of Perth and Peel The urban forest of Perth and Peel

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1 The urban forest statistical report CSIRO 2009 Urban Monitor

2 Disclaimer This document has been published by the Western Australian Planning Commission. Any representation, statement, opinion or advice expressed or implied in this publication is made in good faith and on the basis that the Government, its employees and agents are not liable for any damage or loss whatsoever which may occur as a result of action taken or not taken, as the case may be, in respect of any representation, statement, opinion or advice referred to herein. Professional advice should be obtained before applying the information contained in this document to particular circumstances. Western Australian Planning Commission Published by the Western Australian Planning Commission Gordon Stephenson House 140 William Street Perth WA 6000 Locked Bag 2506 Perth WA 6001 Published website: corporate@planning.wa.gov.au tel: fax: National Relay Service: infoline: The Department of Planning owns all photography in this document unless otherwise stated. This document is available in alternative formats on application to Communication Services. 2

3 Contents Introduction 2 What is the urban forest? 2 Where does urban forest data come from? 4 How is the urban forest being measured? 5 How could the urban forest information be used? 6 The urban forest mapping 7 Tree canopy by suburb 7 Tree canopy by land use 10 Low risk parkland 10 Medium risk road reserves 11 High risk commercial, residential and industrial street blocks 11 Suburb risk profiles 15 Metropolitan central subregion case studies 15 Leederville 15 Crawley 15 Applecross 16 Murdoch 16 Metropolitan outer subregion case studies 17 Hillarys 17 Joondalup 17 Guildford 18 Midland 18 Medina 19 Kwinana town centre 19 Maps 20 Suburbs 20 Land use 20 North west subregion 20 North east subregion 20 Central subregion 20 South west subregion 21 South east subregion 21 Peel subregion 21 References 21 3

4 Introduction The Department of Planning has responded to the need for a consistent data source on tree canopy cover across the Perth and Peel regions with this report. The report includes a comprehensive series of maps showing the density and distribution of tree canopy cover over the metropolitan area in The tree canopy data is intended to provide a valuable baseline for future modelling of the urban forest derived from the processing of high resolution digital photography captured by Western Australian Land Information Systems (WALIS). The data are available due to the CSIRO s Urban Monitor prototype free data sharing which has processed high resolution digital photography for the year While high resolution digital photography is available for subsequent years, it has not yet been processed to enable the tree canopy to be measured. It is hoped that this report will raise the profile of tree retention, protection and enhancement measures among the community and help local government and research institutions in their efforts to formulate a strategic response to tree canopy retention. The level of interest in this data set and feedback on suitability and application will help the processing of more recent aerial photography to establish important trends affecting the urban forest. Tree canopy cover and the multiple environmental, social, psychological and recreational benefits that trees provide are reflected in the title urban forest, which suggests a holistic ecosystem sustained in the urban environment. It is clear from urban forest strategies in Sydney and Melbourne and local examples from the Cities of Armadale and Vincent that there is a need to more closely monitor, care for and protect our significant trees and connected canopies in highly urbanised areas. What is the urban forest? The urban forest for the purposes of this report has been defined as the collection of native and exotic tree species, three metres tall and above, that grow in the urban environment. Individual trees located on private lots, public streets and in parks and gardens all contribute to an urban tree canopy that provides social, economic and environmental benefits to the metropolitan area. While trees in gardens and parks and on streets have always been valued for their individual aesthetic contribution to neighbourhoods and town centres, the array of environmental benefits they provide collectively is perhaps not as well understood and valued. 4

