Contents
Introduction ............................................................................................................................................ 3 Baseline Data .......................................................................................................................................... 4 Tree Canopy Cover .............................................................................................................................. 4 Tree Canopy Cover Change 2014-2018............................................................................................... 6 Urban Heat Island Effect ..................................................................................................................... 8 Heat Vulnerability ............................................................................................................................... 9 Tree Canopy Cover Prioritisation .......................................................................................................... 10 Canopy Enhancement Plan ................................................................................................................... 11 Vacant sites ....................................................................................................................................... 11 Canopy Enhancement Areas ............................................................................................................. 12 Open Space ....................................................................................................................................... 17 Supporting Work for Increasing Canopy Cover..................................................................................... 18 1. Integrated blue green design and passive irrigation .................................................................... 18 Targets for tree irrigation using alternative water sources .......................................................... 19 Types of passive irrigation opportunities in Hobson’s Bay ........................................................... 19 Cost of passive irrigation solutions ............................................................................................... 21 Possible pilot sites for exploration ................................................................................................ 22 2. Green Streets Program ................................................................................................................. 23 3. Lagunaria Replacement Program .................................................................................................. 25 Implementation of the Canopy Delivery Plan ....................................................................................... 26 Further steps ......................................................................................................................................... 28 Appendix 1 – Prioritisation criteria ....................................................................................................... 29 Appendix 2 – WSUD Typologies ............................................................................................................ 30 Appendix 3 – Green Streets Program ................................................................................................... 31 Appendix 4 – Lagunaria Replacement Program.................................................................................... 32
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Introduction Hobsons Bay City Council recently developed and adopted their first Urban Forest Strategy (2020), which outlines an ambitious target to achieve 30% tree canopy cover by 2040, focusing on three different land use types: parks, streets and roads and industrial areas. The key objectives of the Urban Forest Strategy are to: 1. Increase Tree Canopy in Hobsons Bay to 30% by 2040 (40% in parklands, 30% in streets and roads and 20% in industrial areas) 2. Develop a diverse and healthy urban forest 3. Adopt a ‘trees led’ approach to city planning, design, and delivery 4. Educate and foster care for urban trees This Urban Canopy Delivery Plan has been developed in direct response to all of these objectives as well as the first priority action listed in the Urban Forest Strategy, which is the development of the Urban Canopy Delivery Plan. In anticipation of this Canopy Delivery Plan, Council has committed to plant 8,000 trees per year to 2025, then reduce to 4,000 trees per year thereafter. The plantings will be distributed across the three aforementioned land use types. The good news is that data over time suggests that Hobsons Bay tree canopy cover is growing and not declining, as seen in other more established eastern suburbs within Melbourne. Further to this, a recent full street tree assessment reveals that our existing tree population is in fairly good heath with a relatively long life expectancy. This means that canopy cover will continue to grow exponentially over the next two decades from the existing tree stock with very few removals required for ageing trees. A thorough on-ground assessment, has found 4,946 vacant street tree sites that are available and ready to be planted now. These vacant sites are all planned to be planted in 2021/2022. This suggests that by the end of 2022, Council will achieve a full street tree stocking rate, which is a significant achievement. This will provide an opportunity for Council to focus on increasing tree canopy cover in priority areas within our open space areas and also creating new tree planting opportunities in our ‘harder to plant’ areas. The ‘harder to plant’ areas for the purpose of this document include existing hardstand areas that will be redesigned to include tree planting opportunities. These opportunities will potentially need a greater level of planning and design as well as budget. This Canopy Delivery Plan looks at the key opportunity areas for Council to focus on over the next ten years. We outline the priority areas that Council manages across the Municipality where more tree cover is needed and explore the opportunities for increasing canopy cover in existing open space, along shared paths, in carparks, along wide streets and within conservation reserves. We also explore how we can maximise tree canopy through smarter planting solutions such as water sensitive urban design and looking at diversifying away from tree species that are deemed to be inappropriate for their location. We also note, that given 54% of the Municipality is private land, the community and private landholders have a significant role to play in contributing to the urban forest by planting trees and vegetation on their own properties. As a result, Council is proposing to run a Green Streets Program that seeks to collaborate with residents to plant street trees and to increase awareness and knowledge about planting on private property.
