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

0

100

200

300

Trees(x10000)

Trees/ha TreeCover

(%)

0

100

200

300

Trees(x10000)

Trees/ha TreeCover

(%)

0

100

200

300

Trees(x10000)

Trees/ha TreeCover

(%)

0

100

200

300

Trees(x10000)

Trees/ha TreeCover

(%)

0

100

200

300

Trees(x10000)

Trees/ha TreeCover

(%)Oakland Chicago

AtlantaBaltimore

New York

We like our space/ PNW Science Findings

0

0.1

0.2

0.3

0.4

0.5

19821997

Developed land (ha/cap)

We like our space/ PNW Science Findings

0

200400

600

8001000

1200

14001600

1800

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)

0

20

40

60

80

100

120

140

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

0

20

40

60

80

100

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

0

100

200

300

400

500

600

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

0

10

20

30

40

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?