5 Urban forestry is a specialised field of forestry described in Helm s Dictionary of Forestry (1998) as the science and art of managing trees, forests and natural ecosystems in and around urban communities to maximise the physiological, sociological, economic and aesthetic benefits that trees provide society. 1 The City of Melbourne released an Urban Forest Strategy in 2012 which recognised the cumulative benefits of an entire tree population across a town or city. The Melbourne strategy states Looking holistically at the urban forest and its associated ecosystem services allows for consideration of the broader issues of climate change, urban heat island effects and population growth that can be influenced by and that can affect, an urban forest. 2 The term environmental services describes the benefits of individual trees and combined tree populations and promotes the idea that these benefits have an economic value that can be understood as a dollar figure. Tools such as i-tree Eco (i-tree Eco Australia org.au/i-tree-australia) model air pollution amelioration, carbon storage and sequestration, energy savings benefits and structural values of the urban forest and calculate in dollar terms the value of the service being provided. 3 The economic contribution the tree canopy makes to the urban system through provision of substantial environmental services has led to the term green infrastructure gaining currency. Planning the Urban Forest (2009) author JC Schwab states that increasingly communities are realising that green infrastructure is an economical long term investment that reduces the need for much greater expenditures in grey infrastructure. 4 A recent paper on the urban heat island effect that has a local focus is Cool communities: Urban trees, climate and health prepared by researcher Helen Brown of Curtin University. This paper and subject matter received broad media coverage in January 2014 coinciding with nationwide heatwaves. 1 Helms, 1998, Dictionary of Forestry. Quoted in JC Scwab (Ed.) 2009, Planning the Urban Forest 2 City of Melbourne (2012) Urban Forest Strategy. Page 9 3 City of Melbourne (2012) Urban Forest Strategy. Page 22 4 JC Schwab (Ed.), Planning the Urban Forest. 5

6 Brown lists the major benefits of trees in urban areas as being: Reduction of air pollution Reduction in volume of stormwater Mitigation of wind and noise Provision of habitat and support for biodiversity Reduction in UV exposure Air cooling through evapotranspiration Enhanced sense of place and identity Improved mental wellbeing Encouragement of outdoor activity Reduced demand for energy (lower GHG emissions) Increased property values 5 Where does urban forest data come from? Data on the 2009 urban tree canopy have been made available by high resolution digital photography modelling by the CSIRO called the Urban Monitor. The Urban Monitor project was initiated in 2006 by CSIRO Digital Productivity Flagship and its partners to develope a time-series of urban and environmental indicators and systems. The CSIRO s Urban Monitor project offers unparalleled monitoring capability to identify changes in land condition and elevation at a fine scale (for example, 0.1 to 0.3 metres). Though still under development, Urban Monitor has the potential to monitor changes in estuarine, river, wetland, foreshores, non-irrigated native bush areas, urban canopy cover, irrigation uniformity and efficiency in public and private open space, areas undergoing urbanisation and groundwater dependent vegetation. The products generated from the Urban Monitor project have been used to assess changes in urban land use and likely impacts on hydrology, and identify changes in vegetation presence and condition for land managers. 5 Brown, Katscherian, Carter, Spickett. Cool communities: Urban trees, climate and health. Curtin University projects/climatechange.cfm 6

7 An extract from a paper by Peter Caccetta titled Urban Monitor Fine Scale Monitoring of Complex Environments (2011) states The advent of high quality digital photography provides for traditional orthophotographic uses as well as remote sensing uses such as monitoring environmental indicators. A well devised monitoring system, based on consistent data and methods is able to track and communicate changes in features of interest in a way that has not been previously possible. The greater Perth area is being used as a representative example, and research is being conducted by the CSIRO, the State Government and other partners on a range of natural resource and other management issues associated with rapid resource use and climate change. 6 A detailed account of the CSIRO s Urban Monitor technology can be found in Urban Monitor: Enabling effective monitoring and management of urban and coastal environments using digital aerial photography Final Report Transformation of aerial photography into digital raster information products. Dr Peter Caccetta and Joanne Chia of the CSIRO Computational Informatics in Floreat, Western Australia have generously contributed a great deal of their time in intersecting the Department of Planning s shape files and cadastral data with the Urban Monitor to produce the urban tree canopy statistics displayed in this report. How is the urban forest being measured? The urban forest is reporting on the total area of tree canopy cover, not the location or number of individual trees. The CSIRO s Urban Monitor 2009 is the source data for this statistical report and has provided the area of tree canopy cover for all vegetation three metres tall and above. The Department of Planning provided CSIRO with several spatial geographies to measure the area of tree canopy cover to better understand its distribution throughout the metropolitan area. The spatial geographies reflect individual suburbs through to finer grained spatial units such as individual street blocks, road reserve segments and public open space. 6 (2011) Caccetta.P, D.McFarlane, X.Wu and S.Collings. Urban Monitor Fine Scale Monitoring of Complex Environments. 7th International Symposium on Digital Earth, Perth Australia August