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Baseline Data In order to understand how we will achieve our targets and understand where we should be planting, we have analysed the diversity of the existing street and park tree populations, existing tree canopy cover and change over time, urban heat and heat vulnerability. Tree inventory data has been analysed to help understand our current tree population including, where trees are located, their species and useful life expectancy i.e. the amount of time that are tree is likely to remain in the landscape before it needs to be removed due to age, health and/or structure. Further detail on this can be obtained from the Urban Forest Strategy Background paper.
Tree Canopy Cover Tree canopy cover measures all vegetation over 3m in height across the Municipality. Image 1 shows the level of canopy cover in 2018 and where canopy is very low i.e. below 5% cover (shown in dark red and orange) and areas where canopy is much higher (areas in green and dark blue).
Image 1: Tree canopy cover by mesh block for 2018. Source: DELWP, 2021, Spatial Data mart.
The industrial areas around Altona as well as the wetlands and conservation reserves, which do not support vegetation higher than 3m and are not intended to, are all recognised as housing very low levels of tree cover. The residential areas of Altona Meadows and the middle of Seabrook are particularly low on tree canopy.
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Williamstown on the other hand, shows much of its residential area housing good levels of canopy cover and some streets recording around 60% tree canopy cover. The t-intersection of Electra and Pasco Streets in Williamstown is covered by 60% tree canopy cover. This is one of the leafiest streets in Hobsons Bay.
Image 2: Aerial view of 60% tree canopy cover in Williamstown
Image 1: Street view and shade cover provided by 60% tree canopy cover in Williamstown.
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Tree Canopy Cover Change 2014-2018 In 2018, 6.2% of the Municipality was covered by tree canopy. In 2014 it was only 5.5%. This shows that tree canopy cover grew over the four-year period from 2014 to 2018. Tree Canopy cover has also been measured for different land types, some of which are owned by Council, such as roads and parkland and other land which is privately owned such as commercial, industrial, and residential land. All land types within Hobsons Bay saw an increase in tree canopy cover from 2014 to 2018. Roads saw some of the biggest increases in tree canopy cover, reflecting Council’s robust program of tree planting.
Land Type Commercial Education Hospital/Medical Industrial Roads Parkland Residential Whole Municipality
Ownership Private Public and Private Public and private Private Public Public Private
2018 3.1%
2014 2.8%
Net change 0.4%
9.7%
9.0%
0.7%
8.2%
6.6%
1.5%
2.4% 10.0% 4.9% 6.9% 6.2%
2.0% 8.5% 4.3% 6.3% 5.5%
0.4% 1.4% 0.7% 0.6% 0.7%
Table 1: Tree canopy cover by land type across Hobsons Bay for 2018. Source: DELWP, 2021, Spatial Data mart.
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Image 4: Tree canopy cover change by mesh block for 2018. Source: DELWP, 2021, Spatial Data mart.
Image 4 shows where this growth occurred. Tree canopy cover grew along the road network and within parks throughout Altona Meadows and Seabrook, along river corridors and within streets and parks in Williamstown and Newport. Individual land parcel losses can be seen in Laverton, Altona and Newport as coloured in orange and red. There are many reasons behind these losses such as private development, streetscape or parkland upgrades, major projects undertaken by the State Government and even through residents’ personal preferences for trees in backyards. There are protections in place for trees on private property over a certain size, though Council permission can be sought to remove them through a permit process. The overall trend in canopy growth bodes well for places like Seabrook and Altona Meadows, which currently have very low levels of tree cover. There has been very little tree removal and much tree canopy gain.
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Urban Heat Island Effect
Image 5: Urban heat by SA2 by for 2018. Source: DELWP, 2021, Spatial Data mart.
