Someone asked, “Why go on about street trees?”

Trees are good for us.  Street trees (or public trees) create enormous financial & aesthetic benefit for human beings, not to mention the benefit to wildlife.  The benefit of street trees can be summarised as the following:

  • Property values increase when there are visually beautiful street trees within view.  If the street is tree-lined or there is a beautiful tree directly in the front of the property, real estate agents use this as a selling point.  Streets that are barren of trees generally have a lower value regardless of the housing.  If you want to immediately lower the value of your property, get the council to remove a large tree from outside your property.  The exception is where removing a tree will increase a water view, though some Councils replace a tree which has been deliberately poisoned with a billboard.  A billboard blocking your water views while new trees grow will certainly lower property values.
  • Trees create shade.  Shade benefits pedestrians, provides a cool spot on hot days for people to enjoy the outside & lowers household cooling costs.  Even if trees do not directly shade the house, their presence reduces & cools the air temperature around the house.  Windows can be opened to allow the flow of cool air instead of relying on air-conditioning systems, which reduces further household energy costs & lowers the impact on global warming.  The air-cooling ability of trees also lowers ground-level ozone, which contributes to greenhouse gas creation.
  • Trees remove carbon dioxide (CO2) from the surrounding air through their leaves.  They store CO2 in their trunk lowering air pollution levels.  The more trees in an area, the better the air quality & the more trees, the more beneficial it is for our planet. Street trees remove 9 times more pollutants from vehicles than trees located further away from the road.  Obviously an older, larger tree has more ability to remove CO2 from the air than does a short stature tree (7.5 metres or less).  Interestingly, Marrickville Council requires replacement trees on private land to be ‘up to’ 5 metres, just a little bit higher than the average house gutters leaving plenty of red roof tiles visible.  I would guess that more than half the street trees in Marrickville LGA are short stature trees.
  • Trees produce oxygen.  A mature tree will produce enough oxygen to support 2 human beings & will absorb 20 kg CO2 per year. A recent study in the US (USDA Forest Service Pamphlet #R1-92-100) stated that one street tree generates US$31,250 worth of oxygen & provides US$62,000 worth of air pollution control over 50 years.  This translates into enormous cost benefit to the community.
  • The leaves of trees collect air-borne particles matter such as dirt, dust & the sooty bi-product from car & truck exhausts.  If you live on a busy street, you will notice this collecting on your windows, ledges & front door.  Asthma & other respiratory illnesses are exacerbated by exhaust pollution from vehicles.
  • Trees reduce storm water runoff by collecting water through their leaves, bark & roots.  This process often collects pollutants that would otherwise end up in our drains & ultimately in our rivers.
  • Trees also reduce soil erosion.
  • Street trees help buffer & deflect traffic noise thereby reducing noise pollution.
  • Research has shown that street trees with large canopies give drivers the impression of narrower streets, which results in reduced speed.  Reduced speed result in less traffic accidents.
  • Finally street trees provide much needed food (if they are natives) & housing for birds and small animals like panda bears (just joking!).

Not bad for the humble street tree. Not only are trees good for us, their presence results in higher property values.  Areas that have many large trees are regarded as ‘better suburbs’ & housing prices reflect this.   Much of the housing stock on the North Shore is not very different from much of the housing in the Marrickville local government area (LGA).  The North Shore area looks wealthy & beautiful mainly because they have tall trees everywhere. The majority of streets, including main roads have many more tall street trees than in Marrickville LGA.  Their parks have at least a third more tall trees.  There is a significant tree canopy.  The area looks green & one’s eyes are not attracted to red tiled roofing.  Residents plant & keep large trees on their properties.  It could be argued the North Shore has larger properties than the Inner West & I would agree with this point.  However, there are many half-acre blocks in our LGA as well.  We also have many wide streets allowing for the planting of tall street trees.

Paddington, Balmain & Birchgrove are 3 areas with dense housing & small streets.  These suburbs refute the ‘no space’ argument.  They are green with tall trees everywhere, including street trees & they are not hacked into bonsai-ed stumps.  Once again, the property values reflect this.  Every time I go there I am shocked at how many trees there are.   Why can’t we have the same in this LGA?

Finally, a trip to the western suburbs earlier this year showed me that the green canopy has spread down from Eastwood & surrounds. Street after street were lined with close plantings of beautiful eucalypts & other tall native trees.  In my opinion, the lines between so called ‘good’ & ‘less good’ areas have blurred considerably as they have got greener.  In comparison, most of the Marrickville LGA is bare.  We can stand & count the tall trees on the horizon.  Close-by at Arncliffe, Earlwood & Bardwell Valley, the tall street trees are back & they can’t be counted in under 10 fingers.

An exception is Stanmore in the Marrickville LGA.  Stanmore was no-where near a green & leafy 20 years ago.  Now most of the suburb looks wonderful & it is my belief this is because of the street trees.  This proves it can be done, as the housing in Stanmore is just as dense as in other areas in Marrickville LGA.  We need to keep the tall trees we have & plant new ones in our streets, parks & barren spaces.  If other councils in Sydney can do what is needed to manage & care for such trees, so can our council.

With global warming a reality, I do not think it will too long before trees will be deemed an absolute necessity in urban planning & not something councils consider as expendable.  Without public trees, our streets & homes will be baking hot & many of us will not be able to afford the high costs of running air-conditioners or other cooling systems, even if there is no energy use restrictions.

I would be interested in your comments.


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