Street Tree Inventory Report Downtown Neighborhood

Transcription

1 Street Tree Inventory Report Downtown Neighborhood November 2013

2 Street Tree Inventory Report: Downtown Neighborhood November 2013 Compiled by: Jeff Ramsey, Angie DiSalvo, Danielle Fuchs, Jeremy Grotbo, and Shannan Stoll Portland Parks & Recreation Urban Forestry Downtown Tree Inventory Organizers: Mehmet Balkan, Laura Holloway, and Hannah Prather Staff Neighborhood Coordinator: Jeff Ramsey Data Collection Volunteers: Susan Bliss, Betsy Breyer, Charles Brock, Aaron Choate, Casey Cunningham, Desirea Daranno, Amber Davis, Anna Dodson, Mattew Downs, Sarah Eastman, Ken Finney, Sara Fisher, Cynthia Glidden, Lee Greer, Nancy Hawver, Laura Holloway, Aulani Johnson, Noreen Johnston, Daryl Justice, Jeff King, Bill Kownacki, Howard Kronish, Natasha Lipai, Craig Loftin, Linda Loftin, Mat Millenbach, Maysa Miller, Amanda Morse, Jen Morse, Patty Newland, Adrienne Nichols, Carol Orange, Mary Ann Pastene, Ann Ramsey, Cara Ramsey, Tim Ramsey, Bruce Richard, Beppie Shapiro, Ryan Sipe, Mary Vogel, Steven Cody Wall, Lili Wheary, Lea Wilson, Emily Wilson, Samantha Wolf, and Robert Zimmerman Data Entry Volunteers: Dianna Choi, Megan Cohen-Doyle, Debby Danner, David Dearth, Mike Ellis, Erin Etchison, Rosalie Gordon, Tyler Jennings, Marie Jones, Lauren Kael, Alyssa Kocsis, Sean McMillen, Ryan Sipe, Jenni Smith, Rebecca Wetherby, Emily Wilson, and John Zalewski Arborist-on-Call Volunteers: Matt Allen, Sean McMillen, and Hannah Prather GIS Technical Support: Josh Darling, Portland Parks & Recreation Financial Support: Portland Parks & Recreation Cover Photo: Volunteers collecting tree inventory data in Downtown neighborhood ver. 11/7/13 Portland Parks & Recreation 1120 SW Fifth Avenue, Suite 1302 Portland, Oregon (503) 823-PLAY Commissioner Amanda Fritz Director Mike Abbaté

3 Table of Contents Project Overview Executive Summary Neighborhood Characteristics Urban Forest Composition Tree type composition Tree type importance values Species diversity Functional tree type and mature tree size distribution Size Class Distribution Tree Condition Planting Site Composition Planting site type Planting site size Right tree in the right place Stocking Level Replacement Values Environmental and Aesthetic Benefits Recommendations References Appendices A: Methods B: Street trees of Downtown by tree type C: Street trees of Downtown by size (map) D: Small street trees (trees 6 DBH) (map) E: Large street trees (trees > 24 DBH) (map) F: Poor and dead street trees (map) G: Planting site types (map) H: Available street tree planting spaces (map) Portland Parks & Recreation i

4 Volunteers, guided by Portland Parks & Recreation Urban Forestry staff, collected data on all 3,617 street trees within Downtown neighborhood to compile the neighborhood s first complete street tree inventory. The data are being used to inform the creation of a Neighborhood Tree Plan to guide volunteers in caring for their community s trees. ii Street Tree Inventory Report Downtown 2013

