Green v Grey: What will our cities look like as temperatures and populations rise?
Australia’s largest urban greening initiative has revealed 67 percent of suburbs and cities across the country will face significant challenges in growing and maintaining green cover in the future, as our cities grapple with a rising population, and grey spaces expand with urban development.
Where Will All The Trees Be?1, the third report in Australia’s only national tree canopy benchmarking series, led by RMIT University and Greener Spaces Better Places, confirms the majority (69 percent) of our urban areas have lost green cover (trees and shrubs) since 2013, spanning 131 urban and peri-urban Local Government Areas (LGAs). While promisingly over the last four years 63 percent of places increased their green cover, during the same period, 73 percent of LGAs increased their grey cover (hard surfaces such as roads, pathways, pavement and roofs).
A growing population means more pressure on green cover in our suburbs and cities. As our cities and suburbs grow, it is vital our green cover keeps pace.
Associate Professor Joe Hurley, RMIT lead researcher, says that while some places are defying the odds and growing thriving urban forests, others have reported concerning levels of loss and face significant challenges to grow their green cover in the future.
“Fundamentally, as our suburbs, towns and cities grow, so should our green cover — but in order to increase our urban green cover, we need to understand what’s happening where, and why,” explains Professor Hurley.
“From this study, we can see green cover varies wildly by place. For example, Cairns Regional Council has Australia’s highest recorded level of green cover, with 82.9 percent, whereas Wyndham City Council has Australia’s lowest recorded level of green cover with 5.4 percent. However, this isn’t a full and fair picture of what is going on.
“Cairns have a higher than average rainfall and contain large areas of native forest. Whereas Wyndham contains large areas of grassland and agricultural land, limiting its opportunities for urban greening. It is important to recognise that place type and context really matters.
“This study is a deep dive into the rates of increase and decline of urban greening across Australia, but through the lens of six different place types determined by rainfall, urbanisation and population density. These place types help us more usefully compare performance within and across cities to understand what improvement might be possible with concerted effort, and what deterioration might occur with complacency.”
“Over time, changes in population will be inevitable, but there’s no reason why our cities can’t have thriving urban forests. There are great examples all over Australia of how this can happen,” Professor Hurley adds.
The study identified the following as best on ground — places that have maintained or grown their green cover despite population pressures or grey cover increases:2
- City of Whittlesea, Victoria (suburban, spacious and low rainfall)
- Logan City Council, Queensland (suburban, spacious and high rainfall)
- City of Greater Dandenong, Victoria (urban, spacious and low rainfall)
- Kwinana City Council, Western Australia (urban, spacious and high rainfall)
- City of Unley, South Australia (urban, spacious and low rainfall)
- The City of Parramatta, New South Wales (urban, compact and high rainfall)
Meg Caffin, urban forest expert and research consultant, claims, “To help stem green cover loss and ensure the future viability of our urban forests in our suburbs and cities, we can plan better and plant now. We can also learn from who is doing this well, even within the context of challenges, and drive change within government, businesses and the community.”
In the face of a changing climate, green cover is crucial for mitigating the impacts of urban heat, cooling our urban landscapes and providing a range of social, environmental and economic benefits.”
Covid-19 has had a massive impact on the world and our behaviour. Among the disruption, urban greenspaces have played a critical role in boosting resilience during the pandemic, helping with both physical and mental wellbeing.3 As gyms and swimming pools closed, use of parks and recreational areas skyrocketed. In Sydney alone, Centennial Park visits were estimated to be up by 20 percent, Moore Park’s golf and tennis courts saw a 50 percent increase in numbers, and use of Western Sydney Parklands doubled.
Dr Dominique Hes, regenerative development expert, explains: “Healthy, happy and liveable cities rely on urban greening for a range of benefits, and are critical for mental and physical wellbeing. Studies show as little as 20 minutes in greenspaces can reduce stress due to how our brains are wired. Our brains evolved in nature, and when surrounded by greenspaces the fight or flight and emotional parts of the brain are less on edge — this affinity to connect to nature is called biophilia. This innate connection has never been more evident than during the Covid-19 pandemic, where we’ve become acutely aware of the importance of access to nature in our everyday lives.”
“Green cover increases biodiversity and helps to cool our urban environments. It also works to mitigate the effects of climate change by absorbing carbon dioxide from surrounding environments, pumping oxygen back into the atmosphere, working as the lungs of our cities. If we plan ahead and plant now, we can grow interconnected, regenerative and prosperous places for people to live, work and relax into the future,” adds Dr Hes.
ABOUT WHERE WILL ALL THE TREES BE?
Where Will All The Trees Be? is an assessment of land cover across 131 Local Government Areas (LGAs) as places in Australia, covering all significant urban centres, using the i-tree sampling methodology (a widely used approach developed by the United State Department of Agriculture Forest Service) led by RMIT University and Greener Spaces Better Places, and funded by Hort Innovation.
This research repeats similar studies done in 2013 and 2016, providing updated 2020 cover figures and allowing cover trends to be established across the three timepoints.
The majority of aerial imagery used for this study is from November 2019 — March 2020 (to correspond with the leaf-on period for all trees). In some locations images from earlier periods (back to January 2018) are used where more recent high-quality images were not available.
The assessment of land cover is coupled with a review of state statutory planning policy regarding likely influence on the presence of trees through their retention, removal, management and establishment, and a survey of local government professionals working in urban forest management. Using the i-tree results and survey results, we produce a summary LGA assessment and future outlook for each of the 131 LGAs in the study and present a brief analysis of elements of the cover assessment method being used to inform future studies. The full research paper can be found HERE
ABOUT GREENER SPACES BETTER PLACES
Greener spaces make better places. They cool our cities, and make our neighbourhoods healthier and more appealing to work, play and relax. That’s why government, universities, not-for-profits, business and industry have come together as a national initiative — Greener Spaces Better Places — to ensure that as our urban areas grow, so do our greenspaces. Our mission is to make Australia’s towns and cities the greenest in the world. To find out more visit greenerspacesbetterplaces.com.au
Greener Spaces Better Places is funded through the Hort Innovation Nursery Fund, using the Nursery Marketing Levy. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. Learn about it at horticulture.com.au
- Where Will All The Trees Be? is funded by Hort Innovation. Green cover is defined as trees over 3 metres and shrubs under 3 metres. Grey cover is defined as hard surfaces such as roads and pavement.
- Able to be used as a reference point for areas with similar climate or challenges.
- Samuelsson K, Barthel S, Colding J, Macassa G, Giusti M (2020) Urban nature as a source of resilience during social distancing amidst the coronavirus pandemic. Landsc Urban Plan. https://doi.org/10.31219/osf.io/3wx5a
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