You are currently browsing the tag archive for the ‘The Conversation’ tag.

North Newtown streetscape providing lots of shade

North Newtown streetscape providing lots of shade.  This is a normal streetscape for this area.

Compare with a street in Dulwich Hill that actually has many street trees

Compare with a street in Dulwich Hill that actually has many street trees

There is an interesting article in The Conversation written by Prof. Rod Keenan & Benjamin Preston, both from the University of Melbourne.

Some points in the article –

  • Victoria currently has an average of 9 days per year of temperatures above 35C.  No action on greenhouse emissions will likely result in an average of 21 days a year with temperatures above 35C by 2070.
  • “Combine that with increasing urban density, more hard surfaces & less greenery, & a larger, older & more multicultural population, & the potential impacts from heatwaves start to multiply rapidly.”   Think of the development already in Marrickville municipality & the huge amount of development to come.

The Authors suggest two ways to help mitigate this & I think these are applicable Australia-wide –

  1. Increasing the ‘green infrastructure’ by 10%.  Green infrastructure means street trees, parks, green roofs, green walls & retaining water.

I’d suggest 10% is the absolute minimum, but can you imagine the positive change if the Marrickville urban forest was increased by 10%.

The City of Melbourne is planning on increasing their urban forest canopy cover from 22% to 40%. The City of Sydney is aiming to increase their urban forest by 50% by 2030 (just 16-years away) to help lower the urban heat island effect.

  • 2. Education.

“Health awareness programs can promote related benefits such as improved air quality; planners can reduce the red tape involved in planting street trees; local governments can identify priority neighbourhoods for development, protect existing greenery, & implement water-sensitive urban design.” 

“Increasing green infrastructure will also require the use of private space – one major challenge will be to give private landowners the incentive to keep or install greenery & incorporate vegetation into building design.”

Although Sydney has not experienced a true heatwave this summer, it has been very hot.  Melbourne & Adelaide both experienced two heatwaves this January, baking over a number days.  On 16th January, Adelaide was given the title of ‘the hottest city in the world’ with a temperature of 44.2C, still short of the forecasted 46C.

An article on Care2 discusses the American city of Phoenix trying to cope with 100-degree nights.  “The city averages more than 100 days a year with temperatures reaching over 100 degrees. (37.7C)   In 2013, 115 days hit 100 degrees. In 2011, the city set a new record for days over 110 degrees (42.3C) with 33. That’s over one month of the year with scorching highs. This winter has so far been warmer than average.”

Temperatures are rising everywhere.  The urban heat island effect is increasing those temperatures, & importantly, not allowing the temperature to drop after the sun goes down.  Phoenix has “a shade plan for the built environment & also a plan to “frankly just plant more trees.”  See –

We need to start planting now in both private & public spaces if we are to ever hope to be able to cope with projected temperatures.  Sydney’s temperature is expected to be like living in Rockhampton in Subtropical Queensland.  See –

Marrickville Council needs to decide how much to increase the urban forest & set & meet targets to achieve this.  The yearly budget allocation needs to be such to allow this to be achievable.   I have often wondered whether public trees & parks are lower down in the budget & whether these are seen as not as important as grey infrastructure.

Certainly we need to do what we can to keep the trees we have & this means treating them for diseases, fertilizing, mulching & pruning where necessary.

In my opinion, the community needs to help Council keep new trees alive by continuing to water trees once a week when Council has stopped water 12-weeks after planting.  It only takes a few hot days to lose a tree & if we look realistically, the bulk of our street trees are living in very harsh conditions.  Many are either hemmed in by concrete or in visibly dry & compacted soil.

I know there are many who will baulk at the idea of watering a public tree, but it is commonplace in many countries overseas.   The US for example, has a strong community involvement in public trees, whether planting them or looking after them.  Both the US & the UK have community ‘Tree Wardens’ looking after public trees.  These people are not tree experts.  They receive training by their Local Council to do the work they do.

Keeping that tree alive will help reduce your power bills as they help cool the air around your house.  Street trees clean up the air by removing particulate matter from vehicles, so better quality air comes into your home.  They also increase the value of your residence or business amongst many other benefits, so it stands to reason that taking care of the tree outside your property brings significant returns.  Better a living healthy tree, than a dead tree or a sapling that struggles to grow & may take many years to reach a decent size.

Older larger trees are far better at carbon sequestration than smaller trees – another reason why it makes sense to look after them.

You can read the full article here –

Tall shady street trees are the norm in Chippendale

Tall shady street trees are the norm in Chippendale

Canterbury Road - this section is mega-hot on a sunny day.

Canterbury Road – this section is mega-hot on a sunny day.

While there are street trees, this is still a hot street in Marrickville

While there are street trees, this is still a hot street in Marrickville


Young street trees & landscaping outside the old seagrass factory in Stanmore that has recently been developed into housing.

The Conversation – “an independent source of information, analysis & commentary from the university & research sector” has published yet another fabulous article, this time about trees.  The article was written by Gregory Moore – Doctor of Botany, University of Melbourne & published 30th January 2012.

