Increasing urban tree canopy cover and delivering Green Grid connections

The Greater Sydney Green Grid is a long-term vision for a network of high quality green spaces that connects communities to the natural landscape. It links tree-lined streets, waterways, bushland corridors, parks and open spaces with centres, public transport and public places.

Tree-lined streets, urban bushland and tree cover on private land form the urban tree canopy. The urban tree canopy is a form of green infrastructure that mitigates the urban heat island effect, with a 10 per cent increase in tree canopy cover reducing the land surface temperature by 1.13 degrees Celsius³³. The urban tree canopy also supports cleaner air and water and provides local habitat. Trees remove fine particles from the air and help insulate against noise pollution, particularly along busy road corridors. The urban tree canopy can also help make communities more resilient, by reducing the impact of heatwaves and extreme heat.

The urban tree canopy

As one of the most urbanised districts in Greater Sydney, some suburbs have high proportions of hard surface areas and correspondingly low levels of tree canopy cover. Suburbs such as Botany Bay, Randwick, Marrickville, Ashfield through to Strathfield have low tree canopy cover. Botany Bay, for example, has only 12.1 per cent tree cover, compared to North Sydney (28.6 per cent) and Pittwater (59 per cent)³⁴. By contrast, other established neighbourhoods have streets lined with mature trees that add to the character and appeal of the District's landscape.

The NSW Government has set a target to increase tree canopy cover across Greater Sydney to 40 per cent. Figure 25 shows tree canopy cover in the urban area in 2011.

Sustaining boulevards of trees along the District's busiest roads (such as Oxford Street, King Street, South Dowling Street, Princes Highway, Cleveland Street, Hume Highway, Marrickville Road, Parramatta Road and Canterbury Road) is an important step towards improving amenity and air quality, and cooling the Eastern City District. Along many busy roads, where there is limited space to plant new trees, there may be opportunities to plant other forms of green ground cover, such as garden beds and hedges, that can help improve air quality.

Trees are valued by residents, and contribute to the streetscape, character and amenity of the District. As the District continues to grow and change, the urban tree canopy will come under pressure. This means that the urban tree canopy will become even more important for supporting sustainable and liveable neighbourhoods.

The tree canopy may be formed by a mix of native and exotic, deciduous or evergreen trees, which provides shade in summer while allowing sunlight into homes and onto roofs for solar power, particularly in winter.

The relatively small proportion of landscaped area compared to built area on privately owned land, and constrained public streets and spaces, limit opportunities for widespread tree planting and green infrastructure, especially large trees with shadegiving tree canopy.

Therefore, urban renewal and transformation projects will be critical to increasing urban tree canopy cover. This can be complemented by other green cover, including rain gardens, green roofs and green walls. Green cover can help slow and store stormwater and improve water quality, filtering pollution before it reaches the District's waterways.

Challenges to extending the urban tree canopy in public and private include the lack of sufficient space within existing street corridors, and the competition with other forms of infrastructure both above and below the ground. Opportunities to relocate power lines underground or bundle them may be explored at a local or precinct scale, particularly in areas experiencing urban renewal, to provide space for the urban tree canopy and enhance the public domain. Extending the urban tree canopy should be balanced with the need to allow sunlight into homes and onto roofs for solar power.

The District's councils generally provide guidance on enhancing tree canopy and tree cover in the urban environment, and information on street trees. Some encourage permeable surfaces to allow rainwater to soak into the ground and reduce stormwater run-off, which supports the growth of canopy trees and vegetation, and reduces pollution, flooding and urban heat. Where trees are lost as a result of development, some councils, such as Randwick, have developed programs to plant replacement trees in the public realm.

The NSW Department of Planning and Environment's Apartment Design Guide provides the requirements for landscape areas that can support the urban tree canopy. The NSW Department of Planning and Environment is preparing an urban tree canopy manual, as part of a green infrastructure policy framework, to support the expansion of the urban tree canopy.

Connecting the Greater Sydney Green Grid

Enhancing the amenity and activity within, and accessibility to, the Greater Sydney Green Grid will promote a healthier urban environment, improve community access to recreation and exercise, encourage social interaction, support walking and cycling connections and improve resilience.

The long-term vision for the Greater Sydney Green Grid in the Eastern City District is shown on Figure 21. This vision will be delivered incrementally over decades, as opportunities arise and detailed plans for connections are refined. Green Grid Priority Projects have been selected to provide district-scale connections that link open space, waterways and bushland. Table 5 lists Green Grid Priority Projects for the District.

The Great Coastal Walk, the Federation Track (linking Circular Quay with Centennial Parklands and the Cooks River Corridor), Wolli Creek Regional Park and the Iron Cove Bay Run form part of the Greater Sydney Green Grid. Green Grid improvements will benefit the densely populated neighbourhoods of Burwood, Summer Hill, Marrickville and Leichhardt by linking these to the Harbour and Parramatta River, Cooks River and other open space corridors.

Councils will lead delivery of the Greater Sydney Green Grid through land use planning and infrastructure investment mechanisms such as development and land use controls, agreements for dual use of open space and recreational facilities, direct investment in open space, and other funding mechanisms such as local development contributions and Voluntary Planning Agreements.

State regional and district parklands and reserves form a principal element of the Greater Sydney Green Grid for both biodiversity and recreation purposes.

The NSW Government supports the delivery of regional open space and Green Grid connections through the Metropolitan Greenspace Program. The NSW Government also supports delivery of regional open space using Special Infrastructure Contributions.

Transport for NSW is establishing a Principal Bicycle Network in collaboration with councils. Opportunities to integrate the Principal Bicycle Network with the Greater Sydney Green Grid will be an important part of linking centres.

In some areas, rail lines and other linear infrastructure prevent connectivity. Where feasible, planning and investment must consider opportunities for connections across rail lines, roads and other linear infrastructure.