The trees of Mahoney Reserve

I had been meaning to get down to Mahoney Reserve on the corner of Illawarra & Wharf Roads Marrickville South since I saw ghostly skeletons of Poplar trees in the distance a

Showing the dead Poplars & giving an idea of their height

couple of weeks ago.  Once we got down to have a look it became apparent that all the Poplars are dying. 6 Poplars are stone dead. I was told they died last year. They stand like mutilated sentinels, a ghostly grey.

This is an avenue of 21 Poplars planted around 40-years ago. As a guess, each tree would be about 22-26 metres tall. These are substantial trees in Marrickville LGA as there are not many of this height & size. They are also landmarks as they are visible from many areas on both sides of the river.

In my amateur assessment, the trees have been killed by boring insects as there is evidence of borer holes all through these trees.  Only the 3 Poplars situated along Illawarra Road appear to be savable.  They seem to be in reasonable condition with only small amounts of dieback. They too have evidence of boring insects, but like the Poplar further along the Cooks River, intervention by chopping back the offending branches may just be what will allow them to survive if the borers have not yet reached the trunk. (See – http://savingourtrees.wordpress.com/2010/12/22/can-this-poplar-be-saved/ )

TreeHelp.com http://www.treehelp.com/trees/trees-insects.asp says the following –  “Boring insects are often the most harmful to trees & if left untreated can cause death. Boring, or tunneling, insects cause damage by boring into the stem, roots, or twigs of a tree. Some lay eggs which then hatch & the larvae burrow more deeply into the wood blocking off the water-conducting tissues of the tree.  Boring insects generally feed on the vascular tissues of the tree. If the infestation is serious, the upper leaves are starved of nutrients & moisture & the tree can die. Signs of borer infestation include entry/exit holes in the bark, small mounds of sawdust at the base & sections of the crown wilting & dying. It is important to regularly monitor a tree’s trunk for signs of boring insects to enable early identification & quick treatment. The key is to prevent infestation by keeping the tree as healthy as possible. This includes proper pruning, watering, mulching & fertilization. Pruning should be done in late fall or winter to avoid attracting insects to open wounds. Dead or fallen wood should be removed immediately. Once borers are present, control becomes extremely difficult, but steps should be taken to prevent further damage & to stop the spread to surrounding trees.”

A double row of Casuarinas dividing Mahoney Reserve & Marrickville Golf Course. These trees don't reach half the height of the Poplars

From my reading I understand that all trees should be checked periodically for signs of disease. Borer infestations can be diagnosed before dieback starts by seeing holes on the trunk or branches. At this state, systemic, chemicals can be put into the ground around the tree (maybe a problem with the Cooks River metres away, though they say the chemicals are non-toxic). Chemicals are also injected into the tree to kill off all boring insects at whatever stage of development they are at.  There is also a technique of literally skewering the insect to death.  Then the tree is fertilized to help fend off the stress it has been under.  If the tree is severely infected, it needs to be destroyed on site to prevent taking the insects to another location. The trunk & roots need to be removed from the soil as well & the soil treated before any new trees can be planted.

One by one we looked at the trees along the Wharf Road side of Mahoney Reserve. It was difficult to find a tree that wasn’t showing borer holes & rot.  Many had ant infestations as well.

The trees of Mahoney Reserve are very sick. Dieback takes a while to manifest, sometimes up to 5 years. My limited knowledge tells me that planting new trees will just provide further resources for the boring insects that are in control of this area unless the infestation is removed.

The Poplars especially, with their 2-3 metre girth are substantial carbon sequesters.  To have lost 6 & have the rest at serious risk of being chopped down as well is devastating on a number of levels.  Big canopy trees is what the park needs to replace the trees that have died & any others that will be lost.

We saw boring damage on about 70 trees in the one park & there are probably more. Just leaving the problem play itself out is not a solution. This park needs a comprehensive management plan to ensure what trees can be saved are saved & a replacement program be implemented to plant trees that will produce substantive trunks & shade. Shaded avenues along the parks & the river walks will be more & more essential as the sun is getting hotter & hotter.

I put up a 2 minute YouTube of Mahoney Reserve showing the trees – http://www.youtube.com/watch?v=pGlpS_YcRLY&feature=BF&list=ULPOgkK3s0Qo0&index=6

The avenue of dead & dying Poplars are on the left to centre with Casuarinas on the right

Can this Poplar be saved?

a section of the avenue of Poplars next to Mackey Park

The Cooks River pathway further on from Mackey Park has 2 stunning avenues of Poplar trees. Poplars are also used to great effect in Steele Park further along the river.