Greg Moore Senior Research Associate of Burnley College, University of Melbourne was Principal of Burnley from 1988 to 2007, & Head of the School of Resource Management at the University from 2002 to 2007.  With a general interest in horticultural plant science, revegetation & ecology, Greg is particularly interested in arboriculture. He was inaugural president of the International Society of Arboriculture, Australian Chapter, & has been a member of the National Trust’s Register of Significant Trees since 1988 & chair since 1996. He has served the Board of Greening Australia (Victoria) since 1988 & chaired Treenet since 2005. He is on the board of Sustainable Gardening Australia & is a trustee of the Trust for Nature. He has written two books, contributed to three others & has published over 120 scientific papers & articles.”

‘The Conversation’ allows this article to be republished so here it is in full.  The use of bold is my emphasis.

For a great return on investment, try trees

Perhaps it is a pity that so many Australians think of our parks, gardens, streetscapes & urban landscapes only in terms of their aesthetics. While green spaces are beautiful & decorative, these attributes can mask the many functions vegetation serves in cities, to the point where its economic, social & environmental benefits are overlooked. Yes, trees are beautiful; but more than that, they save our cities a lot of money.

Cities are biodiversity hot spots because of the variety of habitats available in public & private open space, including front & back yards. Urban landscapes & trees have been wonderful but silent assets in our cities for decades & even centuries.

One of the many mature Fig trees in Johnson Park Dulwich Hill. They & other mature trees in this park are a real asset to this community.

They are major urban infrastructure assets. I often hear it said that; “There are better things to use water on than plants and gardens”, but I challenge you to name them. What else delivers so many benefits immediately: benefits that last centuries into the future, which prolong healthy lives & make cities both sustainable & livable?

At a time of climate change, it is worrying that both private and public open spaces are threatened by urban renewal & development that puts at risk long-term sustainability. In many of these developments there is insufficient open space – public or private – to plant large trees, & the opportunities for vegetation to ameliorate the heat island effect, lower wind speed, provide shade & reduce energy use are lost. This affects the economic viability of such developments, as well as its long term environmental sustainability.

The shade provided by trees drops temperatures by up to 8°C: there is real economic value in that. Shade can reduce air conditioner use by 12-15%, which also decreases carbon emissions from our largely brown-coal-generated electricity.

When 11 million trees were planted in the Los Angeles basin, it saved US$50 million per annum on air conditioning bills. Large trees were removed from school grounds in the name of safety after the Black Saturday fires, without thought of the shade they provided. Consequently, large shade sails had to be provided to protect students from excessive summer sun.

It is more difficult to place a value on reduced wind speeds (up to 10%) due to the presence of vegetation, or on protection that trees provide from hail. However, we do know that under climate change winds will be stronger & that severe storms will be more prevalent. Indeed, Victoria has already suffered the effects of several major wind & hail storm events over the past few years.

Urban vegetation also removes atmospheric pollutants. It was calculated that the vegetation of New York provided US$10 million of benefit in pollution removal in 1994. resources/downloads/Tree_Air_Qual.pdf  Sadly there are few similar studies for Australian cities. However in the only study of its kind, economists found that each Adelaide street tree provides a minimum annual benefit of $200 per year & that it was an under-estimate of the real value.

Vegetation also holds & absorbs water during more intense rainfall events – unlike concrete & paved surfaces. The economic value of reducing localised flooding could be substantial.

Vegetated landscapes, especially those containing trees, improve human heath, extend life spans, reduce violence & vandalism, and lower blood pressure.

Vegetation humidifies the air, easing breathing & reducing the need for medication in those with respiratory difficulties. In reducing the urban heat island effect, trees can also substantially reduce the excess deaths that occur, predominantly among the elderly, during heat waves. It is often forgotten that the fires of Black Saturday killed 172 people, but the heat wave surrounding it was responsible for 374 deaths.

Petersham is lucky to have such a lovely streetscape.

There is ample evidence that treed landscapes foster both active & passive recreation. Green & leafy environments will be one of the vital strategic tools in dealing with children lacking exercise & becoming obese, encouraging an ageing population to exercise & curbing ever-increasing health costs. The human health benefits can save society a truck-load on medical & social infrastructure costs.

Melbourne is one of Victoria’s biodiversity hot spots. The parks, gardens, streets & front and backyards provide a very diverse range of plant species that generate a myriad of habitats & niches for wildlife. High density urban developments & inner city renewal make it virtually impossible to grow trees in places that were once green & leafy. We rarely ever see the real costs of such developments.

In the past decade tree populations in many Australian cities have declined, particularly with the loss of private open space. While the costs, damage & nuisance values attributed to trees are widely known, the benefits they provide are often subtle & under-appreciated.

Urban vegetation provides economic & ecological services to society. They are assets which warrant the expenditure of resources such as labour, energy & water. Such expenditure is not wasted: trees & urban landscapes provide far more economically & ecologically than they use. In any comprehensive & fair calculation urban trees & landscapes are worth more than they cost.

* data-tracker

This article was originally published at  Read the original article –

Landscaping with young trees has been used to block off a road connecting with Ewart Street Dulwich Hill. It always looks good. Unfortunately one tree has been lost.

