Article Figures & Data
Figures
- Figure 1.
Heat map showing heritage tree appraisal results (USD) using 5 different urban tree techniques in Sydney and Toronto. Converted appraisals in Australia at the rate of 1 AUD = 0.67 USD. Converted appraisals in Canada at the rate of 1 CAD = 0.73 USD. Trees are arranged from the highest (left) to the lowest (right) condition rating (%). Trees with higher condition ratings generally represented the highest estimates, and trees with lower condition ratings represented the lowest estimates. Z Privately-owned tree.
- Figure 2.
Boxplot depicting estimates for each appraisal technique for all trees in their respective locations. Sydney appraisal values had higher variability than those for Toronto, and CAVAT had the highest variability in both locations.
- Figure 3.
Heat maps showing correlation coefficients between appraisal estimates and key factors for each technique in Sydney (A) and Toronto (B). Key factors include condition rating, DBH, tree height, and crown size (measured by dripline diameter), as outlined by Thyer.
- Figure 4.
Scatter plots showing the relationship between the appraisal estimates and DBH in Sydney (A) and Toronto (B) for each appraisal technique.
- Figure 5.
Heat map depicting heritage trees and the appraisal estimates based on their morpho-physiological stage (Fay and Butler 2017). CAVAT produced the highest estimates for heritage trees in the mature phases and was notably among the lowest for trees in ancient phases. Thyer was among the highest estimates for trees in ancient phases. All techniques typically produced higher estimates for mature trees compared to ancient trees.
- Figure 6.
Bar plot showing the mean influence (%) of heritage status on appraisal estimates in Sydney and Toronto. Dark blue indicates the mean percentage increase due to heritage status, while light blue represents the potential maximum mean percentage increase attributable to heritage status. Heritage status has no impact on the TFT. In CAVAT, the mean percentage increase matches the maximum attributable percentage increase for all trees, i.e. the level of heritage recognition or qualities have no impact.
- Figure 7.
Bar plot showing a comparison of Kew Gardens Oak appraisal estimates with and without heritage status against the maximum possible points for heritage status in each technique. The oak is in a mature phase and judged to be in nearly ideal condition.
- Figure S1.
Heritage trees in (A) Sydney, NSW, Australia; and (B) Toronto, Ontario, Canada: (1) Glebe Church Eucalypt: Eucalyptus paniculata “Grey Ironbark”(2) Glebe Playground Fig: Ficus obliqua “Small-Leaved Fig, (3) Hyde Park Kauri: Agathis robusta “Queensland Kauri”, (4) Royal Botanic Gardens Sydney (RBGS) Eucalypt: Eucalyptus robusta “Swamp Mahogany”, (5) Royal Botanic Gardens Sydney (RBGS) Weeping Lilly Pilly: Waterhousea floribunda “Weeping Lilly Pilly”, (6) Royal Botanic Gardens Sydney (RBGS) Monument Oak: Quercus robur “English Oak”, (7) Coronation Park Monument Oak: Quercus robur “English Oak”, (8) Clarence Square Horse Chestnut: Aesculus hippocastanum “European horse-chestnut”, (9) Kew Gardens Oak: Quercus rubra “Northern Red Oak”, (10) Leaside Church Oak: Quercus alba “White Oak”, (11) Humewood American Elm: Ulmus americana “American Elm”, (12) Mount Pleasant Cemetery Maple: Acer saccharum “Sugar Maple”.
Tables
- Table 1.
Species and key characteristics of heritage trees appraised. Crown diameter was measured per Thyer guidelines. Estimated age is based on heritage recognition details and historical documentation. Tree condition rating is based on the framework established in the Guide for Plant Appraisal (CTLA 2020). Tree selection criteria was determined based on the Tree-AH guide for assessing heritage trees (Barrell 2024). RBGS (Royal Botanic Gardens Sydney).
Sydney Glebe Church Eucalypt Glebe Playground Fig Hyde Park Kauri RBGS Eucalypt RBGS Weeping Lilly Pilly RBGS Monument Oak Species Eucalyptus paniculata Ficus obliqua Agathis robusta Eucalyptus robusta Waterhousea floribunda Quercus robur Location 33°52’49”S, 151°11’13”E 33°52’42”S, 151°11’04”E 33°52’29”S, 151°12’43”E 33°51’54”S, 151°13’06”E 33°51’55”S, 151°13’00”E 33°51’44”S, 151°12’52”E DBH (cm) 109.0 230.0 128.5 78.5 150.0 94.5 Height (m) 17.4 14.3 24.5 16.5 20.0 14.1 Crown diameter (m) 11.5 31.4 23.9 20.5 17.0 20.0 Estimated age (years) 174 141 124 208 196 89 Condition Good Excellent Excellent Good Excellent Poor Ownership (public or private) Private tree Public tree Public tree Public tree Public tree Public tree Selection criteria Cultural and scientific qualities Visual qualities Emerging (visual) Cultural and scientific qualities Cultural qualities Cultural qualities Toronto Coronation Park Monument Oak Clarence Square Horse Chestnut Kew Gardens Oak Leaside Church Oak Humewood American Elm Mount Pleasant Cemetery Maple Species Quercus robur Aesculus hippocastanum Quercus rubra Quercus alba Ulmus americana Acer saccharum Location 43°38’00”N, 79°24’25”W 43°38’39”N, 79°23’38”W 43°40’09”N, 79°17’52”W 43°42’06”N, 79°22’24”W 43°41’00”N, 79°25’37”W 43°41’42”N, 79°23’11”W DBH (cm) 80.0 99.5 162.0 119.5 164.0 102.5 Height (m) 18.2 12.8 24.7 16.1 24.3 20.0 Crown diameter (m) 19.3 15.9 30.7 23.9 27.8 26.3 Estimated age (years) 87 98 224 188 214 151 Condition Good Fair Excellent Excellent Good Fair Ownership (public or private) Public tree Public tree Public tree Private tree Public tree Public tree Selection criteria Cultural qualities Emerging (visual) Cultural, scientific, and visual qualities Cultural and scientific qualities Visual and scientific qualities Visual qualities - Table 2.
