Post on 03-Jan-2016
transcript
Forestry & Society
Urban Forestry
HORT/RGSC 302
J.G. Mexal
Spring 2001
2001 Pecan-ference
The Value of Trees/Pirone 2000
• Supply Oxygen• Sequester Carbon Dioxide• Reduce Noise Pollution• Trap Particulates• Alter Microclimate• Improve Aesthetics• Enhance Outdoor Urban Spaces• Alter the Character of a Community
Forestry & Society
Urban Forestry/urban areas
J. For. 99:37-42:’01
Forestry & Society
Urban Forestry/urban areas
J. For. 99:37-42:’01
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Trees(x10000)
Trees/ha TreeCover
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Trees/ha TreeCover
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Trees(x10000)
Trees/ha TreeCover
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Trees/ha TreeCover
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Trees(x10000)
Trees/ha TreeCover
(%)Oakland Chicago
AtlantaBaltimore
New York
We like our space/ PNW Science Findings
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19821997
Developed land (ha/cap)
We like our space/ PNW Science Findings
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1982-1997
Developed land (1,000 ha)
• Urban areas have lost 21% of forest cover in last 10 yrs– Satellite survey of 448 communities– Cost = $234 billion in health, environmental
costs– Reco = plant 1.7 billion trees to replace 10% of
those lost– Atlanta, GA= one of worst impacted
Forestry & Society
Urban Forestry/urban areas
http://www.cnn.com/2003/TECH/science/09/18/cities.trees.reut/index.html
Forestry & Society
Urban Forestry/urban areas
J. For. 99:37-42:’01
15 trees/cap
9 trees/cap
251 trees/cap.
35 trees/cap
22 trees/cap
28 trees/cap
“Urban Heat Island” effect for California
counties / J.Am. Phy. & Sur.
County Population
Tipping Point?
Forestry & Society Cost Effectiveness of Tree Planting/CA
0 40 80 120 160
So Ctr Valley
Low Desert
High Desert
No Ctr Valley
Mid Ctr Valley
Inland Empire
South Valley
No Coast
Central Coast
So Coast
Mountains
$/tree
Maximum Planting Costs ($/tree)
Urban Forestry Research, Oct’01)
Tree Size Community Value ($)
Annual Value ($/yr)
Small $960 over 60 yrs $16/yr
Medium
Large $4,440 over 120 yrs $37/yr
Forestry & Society
Cost Effectiveness of Tree Planting/CA
http://cufr.ucdavis.edu
Urban forestry
Rainfall Interception by Trees/ Urb.For. Res. Jul.’02)
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0 200 400 600 800 1000 1200 1400
Total (gal)SummerWinter
Projected Crown Area (ft2)
Interception (gal.)
Forestry & Society
Control Stormwater with Trees/Urban Forest Research 7/’02
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0 200 400 600 800 1000 1200 1400
Deciduous (summer)Evergreen (summer)Deciduous (winter)Evergreen (winter)
Projected Crown Area (ft2)
Rainfall Interception/ 1/4” event (gal)
Forestry & Society Effectiveness of Tree Planting/CA
Trees for a Green LA will plant 200,000 trees• Cost: $7,500,000• Energy Savings: $10,500,000 (81 kw/tree/yr)
– Cut cooling costs 15-35%
– Cut heating costs 10-15%
• Air Quality Improvements– NO2 reduction: 26 kg/tree
– O3 reduction: 10 kg/tree
– PM10: 9 kg/tree
– SO2: 2 kg/tree
• Carbon Sequestration: 4.35 tons/tree• Decreased stormwater runoff: 50 gal/tree
Total Benefit =$131,000,000
Urban Forestry Research, Oct’01)
Air Pollution Removed by Trees/Chicago
