5. Perception of Value
We take care of things we value
New red car – What are you willing to pay?
Ferrari 488 GTB - Features:
Twin-turbocharged 3.9-liter
V8, 660 horsepower
Yugo - Features: Rear-window
defogger so owner can keep
hands warm while pushing
vehicle
7. Urbanization
World = 54% urban (3.9 billion urban inhabitants)
By 2050 = 66% urban (6.4 billion urban inhabitants)
www.globalchange.umich.edu
8. Projected urban land increase (2010-2060):
+2 million acres/year
Urban land (conterminous U.S.)
2010 = 67.8 million acres (3.6%)
2060 = 163.1 million acres (8.7%)
Increase greater than size of Montana
Urban population increase
Approximately 90% urban population (2060)
Delaware land area = 1.2 million acres
10. Urbanization Issues – Energy Use
One trillion BTU =~ 250,000 tonnes of TNT
Daily world energy use = 60 million tons of coal
= pile of coal: 10 ft x 1 mile x 4.4 miles
theenergyharginger.com
11. Urbanization Issues – Air Pollution
3.7 million deaths from outdoor air pollution (2012)
World’s largest single environmental health risk
Air pollution mortality (2010) – Nature, 2015
12. Urbanization Issues - Others
Increased air temperatures
Water flow / quality issues
Crowding
Stress…
Source: NASA: Bright red = 65oC; Dark green / blue ~ 25oC
14. Tree Benefits - Tangible
Shade / Cool Air
Aesthetics
Wildlife
15. Tree Benefits – Less Tangible
Pocket book ($)
Altered building energy use / altered emissions
Products (26M t wastewood/yr), jobs
Human Health
Water quality
Air quality, UV radiation
Physiological changes
Environmental Quality / Regulations
Air quality, water quality, carbon, air temperature
Other
Biodiversity, neighborhoods, crime…
16. Tree Costs
Maintenance / planting / removal
Leaf clean-up
Damaged sidewalks
Blocked views
Branch drop
Crime perception
Pollen
Increased energy use
VOC emissions
Maintenance emissions, pesticides, excess fertilization
17. Annual U.S. Urban Forest Values > $18 billion/yr
Avoided energy use = $7.8 billion*
39 million Mwh/year; 246 million MMBTU /year
Air pollution removal = $4.7 billion
717,000 tons/year; ~580 avoided deaths / year
Carbon sequestration = $3.7 billion
29.4 million tons / year
Avoided emissions = $2.2 billion*
21.5 million t CO2; 93,000 t pollutants /year
Oxygen production = $0
75 million tons per year
Total = $18.4 billion
$770 per acre of tree cover *preliminary results
18. Five General Messages about Urban Forests
There are global problems
Trees can help
Nature and people interact
19. Tree Cover Urban / Community Land
~80% of U.S. urban land is within forested areas
20. Nature and Humans
What percent of trees in cities are planted?
Nowak, D.J. 2012. Contrasting natural regeneration and tree planting in 14 North American cities. Urban
Forestry and Urban Greening. 11: 374 – 382
21. Planting varies by city population density
and region
Nowak, D.J. 2012. Contrasting natural regeneration and tree planting in 14 North American cities. Urban Forestry and
Urban Greening. 11: 374 – 382
22. Percent planting varies by land use
Nowak, D.J. 2012. Contrasting natural regeneration and tree planting in 14 North American cities. Urban Forestry and
Urban Greening. 11: 374 – 382
23. Percent of Total Tree Cover in Cities by Land Use
Forest
(40% TC)
Grass
(20% TC)
Desert
(10% TC)
25. Why Don’t We Have More Urban Trees?
It is expensive to keep trees out
US mowing ~$49-134 billion / year
26. Why Don’t We Have More Urban Trees?
It is expensive to keep trees out
27. Five General Messages about Urban Forests
There are global problems
Trees can help
Nature and people interact
Costs are unavoidable
28. Costs are Unavoidable
People in association with trees = costs
Goal = reduce costs; increase values
No trees ≠ no costs
Costs of gray infrastructure and mowing
29. What if we didn’t maintain gray infrastructure?
30. What if we didn’t maintain gray infrastructure?
31. Five General Messages about Urban Forests
There are global problems
Trees can help
Nature and people interact
Costs are unavoidable
Change is coming
33. Major Driver of Change in the Future
Development
Climate Change
34. Major Driver of Change in the Future
Development
Climate Change
Insects and Diseases
Emerald ash borer range (2013)
Ash dieback
(Hymenoscyphus
fraxineus)
35. Major Driver of Change in the Future
Development
Climate Change
Insects and Diseases
Invasive species
36. Tree Cover Change
In the U.S., urban tree cover dropping:
20,000 acres per year
4.0 million trees per year
37. Steps to Sustainability
Assess resource – what do you have?
Understand resource – what can it do?
Plan – what do you want?
Right location, right tree, right time; across scales
Implement Plan
Monitor – did you get there?