Urban heat is increasingly becoming an issue for the health and wellbeing of the community, particularly during periods of extended hot days. This is where the hard surfaces of an urban environment store the heat from the sun’s rays, then re-radiate it out at night-time. When occurring at a scale large enough e.g. suburb, municipal or city scale, the radiated heat keeps night-time temperatures higher for longer. This has well researched impacts on human health and wellbeing but also on our urban environments. The most effective way of mitigating this heat is to reduce the amount of hard surfaces that receive direct sunlight through the natural shading of tree canopies. Increasing the amount of stormwater infiltrated into urban soils also helps to cool the urban environment by providing soil moisture to vegetation to create evapotranspiration. Therefore, understanding where these heat impacts are greatest, gives us the ability to target these areas for greater tree canopy cover. In Hobsons Bay, these hotspots occur around Altona Meadows, Seabrook and in the industrial parts of the Municipality. The Altona Meadows and Seabrook hotspots are the most concerning as they cover the majority of the residential areas in those suburbs. These areas are consequently also the areas with lowest tree canopy cover.
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Heat Vulnerability
Image 6: Urban heat vulnerability by SA1 by for 2018. Source: DELWP, 2021, Spatial Data mart.
Some members of our communities are more vulnerable to these heat impacts than others due to their age, health, quality of housing and ability to cool their homes. Image 4 helps us to understand where the more vulnerable communities are. Again, they occur in Altona Meadows, Seabrook and around the industrial areas of Altona North and Kingsville. These areas should be targeted for increased canopy cover to help support these vulnerable communities in managing the impacts of urban heat.
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Tree Canopy Cover Prioritisation
Image 7: Priority areas for increased canopy cover. Source: Both Council held and DELWP dataset, 2021.
Using the baseline data such as canopy cover, urban heat, heat vulnerability, and highlighting areas where the community are likely to be more exposed to heat due to pedestrian activity such as around schools, parks, playgrounds, kinders and libraries, we have developed a network of streets and open spaces that should be prioritised for increased tree canopy cover. Appendix 1 includes the criteria for inclusion as a priority. Areas in most need are coloured in red, orange, and yellow. This includes Altona Meadows, Laverton, Seabrook, and parts of Altona North. Whilst Williamstown scores low on priority, there are still ample opportunities to improve canopy cover within streets and parks there. This prioritisation framework will be used to inform our tree planting program each year, ensuring that we continue to target the planting of shade in areas of need.
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Canopy Enhancement Plan Vacant sites
Image 8: Location of vacant street tree planting sites. Source: Council data
An on-ground validation of the streetscape network has found 4,946 vacant street tree sites that are ready to be planted. In filling these sites, Council will achieve a full stocking rate of its street tree assets. As discussed, it is likely that all of these sites will be planted by 2022. Once fully stocked, Council will maintain this stocking level by replacing any street trees that are removed through the regular maintenance cycle on an annual basis.
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Canopy Enhancement Areas
Image 8: Canopy enhancement opportunities across Hobsons Bay. Source: Council, DELWP and consultant data, 2021.
These canopy enhancement areas are key opportunities for Council to focus on in increasing tree canopy cover that are not considered to be standard street tree planting sites. Many already have some tree cover within them, however there is clear opportunity to improve it. Some of these opportunities such as wide streets are likely to require streetscape redesign and engineered solutions to improve the growing conditions for new street trees. These sites have been identified using on-ground assessments coupled with spatial mapping of key data such as wide streets and shared paths. It is estimated that an additional xm2 of tree canopy cover could be added to the Municipality if the following opportunities are explored. Opportunity Planting Sites: These sites have been identified through an on-ground assessment as parcels of land that are currently very low on canopy, that are not along streets but have capacity to be significantly planted out with trees. Many are along waterways and could support indigenous species to improve biodiversity connectivity and local ecological values
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Shared paths: Council have mapped 61kms of shared paths. Many of these have ample opportunity to improve shade cover, improve landscape amenity and enhance biodiversity as many run alongside waterways. Covering half of these paths with canopy cover could add an additional 150,000m2 of canopy cover.
Image 9: An example of a shared path in Williamstown with almost no tree canopy cover.
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Carparks: Council has mapped 359,360m2 of at grade carparking across the Municipality. There is ample opportunity to improve tree cover over some of these. However, this may require redesign or resurfacing of the carpark. As a result, any new carpark, renewal or resurfacing works must seek to include an increase in tree canopy cover as part of the new design.
Image 10: An example of three carparks within the Bruce Comben Reserve in Altona Meadows that have virtually no tree cover.