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J F M A M J J A S O N D
OzoneParticulatesNO2SO2CO
Month
Tons
Forestry & Society
Urban Forestry -- Biomass/ Kraimer, unpubl
Roots = 362 kg/tree
Trunk = 263 kg/tree
Branches= 332 kg/tree(large)
Branches= 209 kg/tree(small)
Leaves = 64 kg/tree
Husks = 10 kg/tree
Pecans = 28 kg/tree
Total= 1,270 kg/tree
Forestry & Society
Urban Forestry The Value of Trees
• Commensurable values– nut production– biomass production
• Non-commensurable values– CO2 capture
– O2 release
– Pollution Control– Altered Microclimate– Beauty
Forestry & Society
Urban Forestry CO2 capture
Basic Photosynthetic Reaction
• CO2 + H2O CH2O + O2
• 1.47 lb 0.60 lb 1.00 lb 1.07 lb
λ
Forestry & Society
Urban Forestry CO2 captureBasic Photosynthetic Reaction
• CO2 + H2O CH2O + O2
• 1.47 lb 0.60 lb 1.00 lb 1.07 lb
λ
Kernal= 0.16
OM =0.42 Thinnings= 0.21
Fixed C= 0.21
Respired back to CO2
Forestry & Society
Urban Forestry CO2 capture
• 1 tree captures 330 lb CO2 (90 lb C)
• 1 acre captures about 6,600 lb CO2
– value = $66/ac (@ $20/BDT)– balance = 7,500 vehicle miles
• 43,000 ac capture about 283,000,000 lb.– value = $2,838,000– balance = 21,000 vehicles (@15,000mi/vehicle)
Forestry & Society
Urban Forestry Oxygen Release
• 1 acre of pecans: 2.42 tons O2/yr
• 43,000 acres: 104,000 tons O2 /yr
• One persons uses about 400 lb O2/yr. Thus, NM WTx pecans supply enough oxygen for 520,000 people!
Forestry & Society
Urban Forestry Pollutant Trapping /McPherson
• 1 tree traps 10 lb of pollutants – 4 lb 03 – 3 lb particulates
• 1 ac of pecan traps 500 lb of pollutants– pollutants:
• 200 lb ozone• 150 lb particulates
– value: $2,250/ac in emission reduction credits
• 43,000 ac traps 10,750 tons of pollutants– value: $96,750,000 in E.R.C.
Forestry & Society
Urban Forestry Altered Microclimate
• Pecans leaf out late when homes may still need solar heat.
• Pecans defoliate late when homes may still need air conditioning.
• Save $20-30/home in A/C costs.
Benefits of windbreaks
Forestry & Society
Urban Forestry Altered Microclimate
Obstruction Filtration
Guidance Deflection
Forestry & Society
Urban Forestry Altered Microclimate
Forestry & Society
Urban Forestry Altered Microclimate
10X the tree height
Forestry & SocietyUrban Forestry/Windbreaks- Caborn 1957
Dense composition
Loose Composition
Wind Flow through Windbreaks
Forestry & Society
Agroforestry- Windbreaks/ Spurr 1964
Forestry & SocietyUrban Forestry/Windbreaks- Geiger 1950
Very Dense
Dense
Loose
Forestry & SocietyUrban Forestry- Sound Attenuation/
Urban Forestry 1988
Forestry & Society
Urban Forestry Altered Microclimate
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Tucson Denver Dallas
Wind Reduction
ET CoolingShade
TotalSavings
$/25 ft tree
McPherson & Rowntree ‘93
Reduce A/C ~9%
Forestry & Society
Urban Forestry The Value of TreesConclusions:
• The importance of trees in an urban environment includes environmental, aesthetic and cultural values.
Forestry & Society
Urban Forestry/Review Questions
• What benefit are trees in an urban environment?• How are windbreaks useful? What do they do?• What is the basic photosynthetic reaction? How
much CO2 is removed from the atmosphere and how much oxygen is released for each pound of carbohydrates created?
• How many trees should you plant in your lifetime to meet your needs? Explain?
• How are trees in the landscape important?