Urban Forest Diversity Definition and Determination Joe R

Home , Hardiness zone

Urban Forest Diversity Definition and Determination Joe R. McBride Department of Landscape Architecture and Environmental Planning University of California Berkeley, CA

1 Objectives

1. Define urban forest diversty 2. Describe measurement of species composition in urban forests 3. Identify factors contributing to urban forest species diversity 4. Identify trends in species diversity 5. Discuss the potential consequences of these trends 6. Review recommendations for establishment and maintenance of urban forest diversity

2 Urban Forest Diversity

“The complexity of tree species composition, the size distribution of trees, and the patterns of distribution of trees within an urban forest”

3 Importance of Diversity

1. In natural ecosystems there is a relationship between stability and diversity 2. Maintaining more diverse urban forests promotes greater stability 3. Diversity adds to functional and aesthetic values of urban forests

4 Measures of Species Composition 1. Species Richness 2. Species Abundance 3. Species Diversity

5 Species Richness

Number of species in an area

6 Tree Species Richness in Three California Cities City Richness South Lake Tahoe 35 Menlo Park 145 Santa Barbara 1,226

7 Species Abundance

Relative numbers of individuals of species

8 Abundance of Street Trees in Berkeley

9 Species Diversity

Measure of species richness and abundance

10 Species Richness

Species Urban Forest #1 Urban Forest #2

A  

B  

C 

D 

11 Species Abundance

Species Urban Forest #1 Urban Forest #2

A 100 380

B 90 15

C 125 15

D 80 15

12 Simpson’s Diversity Index

D = 1 D = diversity index 2 (pi) pi = proportion of individuals in the population belonging to species i

13 Simpson’s Divesity Indicies of Hypothetical Urban Forests 3

Urban Forest #1 Urban Forest #2 Urban Forest #3

Proportion of Population Represented by Species (pi)

QuickTime™ and a are neededQuickTime™ decompressor to see this and picture. a decompressor QuickTime™ and a are needed to see this picture. are neededQuickTime™ decompressor to see this and pict a u decompressor Forest ______are needed to see this picture. Simpson’s Index 1 0.50 0.50 0 0 2.00 2 0.425 0.25 0.20 0.125 2.98 3 0.25 0.25 0.25 0.25 4.00

14 Comparison of Urban Forest Diversity

City Simpson’s Diversity Index Mt. Vernon, Ohio 2.1 Newark, New jersey 2.3 Austin, Minnesota 2.7 Perrysburg, Ohio 3.0 Eugene, Oregon 3.3 Los Angeles, California 3.9 From: McPherson and Rowntree, 1989

15 Factors contributing to the variation in Urban Forest Species Diversity

1. Climate 2. Tree Species Richness of Local Biome 3. History 4. Expert Advise 5. Spiritual/Psychological Values 6. Availability of Planting Stock 7. Epidemics of Insects and Disease 8. Public Popularity

16 Climate and Urban Forest Diveristy Species Richness Analysis

17 Koppen’s Climate Classification

QuickTime™ and a decompressor are needed to see this picture.

From: FAO - SDRN - Agrometeorology Group - 1997

18 Cities Surveyed in each Climate Zone

Tropical Moist Moist, Mid-latitude, Mild Winters Bangkok Beijing Lagos Moscow New Delhi Stockholm Rio de Janeiro Tokyo Singapore

Dry Climates Polar Cario Murmansk Dubai Nuuk Lhasa Reykjavik Phoenix

Moist, Mid-latitude, Mild Winters Athens New York Brasilia Paris Buenos Aires Quito Cusco Seattle Hong Kong Sydney Jacksonville Tel Aviv London Vancouver Los Angeles

19 Moscow - Distribution of Samples

20 Urban Forest Surveys

21 Street Data Form

Cross-section Sketch

22 Climate and Species Richness

Koppen Climate Example City Average Species Richness Tropical Moist Singapore 37

Dry Cairo 28

Moist, Mid-latitude New York 48 with mild winters Moist, Mid-latitude Moscow 32 with cold winters Polar Murmansk 9

23 Urban Forest Species Richness in Relation to Climate

50 A = Tropical Moist Climates • B = Dry Climates C = Moist, Mid-latitude Climates with mild winters 40 D = Moist, Mid-latitude Climates ¨ with cold winters •E = Polar Climates • 30

•

10 •

A B C D E Koppen¨ Climate

24 Frost Hardiness Zones

QuickTime™ and a decompressor QuickTime™ and a are needed to see this picture. decompressor are needed to see this picture.

