The value of urban trees

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 30^th 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. http://www.epa.gov/hiri/

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.  http://bit.ly/AwLn4P

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. http://bit.ly/sCl4kM

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.  http://nrs.fs.fed.us/units/urban/local 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.   http://bit.ly/x5qRKd

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. http://www.treenet.org/images/stories/symposia/2009PDFs/2009%20people%20and%20trees%20providing%20benefits%20overcoming%20impediments%20dr%20jane%20tarran.pdf

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. http://bit.ly/zkz1K9

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 http://theconversation.edu.au/content/5050/tracker

This article was originally published at http://theconversation.edu.au  Read the original article – http://theconversation.edu.au/for-a-great-return-on-investment-try-trees-5050

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.

What is green space worth?

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 9^th 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. http://www.tandfonline.com/doi/abs/10.1080/07293682.2010.508204

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.  http://phg.sagepub.com/content/33/6/743.short

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.  http://www.springerlink.com/content/g1277273381828l7/

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. http://www.shef.ac.uk/mediacentre/2011/public-willing-to-pay-more-for-greener-urban-spaces.html

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.  http://www.tandfonline.com/doi/abs/10.1080/13606710500348060  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 http://www.sciencedirect.com/science/article/pii/S0749379704003046 & Billie Giles-Corti http://jech.bmj.com/content/62/5/e9.abstract 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 http://eab.sagepub.com/content/30/1/3.short & 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 http://www.sciencedirect.com/science/article/pii/S0921800999000130 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. http://www.sciencedirect.com/science/article/pii/S1618866706000732

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.”  http://theconversation.edu.au/content/4703/tracker

The link to this article is here – http://theconversation.edu.au/what-is-green-space-worth-4703

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