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Wide Streets Hobsons Bay houses some significantly wide streets. A few of these, particularly in Williamstown, already have a good cover of canopy; however, space could be further maximised within all streets over 20m in width. Many of the 30m wide streets are found in Williamstown and traditionally they allow for ample street parking. There is significant opportunity to redesign these streets to better filtrate stormwater while supporting greater canopy cover.
Image 11: An example of a 30m wide street in Williamstown with significant potential to redesign the street and increase tree canopy cover whilst maintaining on street carparking.
Image 12: An example of a 20m wide street in Altona Meadows where streetscape redesign or collaboration with residents could see improved street functionality and tree canopy cover.
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Road Rehabilitation Program: Council has recognised the benefits of incorporating better street tree solutions into the existing Road Rehabilitation program. This has the added benefit of streamlining budgets but also allowing for more engineered blue green solutions such as passive stormwater filtration. Given that the road is being reconstructed, the planning of these works create significant opportunity to enhance tree canopy cover.
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Open Space The prioritisation work has identified those parcels of open space that are higher priority for tree cover than others using the same prioritisation criteria that was used for streets and is included in Appendix 1. There is a concentration of higher priority open space parcels in Altona Meadows and within Altona North and Brooklyn.
Image 13: Priority parcels of open space for increased canopy cover. Source: Both Council and DELWP data, 2021
High Priority Open Space areas that demonstrate tree planting opportunities include: • • • • • • • • • • • • • •
Laverton Railway Reserve – new trees have already been planted which will grow. Explore all sites for any remaining tree planting Altona Meadows Community Park – medium capacity Bruce Comben Reserve Skeleton Creek Linear Parkland Seabrook Pipeline Reserve – some trees already planted St Anthony Court Reserve Seabrook Dunnings Road Drainage Reserve Seabrook Alma Avenue Reserve, Altona Meadows Graham HD Reserve Altona Meadows BMX Park Den Dulk G Reserve, Altona Duane Reserve (Pipeline Reserve), Brooklyn. New trees have already been planted. Explore all sites for any remaining tree planting Bond AW Reserve (especially along southern path), Altona North Cooper RJ Reserve. Still some remaining areas to plant trees
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•
Foreshore reserves including Charles Bates Reserve, Burgoyne Reserve, Hatt Reserve, Cyril Curtain Reserve, Glouster Reserve and Rifle Range Reserve.
Supporting Work for Increasing Canopy Cover 1. Integrated blue green design and passive irrigation Provision of water and maintenance of a soil moisture plays a key role in tree health and in canopy growth. Providing trees with greater access to water through either active or passive irrigation is an important strategy for the creation of healthy canopies, particularly in urban and street planting settings where access to natural soil moisture is often constrained. Future planning will also be required to transition through the changing climate, where hotter, drier conditions will place further stress urban trees. Passively irrigated trees can grow at the double the rate1, and create tree canopies that are 20% larger2. While provision of water is a key part of a canopy strategy, it can also deliver a range of other benefits if alternative water resources such as stormwater runoff can be harnessed for tree irrigation. As part of this canopy plan, a series of standard designs have been developed for the Hobson’s Bay context, which integrate passive irrigation of trees using runoff from adjacent roads and paved surfaces. By utilising stormwater to passively irrigate trees, we can also: •
Treat stormwater before it enters local waterways and Port Phillip Bay, removing sediment and nutrients as runoff filters through the soil profile and is taken up by the tree. This helps to protect and improve water quality in receiving waters;
•
Slow or remove the amount of stormwater runoff entering waterways, by holding water in the soil profile and aiding evapotranspiration. This helps to mimic natural flow patterns in waterways and can reduce downstream flood risk and erosion;
•
Enhance localised cooling and mitigation of the urban heat island effect by enhancing evapotranspiration while also increasing shade through additional canopy growth; and
•
Reduce or avoid the need to use potable water resources for irrigation during establishment and during dry periods.
