The humble street tree is one of the most powerful strategies for enhancing the sustainability of a community, and therefore our cities. And more broadly, green infrastructure is an essential strategy for economic development, climate protection, health and wellbeing, as well as social inclusion. But whilst it is easy for me to just make these statements, backing it up with robust research is often challenging.
This new report from AECOM is perfect timing, and indeed builds on the existing body of work looking at the role of green infrastructure in building thriving cities. As we enter more intense – and warranted –dialogue about the future growth of our cities, ensuring that priority infrastructure recognises street trees and other green infrastructure will be critical to creating better cities. — Adam Beck
Tree-lined streets. Parks and green spaces. Urban forests. They enhance a city’s liveability, making them more enjoyable to live in. They protect us from harsh weather and filter air and water pollution. But according to a recently published report, they offer other benefits.
The report, ‘Green infrastructure: a vital step to brilliant Australian cities’, was prepared by engineering consulting and related services firm Aecom Australia. It is a combination of the company’s research, interviews with city council and state agency officials. While the report concentrates on three Sydney suburbs, its findings apply far more broadly.
So what’s the issue here? Are we in danger of losing our trees?
The report notes that Australian city populations are expected to grow quickly – and that Sydney’s will be close to double what it is now by 2056. Demand for housing and jobs will increase; services like health care and transportation will be strained. More people and climate change-related rising temperatures will increase demands on energy resources. And there will be less space available for trees, parks and green open areas as cities become increasingly crowded.
The report focuses on street trees because they are the ones most likely at risk. They are commonly thought of as costs rather than green infrastructure. If a city has a tight budget or is looking at a budget shortfall, city leaders are going to look at cutting costs. As the report asserts, Australian regulations and business models don’t push developers, energy companies, cities or other entities to think of trees as ‘essential infrastructure’.
Cities can take several steps toward preservation of green infrastructure. As the Aecom report states ‘They must first reassess its value as vital infrastructure, then show how it is part of a broader plan for the city. Cities also can harness community support for regulatory change, then apply smarter management of trees, parks and other green infrastructure’. The steps are explained in detail in the report.
What else do trees do for cities?
Also, trees are valuable assets. Aecom’s research found that a 10% increase in the leaf canopy of street trees can result in an average increase in property values of $50,000. Governments don’t routinely place a value on green infrastructure as they do for roads, bridges, buildings and other infrastructure.
But, as the report says, they are worth millions of dollars for Australian cities. And it’s not simply about property values. One study cited found that doubling the leaf canopy in cities that have periods of prolonged high temperatures could reduce heat-related deaths by 28% and lower air temperatures as well as the temperature of concrete and asphalt. Another cost benefit? High temperatures cause asphalt to deteriorate more quickly. Trees can reduce surface temperatures and reduce cooling costs for buildings. Shouldn’t that be included in the green infrastructure value equation?
Trees also promote health in a number of ways and provide a more pleasant, attractive environment for pedestrians and cyclists which in turn can reduce the number of cars on the roads.
Also, more development and a greener urban environment don’t need to be in conflict. As the report explains, well-planned green infrastructure is a plus for development projects because of its ability to make an area more attractive, add to property values while cutting energy costs, reducing pollution and more.
Doug Peeples is a writer specializing in technology and energy. Follow @smartcitiesanz on Twitter.