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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 South Lake Tahoe Menlo Park Santa Barbara Richness 35 145 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 (pi)2 D = diversity index pi = proportion of individuals in the population belonging to species i 13 Simpson’s Divesity Indicies of Hypothetical Urban Forests Urban Forest #1 Urban Forest #2 3 Urban Forest #3 Proportion of Population Represented by Species (pi) Forest ___ are needed QuickTime™ decompressor to see this and picture. a ___ ___ ___ QuickTime™ and a decompressor are needed to see this picture. are needed QuickTime™ decompressor to see this and pictu a QuickTime™ and a decompressor 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 Index Simpson’s Diversity 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 Bangkok Lagos New Delhi Rio de Janeiro Singapore Dry Climates Cario Dubai Lhasa Phoenix Moist, Mid-latitude, Mild Winters Beijing Moscow Stockholm Tokyo Polar Murmansk Nuuk Reykjavik 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 Tropical Moist Example City Average Species Richness Singapore 37 Dry Cairo Moist, Mid-latitude New York with mild winters Moist, Mid-latitude Moscow with cold winters Polar Murmansk 28 48 32 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 D = Moist, Mid-latitude Climates with cold winters E = Polar Climates • 40 ¨ • • 30 • 20 10 • A B C Koppen ¨ Climate D E 24 Frost Hardiness Zones QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. 25 Urban Forest Species Richness in Relation to Hardiness Zones Hardiness Zone Temperature Range (oF) Example City 3-4 -40 to -20 Murmansk Average Species Richness 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 3-4 = -40 to -20o F 5-6 = -20 to 0 7-8 = 0 to 20 9-10 = 20 to 40 11-12 = 40 to 60 13-14 = 60 to 80 50 • • • 40 ¨ • 30 • 20 10 • 3-4 5-6 7-8 9-10 Hardiness Zone 11-12 13-14 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 Rio de Janeiro Singapore Brasilia Lagos New Delhi Broadleaf Evergreen Forest Grassland Hong Kong Sydney Tokyo Buenos Aires Johannesburg Tehran Deciduous Forest Desert New York London Paris Cairo Dubai Phoenix Mixed Deciduous-Coniferous Forest Tundra Beijing Moscow Stockholm Murmansk Nuuk Reykjavik Coniferous Forest Highlands Jacksonville Seattle Vancouver Cusco Lhasa Quito Mediterrean Woodland-Scrub Athens Los Angeles Tel Aviv 34 Average Tree Species Richness in Cities in Different Biomes Biome Tropical Forest Broadleaf Evergreen Deciduous Forest Mixed Deciduous-Coniferous Forest Coniferous Forest Mediterranean Woodland-Scrub Savanna Grassland Desert Tundra Highland Average Number of Tree Species* 35 36 49 32 45 49 51 41 29 9 34 * Trees in the public right-of-way 35 36 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 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 Biome* Deciduous Forest Grassland Broadleaf Evergreen Coniferous Forest Presence of London Plane Tree** British Non-British Colonial Colonial Cities(%) Cities(%) 100 100 100 50 100 0 100 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 tr ee Spacin g (ft.) Lond on 40 N ew Yor k* 40 N ew De lhi* 40 Cairo * 40 Ho ng Kong* 40 Lagos* 40 Singa pore * 40 Vancouv er* 40 Syd ney* 50 Johanne sbu rg* 35 Par is 38 Seatt le 35 Athen s 30 Stoc kho lm 28 Tokyo 25 Moscow 20 Teh ra n 20 * Forme r British Colon ial City; Modal Spacing of Trees in Boulevard Medians 45 National Pride QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor 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 decompressor are needed to see this picture. QuickTime™ and a decompressor 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 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 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 decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. Bishop Ranch Business Park 56 Trees Planted at Bishop Ranch Business Park Black locust Callery pear Canary Island pine Chinese pistache Coast live oak Cork oak Crape myrtle Deodar cedar Evergreen ash Hollywood juniper Honey locust Italian stone pine Lombardy poplar London plane Redwood Tulip tree Gledista triacanthos Pyrus calleryana Pinus canariensis Pistacia chinensis Quercus agrifolia Quercus suber Lagerstroemia indica Cedrus deodara Fraxinus uhdei Juniperus chinensis Robinia pseudoacacia Pinus pinea Populus nigra ‘italica’ Platanus x acerifolia Sequoia sempervirens Liriodendron tulipfera 57 Trees not Planted at Bishop Ranch Business Park Cherry Crabapple Gingko Strawberry Tree Mulberry Prunus spp. Malus spp. Gingko biloba Arbutus unedo Morus spp. 58 Messy Tree Fruit QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a 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. 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 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 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 Bangkok New Delhi Singapore Hong Kong Dubai Tree Bo Tree Neem Tree Bo Tree Bo Tree Ghaf tree Scientific Name Ficus religiosa Azadirachta indica Ficus religiosa Ficus religiosa Prosopis cineraria 72 Bo Tree Nepal 73 Bo Tree Bangkok 74 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 Northeast Species Planted 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 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 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 Conifer Hardwoods Number of Species 6 3 Percent 67 33 Trees offered for sale in Lake Tahoe Basin in 1995 Tree Type Conifer Hardwoods Number of Species 30 80 Percent 27 73 85 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 86 QuickTime™ and a decompressor are needed to see this picture. American Elm - Dutch Elm Angsana - Angsana Wilt Disease Green Ash - Emerald Ash Borer Horse Chestnut - Bleeding Canker Disease; Leaf Miner Moth 87 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 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, California Menlo Park, CA 1975 10010080100- Age Structure of Sweetgum and California Pepper Tree Sweetgum Age Structure of Sweetgum and1975 California Pepper Tree Menlo Park, CA California Pepper Menlo Park, CA 1975 Sweetgum Sweetgum California Pepper California Pepper 80% 6080- California Pepper 1975 1905 % 60% 4060402040- 1925 20200-191945 0-19 0-19 Sweetgum 20-39 20-39 20-39 1885 40-59 60-79 Age 40-59 60-79 40-59 Age 60-79 Age 80-99 80-99 80-99 100-120 100-120 100-120 90 Trends in Species Diversity 91 Trends in Tree Diversity Cities w ith street trees freq uencie s of 50 percen t or greater Biom e City Species Decid uous For est Lond on Lond on Plane Tree 67 Par is Lond on Plane tr ee 67 Jacks onville Live Oak 70 Laur el O ak 50 Moscow Co m mo n Lim e 83 Beijing Jap ane se Pago da T ree 56 Stoc kho lm Co m mo n Lim e 50 Bu eno s Aires Gr een Ash 67 Teh ra n Or ien tal Pl ane Tree 54 Lhasa Chin ese Wh ite Poplar 67 Co nife r For est Mixed De cid uou sCo ni ferous Forest Gr assland H ighl and Freq uen cy 92 Species Richness in American vs. European Cities American Cities City European Cities Species Richness* New York 2.4 City London Species Richness* 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 QuickTime™ and a decompressor are needed to see this picture. Average Maximun Temperature* = 69o F 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 decompressor are needed to see this picture. Redding Average Maximun Temperature* = 98o F Extreme Maximum Temperature = 118o F QuickTime™ and a decompressor are needed to see this picture. Palm Springs Average Maximun Temperature* = 108o 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) Total Hardwoods Conifers Number 110 80 30 106 107