5 Project Overview This report provides the results of a street tree inventory conducted in Downtown neighborhood in 2013, along with Portland Parks & Recreation (PP&R) Urban Forestry staff recommendations to improve the condition of the urban forest. Street trees were inventoried in Downtown in summer 2013 by trained volunteers and PP&R Urban Forestry staff. Over the course of four work days, 49 volunteers contributed 267 hours collecting data on 3,617 trees. Street trees at every tax lot in the neighborhood were inventoried (see Appendix A for inventory methods). Data collected included tree type (species or genus), condition, size (diameter at breast height), planting strip width, planting site type, and presence of overhead high voltage wires. Data were supplemented with available planting space data collected by the Bureau of Environmental Services. Data analysis and recommendations were completed by PP&R Urban Forestry staff. Volunteers trained in tree identification and data collection acted as team leaders. Volunteer teams collected data on paper maps and forms. Questions regarding species or site identification were answered by certified arborists or PP&R staff during data collection. Staff conducted spot checks on data to verify accuracy. The data were later digitized and entered into an ArcGIS geodatabase by volunteers. Organizers in the Downtown neighborhood were essential to coordinating work days, recruiting volunteers, and promoting the project within the community. A special note of thanks is due to inventory organizers Mehmet Balkan, Laura Holloway, and Hannah Prather for their dedication to the project. If you would like to get involved with Downtown s urban forest, contact the Portland Downtown Neighborhood Association by visiting or contact PP&R Urban Forestry. Data from the inventory are available to the public in spreadsheet or ArcGIS format. Visit the Tree Inventory Project website at to learn more about the project and download reports, data, and maps. Volunteers were essential to organizing and completing the tree inventory: 49 volunteers contributed over 267 hours to completing the project. Portland Parks & Recreation 1

6 Executive Summary During the summer of 2013, the Downtown neighborhood conducted a street tree inventory with Portland Parks & Recreation Urban Forestry. Forty-nine volunteers contributed 267 hours identifying, mapping, measuring, and assessing every street tree in the neighborhood. URBAN FOREST STRUCTURE The street tree population consists of 3,617 trees of 45 types. Fifteen tree types comprise 91.5% of the resource. Norway maples (20.9%), red maples (19.0%), London planes (9.2%), oaks (9.0%), and lindens (8.2%) are the most common trees. Thirty-eight tree genera are found in the neighborhood. The Acer genus comprises a significant portion of the resource at 43.2%, followed by Platanus at 9.2%. Twenty-one tree families are represented. 43.3% of trees are in the Sapindaceae (soapberry) family, 9.2% are in the Platanaceae (plane) family, 9.2% are in the Fagaceae (beech) family, and 8.2% are in the Malvaceae (mallow) family. All other families represent 6% or less of the population each. Broadleaf deciduous trees account for 98.5% of all street trees. Large form trees account for 53.8% of the population, followed by medium (41.5%) and small (4.7%) form trees. Downtown s trees are unevenly distributed, with more trees in medium diameter size classes. Twenty-four percent of all trees are 6 diameter at breast height (DBH) or less, 28% are between 6.1 and 12.0 DBH, 30% are between 12.1 and 18.0 DBH, and 19% are larger than 18.1 DBH. 43.7% of trees rated good, 50.9% rated fair, 5.0% poor, and 0.4% are dead. Of the most commonly found tree types, the healthiest are sweetgum, hawthorn, and tulip poplar, of which 100% were rated good or fair. In poorest condition are Norway maple and honey locust, of which at least 9% rated poor. PLANTING SITES AND STOCKING LEVEL Street trees are found in 98.8% improved rights-of-way sites and 1.2% unimproved rights-of-way. 90% of all street tree planting spaces are currently stocked with trees. 397 available planting spaces have been identified, including 20 high priority spaces in existing sites and 377 sites that would require concrete removal. REPLACEMENT VALUES The replacement cost of the street tree population is valued at $14,818,626. The tree types with the greatest replacement values were Norway maple ($4,034,208), London plane ($2,274,824), red maple ($2,163,999), and oak ($1,682,150). These four tree types account for 68.5% of the total replacement value. ENVIRONMENTAL AND AESTHETIC BENEFITS Downtown s street trees provide $560,000 annually in environmental services and aesthetic benefits, including $429,000 in property value increases, $7,800 in air quality improvement, $3,600 in carbon dioxide reduction, $22,800 in energy savings, and $98,800 in stormwater processing. Each tree provides an average of $155 worth of benefits annually. 2 Street Tree Inventory Report Downtown Neighborhood 2013