25 Urban Forest Species Richness in Relation to Hardiness Zones

Hardiness Temperature Example City Average Zone Range (oF) Species Richness 3 - 4 -40 to -20 Murmansk 9

5 - 6 -20 to 0 Moscow 32 7 - 8 0 to 20 Paris 42 9 - 10 20 to 40 Athens 42 11 - 12 40 to 60 Cairo 46 13 - 14 60 to 80 Dubai 30 26 Urban Forest Species Richness in Relation to Hardiness Zones 50 3-4 = -40 to -20o F • 5-6 = -20 to 0 7-8 = 0 to 20 • • 9-10 = 20 to 40 40 11-12 = 40 to 60 ¨ 13-14 = 60 to 80 • 30 •

10 •

3-4 5-6 7-8 9-10 11-12 13-14 Hardiness Zone

27 Factors contributing to the variation in Urban Forest Speices Diversity

1. Climate 2. Tree species richness of local biome 3. History 2. Spiritual/Psychological Values 4. Safety 5. Expert Advise 6. Availability of Planting Stock 7. Maintenance Costs 8. Epidemics of Insects and Disease

28 Biomes of the World

29 Tropical Forest Biome - Distribution and Climate

30 Coniferous Forest Biome - Distribution and Climate

31 32 33 Cities Surveyed in each Biome

Tropical Forest Savanna Bangkok Brasilia Rio de Janeiro Lagos Singapore New Delhi Broadleaf Evergreen Forest Grassland Hong Kong Buenos Aires Sydney Johannesburg Tokyo Tehran Deciduous Forest Desert New York Cairo London Dubai Paris Phoenix Mixed Deciduous-Coniferous Forest Tundra Beijing Murmansk Moscow Nuuk Stockholm Reykjavik Coniferous Forest Highlands Jacksonville Cusco Seattle Lhasa Vancouver Quito Mediterrean Woodland-Scrub Athens Los Angeles Tel Aviv 34 Average Tree Species Richness in Cities in Different Biomes

Biome Average Number of Tree Species* Tropical Forest 35 Broadleaf Evergreen 36 Deciduous Forest 49 Mixed Deciduous-Coniferous Forest 32 Coniferous Forest 45 Mediterranean Woodland-Scrub 49 Savanna 51 Grassland 41 Desert 29 Tundra 9 Highland 34 * Trees in the public right-of-way

35 36 Factors contributing to the variation in Urban Forest Species Diversity

37 Historical Factors Influencing Urban Forest Tree Species Diversity

1. Exploration 2. Colonization 3. National Pride

38 John Bartram

Commonly Encountered English Park Trees Introduced by Bartram

Eastern White Pine Honey Locust Scarlet Oak Silver Maple Southern Magnolia Sugar Maple Sweetgum Sycamore Tulip Tree

39 David Douglas

Commonly Encountered English Park Trees Introduced by Douglas

Douglas-fir Grand Fir Noble Fir Sitka Spruce

40 Oglethorpe’s Plan for Savannah, GA

41 Tree Species Introduced to America during the British Colonial Period

Introduced Tree Species Italian Poplar Italian Cypress English Oak European Birch Paper Mulberry English Holly Weeping Willow

42 British Colonization and the spread of London Plane Tree

London 43 Occurrence of London Plane trees in British Colonial Cities Presence of London Plane Tree** British Non-British Colonial Colonial Biome* Cities(%) Cities(%) Deciduous Forest 100 100 Grassland 100 50 Broadleaf Evergreen 100 0 Coniferous Forest 100 0 Average 100 38

* Biomes with cities in which London Plane tree was one of the top five most frequently encountered street tree species ** London Plane tree was one of the tops five most frequently encountered species

44 City Mod al Boule var d tree

Spacing (ft.)

Lond on 40 New York* 40 Modal Spacing of Trees New Delhi* 40

Cairo* 40 in Boulevard Medians

Ho ng Kong* 40

Lagos* 40

Singa pore* 40

Vancouv er* 40

Syd ney* 50

Johanne sbu rg* 35

Paris 38

Seattle 35

Athen s 30

Stockho lm 28

Tokyo 25

Moscow 20

Teh ran 20 45 * Forme r British Colon ial City; National Pride

QuickTime™ and a QuickTime™ and a decompressor decompressor are needed to see this picture. are needed to see this picture.

46 Lombardy Poplar

Boston Commons, ca. 1750 47 Pennsylvania Avenue, Washington

Ca. 1800

1865 48 National Pride

QuickTime™ and a QuickTime™ and a decompressor decompressor are needed to see this picture. are needed to see this picture.

49 WangFuJing Shopping District - Beijing

QuickTime™ and a decompressor are needed to see this picture.

50 Factors contributing to the variation in Urban Forest Species Diversity

51 Expert Advise 1. Arborist’s Experience with Trees 2. Maintenance costs 3. Safety

52 53 Number of Recommended Species for San Francisco

Number of Organization Recommended Species Friends of the Urban Forest (2007) 54 San Francisco Department of Urban Forestry (1998) 200

54 Maintenance Problems influencing Tree Selection

Tree Debris Sidewalk and Curb Damage Frequent Pruning Requirements Safety

55 Tree Debris

QuickTime™ and a QuickTime™ and a decompressor decompressor are needed to see this picture. are needed to see this picture.

