Overall tree canopy is in decline and we need a Tree Canopy Improvement Strategy that will provide a planned approach to arrest this decline and help us reach our target of 25% cover by 2045.

The diagram below shows that the City's tree canopy cover had decreased from a peak of 15.51% in 2008 to 13.84% in 2020. Our tree canopy cover is currently lower than most local government areas in metropolitan Adelaide.

What do we mean by tree canopy cover?

Tree Canopy cover is the amount of cover the crown of the tree provides over an area of land when seen from above. It is usually expressed as a percentage of or square metres. As an individual tree grows and the crown expands, the canopy cover increases. When all the trees in an area such as a Council are measured, this gives us the tree canopy cover measure of a City.

The chart below demonstrates how our City has changed over time. We have measured the changes on private and public lands which, when combined, gives us a City-wide measure.

The three categories are:

• tree canopy cover - this is the measure of how much of the land is covered by trees;
• impervious cover - this is the measure of how much of the land is covered by buildings, driveways, paved courtyards, footpaths and roads; and
• plantable space cover - this is the measure of how much of the land could be planted with trees.

This pie-chart shows how the City is covered by proportions of cover types.

With almost two-thirds of the City being impervious, this has impacts in relation to heat and stormwater.

Impervious surfaces tend to absorb heat during the day and radiate this heat at night, leading to urban heat islands. Impervious surfaces also act as a barrier to rain settling into the ground, and shed this water into the stormwater system, sometimes causing localised flooding.

When we plant more trees and increase canopy cover, this cools down the City and intercepts falling rain, lessening the effects caused by impervious surfaces.