Why do we need to increase our canopy cover

1. Protection from extreme heat events

Heatwaves cause more deaths in Australia than the sum of deaths from all other natural disasters combined. Projections indicate that the annual number of days above 35°C is likely to increase from the nine days currently experienced in Melbourne to up to 21 days by 2070.

Whilst heatwaves can affect anybody, demographics show that some vulnerable segments of the population in Melbourne’s west are at high risk, with large proportions of very young (0-4 years old), older people (65+), as well as a high percentage of people with disabilities.

Large canopy trees provide a cooling effect by shading and providing evaporative cooling through the air. Whilst the benefits of shading are obvious, the value of evaporative cooling is not as widely known. It is achieved through evapotranspiration, the evaporation of water from within leaves. This is a very cost and energy efficient way to regulate outdoor air temperature and can provide significant relief to people during heatwaves.

2. Help to reduce the Urban Heat Island effect (UHI)

Adding to the impact of heatwaves and increased average temperatures is the increasing urbanisation across our municipality. Infill development creates significant amounts of hard surfaces in the form of buildings, roads and car parks. These hard surfaces store and store and trap heat during warmer periods, which results in our urban areas reaching much higher temperatures than their natural surroundings. This phenomenon is referred to as the Urban Heat Island Effect (UHI).

Our street trees, combined with our parks and gardens, are the first line in this battle against the urban heat-island effect.

The thermal image below demonstrates the role large mature trees play in reducing heat during a warm summer’s day in Melbourne’s CBD. The surface temperature below the tree measured 31.5 degrees Celsius compared with nearby surfaces reaching 50.8 degrees Celsius.

A thermal image demonstrating the role large mature trees play in reducing heat during a warm summer’s day in Melbourne’s CBD.


Many residential areas within our municipality are at risk during extreme heat events due to the lack of tree cover combined with the presence of many built surfaces (concrete, asphalt etc.).

Residential areas of Altona Meadows and the middle of Seabrook are currently particularly low on tree canopy. Through the planting of all available locations in these areas, we intend to create a more liveable, healthy community for our residents to enjoy for generations to come. 

two images showing urban heat and tree canopy cover throughout Hobsons Bay in 2018


3.To help reduce crime

Research has found that increased tree canopy cover leads to less crime. This challenges the common misconception that additional trees provide cover for would be criminals.

Two separate studies have been carried out in the US in recent times. One in Baltimore in 2012 and a second in New Haven, Connecticut in 2015. The studies both found an inverse relationship between tree canopy and rates of crime. As the tree canopy increased in each area, rates of crime decreased.

The researchers in Baltimore found a 10 percent increase in leaf canopy was associated with a 12 percent decrease in crime.

The researchers in New Haven similarly found that greater tree canopy coverage was associated with lower rates of violent, property and total crime.

It is speculated that by having healthy tree lined streets, the community are encouraged to get outside. This increases passive surveillance and discourages anti-social behaviour. Healthy tree lined streets also encourage our community to take pride in their area and report any anti-social behaviour.