QuickTime™ and a decompressor are needed to see this picture.

56 Bishop Ranch Business Park Trees Planted at Bishop Ranch Business Park

Black locust Gledista triacanthos Callery pear Pyrus calleryana Canary Island pine Pinus canariensis Chinese pistache Pistacia chinensis Coast live oak Quercus agrifolia Cork oak Quercus suber Crape myrtle Lagerstroemia indica Deodar cedar Cedrus deodara Evergreen ash Fraxinus uhdei Hollywood juniper Juniperus chinensis Honey locust Robinia pseudoacacia Italian stone pine Pinus pinea Lombardy poplar Populus nigra ‘italica’ London plane Platanus x acerifolia Redwood Sequoia sempervirens Tulip tree Liriodendron tulipfera

57 Trees not Planted at Bishop Ranch Business Park

Cherry Prunus spp. Crabapple Malus spp. Gingko Gingko biloba Strawberry Tree Arbutus unedo Mulberry Morus spp.

58 Messy Tree Fruit

QuickTime™ and a QuickTime™ and a decompressor decompressor are needed to see this picture. are needed to see this picture.

QuickTime™ and a

QuickTime™ and a decompressor are needed to see this picture. decompressor are needed to see this picture.

59 Sidewalk and Curb Damage

60 Frequent Pruning Requirements

London Plane Tree

Evergreen Ash

Chinese Elm 61 Expert Advise on Planting under Power Lines

62 Space for Trees

30’

20’

63 Recommended Number of Species (<25’ tall)

City “SafeTree” Other Authorities Seattle 32 86 (Jacobson, 1989) Los Angeles 18 61 (Perry, 1989) Jacksonville 6 39 (Nelson, 2003)

64 Safety Considerations for Trees in Traffic Circles and Medians

Traffic Circles - Berkeley, CA “No oak trees or other species characterized by having strong wood”

Medians - Palo Alto, CA “No trees in medians less than 4’wide” “No trees that will reach reach a diameter greater than 12” ten years after planting”

65 Tree Debris and Safety

Sweetgum

QuickTime™ and a decompressor are needed to see this picture.

Tulip Tree 66 Chinese Elm and Branch Failure

QuickTime™ and a decompressor are needed to see this picture.

67 Factors contributing to the variation in Urban Forest Species Diversity

68 Spiritual/Psychological Value of Trees

Religious Symbolism of Trees Feng Shui Early Childhood Environment

69 Trees Common to Cemeteries

San Francisco

Oakland London 70 World’s Most Common Cemetery Trees

71 Cities in which trees with religious symbolism are commonly used as street trees

City Tree Scientific Name Bangkok Bo Tree Ficus religiosa New Delhi Neem Tree Azadirachta indica Singapore Bo Tree Ficus religiosa Hong Kong Bo Tree Ficus religiosa Dubai Ghaf tree Prosopis cineraria

72 Bo Tree

Nepal 73 Bo Tree

74 Bangkok 75 Feng Shui

Tree Placement: Locate trees so they do not block the flow of energy through the house. Avoid tree placement in front of doors and windows.

Trees to be Avoided 1. Trees that grow downward • Weeping willow • California pepper tree 2. Trees with sharp pointed leaves • Holly • Santa Lucia fir 3. Trees with thorns • Honey locust • Silk cotton tree 76 Psychological Importance of Trees

77 Early Childhood Environment Hypothesis

Clare Cooper Marcus

78 Danville, CA

79 Preferred Species of Homeowners in Danville, CA (Wortheim, 1973)

Childhood Region Species Planted Northeast Sugar Maple Birch

Southeast Southern Magnolia Sweetgum

Central Rocky Mountains Blue Spruce Grand Fir

Southwest Cottonwood Yellow pine

California Redwood Coast Live Oak

80 Factors contributing to the variation in Urban Forest Species Diversity

81 Tree Nursery

QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

From: reenurseries.us 82 South Lake Tahoe

Summer Cabin

Year Round Residence 83 South Lake Tahoe Nursery

84 Tree Species occurring around Summer Cabins before 1950

Tree Type Number of Species Percent Conifer 6 67 Hardwoods 3 33

Trees offered for sale in Lake Tahoe Basin in 1995 Tree Type Number of Species Percent Conifer 30 27 Hardwoods 80 73

85 Factors contributing to the variation in Urban Forest Species Diversity

86 QuickTime™ and a decompressor are needed to see this picture.

American Elm - Dutch Elm Green Ash - Emerald Ash Borer

Angsana - Angsana Wilt Disease Horse Chestnut - Bleeding Canker Disease; Leaf Miner Moth 87 Factors contributing to the variation in Urban Forest Species Diversity