8 The tree canopy coverage for suburbs simply calculates the area of tree canopy as a percentage of the total land area of the suburb and provides context to the more detailed mapping as well as allowing comparisons between suburbs. An important aspect of measuring the extent of the tree canopy across the metropolitan area was to also understand the degree of risk to the health and longevity of the canopy depending on its location and likelihood of future development impacts. Three very broad land use categories were selected to reflect a low, medium and high level of risk to the ongoing health and longevity of the tree canopy. The low risk category reflected tree canopy in public parks, open space, educational campuses and private recreation grounds such as golf courses. The medium risk category reflected tree canopy in road reserves which is Crown land vested with local authorities for management and maintenance, however State statutory authorities have an equal or higher level of authority to use the road reserve for infrastructure upgrades. The road cadastre was broken up into road segments at each intersection to more accurately reflect the variation in tree canopy cover along a roadway. The high risk category reflects tree canopy on private lots that are grouped together as street blocks supporting residential, commercial and industrial uses. Australian Bureau of Statistics (ABS) mesh block land use categories of residential, industrial, commercial, hospital/medical, agricultural and transport were used to identify high risk areas for tree canopy loss. The mesh blocks had the cadastral road areas removed to create a shape file that defined street blocks. Using 2011 ABS mesh blocks provides two primary benefits to presenting tree canopy data. Firstly it enables a simplified and consistent way of identifying land uses as opposed to the varied classifications and zoning types within the various local planning schemes covering the metropolitan area. Secondly mesh blocks are the smallest structures within the Australian Statistical Geography Standard (ASGS), a hierarchical classification of geographical regions that consists of a number of interrelated structures. It provides a common framework of statistical geography and enables the production of statistics which are comparable and can be spatially integrated. 7 7 ABS Meshblocks_WA_2011 metadata statement geography 8

9 How can the urban forest information be used? The analysis and mapping provided in The urban forest: Perth and Peel is concerned with the spatial distribution of trees across three broad land use categories and aims to generate discussion around their associated planning controls. While the 2009 tree canopy data is a useful snapshot, in time the real value of the dataset will be as a time series to monitor and report on canopy cover and the effects of land use, infrastructure and development policies. This paper documents where our trees are located in the urban realm providing a 2009 baseline to monitor future improvements or areas of concern regarding tree canopy loss. It will provide a detailed data set for further research and analysis by the Department of Planning and external parties, such as investigating the correlations between high levels of canopy coverage and household energy and water use, property values, health and lifestyle choices, housing types as well as comparison between suburbs, street blocks, activity centres and corridors. The information would be valuable for local governments who are researching or implementing urban forest strategies and could provide the foundations for an overarching urban forest strategy for Perth and Peel by the Department of Planning. 9

10 The urban forest mapping Tree canopy by suburb Suburb maps have been presented at the regional and subregional scale to display the results for all suburbs in the Perth and Peel region. Analysis of the tree canopy by suburb allows for easier comparison of smaller geographical areas that share similar land use patterns and a greater appreciation of the factors affecting tree canopy coverage in the urban context. Results by suburb can be aggregated to reflect local government area canopy cover. As a statistical geography they can withstand future local government amalgamations, therefore ensuring the relevance of tree canopy cover measures over time for ongoing monitoring. In addition, measures by suburb are a good method for engaging and communicating with the general public in relation to the retention of the urban tree canopy. The amount of tree canopy cover in suburbs is a product of several factors, such as: physical environment (landform, drainage, soils) the age of the suburb the road structure the subdivision pattern lot sizes land uses the built form the town planning scheme zoning The extent to which current planning policy and development controls should/can manage these factors in relation to encouraging adequate tree canopy cover is the key question going forward. The following aerial photographs help to associate the tree canopy cover percentages with examples of the suburban built and natural environment. 10