There is also a need to increase irrigation of street trees to support tree species that are likely to be vulnerable to future climates. A recent examination of the resilience of trees to climate change identified that a substantial proportion of the existing trees in Hobson’s Bay would not be able to survive future climates.3 Tree populations were examined across 10 local government areas in Melbourne, including Hobson’s Bay, and 58% of existing trees in the municipality were found to be at
1 Grey, V., Livesley, S.J., Fletcher, T.D. and Szota, C. (2018a) Establishing street trees in stormwater control measures can double tree growth when extended waterlogging is avoided. Landscape and Urban Planning, 178, 122-129. 2 Based on observed canopy data for semi-mature trees with and without passive irrigation in City of Melbourne, City of Yarra and City of Port Phillip (Urban Forest Consulting). 3
Clean Air and Urban Landscapes Hub (2017). Risks to Australia’s urban forest from climate change and urban heat. Available at: https://nespurban.edu.au/wp-content/uploads/2018/11/CAULRR07_RisksAustralianUrbanForest_Oct2017.pdf
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risk under a business-as-usual scenario.4 To manage this risk, provision of irrigation is flagged as a key strategy to improve survival rates.
Targets for tree irrigation using alternative water sources The Werribee Catchment IWM Plan sets outs out targets for the proportion of street trees that should be supported by irrigation from an alternative water source (e.g. passive irrigation from stormwater runoff or a recycled water supply). The targets for this measure (Measure 5.1) are expressed at a local government area level, and are as follows for Hobson’s Bay: Timeframe
Current Performance 2030 Target 2050 Target
% of street trees supported by an alternative water source 0% 9% 23%
It is important to note that the IWM targets relate to number of trees rather than canopy area, and it is only targeted at street trees. There may be opportunities to source recycled water supply for irrigation of trees in the Altona area from the Altona Treatment Plant, and this could be discussed further with Greater Western Water. However, the primary method of sourcing an alternative water supply for irrigation of trees in the municipality is likely to be through the use of passive irrigation, which can be designed into many tree planting situations (see standard drawings provided) but does require forethought and additional budget.
Types of passive irrigation opportunities in Hobson’s Bay Passive irrigation of trees using stormwater runoff from roads and adjacent surfaces is an emerging area of focus in the Melbourne Region. Various system installations have been delivered in urban streets in the last 10-20 years, trailing a variety of design approaches and helping councils to learn techniques and refine designs and maintenance protocols. However, installations are largely considered pilot projects or targeted at high profile areas, and the practice is not widely mainstreamed due to the additional design and construction investment required. City of Melton is currently delivering the largest scale installation of passive irrigation systems for street trees in partnership with developers across their growth areas. Passive irrigation can be installed in the majority of street tree planting sites, but the cost and difficulty will depend on site conditions. There are several guidance documents available that can be used to select and trouble-shoot site challenges to find passive irrigation solutions: •
CRCWSC (2020) Designing for a cool city: Guidelines for passively irrigated trees. Available: https://watersensitivecities.org.au/content/designing-for-a-cool-city-guidelines-for-passivelyirrigated-landscapes/
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Victoria State Government (2019) Trees for Cooler and Greener Streetscapes – Guidelines for Streetscape Planning and Design. Available: https://www.planning.vic.gov.au/policy-andstrategy/planning-for-melbourne/plan-melbourne/cooling-greening-melbourne/trees-forcooler-and-greener-streetscapes
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Number of trees classified as ‘yellow’, ‘orange’ or ‘red’ level risk, reflecting that the temperature is warmer than 80%, 90% or 97.5% of the locations where this species is found under a future climate (RCP8.5) scenario.
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Five standard drawings have been developed for the Hobson’s Bay municipality, which provide passive irrigation solutions for some typical planting situations or ‘typologies’. These have been prioritised through discussions with councils. It should be noted that these solutions don’t necessarily represent the least-cost opportunities, but rather focus on areas where more design insight was needed to provide solutions. There are other simple and low-cost solutions for passive irrigation of individual trees in soft nature strips available5. Typical planting situation 1. Infiltration trench in nature strip: Where multiple trees are being planted in tandem with a road reconstruction, where an irrigation trench can be created along a nature strip.
Example suitable street6
Standard drawing Passive irrigation trench
Ajax St
2. Kerb outstand: Tree is positioned in the roadway within an outstand which may also be used for traffic calming purposes.
Terraced tree pit
Tait St 3. In-road flush surface: In areas where footpaths are too narrow for planting, but trees could be accommodated within parking areas at the edges of the roadway, with flush edges to the road. Suitable for low traffic environments. Can use bollards on edge to delineate. 4. In-footpath with grill: For planting behind kerb in a paved footpath area where a tree grill is required for pedestrian safety.