These trees are very beautiful.  They create significant areas of dappled shade in summer & lose their leaves in autumn letting in the winter light.  The trunks of some of the bigger trees behind Mackey Park are around 3-4 metres. These are big substantial trees that are a landmark to this area & can be seen from many locations along the river.

In my opinion the presence of these trees makes this section of the Cooks River pathway in Marrickville South really lovely.  When the wind is blowing the sound created as the wind passes through the leaves is very special.

These trees are being considered for the chopping block because there is belowground infrastructure here & because the soil is poor.  I don’t know enough about the issues to present an argument at this stage.  Just be aware that Council is thinking of removing them.

close-up of the borer affected branch that fell

Unfortunately 1 of the smaller trees dropped a branch last November 2010.  Borers had literally shredded the inside of the trunk until it was unable to maintain its weight & dropped.  What is left is around 1.5 metres of remaining branch extending from the trunk.  No one would know if the borers have travelled that far unless they removed the branch at the point where it connects to the trunk.

I don’t think Marrickville Council is going to bother to check this out as I was told the tree will be chopped down.  If a tree has borers in its trunk it is dangerous because it will do exactly as the branch did & fall.  However, there is a significant chance that the borers haven’t reached that far.

I put up a YouTube video of this tree when the branch & evidence of borers was still available to see. Unfortunately, I have deleted the video & Council has taken away the branch so I cannot re-film it.  However, a Arborist did manage to see the video before it went to its grave & pointed out to me that it is quite likely that the trunk itself does not have borer infestation. He said checking is easy to do & chopping off the offending branch is far cheaper than chopping down a whole tree.

The arrow shows the remaining 1.5 metre branch

I would suggest that Marrickville Council does not want to bother doing this because they think many of the older trees need to be removed & because they are thinking about removing this avenue of trees in time anyway. With this plan, they wouldn’t try to save a tree even if it was a simple thing to do.

I firmly believe that we need to keep our older & larger trees. They are very valuable on many fronts. A Councillor recently said they are “a written asset, not a real asset”. I disagree.  They a valuable asset. As an example of the dollar value of trees, the 14 Laman Street Figs in Newcastle were valued at 1 million dollars.  In England & the US trees are valued, & basically, the older they get, the more they are worth.  It’s time we stopped thinking of trees as expendable infrastructure & start doing whatever we can to care for them to ensure their longevity.

With climate change bearing down on us, I believe we cannot afford to remove the very things that all the experts believe are what will help mitigate global warming. Aside from the craziness of removing a healthy tree because it is not a native, these trees are beautiful. I have asked many people what they think of them over the last few weeks & everyone I have spoken with loves them.  I am not alone then & I suspect the community may have something to say against their removal.

I would like Marrickville Council to leave these trees alone. I do not believe planting native trees here will be a better choice.  I also think Council should check the branch to see if borers have reached the trunk. Of course if they have reached the trunk, the tree should go.  However, in the past when trees were saved as a norm, the Tree Surgeon, as Arborists were known then, would scrape out the infestation providing it was small enough, then fill the hole with what I as a kid called tree cement. It’s not the correct term, but you get the idea.  A number of the Pines at Brighton le Sands have had work like this done. Rockdale Council obviously thinks these trees are special.  It all depends on the motivation of Marrickville Council. If they don’t want the tree, they will go for the easiest option & chop the tree down.

The UN has declared 2011 as the International Year of Forests. These trees are part of our urban forest.

The tree to be removed is in this section of the avenue of trees. It is the 4th tree inwards on the right side of the photo. Removing it will leave a large gap

About the 3 new street trees up for removal

On 19^th March, the following 3 street trees were put up on Marrickville Council’s web-site for removal.

1. Mature Corymbia citriodora (Lemon Scented Gum) outside 11 Union Street Dulwich Hill.  This tree was the first campaign for SoT in June last year.  At that time Council said the problem was ‘whole tree failure’ which I & other members of the community disputed.

showing the recent splits & the 'bleeding' from the nails which were hammered in last June 2009 - using a wide angle lens makes the tree appear taller than it is

The outcome was Council surveyed the tree & intended to monitor to see if the lean increased.  Their report says a lot has happened to this tree since then.

