Article Figures & Data
Figures
- Figure 1
The age structure for the category All Street Trees showed a relatively low percentage of young trees (e.g., Callery pear) to replace an abundance of older trees, such as Modesto ash and sycamore/plane.
- Figure 2
Modesto ash accounted for 14% of the street tree population and produced 22% of total benefits. Because of their relatively old age and large size, they make a substantial contribution to airquality improvements. Also, Modesto ash is a low emitter of BVOCs (Benjamin and Winer 1998). Unlike air-quality benefits that reflect the total amount of leaf area, aesthetic and other benefits depend on the rate that leaf area is added and are relatively more important than air-quality benefits for more recently planted species such as the Callery pear.
- Figure 3
Annual benefits per tree varied with tree species, depending on size and growth rate. On average, benefits increased from $20 for 5-year-old trees to $100 for trees 5 years and older. For young trees, rapid-growing species such as sycamore/plane and Raywood ash produced the greatest annual benefits per tree. For old trees, species such as silver maple, honeylocust, Moraine ash, and hackberry produced the greatest benefits because they continue growing long after planting.
Tables
Tree numbers Basal area Leaf area Canopy cover No. % total m2 % total 1,000 m2 % total 1,000 m2 % total Modesto ash 10,592 14.0 310 32.8 4,999 28.4 1,446 24.1 Chinese pistache 9,709 12.8 55 5.8 1,557 8.8 692 11.5 Callery pear 8,019 10.6 31 3.3 718 4.1 287 4.8 Zelkova 5,046 6.7 34 3.6 831 4.7 380 6.3 Chinese hackberry 4,662 6.2 66 7.0 1,610 9.1 520 8.7 Hesse ash 4,082 5.4 9 1.0 173 1.0 78 1.3 Raywood ash 3,953 5.2 41 4.3 869 4.9 256 4.3 Marshall ash 3,464 4.6 15 1.6 488 2.8 206 3.4 Ginkgo 3,434 4.5 15 1.6 285 1.6 92 1.5 Sweetgum 2,956 3.9 26 2.7 626 3.6 138 2.3 Moraine ash 2,921 3.9 68 7.2 1,094 6.2 317 5.3 Honeylocust 2,916 3.9 49 5.2 901 5.1 402 6.7 Sycamore/plane 2,039 2.7 33 3.5 658 3.7 245 4.1 Silver maple 1,254 1.7 83 8.7 1,147 6.5 276 4.6 Other street trees 10,582 14.0 110 11.6 1,668 9.5 663 11.0 Total street trees 75,629 100.0 947 100.0 17,624 100.0 5,997 100.0 Expenditure Tree establishment Planting $167,062 Irrigation/pruning 75,136 Basin repairs 15,200 Nursery 13,693 Subtotal $271,090 Mature tree care Pruning $1,127,117 Tree and stump removal 342,896 Root pruning and barriers 85,208 IPM 67,747 Storm clean-up 4,874 Subtotal $1,627,842 Administration Supervisory and clerical staff $315,572 Other expenditures Sidewalk and curb repair $297,586 Leaf clean-up 106,426 Claims 68,000 Total expenditures $2,686,516 Revenue Service credits $10,132 Development fees 46,000 Contracts 7,000 Total revenue $63,132 Net expenditures $2,623,384 Benefit category Total $ % of total benefit Avg $/tree Environmental Energy 1,000,560 20.2 10.97 CO2 449,445 9.1 4.93 Air quality 1,442,036 29.1 15.82 Stormwater 616,139 12.4 6.76 Environmental subtotal 3,508,180 70.7 38.48 Aesthetic and other 1,455,636 29.3 15.96 Total benefits 4,963,816 100.0 54.44
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