11 Tree canopy cover examples by suburb (built form examples reflect a 1.5 km x 2 km spatial area) 0-5% Welshpool Clarkson 5%-10% Balcatta Warnbro 10%-15% Booragoon Gosnells 15%-20% Wembley Downs Medina 11

12 20-25% Maida Vale Crawley 25%-30% Roleystone Kalamunda 30%-40% Bickley 40%+ Nanga Brook 12

13 Tree canopy by land use In order to make the tree canopy data more accessible and relevant for planning and community purposes we have plotted tree canopy cover results for individual street blocks, road reserves and parkland. The 2009 tree canopy cover results have been displayed by local government area in the outer subregions and by quadrants in the central subregion. The tree canopy results for street blocks and parkland are displayed together on one map with road reserves and parkland displayed together on an additional map for improved legibility. Three broad land use categories have been selected to reflect different planning policy environments, likely development and infrastructure impacts and highlight roles and responsibilities of State agencies, local governments and land owners. Low risk parklands Trees within a parkland setting are considered to be low risk because these areas are designated as spaces for biodiversity, recreation, and relaxation with few development pressures. Education spaces do not provide the same level of protection for trees as zoned parks and reserves and often have active building programs such as university campus upgrades or initiatives such as the 2007 to 2010 Commonwealth Building the Education Revolution program. However there is generally a greater appreciation, flexibility and duty of care toward tree preservation and active tree planting and maintenance programs than in residential, commercial and industrial land uses. The spatial units we have chosen to reflect the tree canopy data are fine grained, however it is likely that very small local parks consisting of a couple of lots within a predominantly residential, commercial or industrial street block will not be recognised as being part of the low risk parkland category. This issue is most significant when defining risk profiles for each suburb as our analysis suggests that our method may have missed up to six per cent of all parkland in the form of local pocket parks. 13

14 Medium risk road reserves The road verge provides the opportunity for regular tree planting and maintenance by local authorities to provide continuous and converging tree canopies for shade and aesthetics, often playing a role in the character of a suburb. Road reserves are shared spaces with multiple functions; the road reserve is Crown land vested with the local government authority for general management however State statutory authorities have an equal or higher level of authority to use the road reserve. Road reserves are underground and above ground infrastructure pathways used for active transport purposes. Tree canopy in road reserves is considered medium risk due to infrastructure maintenance and upgrades which can damage or remove trees. Road widening can also have a significant impact on established trees and may result in complete removal of existing trees with no space for replacement trees. The benefit of road reserve management that underpins the medium risk status is that infrastructure and maintenance activities are often highly controlled, subject to policy and programmed with the opportunity for multiple stakeholder engagement. The road reserve boundaries have been defined by Landgate cadastre using polygons with a usage type that includes the term Road. High risk commercial, residential and industrial street blocks Trees on private lots are at the greatest risk of development pressures because there is very limited protection for established trees under statutory policies. While residential extensions and redevelopments are a common cause for tree felling, trees can be removed on private land at any time for any reason (structural integrity, overhanging limbs, invasive roots and shedding of leaves and nuts are a few reasons). The motivations of private landowners hosting residential, commercial or industrial functions are the most varied and uncoordinated of the three land use categories we have identified. It is likely that planning policies, schemes and structure plans that increase densities and allow for further subdivision will trigger increased development activity and subsequent tree canopy loss. It is the intention of this paper to provide tree canopy statistics that can help State and local governments understand the magnitude of the risk to the tree canopy and to help define roles and responsibilities in the policy arena to improve tree replacement and establish tree protection mechanisms. 14