Flush kerb tree pit
Franklin St
Grated tree pit
Ford St
5 Example: https://www.spacedownunder.com.au/ 6 Image credits: Google Maps Streetview
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5. Expanded tree pit under paving: In carparks, squares or plazas where an expanded underground soil area is desired to support a large tree.
Structural tree pit
Harrington St Carpark The standard drawings for these typologies are included in Appendix 2.
Cost of passive irrigation solutions The cost of creating a passive irrigation system will always depend on a range of site factors, including integration of services, connection to drainage and whether the retrofit can be integrated with other works, but cost can be minimised through site investigations and responsive design. Costs will also reduce where works can be coupled with other planned works such as road or footpath reconstructions. The estimated typical costs of the typologies and simple passive irrigation applications are summarised in the table below. It should be noted that market costs for these works could vary substantially. Like most new practices or technology, market costs are likely to be higher initially as contractors are unfamiliar with the design and some upskilling will need to occur. It is also likely that costs will reduce if installations are done in bulk. Estimated typical costs of passive irrigation system per tree (in addition to conventional tree planting)
Passive irrigation system
Capital cost range
Simple kerb cut-out to sunken surface or inlet to belowground infiltration system 1. Infiltration trench in nature strip: Where multiple trees are being planted in tandem with a road reconstruction, where an irrigation trench can be created along a nature strip. 2. Kerb outstand: Tree is positioned in the roadway within an outstand which may also be used for traffic calming purposes. 3. In-road flush surface: In areas where footpaths are too narrow for planting, but trees could be accommodated within parking areas at the edges of the roadway, with flush edges to the road. Suitable for low traffic environments. Can use bollards on edge to delineate. 4. In-footpath with grill: For planting behind kerb in a paved footpath area where a tree grill is required for pedestrian safety. 5. Expanded tree pit under paving: In carparks, squares or plazas where an expanded underground soil area is desired to support a large tree.
$750 - $1500 $1000 - $2000
Annual maintenance cost $150/year Typical maintenance costs for a passively irrigated tree
$3000 -$5000
$2000 - $4000
$3000 - $8000
$6000 -$10000
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While the capital cost of passive irrigation is wide-ranging and site dependant, there are also very significant economic benefits that can be demonstrated for passively irrigated trees, including: •
Increased property prices for larger canopy trees: A study of property prices in Perth showed that a 10% increase in canopy cover in a tree lined street correlated with a 1.8% increase in property prices.7
•
Removal of stormwater pollutants from Port Phillip Bay: A passively irrigated tree can be designed to have a similar performance to a street raingarden, if the catchment area draining to it is sufficient. Twenty passively irrigated trees along a 1km stretch of street could expect to remove 6.5 kg of Total Nitrogen (TN) per year8. In Melbourne, the offset value of nitrogen is $7,246 kgTN/year (capitalised), representing the mean cost of delivering the equivalent stormwater treatment.
•
Avoided costs of premature tree death: In addition to the cost of replacing trees that die earlier or in drought conditions because of lack of access to water, there is also a loss in benefits delivered by the tree when a large canopy tree is replaced by a juvenile tree that takes many years to mature. City of Melbourne lost hundreds of trees prematurely during the Millennium Drought, and analysis shown that depending on the size of the original tree, this resulted in a loss of community benefits ranging from $900 - $26,000 per tree9.
Possible pilot sites for exploration Passive irrigation can be delivered in the majority of planting situations, but the practicality and cost of creating passive irrigation systems for trees will vary substantially with site conditions. It is recommended that all situations are reviewed for opportunity, with the aim of delivering passive irrigation to at least 25% of planting sites. As the introduction of passive irrigation techniques will involve some capacity building and familiarisation for Hobson’s Bay staff and contractors, it it recommended that a series of pilot sites are delivered in the first 1-2 years of the Plan. Pilot sites should implement a range of techniques to refine the approach and provide staff with a range of solutions to apply as part of a mainstreaming of the inclusion of passive irrigation.
