Tree Canopy Cover in the City of Burnside
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Tree Canopy Cover in the City of Burnside Benchmark Assessment 23 September 2016 Tree Canopy Cover in the City of Burnside – Benchmark Assessment A report prepared for the City of Burnside Prepared by Seed Consulting Services 106 Gilles Street, Adelaide, South Australia 5000 www.seedcs.com.au Report should be cited as: Seed Consulting Services (2016) Tree Canopy Cover in the City of Burnside – Benchmark Assessment. A report prepared for the City of Burnside, South Australia. Front cover photo credits 1 2 3 4 5 1. Mount Osmond; Panoramio; Photo by: Sebastian Levesque (n.d.); 2. Cator St, Glenside; Google Earth Street View (2016); 3. City of Burnside boundary; Google Earth 2015; Compiled by: Jenni Garden; 4. Hazelwood Park, Hazelwood Park; Panoramio; Photo by: dorriec (n.d.); 5. Cator St, Glenside; Google Earth Street View (2016). Document Control Document Information Information Document Owner City of Burnside Project ID 657_CoB_iTC Last Saved Date 23 September 2016 File Name 657_Report_FINAL_230916 Document History Version Issue Date Changes V1 Draft 29 June, 2016 First draft for comment Final 23 September, 2016 Final report – no council edits requested Document Approvals Role Name Signature Date Project Director Jenni Garden n/a Written By Jenni Garden 25 June, 2016 Mark Siebentritt Checked 28 June, 2016 23 September, Final version checked Jenni Garden 2016 Disclaimer The information contained in this Seed Consulting Services (Seed) report is given in good faith and has been derived from sources believed to be reliable and accurate. Seed accepts no legal liability for the accuracy of field data, analytical results or mapping data provided as part of this report or for any associated loss in productivity, business or such like through third part use of this data. Seed accepts no legal liability for failure of third parties to obtain any necessary government or other agency permits or approvals with respect to any issue raised in this report where approvals may be required. The material and opinions in this report may include the views or recommendations of third parties, which may not necessarily reflect the views of Seed, or indicate Seed’s recommendation regarding a particular course of action. Seed does not provide advice of an investment or commercial valuation nature. Seed does not accept any liability for investment decisions made on the basis of environmental or other information provided in this report. Page Contents Executive Summary ................................................................................................. 6 1 Introduction ........................................................................................................ 8 1.1 Objectives .................................................................................................................................... 8 2 Approach and Methodology ........................................................................... 10 2.1 Survey area ............................................................................................................................... 10 2.2 Selection of points ..................................................................................................................... 10 2.3 Land-cover categories ............................................................................................................... 11 2.4 i-Tree Canopy settings .............................................................................................................. 13 2.5 Land cover assessment time periods ....................................................................................... 13 2.6 Calculating statistical significance ............................................................................................. 13 2.7 Potential assessment errors and considerations ...................................................................... 14 3 Results .............................................................................................................. 16 3.1 Current land cover across the City of Burnside ........................................................................ 16 3.2 Current land cover across each suburb .................................................................................... 18 3.3 Land cover change over time .................................................................................................... 24 4 Discussion ....................................................................................................... 26 4.1 Key findings ............................................................................................................................... 26 4.2 Implications of tree declines ...................................................................................................... 27 4.3 Future opportunities .................................................................................................................. 28 5 Attachments ..................................................................................................... 30 Attachment A. Power analysis and process used by i-Tree Canopy to allocate and classify points .... 31 Attachment B. Number of points, percent cover (%), and equivalent land area for each land cover category in 2015 relative to the 10,780 points sampled across the City of Burnside. .......................... 32 Attachment C. i-Tree Canopy reports for the 28 suburbs assessed in 2015. ....................................... 33 Attachment D. i-Tree Canopy reports for the 28 suburbs assessed in 2010 ...................................... 118 Figures Figure 1. Suburbs assessed within the City of Burnside ................................................. 9 Figure 2. Points classified within the City of Burnside. ................................................. 17 Figure 3. Estimated land cover across the City of Burnside in 2015............................. 18 Figure 4. Percent impervious cover by suburb in 2015 .................................................. 21 Figure 5. Percent canopy cover by suburb in 2015 ........................................................ 22 Figure 6. Percent plantable space cover by suburb in 2015 .......................................... 23 Figure 7. Trends in land cover change between 2010 and 2015 for the suburbs of Burnside, Glenside and Magill. Refer to Table 4 for further details............................... 25 Tables Table 1. The 28 suburbs and their areas (ha) assessed for this project. ...................... 10 Page Table 2. Land cover categories used for analyses ......................................................... 11 Table 3. Land cover in each suburb, ordered by increasing canopy cover .................. 20 Table 4. Changes in land cover between 2010 and 2015 for the suburbs of Burnside, Glenside and Magill. ......................................................................................................... 25 Plates Plate 1. Examples of land cover categories from i-Tree Canopy. .................................. 12 Plate 2. Examples of photo skew between aerial images. .............................................. 15 Page Executive Summary Green infrastructure, in particular tree canopy cover, is an increasing priority in urban areas nationally and internationally. Despite a well-recognised suite of benefits provided by urban trees on human and environmental health and well-being, climate change mitigation and adaptation, infrastructure lifetimes, and economic prosperity, a number of barriers to increasing tree canopy cover in urban areas still persist. Being able to measure and monitor changes (trends) in land cover, particularly canopy cover, within suburbs will be important for informing decision-making, assessing the success of greening objectives and activities, and prioritising the type and location of activities to best promote desired outcomes. Seed Consulting Services (Seed) was contracted by the City of Burnside (Council) to undertake an assessment of land cover within the City’s 28 suburbs using the i-Tree Canopy software. In addition, three suburbs were selected by Council to investigate historical land cover and assess trends in land cover change over time. With a focus on canopy cover and plantable space opportunities, the assessment aimed to establish canopy cover benchmarks which may be used to monitor future change over time and provide information to underpin decision-making regarding green infrastructure. Key findings from the assessment were: 10,780 points were assessed within the City of Burnside (385 points per suburb); 10 of the 14 land cover categories considered were identified occurring within the City; current land cover across the City is dominated by impervious surfaces, followed by canopy cover, plantable space, and other land covers (e.g. water) (see pie chart below) o the current estimated canopy cover of 31.28% across the city is slightly higher than the 30.2% reported in the National Benchmarking Report1 for the year 2013; just over 22% (~ 6km2) of the City area (public + private tenure) provides opportunities for planting additional trees (see pie chart below); land cover proportions amongst suburbs varied: o percent impervious cover is highest in Eastwood and lowest in Waterfall Gully; o percent tree/canopy cover is highest in Waterfall Gully and lowest in Glenside; o percent plantable space is highest in Leawood Gardens and lowest in Eastwood; in Burnside, Glenside and Magill impervious cover has increased