88 Trends in Species Planting - Tokyo

From: Cheng and McBride, 2000

89 Maintenance and Preference:

Age Structure of Sweetgum and California Pepper Tree Menlo Park,Menlo CaliforniaPark, CA 1975 Age Structure of Sweetgum and California Pepper Tree 100-Age Structure ofMenlo Sweetgum Park, CA and 1975 California Sweetgum Pepper Tree Menlo Park, CA 1975 California Pepper 100- Sweetgum 100-80- SweetgumCalifornia Pepper California Pepper 80- 1975 % 60- 80-

% 60- 1905 California Pepper % 40- 60-

40- 20- 40- 1925 1885 20- 20- 0-191945 20-39 40-59 60-79 80-99 100-120 Age 0-19 20-39 40-59 60-79 80-99 100-120 0-19 20-39 40-59 Age 60-79 80-99 100-120 Age

Sweetgum 90 Trends in Species Diversity

91 Trends in Tree Diversity

Cities with street trees freq uencie s of 50 percent or greater

Biome City Species Frequency

Deciduous Forest London London Plane Tree 67

Paris London Plane tree 67

Conife r Forest Jacksonville Live Oak 70

Laur el O ak 50

Mixed Decid uou s- Moscow Common Lime 83

Coniferous Forest Beijing Japane se Pagoda T ree 56

Stockho lm Commo n Lim e 50

Grassland Bueno s Aires Green Ash 67

Tehran Or ien tal Pl ane Tree 54

Highl and Lhasa Chin ese Wh ite Poplar 67

92 Species Richness in American vs. European Cities

American Cities European Cities City Species Richness* City Species Richness* New York 2.4 London 1.5 Los Angeles 2.5 Athens 2.2 Seattle 2.2 Stockholm 1.2 Phoenix 4.0 Cairo 1.1 Average 2.8 Average 1.5 * Average number of street tree species in 25 sample plots Sample plot 300’ long, trees on both sides of the street recorded

93 Consequences of Trends in Diversity

1. Risk of Disease or Insect Epidemics 2. Risk of Widespread Mortality due to Abiotic Factors 3. Homogenization of Urban Forest Aesthetics

94 Risk of Disease or Insect Epidemics

Ames, Iowa - 1969 Ames, Iowa - 1970 95 Risk of Widespread Mortality due to Abiotic Factors

96 Global Climate Change

San Francisco

o QuickTime™ and a Average Maximun Temperature* = 69 F decompressor are needed to see this picture. Extreme Maximum Temperature = 97o F

Tijuana

QuickTime™ and a decompressor are needed to see this picture. Average Maximun Temperature* = 75o F Extreme Maximum Temperature = 108o F

* July Temperature 97 Global Climate Change

QuickTime™ and a QuickTime™ and a decompressor are needed to see this picture. decompressor are needed to see this picture.

Redding Palm Springs Average Maximun Temperature* = 98o F Average Maximun Temperature* = 108o F Extreme Maximum Temperature = 118o F Extreme Maximum Temperature = 123o F

98 Aesthetics of the Urban Forest

99 Lack of Aesthetic Variety

Moscow London Beijing

QuickTime™ and a decompressor are needed to see this picture.

Common Lime = 83% Pagoda Tree = 56%

London Plane = 67%

100 Urban Forest Diversity Recommendations

101 Recommendations

Barker (1975): Species = 5% Grey and Deneke (1986): Species 10-15% Moll (1989): Genus = 10%; Species = 5% Santamour (1990): Family = 30%; Genus = 20%; Species = 10% Miller and Miller (1991): Proven Species = 10% Richards (1993): No numerical limits on proven species; Diversity of size classes more important Raupp et al. (2006): Diversify in response to known pest problems (e.g., Emerald Ash Borer, Asian Longhorn Beetle)

102 “Urban foresters should take steps now to diversify the types of trees that are planted in cities to avoid catastrophic tree losses or massive and expensive tree protection programs.”

Michael J. Raupp, Anne Buckelew Cumming, and Erin C, Raupp, 2006

103 End

104 Most Frequently Encountered Street Trees in Survey of 33 Cities

Common Name Scientific Name

1. London Plane Tree Platanus x acerifolia

2. Rowan Sorbus aucuparia

3. Common Lime Tilia europea

4. Canary Island Date palm Pheonix canariensis

5. Norway Maple Acer platanoides

6. Honey Locust Gleditsia triacanthos

7. Jacaranda Jacaranda mimosaefolia

8. Angsana Pterocarpus indicus

9. Carolina poplar Populus x canadensis

10, Silver Birch Betula pendula

105 Trees offered for sale in Tahoe City and South Lake Tahoe in 1995

Species (and cultivars) Number Total 110 Hardwoods 80 Conifers 30

106 107