinsydney Semi-mature vigorous tree Join Date: Nov 2007 Location: Sydney Posts: 76	Re: Unsuitable tree species For some reason Sydney is full of Lophostemon confertus planted under street wires. They are always chopped off at about half height, and look absolutely awful.

10th January 2008, 03:23 AM	#4 (permalink)
JayD Over mature heritage tree Join Date: Feb 2007 Location: Sydney Posts: 885	Re: Unsuitable tree species Hi Phill, They plant Lophostemon confertus ( brush box) here in Sydney as they adapt well to pruning needed around power lines. My favorite tree, They have some grand old girls in Gore Hill Cemetary,Which I and a few others deadwooded last year,It was a challeging job as we had to be extreemely carefull of the old headstones as they are very brittle. __________________ Free Tree and Green Industry Link Directory

10th January 2008, 03:26 AM	#5 (permalink)
JohN Dee Over mature heritage tree Join Date: Feb 2007 Location: Sydney, Australia Posts: 728	Re: Unsuitable tree species The brushbox/london plane's wern't chosen to be the predominant street trees. They just survived the most out of all the trees originally planted. Brush boxes adhear to the harsh pruning that goes on around the wires really well. __________________ Climber with slow climbing speed, must make up with mighty chainsaw roar. Free Tree and Green Industry Link Directory Red : Green : Blue

10th January 2008, 06:32 AM	#7 (permalink)
TreeDimensional Banned Join Date: Feb 2007 Location: Canada Posts: 385	Re: Unsuitable tree species Sean, its very interesting to read of tree failures in other regions of the world. A few years back a group of Arborists in the US started collecting data on different types of failures. Apparantley not just anyone can contribute to the database, you are required to take a course. With the regulatory system in Australia, could it be to everyone advantage to have a component on tree failures as part of the educational training. This would allow a a list of tree failure traits to be developed for each region? It is really interesting to note that in Canada, we use hardiness zones that take into account the lowest temperature a species of tree can handle. Do you folks down there use a sytem that takes into account, say, drought? The picture of the tree that failed in your original post appears to be windthrown, and I would concur that there doesn't appear to be a lot of major anchoring roots outside the root plate, they may have broken when the tree fell. But the thing that first came to mind was, whow there are a lot of trees nearby. I was at a workshop in which Dr. Kim Coder reminded us that the best thing that you could do for a tree was to give it room. It appears that the tree in the pic had a very dense canopy, that didn't allow the extra wind through. There are so many factors to consider when looking at a tree failure, but a lot of the failures might be prevented IF the people planting new trees knew of the traits of partiular trees to fail in particular enviornments. Proper tree in the right place. (Site appropriate trees) I am also glad to here that its not just Canadians that put 60' trees under 30' power lines. I figured we were a little shy on the learnig curve. It doesn't appear that we are alone. While it was interesting to read that you folks have a few species that tolerate harsh crown reduction pruning, wouldn't it be better to control what may be planted under the overhead infrastructure? Just a few thoughts, carry on!

10th January 2008, 06:49 AM	#8 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 6,846	Re: Unsuitable tree species Here's a link to the Australian Tree Failure database. Australian tree Failure Database With all due respect to the producers of such and their intentional goodwill it's a chronic dead duck. Try get some data out of it? It's now 2008 and it was last updated 2004. Hmmm, maybe I should take it off their hands and fix it... but knowing how much effort it is for people to post I can see why they'd shun at filling that out. Here's who needs to be completing that info, insurance companies and councils predominantly, I would say the bulk of failures would fall into those 2 buckets. __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping Brisbane Tree Care, Consultations and Arborist Reports Forum Sponsors

10th January 2008, 07:21 AM	#9 (permalink)
TreeDimensional Banned Join Date: Feb 2007 Location: Canada Posts: 385	Re: Unsuitable tree species Ekka, from what I've seen, it appears that if they asked you to fix it, I'm bettin' on you. I must admit though, at least you can get in to see the form, the US people won't even let you do that. I whole heartedly agree that the departments you mentioned SHOULD be doing the reporting. If your property tax system is like ours, the greenspace aorund your home will dictate property values. Who Benefits from increased property values, the councils. Here its not that the greenspace is taxed in the value of the home, but the resale of a nice yard supercedes one thats not. If mother nature decides to teach us a lesson, she will always win. I personally like to see trees used to keep the revenue to the "man" in check. If we reduce the wind off the heated buildings in the winter and can shade the house in the summer, utility consumption is dramatically reduced. Of coarse tree perform much more than wind and sun abatement, noise reduction is the one thing that trees perform well. We have a 2 row shelterbelt between the house and the highway (1/4 mile away). There is a dramatic differance between summer and winter tire whine from highway tractor trailers. Its nice to have silence after hearing chainsaws and chippers all day.

11th January 2008, 03:14 PM	#10 (permalink)
philinsydney Semi-mature vigorous tree Join Date: Nov 2007 Location: Sydney Posts: 76	Re: Unsuitable tree species Has anyone noticed the jacarandas at Circular Quay West? They are threadbare on their water-facing side; presumably they hate the sea breezes carying salt on to their leaves. Is Sydney City Council so determined to have jacaranda flowers that it will allow the trees to suffer to this extent?

11th January 2008, 09:45 PM	#11 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 6,846	Re: Unsuitable tree species What, no picture? __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping Brisbane Tree Care, Consultations and Arborist Reports Forum Sponsors

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