Tilman Park Tempe has some lovely features & some beautiful tall trees, including a Fig. Boulders are placed under the Fig so you can sit in the shade & watch the park.

Today I came across a wonderful article from the website The Conversation – “an independent source of information, analysis & commentary from the university & research sector.”  The article was written by Jason Byrne – Senior Lecturer/First Year Advisor at Griffith University & published 9th January 2012.

Bain Playground Stanmore has lovely mature trees & a great streetscape.

“Jason Byrne is an urban geographer by training. He undertook his PhD at the University of Southern California (Los Angeles) where he was a fellow in the Center for Sustainable Cities. Jason is also a Senior Fellow with the Johns Hopkins University Institute for Policy Studies. He has previously worked as a town planner & environmental policy officer with the Western Australian government. Jason’s research interests include: urban nature parks & green-space planning; equity & fairness in planning (environmental ethics & justice); open space & healthy cities; ecological modernisation & sustainability; & climate change adaptation & urban resilience.

Because the The Conversation allows this article to be republished I thought it best if I did just that, rather than write a description with the web-link.

This article is very relevant to Marrickville LGA.  It’s great for me to be able to share what an expert thinks about the value of green space, especially in high-density urban areas & increasing urban consolidation. The use of bold is my emphasis.

“What is green space worth?

Recent patterns of residential development in Australian cities are threatening to overwhelm green space in our urban cores. Policies of urban consolidation have concentrated medium to high density residential development in inner ring suburbs where green space is comparatively scarce. And the zoning & development regulations of many local authorities actually allow a reduction of green space for higher density development – usually without any justification.

The Poplar trees along the Cooks River near Mackey Park Marrickville South make this a lovely cool & shady walk. There is always lots of bird song & when there is a breeze the leaves make a beautiful sound.

Everyone likes parks, but we may be greatly undervaluing their importance to our health & wellbeing, & to the wellbeing of other species. Rather than losing our green spaces, we should be assessing the evidence on their value & making informed decisions about how much green space we need.

To the casual observer, urban parks & green spaces might appear commonplace. But even a cursory examination of green space distribution within most cities shows that urban green space is neither uniformly accessible nor equitably distributed.

Generally the older & denser parts of many cities, which often were developed during the industrial revolution, tend to have relatively poor park access. But suburbs that have developed since the late 1950s have comparatively better access to various types of green space.

The spatial pattern of urban green space distribution reflects diverse factors linked to urban land & property markets, changing land use planning philosophies, histories of settlement & development, & in some cases, institutionalised racism and elitism.

Before the development of formalised park & recreation planning systems in the late 1800s & early 1900s, park & green space planning in the United Kingdom, United States, & Australia was relatively haphazard.

Some cities, like Adelaide, are park rich due to visionary administrators. In London royal parks were opened to the public, a product of elite benevolence.  Other cities, like Canberra, grew while new ideas about park planning gained popularity.

But some cities are park poor. Inner ring residents in Los Angeles for example, have less public park space per 1,000 residents than the size of a suburban backyard.

So can we put a value on urban green space?

Research by John Henneberry, a Professor of Town & Regional Planning at the University of Sheffield, suggests people in Sheffield may be willing to pay sizeable sums to access high quality urban green space.

This should not come as a surprise. From their early origins in the UK & US, parks were known to raise property values & people were prepared to pay a premium to live near them. Frederick Law Olmsted & Harland Bartholomew openly acknowledged this when they developed Central Park in New York.

Studies by John Crompton & others have found widespread evidence supporting the notion that proximity to green & open space pushes up property values.  But reducing the benefit of parks & green space to a line on a ledger sheet can be both misleading & inaccurate.

Beyond an economic calculation, researchers have discovered that urban green spaces provide a wide variety of benefits. You don’t have to use these spaces to benefit from them. Parks can improve physical & mental health, ecosystem services & urban biodiversity.

Public health researchers like Ariane Bedimo-Rung & Billie Giles-Corti have found that living close to urban green spaces like parks & trails can increase urban residents’ levels of physical activity & reduce the likelihood of being overweight or obese. This reduces the risk of diabetes & several types of cancer.

Frances Kuo & her colleagues have found that proximity to urban green space can lower the incidence of domestic violence, stress & depression & may even mitigate attention deficit disorder in children.

Ecological economists including Bolund & Sven Hunhammar have found urban green spaces also provide a range of free ecosystem services. They reduce noise levels, lower pollution, & reduce flooding.  And some ecologists have also found that urban parks can harbour rare & endangered species & promote biodiversity.

We need strong evidence to support the density imperative, evidence that we presently lack. Until we can accurately gauge the green space needs of higher density residents, it may be folly to blindly pursue policies of urban consolidation.

In a time of economic uncertainty, when local councils are looking to develop “surplus” land assets such as “underutilised” park spaces, we need to carefully evaluate the true values of these spaces, before they are sold off to bolster ailing municipal coffers. To do otherwise could be more costly than we might imagine.

The link to this article is here –

Because there is shade Wicks Park is a great place to be on a hot day.



© Copyright

Using and copying text and photographs is not permitted without my permission.

Blog Stats

  • 619,977 hits
%d bloggers like this: