Higher-density cities need greening to stay healthy and liveable

Access to high-quality public open space is a key ingredient of healthy, liveable cities. This has long been recognised in government planning policy, based on a large body of academic research showing that accessible green spaces lead to better health outcomes.

However, cities are home to more than just people. We also need to accommodate the critters and plants who live in them. This includes the species who called our cities home before we did.

Greening cities that are becoming denser is a major challenge. Green spaces and density are both good for health outcomes when designed well. However, higher-density development can place added pressure on green space if not well planned and managed.

The South Australian government is leading the way in the design of public green spaces in denser cities by bringing together the multiple actors needed to create change. This includes the Heart Foundation, Departments of Health and Ageing, Environment Water and Natural Resources, Office for Recreation and Sport, the South Australian Local Government Association and the Office of the Chief Architect, as well as researchers from RMIT University and the University of Melbourne.

This is the new shift required for urban greening practice – led by practitioners with support from research evidence provided by (and in collaboration with) academics.

In Victoria, Planning Minister Richard Wynne has called for the suburban backyard to be maintained in the refreshed Plan Melbourne 2017-2050. This policy recognises the importance of private green space by establishing minimum garden areas in new developments.

Another major challenge is increasing urban heat and climate change. Some tree species we know and love will no longer be viable in cities that are several degrees warmer than they were.

Suitable species for future climates need to be selected, as the City of Melbourne has recently demonstrated. Increasing temperatures and the resulting loss of old trees will have adverse consequences for public health, ecology and biodiversity.

Understanding how best to achieve these benefits, and the trade-offs involved in delivering them, is particularly important today. Our cities are growing rapidly. We are seeing increasing populations, greater housing density, rising temperatures, growing rates of obesity, diabetes, stress and depression, and declining native biodiversity.

Why is greening on the agenda?

Urban greening is now recognised as a public health issue. New research has found its benefits include:

• lower rates of anti-depressant prescriptions in neighbourhoods close to woodlands in the UK;

• happier people living in areas with more birdlife; and

• better health outcomes with increased neighbourhood tree coverage in the US.

Ecological research also shows that urban green spaces can support many kinds of birds, bats, bees and plants. Urban greening has even been found to lead to safer neighbourhoods.

Australian urban planning and policy need to embrace these findings. Multiple government portfolios must work together to better plan for green cities that achieve maximum impact for economic, environmental and public health outcomes.

What do we mean by green space?

Green spaces are areas of public and private land covered with vegetation. This includes most areas we traditionally see as public open space: parks, gardens and sports ovals.

Green space also includes other areas of public land: street trees and streetscapes, nature conservation reserves, community gardens, school grounds and public buildings with green walls, facades and roofs. On private land, green spaces include residential gardens, golf courses and greening on and around private buildings.

All these green spaces together provide multiple benefits. The Heart Foundation and South Australian government recently commissioned an evidence review of how quality green space is supporting health, wellbeing and biodiversity. This report shows that green spaces can be designed to provide multiple benefits.

These benefits are delivered by including features that are known to influence physical activity, mental health, social, cultural, environmental and biodiversity outcomes. For example, planting trees in parks, gardens or streets can have many benefits:

• cool cities;

• slow stormwater runoff;

• filter air pollution;

• provide habitat for some animals;

• make people happier; and

• encourage walking.

Greening solutions aren’t simple

The benefits green spaces provide are also influenced by local context: climate, inequity and social disadvantage, culture, or resident/user age and gender.

However, if green spaces are well designed with community input, these local factors can provide opportunities to maximise impact. For example, green space can be more beneficial when provided in areas of social disadvantage with limited existing green space, and trees provide more cooling benefits in hotter cities.

There are no magic bullets. If green spaces aren’t well designed, for example, trees can:

• reduce the area available for some active sports;

• shade rooftop solar panels;

• reduce flower, fruit and vegetable production;

• create mess through fallen leaves; and

• create unsuitable habitat for other kinds of plants and animals.

These complex interactions highlight the need for academics and practitioners to work collaboratively across disciplines and sectors. These should include urban planning, public health, urban ecology, urban forestry, engineering, community development and economics. Knowledge needs to be shared and translated into action.

Our green cities of the future need to be designed to benefit human (and non-human) residents equitably. We need to move beyond a reliance on backyards and parks that were designed according to 19th-century principles (and using 19th-century species).

Cities need green spaces that are well designed, creatively delivered, accessible to all, and managed and maintained with appropriate resources to ensure long-term quality and availability.

Further reading: How urban bushland improves our health and why planners need to listen

Melanie Davern receives funding from the Australian Research Council and the Clean Air and Urban Landscape Hub of the National Environmental Science Program.

Dave Kendal receives funding from the SA Heart Foundation, City of Melbourne, Melbourne Water, the Royal Botanic Gardens Melbourne, the Clean Air and Urban Landscape Hub of the National Environmental Science Program, and the Australian Research Council.

Lucy Gunn receives funding from the NHMRC funded Centre for Research Excellence in Healthy Liveable Communities.

Alison Farrar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.