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, waterway and bushland corridors, parks and open spaces to town centres, public transport and public spaces. The Greater Sydney Green Grid builds on the District's established open space, the Regional Tracks and Trails Framework and the Principal Bicycle Network.

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 Celsius²¹. 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 urban noise pollution, particularly along busy roads. The urban tree canopy can also help make communities more resilient, by reducing the impact of heat waves and extreme heat.

The urban tree canopy

In 2011, the Urban Area of the Central City District had 19 per cent tree canopy cover (refer to Figure 30).

The Hills Shire enjoys extensive urban tree canopy cover and maintains its image as a garden shire with an extensive network of parks, open spaces and rural lands. Blacktown, parts of Parramatta and Cumberland local government areas generally have less tree canopy cover.

The NSW Government has set a target to increase tree canopy cover across Greater Sydney to 40 per cent.

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

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

Urban renewal and transformation projects in the District, including Parramatta Road, GPOP and the Sydney Metro Northwest Urban Renewal Corridor provide opportunities to improve the public domain. A critical part of this will be 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 areas 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.

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.

The District's councils provide guidance on enhancing tree canopy cover, 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 have programs to plant replacement trees in the public realm.

The NSW Department of Environment and Planning's Apartment Design Guide and the new Greenfield Housing Code guide 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 places for 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 Central City District is shown in Figure 24. 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 projects for the District.

Councils will lead the 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 the delivery of regional open space, using Special Infrastructure Contributions. The NSW Government allocated $123 million funding for 2017-18 (administered by the Commission) for the revitalisation of Parramatta Road as part of the Parramatta Road Urban Amenity Improvement Program.

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 green grid connections. Where feasible, planning and investment must consider opportunities for connections across rail lines, roads and other linear infrastructure.

Table 5: Central City District Green Grid Priorities