Study reveals tree canopy decline in Adelaide
Jan 2023
10-year tree canopy decline quantified for the first-time following analysis of artificial intelligence data sets and high-resolution, city-wide aerial imagery by Nearmap.
Jan 2023
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Half of Adelaide suburbs lost at least 9.8% residential tree cover from 2011 to 2021
18 suburbs have seen an increase of at least 10% residential tree cover
10-year tree canopy decline verified and quantified for the first-time following analysis of artificial intelligence data sets and high-resolution, city-wide aerial imagery by Nearmap
ADELAIDE, AUSTRALIA – Half of the suburbs within greater Adelaide have lost at least 9.8 per cent of their residential tree cover over the past decade, according to analysis by location intelligence and aerial imagery company Nearmap.
The Australian technology company has for the first time verified and quantified these changes in tree cover across Adelaide’s suburbs using a consistent dataset of high-resolution aerial imagery, and artificial intelligence insights, captured every year over the past decade: 2011-2021.
The discovery follows consistent and extensive mapping of 281 residential suburbs across Adelaide. The analysis compares tree canopy cover in these suburbs in the same three-month period (January-March) every year.
Nearmap analysis found that substantially more suburbs in greater Adelaide have seen a loss in residential tree canopy than have gained tree canopy.
Over the past decade:
- Half of Adelaide suburbs lost at least 9.8% residential tree cover
- Overall relative* residential tree cover fell by 8.6% (20.1% in 2011, to 18.3% in 2021)
- Specifically, 131 suburbs (of 281 suburbs) have lost at least 10% residential tree cover
- Specifically, 18 suburbs (of 281 suburbs) have seen an increase of at least 10% residential tree cover
The analysis was led by Dr Michael Bewley, Senior Director of Artificial Intelligence Systems, at Nearmap who said: “The consistency, quality, and regularity of Nearmap aerial captures has enabled us to, for the first time, provide a powerful picture of changes of urban forests across residential suburbs in Adelaide over the past decade.
“Nearmap provides location insights and high-resolution aerial imagery over time that put in perspective the balance between built and natural environments as cities across Australia continue to sprawl. By revealing the impact of historical planning decisions on the neighbourhoods we live in and experience every day, Nearmap can give urban planners, designers, councils, and government organisations the information and tools they need to create more resilient and sustainable communities.”
Around 11,700 organisations worldwide – including 90 per cent of Australia’s top construction companies – already rely on Nearmap technology and content, and so do more than 250 customers across government and insurance.
Communities keeping cool vs suburbs competing for shade
Suburbs recording an increase in tree canopy growth over the past decade include Northgate (120% relative* increase in tree canopy coverage, from 4.5% to 10%), Mawson Lakes (110%, from 3.7% to 7.8%), St Clair (74%, from 5.2% to 9%), Walkley Height (88%, from 4.1% to 7.8%) and Seaford Meadows (370%, from 0.9% to 4.5%).
Suburbs with decreasing canopy over the past decade include Mount Para West (74% relative* decrease in tree canopy coverage, from 17% to 4.4%), Blackwood (13%, from 48% to 42%), Bridgewater (9.8%, from 52% to 47%), Eden Hills (11%, from 45% to 40%) and Myrtle Bank (18%, from 28% to 23%).
The tree canopy analysis of Adelaide follows a recent national study by Nearmap of 5,000 suburbs nationwide, where Nearmap revealed residents in Greater Brisbane live in populated suburbs with the highest percentage of tree canopy (79% of Brisbane residents live in areas with total tree cover greater than 20%). Hobart came in a close second with 71% of people living in areas with over 20% tree cover, followed by Darwin at 66%, the ACT at 58%, and Greater Sydney at 44%.
Dr Bryan Boruff, Environmental Geographer and Associate Professor in the University of Western Australia (UWA) School of Agriculture and Environment said: “We know from previous research that removing tree canopy can increase the urban heat island effect, and result in surface temperatures up to 10 degrees hotter than surrounding areas. By appropriately increasing the number of trees in a local suburb we can reduce the associated health impacts and increase wellbeing.
“By monitoring changes in tree canopy cover, we are reminded that maintaining and enhancing tree stocks in our neighbourhoods is important for sustaining the high levels of liveability Australians have become accustomed and for which this country is known.
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1. Methodology: The Nearmap Leafiest Suburbs analysis is based on Nearmap AI data, which detects trees approximately 2m or higher. The national aerial data was collected Oct 2020 - March 2021. Results were aggregated at meshblock level using the 2021 Australian Bureau of Statistics definitions. Approximately 5,000 suburbs were included in the analysis, where Nearmap AI coverage exceeded 99%. The top suburbs are those with the greatest percent tree cover in each 2021 SA4 region, and where there is a minimum population of 1,000 residents (2016 census). City-based metrics analyse all Nearmap AI covered suburbs within the relevant ABS GCCSA region. For the capital city suburb breakdowns, we also refined the analysis to only include ‘residential’ mesh blocks. All percentage figures have been rounded to the closest whole number.
2. Source: Research from RMIT’s Sustainability and Urban planning program
3. Source: “Designing for a Cool City”, CRC for Water Sensitive Cities, 2020, p.17.