7 Pandit, R., Polyakov, M. and R. Sadler (2014) Valuing public and private urban tree canopy cover. Australian Journal of Agricultural and Resource Economics 58(3):453–470 8 City of Yarra (2018) Embedding Green Infrastructure Economic Framework. 9 E2Designlab (2019) Cost Benefit Assessment of Stormwater Harvesting for Princes Park. City of Melbourne
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2. Green Streets Program A Green Streets program is being developed by Council to facilitate a collaborative community component of the Hobsons Bay Canopy Delivery Plan, which is the implementation arm of Councils Urban Forest Strategy. It is based on the Cool Streets Program, which was run in 3 streets across the Municipality during 2019-2020. The program objectives are to: 1. To maximise urban greening benefits at the local scale and showcase integrated climate adapted design responses for whole streets 2. To collaborate with and build local community knowledge of the role, function, and value of urban greening and increased canopy cover in Hobsons Bay 3. To monitor and evaluate the green and blue infrastructure approaches for embedding as business as usual in Councils works programs 4. To support Council’s strategic commitments in particular the Urban Forest Strategy, Biodiversity Strategy, Integrated Water Management Plan, Better Places, Climate Change Adaptation, Living Melbourne, and Greening the West The program will involve the following steps:
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Example streets for application: 1. Lagunaria replacement where the trees have been causing significant issues within a street and need removal 2. A street in Altona Meadows and Seabrook, the residential areas most in need of improved tree canopy cover 3. A wide street that will redesign and reconstruction to better configure carparking but to improve both tree canopy cover and passive stormwater infiltration through installation of typologies 4. Opportunities nominated by residents keen to run the program in their street
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3. Lagunaria Replacement Program Some existing trees within the street tree population, including Lagunaria patersonia, The Norfolk Island Hibiscus is known to cause both respiratory discomfort and skin irritation but are also unsuitable for planting under powerlines and yet have been in the past. As a result, this species in particular is likely to be unsuitable for future use. Council receives a number of resident complaints each year about this species and has in the past sought to remove problematic trees. In response to this, Council is seeking to diversify away from using these species and in some cases actively remove them and replace with more suitable species. Council acknowledges that this program will have short-term detrimental impacts to our canopy coverage targets however it will provide an opportunity to grow a larger canopy over the longer term. Council will seek to plant the most appropriate replacement species for each location. Larger replacement species will be planted, and existing Norfolk Island Hibiscus will be replaced on a two for one basis, in locations where space allows. Norfolk Island Hibiscus will be considered for removal and replaced with alternative species under the following scenarios: 1. Feedback and concerns from residents depending on the level of issues presented at each location. It is recommended to conduct a whole street tree renewal in this case where Norfolk Island Hibiscus make up the dominant species, to improve the overall tree canopy and amenity outcomes 2. Streets where Norfolk Island Hibiscus comprise ≥45% of all trees. Scheduled street tree removal and replacement programs where Norfolk Island Hibiscus compromise the majority of the street’s species 3. From underneath electric lines, particularly High Voltage lines and especially where annual clearances are required. a) Streets where Lagunarias < 45% of all trees but ≥50% are under powerlines b) Streets where Lagunarias < 45% of all trees but <50% are under powerlines 4. Isolated specimens or where low numbers of Norfolk occur within streets to be removed and not replanted on a reactive basis. 5. Specimens adjacent to saltmarsh and coastal complex habitats, mainly in Altona. Some of these scenarios lend themselves to be considered as part of the Green Streets Program, whereby the local residents can actively participate in a redesign of their street to include water sensitive urban design and the replacement of appropriate canopy maximising trees. Whilst we recognise that there would be a short to medium loss of tree canopy cover as these trees are removed, it is anticipated that replaced trees will be supported by passive stormwater filtration through application of wsud typology and be replaced with species that seek to maximise benefits, including provision of canopy. Ideally, replaced canopy (when it reaches semi-maturity) should be greater than existing Lagunaria canopy. The Lagunaria Management Plan is included in Appendix 4.
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Implementation of the Canopy Delivery Plan The core purpose of this Plan is to identify the most effective way for Council to meet its targets as set within the Urban Forest Strategy. From a resource and cost perspective, Council will utilise the following hierarchy of opportunities to plant 100,000 trees by 2040 (8,000 each year to 2025 and then 4,000 per year thereafter): 1. 2. 3. 4. 5. 6.