7 Neighborhood Characteristics The Downtown neighborhood is located in the central core of Portland, roughly bounded by I-405 to the east and south, the Willamette River to the east, and W. Burnside Street to the north (Figure 1). Figure 1: Location of Downtown neighborhood in Portland NORTHWEST GOOSE HALLOW Sunset Hwy SW Taylor St SW Salmon St Interstate 405 Interstate 405 UTHWEST HILLS PEARL W Burnside St SW Washington St SW Alder St SW Broadway Ave SW Clay St SW Market St South Park Blocks North Park Blocks O'Bryant Square Pioneer Courthouse Director Square Park Plaza Blocks SW Madison St SW 4th Ave SW Naito Pkwy SW 3rd Ave SW Main St Keller Fountain Pettygrove City Park Lovejoy Fountain Central Park OLD TOWN- CHINATOWN Hawthorne Bridge Morrison Bridge Interstate 5 Gov. Tom McCall Waterfront Park South Waterfront Park Marquam Bridge Burnside Bridge KERNS BUCKMAN HOSFORD- ABERNETHY 11 SW Harbor Dr Willamette River SOUTH PORTLAND The oldest neighborhood in Portland, Downtown began development as early as the 1840 s and is now known for its central business district, Portland State University campus, and large green spaces along the west bank of the Willamette River and South Park Blocks. One of the most populated neighborhoods in Portland, Downtown residents mainly live in multi-story apartment complexes. Downtown is home to several parks, including Governor Tom McCall Waterfront Park, the South Park Blocks, and the Plaza Blocks of Chapman and Lownsdale Squares. Downtown is located in the Willamette River watershed. Tree canopy covers 17% of Downtown, below Portland s city-wide canopy level of 29% (Metro 2008). Compared to population density city-wide, Downtown is of above average density, with 24 persons per acre (Table 1). Fifteen percent of properties in Downtown are owner-occupied. Table 1: Neighborhood and citywide demographics Demographics (2010 Census) Downtown Portland Area 535 acres 85,376 acres Population 12, ,776 Density 24 persons/acre 7 persons/acre Race % of properties occupied by homeowners 78% white; 6% Hispanic/Latino; 10% Asian; 5% black 15% 54% 76% white; 9% Hispanic/Latino; 7% Asian; 6% black Portland Parks & Recreation 3

8 Urban Forest Composition TREE TYPE COMPOSITION Trees were identified to the genus or species level and categorized as types (Appendix A). Six maple types are identified to the species level: bigleaf, Japanese, Norway, paperbark, red, and silver. All other maples are identified to the genus level only and placed into the other maple type. Downtown s public rights-of-way host a diverse array of tree types. The street tree population consists of 3,617 trees of 45 types (Appendix B). Norway maples are the most common tree type, representing 20.9% of all street trees. Red maples, London planes, oaks, and lindens are also common, representing 19.0%, 9.2%, 9.0%, and 8.2% of trees, respectively. The most common fifteen tree types comprise 91.5% of the resource, leaving the remaining types to represent 1% or less of the resource each (Table 2). Table 2: The 15 most abundant street tree types in Downtown Common Scientific Number % of Mean Name Name of Trees Total Trees DBH maple, Norway Acer platanoides % 15.2 maple, red Acer rubrum % 10.5 London plane Platanus acerifolia % 15.3 oak Quercus spp % 13.7 linden Tilia spp % 12.6 ash Fraxinus spp % 6.1 sweetgum Liquidambar styraciflua % 17.1 elm Ulmus spp % 19.5 pear Pyrus spp % 8.1 maple, other Acer spp % 7.8 zelkova Zelkova serrata % 7.2 honey locust Gleditsia triacanthos % 8.3 hawthorn Crataegus spp % 7.8 tulip poplar Liriodendron tulipifera % 9.6 hornbeam Carpinus spp % 9.9 all other tree types % Of the most abundant tree types, the types with the largest average size are elm and sweetgum, with mean diameters at breast height of 19.5 and 17.1 inches, respectively. London planes have the third largest mean diameter at breast height at 15.3 inches. Thirty-eight genera are represented in the neighborhood. The Acer genus comprises a significant portion of the resource at 43.2%, followed by Platanus at 9.2% (Table 3, Figure 2). All other genera comprise 9% or less of the resource each. 4 Street Tree Inventory Report Downtown Neighborhood 2013