15 Tree canopy cover examples by street block, roads and parkland Urban forest legend Street block Road reserves Parkland 0-5% Joondanna Mount Pleasant Winthrop 5%-10% North Perth Willagee Darch 10%-15% Dalkeith Sorrento Nollamara 15%-20% Melville Joondanna Wembley Downs 15

16 Urban forest legend Street block Road reserves Parkland 20%-25% Palmyra Yokine Huntingdale 25%-30% Gooseberry Hill Palmyra Coolbinia 30%-40% Darlington Medina Coolbellup 16

17 Suburb risk profiles The graphs below show the percentage of land in each suburb that is dedicated to the three broad land uses topped with the percentage of area that has tree canopy coverage. The graphs can help determine the level of risk to a suburb s tree population depending on where the majority of trees are located and whether the suburb will be targeted as an infill location. Central subregion case studies Leederville 50% 45% 4.5% 40% 35% 30% Canopy cover 25% 20% 43.2% 3.4% 3.7% No canopy coverage 15% 10% 22.7% 22.6% 5% 0% Private property Roads Parks Crawley 70% 60% 50% 40% 15.6% Canopy cover 30% 20% 3.6% 2.7% 46.5% No canopy coverage 10% 18% 13.7% 0% Private property Roads Parks 17

18 Applecross 70% 60% 8.9% 50% 40% 30% 57% Canopy cover No canopy coverage 20% 5.34% 10% 0% Private property 19.3% Roads 1.1% 8.3% Parks Murdoch 70% 60% 11.4% 50% 40% 30% 58.6% Canopy cover No canopy coverage 20% 10% 0% 1% 15.9% Private property 0.7% 12.4% Roads Parks 18

19 Outer subregion case studies Hillarys 60% 50% 3.1% 40% Canopy cover 30% 48.8% 1% 2.8% No canopy coverage 20% 10% 22.5% 21.8% 0% Private property Roads Parks Joondalup 45% 40% 2.2% 35% 30% 25% 20% 39.3% 1.5% 5.1% Canopy cover No canopy coverage 15% 10% 25.1% 26.8% 5% 0% Private property Roads Parks 19

20 Guildford 50% 45% 40% 11.4% 35% 30% 6.8% Canopy cover 25% 20% 15% 28.6% 3.1% 37.9% No canopy coverage 10% 5% 12.1% 0% Private property Roads Parks Midland 80% 70% 4.9% 60% 50% Canopy cover 40% 30% 20% 10% 0% 67.3% Private property 1.5% 18.6% Roads 2.5% 5.2% Parks No canopy coverage 20

21 Medina 60% 50% 8.9% 40% Canopy cover 30% 20% 4.1% 3.2% 49.2% No canopy coverage 10% 21.1% 13.4% 0% Private property Roads Parks Kwinana town centre 90% 80% 70% 24.5% 60% 50% 40% 30% 20% 59.9% 1.3% Canopy cover No canopy coverage 10% 0% Private property 14.3% Roads 0% Grand total 21

22 References (2013 EPA) Environmental Protection Bulletin No.20 (2013 City of Sydney) Urban Forest Strategy (2013 Brown, H) Cool communities: Urban trees, climate and health (2013 WAPC) Capital City Planning Framework: a vision for Central Perth (2013 WAPC) Capital City Planning Framework support document: central Perth regional parklands concept. (2012 City of Melbourne) Urban Forest Strategy: Making a great city greener (2012 CSIRO) Urban Monitor: Enabling effective monitoring and management of urban and coastal environments using digital aerial photography (2009 Schwab) Planning the Urban Forest (2007 WAPC) Liveable Neighbourhoods: a Western Australian Government sustainable cities initiative 22

Planning Commission November 20, 2013 URBAN FORESTRY LANDSCAPING CODE UPDATES

1 Planning Commission November 20, 2013 URBAN FORESTRY LANDSCAPING CODE UPDATES 2 Urban Forest: a Major policy emphasis Urban Forest Policy Element Open Space Habitat and Recreation Element Climate Action