Decision making factors. This table shows who decides key factors, specifying whether the influence of each factor is set by the authors in the manuals/guides of each technique or if the decision is left to the appraiser’s judgment. TFT (Trunk Formula Technique); CAVAT (Capital Asset Valuation for Amenity Trees); STEM (Standard Tree Evaluation Method).
TFT CAVAT MIS506/24 Thyer STEM Who decides market inputs Nursery stock price Appraiser Author Author Author Appraiser Planting costs Appraiser Author N/A Author Appraiser Who decides the influence of key factors Location Appraiser Author Author N/A Author Condition weighting Appraiser Author Author Author Author Public benefit N/A Author Appraiser Author Author Climate suitability Appraiser N/A Author Author Author Wildlife habitat N/A Author Author Author Author Who decides key heritage factors Heritage status N/A Author Appraiser Appraiser Author Visual appeal N/A Author Appraiser Author Author Cultural connection N/A Author Appraiser Author Author Scientific value N/A Author Appraiser Author Author - Table 3.
Wholesale nursery tree price and planting costs (in USD) used for techniques. Converted costs in Australia at the rate of 1 AUD = 0.67 USD. Converted costs in Canada at the rate of 1 CAD = 0.73 USD. RBGS (Royal Botanic Gardens Sydney).
Australia (in USD) Glebe Church Eucalypt Glebe Playground Fig Hyde Park Kauri RBGS Eucalypt RBGS Weeping Lilly Pilly RBGS Monument Oak Trunk formula technique Unit cost $16.59/cm2 $14.05/cm2 $17.67/cm2 $12.88/cm2 $14.68/cm2 $19.15/cm2 CAVAT Unit cost $13.26/cm2 $13.26/cm2 $13.26/cm2 $13.26/cm2 $13.26/cm2 $13.26/cm2 Planting cost 150% 150% 150% 150% 150% 150% MIS506/24 Unit cost $11.91/cm2 $11.91/cm2 $11.91/cm2 $11.91/cm2 $11.91/cm2 $11.91/cm2 Thyer Supply and install cost $22.37 $22.37 $22.37 $22.37 $22.37 $22.37 STEM Tree cost $117.25 $150.75 $234.50 $170.85 $160.80 $199.66 Planting costs $1,507.50 $1,507.50 $1,507.50 $1,507.50 $1,507.50 $1,507.50 Maintenance cost $70.35/year $70.35/year $70.35/year $70.35/year $70.35/year $70.35/year Canada (in USD) Coronation Park Monument Oak Clarence Square Horse Chestnut Kew Gardens Oak Leaside Church Oak Humewood American Elm Mount Pleasant Cemetery Maple Trunk formula technique Unit cost $4.80/cm2 $8.07/cm2 $5.51/cm2 $6.99/cm2 $4.97/cm2 $5.56/cm2 CAVAT Unit cost $9.34/cm2 $9.34/cm2 $9.34/cm2 $9.34/cm2 $9.34/cm2 $9.34/cm2 Planting cost 150% 150% 150% 150% 150% 150% MIS506/24 Unit cost $6.34/cm2 $6.34/cm2 $6.34/cm2 $6.34/cm2 $6.34/cm2 $6.34/cm2 Thyer Supply and install cost $17.18 $17.18 $17.18 $17.18 $17.18 $17.18 STEM Tree cost $199.29 $207.32 $192.72 $206.59 $166.44 $219.00 Planting costs $365.00 $365.00 $365.00 $365.00 $365.00 $365.00 Maintenance cost $25.55/year $25.55/year $25.55/year $25.55/year $25.55/year $25.55/year - Table S1.
Wholesale nursery stock adaptation table illustrating the nursery stock details used in the original monetary conversion factor calculations as compared to the details used in this study. The data used was based on the most readily available information in each country while staying true to the original techniques. TFT (Trunk Formula Technique); LCANT (Largest Commonly Available Nursery Tree); CAVAT (Capital Asset Valuation for Amenity Trees); STEM (Standard Tree Evaluation Method).
Original calculation AustraliaX CanadaY TFT LCANT LCANT (NSW) LCANT (Ontario) Tree size 75 to 200-L container 50 to 90-mm caliper CAVAT Top 10 street trees (England) Top 10 street trees (Sydney) Top 20 trees used by the city (Toronto) Tree size 12 to 14-cm cir (1-m height) 100-L container 50-mm caliper (150-mm height) MIS506/24 Market survey (Australia) Market survey (Australia) Average unit cost (Ontario) Tree size 45 to 600-L container sizes 45 to 600-L container sizes 50 to 100-mm caliper sizes Thyer Top 4 to 5 nursery trees sold Average nursery trees sold Converted as a proportion of economic measure Tree size 5-L container 5-L container STEM 5-year-old tree Species specific Species specific Tree size 100-L container 50-mm caliper ↵X EvergreenConnect used to source nursery stock in Australia (plant search; EvergreenConnect, Sunnybank, Queensland, Australia).
↵Y Nursery catalogues used to source nursery stock in Canada (2024 wholesale price list; Kobes Nurseries Inc., Bowmanville, Ontario, Canada)(2024 price list; NVK Nurseries Inc., Dundas, Ontario, Canada)(2024 price list; Uxbridge Nurseries Ltd., Uxbridge, Ontario, Canada).
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