Here are some of the most common questions we get asked here at WATCA. If you've got a question for us, please email via our contact page and we'll get back to you as soon as possible (we're all volunteers and fit our WATCA work around our day jobs).

What do we mean by Tree Canopy and Urban Forest?

Tree Canopy - is the layer of leaves, branches and stems that cover the ground when viewed from above and which give us valuable shade. Tree canopy is commonly used to measure and determine the success of an Urban Forest.

Urban Forest - all Tree Canopy within a particular urban area combines to make up the Urban Forest.  An Urban Forest includes all the trees in an urban area; in our private gardens, our parks and public spaces, our remnant bushland, our streets and other transport corridors, our community gardens..... all our trees!

Urban Forests are being increasingly recognised for their importance in addressing the urban heat island effect and climate change, supporting our amazing biodiversity and promoting mental and physical wellness in our cities and much, much more.

What is the Urban Heat Island Effect?

Loss of large trees and green space is a serious issue in Perth:

  • in new suburbs and for new infrastructure where there is commonly wholesale clearing of land for development; and
  • in established suburbs where existing large trees are routinely removed to make space for bigger buildings without a thought for the consequences to our communities.

These trees are often replaced with hard surfaces, which are usually highly effective at absorbing and storing heat during the day.  This heat is released at night leading to higher temperatures. This is known as the urban heat island effect.  

It results in city dwellers being exposed to much higher temperatures for longer periods each day.  And as climate change takes effect, it is causing our cities to heat up at a much faster rate than our country areas. 

The urban heat island effect has a major impact on the liveability of our cities and levels of community health and wellbeing.  One of the easiest way to address it is to protect and plant more TREES!

How is Perth’s Tree Canopy doing now?

Unfortunately, Perth is not doing well. The WA Department of Planning, Lands and Heritage Urban Tree Canopy Dashboard shows that in 2020 canopy cover across the Perth metropolitan areas was just 16%.

This canopy cover comprised 23% in parks, 14% in road reserves and only 12% within street blocks (largely private land).

Only a small percentage of Perth’s canopy is made up of large trees of more than 8 metres in height, yet it is the large trees over 8 metres in height that provide the greatest environmental benefits.

What is a Tree Canopy Target?

A Tree Canopy Target is a goal in terms of the percentage of tree canopy that covers a particular area. This green infrastructure provides shade, which reduces ambient temperatures and mitigates the heat island effect - where large amounts of hard and dark-coloured surfaces like roads and roofs cause localised warming. 

The higher the percentage of urban tree canopy and larger trees, the greater the environmental benefits including reducing ambient temperatures, mitigating the urban heat island effect, helping to address climate change, providing food and habitat for our wildlife, improving air quality, reducing the impact of storms, helping stormwater absorption and protecting the health of our waterways. 

On top of this trees help to improve our physical and mental health and wellbeing, reduce our heating and cooling costs, increase property values and of course trees help to make our suburbs beautiful and special places to live.

WATCA is advocating for a Tree Canopy Target of 30% by 2040 for Perth. Many cities have a Tree Canopy Target in place, including Sydney and Canberra.  Melbourne and Ballarat are aiming for 40% by 2040, and Hobart for 40% by 2046.


What Legislation currently exists in WA to protect trees on private land in urban areas?

Legislation and regulations relating to trees in urban areas are the responsibility of State and Local Governments.  WA has no State Legislation in place to regulate tree protection on private land.

The Planning and Development Act 2005 deals with development and subdivision across WA, but it contains no specific tree protection provisions, except to allow for local government planning schemes to conserve the natural environment.

Various State Polices and Strategies talk to the need to preserve and enhance the urban forest, but they are not supported by regulations that effectively protect trees.  The only exception is if a tree is on a State or Local Heritage List or a Local Significant Tree Register.

Subdivision is controlled by the State government and the Western Australia Planning Commission’s (WAPC) Model Subdivision Conditions, which routinely require land to be filled, stabilised, drained and/or graded, resulting in most trees being removed as standard practice.

Can my Local Council protect trees in my area?

In the absence of a consistent State planning approach, some Local Governments have attempted to protect significant trees on private property.  Approaches include through local planning scheme provisions (which must be approved by the State Minister for Planning), local planning policy provisions and tree registers, where trees must be nominated generally with the owners’ consent and approved by the Local Government.

Unfortunately, the  implementation and effectiveness of these measures has been limited and piecemeal.

Do other Australian States have legislation to protect trees in urban areas?

Yes!  Many cities across Australia – including Sydney, Canberra and Hobart - and around the world have very successful tree protection legislation in place.  

Canberra’s Tree Protection Act was established in 2005 and seeks to protect both individual trees and the urban forest, as well as to promote community appreciation of trees.  An Urban Forest Bill was recently introduced into the ACT Parliament which, if enacted, will achieve the protection of more trees on public and private land and legislate an Urban Tree Canopy Target of 30%.

Does ‘Tree Regulation’ mean I can’t remove a tree on my own property?

No.  WATCA is supporting regulations that require landowners to seek approval before removing a 'large tree' (see definition below), rather than placing a blanket ban on the removal of trees.

Of course, there may be instances where it is appropriate to remove a tree. For example:

  • If it is declared an unwanted species;
  • If an arborist confirms it should be removed due to its health, structural stability or risk to life or property; and/or
  • If it conflicts with bushfire legislation.

There may also be circumstances where redesign of a development to support tree retention is just not feasible and where this can be verified, approval for removal would also be supported. 

But removing a large tree without a good reason is not OK.

While trees in parks and streets are critical, they are not sufficient to provide the 30% canopy cover that is accepted as optimal to effectively address the growing environmental challenges our suburbs face.  Trees on private land are an essential piece of the jigsaw and we can all play our part by retaining, maintaining and planting trees.

WATCA is not anti-development. Well considered regulations will strike a balance between urban consolidation and preserving trees and precious green spaces. Increased densities and trees can go hand in hand with a bit of extra thought, it doesn't have to be either/or.

We need sustainable and sensitive development that includes space for our existing and future trees.

What is a ‘Large Tree’?

When it comes to defining a ‘large tree’, our research suggests that a tree of 8 metres in height generally fits the bill. This is a bit taller than a two story building. Canopy width and trunk circumference also come into play, but for the purposes of discussion now, we think height is a good indicator.

Canberra is currently updating its tree protection legislation. Under their Urban Forest Bill, trees over 8 metres in height or canopy width will become 'regulated trees'.  We think this is a really sensible benchmark.

The larger the tree, the greater the benefit: large trees provide more shade, more cooling, more food and habitat, more carbon sequestration, less air pollution and less stormwater runoff.

Trees may take several decades to get to maximum size and can live for hundreds of years. Removal of these trees by a landowner on a whim without proper regard for their value is not in the community’s best interests and should not be permitted.


How many trees do we need?

We think the 3-30-300 Rule for developing urban forests and creating greener and healthier cities is the right rule of thumb. It was developed by Cecil Konipjnendijk at Nature Based Solutions Institute and is widely accepted around the world. The rule proposes that everybody living in an urban community should be able to:

    • See 3 trees from their home;
    • Live in a neighbourhood with at least 30% tree canopy cover; and
    • Be no more than 300m from the nearest green space that allows for multiple recreational activities.