This time they say: Asymmetric root–plate development due to restrictive growth environment. (as does a huge percentage of mature trees in Marrickville LGA due to failure to remove cement from around their trunks), buttressing of the base of the tree over the adjacent kerb.  This predisposes the tree to wind-throw in extreme weather conditions.  There is also a risk of whole tree failure if the kerb collapses. Extensive structural root & crown decay in the plane of compressive stress.  This condition is compounded by the tree exhibiting a moderate lean in the plane of decay.  The decay has been caused by the presence of the naturally occurring fungal decay pathogen Armilaria leuteobubalina.  The tree is exposed to south-easterly winds in the direction of lean & in the plane of decay.  This is compounded by the tree exhibiting an asymmetric canopy, with the majority of the canopy being present in the direction of the lean of the tree (what does Council think of all the masses of asymmetric trees which have been made this way by Energy Australia?)  Severance of structural roots on the windward side of the tree as a result of excavations undertaken by Sydney Water.

I interpret the above as: this tree is likely to fall over if there is an extreme weather event, especially if the wind comes from a south-easterly direction or if the sandstone kerb collapses.  The tree has been placed at risk because Sydney Water severed its structural roots.  Finally, the tree has caught a fungal disease & this sews up the argument for removal.  As this fungus stays in the ground for a while, Council will not replace the tree for 2 years. Council does not say what species the replacement will be.

I went to have a look at this tree & its condition has really changed.  In my opinion it needs to go.  I can’t identify Armilaria leuteobubalina, but I can tell when a tree is deteriorating & this one is.  It has recently developed 2 large vertical splits in its trunk that regardless of the other things afflicting this tree, indicate its demise.

Its loss is going to have a dramatic affect on the streetscape as it cascades beautifully over Union Street & is clearly visible from the café on the corner.  The deadline for submissions is 2^nd April 2010.

2. The second street tree is a Eucalyptus scoparia (Wallangarra White Gum) outside 70 Railway Street Petersham.  Council’s report says:  Extensive stem decay & is at risk of

showing the decay & damage by borers

breakage. No disagreement from me with this tree.  It looks like it has or had borers & they entered via a newly cut branch.

I am pleased to note that Council says they will replace it with a Lemon Scented Gum.  I do know a number of Petersham residents who are worried that Council will remove their Gums.  (I just realised how this reads like & will leave it for a bit of fun).  Put in a way that does not sound like dental work, residents fear that Council will remove the Eucalypts, so replacement with a tall growing Eucalypt will please many.  The deadline for submissions is 9^th April 2010.

3.  The third tree required a certain amount of sleuthing on my part to locate because I failed to notice the word ‘adjacent.’  This is another Eucalyptus scoparia (Wallangarra

massive damage to this tree as well as termites

White Gum).  It sits in a lovely little space between 2 types of stairs (ordinary/normal stairs & thrill-seeker/kill off your granny stairs – see photo in this post) that connect Day Street with Hampden Avenue.  There are a number of mature trees in this little triangle of dirt.

Council’s report says: Extensive column decay in trunk. Termite activity evident. Again, both these were easy to see.  I also think the people who live in the house directly next to & below this particular tree may breath a sigh of relief when it goes.  They may have held their breath through a few storms, worried that it would crash on their house.  I know I would have.  Council will replace this tree with a Eucalyptus microcorys (Tallow Wood), which will be nice.  The deadline for submissions is 9^th April 2010.

I was enormously pleased to see that Marrickville Council had used wide sticky tape to fasten the ‘notice of removal’ signs on all 3 trees.  Thank you for doing this.  This is a big

The ramp on the right is very steep - I assume it was used when the quarry across the road was active

change from previous practice of nailing in the signs & seems more effective because all 6 signs are still in place.

I was also very pleased to note the more detailed information provided with the ‘notification for removal.’  Although I recognise this takes more time for Council staff, it helps them in the long run because the community does not have to guess why the trees are up for removal.  All 3 notifications & especially the one in Union Street gave clear & descriptive reasons.  Coupled with the use of tape instead of nails, this is a great improvement & goes to generating goodwill.

Apparently the period for submissions for public trees is 14 days, not 21 as we have experienced throughout the latter half of 2009.  Council says they allow 21 days for submissions if the tree is significant in some way.  14 days doesn’t allow much time, but if we are organised, it can be done.  It also means that I cannot be slow in noticing new trees for removal on their web-site.

I am not going to put in a submission for any of the current trees as I believe they all should be removed.