The 4,946 identified vacant street tree sites which will be planted by 2022 In higher priority open spaces to improve shade, amenity and biodiversity Along shared paths to improve shade, amenity and biodiversity Within harder to plant/hardstand areas Revegetation in conservation reserves Increased shade and amenity in wide streets where space allows (both the 20m and 30m streets) 7. Within carparks 8. Where other Council asset works allow for construction works to support increased tree canopy cover Council will run a 2-year rolling program of assessing opportunity sites each year to inform street and park tree planting. This adaptability will allow planting to be integrated as and when other Council works plans, either asset renewal or capital works, are developed. This rolling program will include: 1. Annual site selection: Using the prioritisation framework and list of opportunity sites, Council will select sites for tree planting to accommodate the 8,000 trees per year 2. Species selection: Existing species within a site will be reviewed and appropriate species selected to ensure adequate diversity, but also climate resilience and suitability to site. 3. Community engagement: An average of three streets or sites will be chosen to run the Green Streets program within which will have detailed community engagement. Community engagement for all other tree planting will be by standard letter box drops to inform residents of upcoming planting. 4. Planting program: Given Council will know 2 years in advance of both the numbers of species of each tree to be planted in a given year, Council can seek to secure high quality tree stock through contract growing by preferred suppliers. 5. Care and maintenance: All trees will be provided with two years of establishment care, including supplementary watering, formative pruning and replacement of failed stock 6. Ongoing evaluation: Viability of the species palette will continually be reviewed and evaluated to ensure Hobsons Bay tree stock is fit for purpose. Tree numbers and tree canopy cover will be continually monitored to ensure progression towards targets. Priority sites will also be continually reviewed, ground truthed and assessed to ensure a clear line of tree planting opportunities for Council. 7. Ongoing public education to raise community awareness of the benefits of trees to health and well-being and to inform the community of progress with the plan.
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Further steps , Council will ensure that 100,000 trees are planted to 2040 in the locations where they are needed the most, and with consideration of growing requirements to maximise both tree canopy cover and overall tree health. This ambitious program will contribute an additional 2,375,075m2 of tree canopy across the public realm of the Municipality. However, without other landholders, in particular residents, contributing their part, Council will find it challenging to meet the targets as set within the Urban Forest Strategy. As a result, Council should utilise both the Green Streets program and ongoing tree planting community engagement program to increase the awareness of Hobsons Bay’s urban forest amongst residents and encourage tree planting on private land. Further to this, Hobsons Bay should further investigate the following actions within the Urban Forest Strategy Action Plan to support Council’s progress in enhancing the urban forest: 1.5 Improve tree protection and planting requirements in planning scheme to increase tree canopy delivery requirements on private land. 4.1 Develop key regional partnerships with organisations such as Greening the West, and with service and utility providers such as VicRoads. 4.2 Strengthen partnerships with other greening agencies such as Landcare, Greening Australia, and local greening community groups. 4.4 Develop partnerships with businesses and offer grants for tree planting on existing industrial sites. Commitment would have to be made with organization to match $2 for every dollar council gives in grants.
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Appendix 1 – Prioritisation criteria Criteria
Threshold
Thermal Hotspot
Mesh block is within hotspot that is 10 degrees Celsius above baseline
2
Mesh block is within hotspot that is 7-10 degrees Celsius above baseline
1
Mesh block has very low canopy cover of less than 5%
2
Mesh block has low canopy cover of between 5% and 10%
1
Mesh block is within area of very high heat vulnerability and very low resilience (score of 5 on the HVI)
2
Mesh block is within area of high heat vulnerability and low resilience (score of 4 on the HVI)
1
Mesh block is within commercial zone
2
Mesh block contains community infrastructure – school, hospital, kindergarten, library, childcare, community/neighbourhood centre
2
Mesh block contains or is within Park/recreation reserve
2
Mesh block contains shared trail
2
Mesh block is within Industrial zone
1
Mesh block is within General Residential area (includes streets and parks)
1
Mesh block contains future proposed program works
2
Tree Canopy Cover
Heat Vulnerability
Pedestrian Intensity
Road Rehabilitation Program
Score
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Appendix 2 – WSUD Typologies
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Appendix 3 – Green Streets Program
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Appendix 4 – Lagunaria Replacement Program
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