9 Table 3: The 15 most abundant street tree genera in Downtown Figure 2: The 10 most abundant street tree genera in Downtown Genus Total # % of of Trees Total Trees Acer 1, % Platanus % Quercus % Tilia % Fraxinus % Liquidambar % Pyrus % Ulmus % Zelkova % Gleditsia % Crataegus % Liriodendron % Carpinus % Cercidiphyllum % Celtis % all other genera % Gleditsia 2% Zelkova 2% Ulmus 3% Pyrus 3% Liquidambar 4% Fraxinus 5% Tilia 8% Other 12% Quercus 9% Platanus 9% Acer 43% Twenty-one families are represented in the neighborhood, and the fifteen most abundant families comprise 98.8% of the resource. Sapindaceae (soapberry), Platanaceae (plane), Fagaceae (beech), and Malvaceae (mallow) are the most commonly found and represent 43.3%, 9.2%, 9.2%, and 8.2% of trees, respectively (Table 4). All other families represent less than 6% of the resource each. Portland Parks & Recreation 5

10 Table 4: The 15 most abundant tree families in Downtown Family Family Tree Types Included Number of % of Scientific Name Common Name in the Family Trees Total Trees Sapindaceae soapberry horsechestnut, maple 1, % Platanaceae plane London plane % Fagaceae beech oak, beech % Malvaceae mallow linden % Rosaceae rose cherry, crabapple, hawthorn, moutain % ash, pear, plum, serviceberry Ulmaceae elm elm, zelkova % Oleaceae olive ash % Altingiaceae sweetgum sweetgum % Leguminosae legume black locust, honey locust, redbud, % yellow wood Magnoliaceae magnolia magnolia, tulip poplar % Betulaceae birch birch, hornbeam % Cercidiphyllaceae katsura katsura % Cannabaceae hemp hackberry % Ginkgoaceae ginkgo ginkgo % Cornaceae dogwood dogwood, tupelo % all other families (6) % TREE TYPE IMPORTANCE VALUES The contribution of a single tree type to the entire resource can be quantified by assigning each tree type an importance value. The importance value is the mean of three relative values: percentage of total trees, percentage of total leaf area, and percentage of canopy cover. The importance value can range from 0 to 100. Importance values were calculated using itree Streets, an urban forest analysis software suite developed by the USDA Forest Service. The higher the importance value, the more the urban forest relies on a single tree type to provide functional benefits, such as canopy cover. Reliance on only a few tree types is risky, as loss from a pest, disease, or a catastrophic event may put excessive strain on the urban forest even though a single tree type may be affected. High importance values do not mean that these tree types should necessarily be used in the future, rather that these species currently dominate the urban forest structure. Norway maple, red maple, and oak have the highest importance values: 26.0, 16.9, and 12.3 respectively (Table 5). Thus, the Downtown urban forest is reliant on these three species due to their maturity, size, leaf area, and prevalence in the neighborhood. The next highest importance values are for London plane (9.5), linden (8.1), elm (6.0), and sweetgum (4.9). All other tree types had importance values of 2.2 or less. 6 Street Tree Inventory Report Downtown Neighborhood 2013

11 Table 5: Tree types with the highest importance values Common Scientific Name Importance Name Value (IV) maple, Norway Acer platanoides 26.0 maple, red Acer rubrum 16.9 oak Quercus spp London planetree Platanus acerifolia 9.5 linden Tilia spp. 8.1 elm Ulmus spp. 6.0 sweetgum Liquidambar styraciflua 4.9 ash Fraxinus spp. 2.2 pear Pyrus spp. 1.9 maple, other Acer spp. 1.8 zelkova Zelkova serrata 1.4 honeylocust Gleditsia tricanthos 1.1 tulip tree Liriodendron spp. 1.0 hawthorn Crataegus spp. 0.9 all other trees 6.0 Total SPECIES DIVERSITY Maintaining a diverse species mix (species diversity) is a critical way to promote a healthy and resilient urban forest. A general rule of thumb for urban forest species diversity is the rule (Santamour 1990). No species should represent more than 10% of the total population, no genus should represent more than 20% of the total population, and no family should represent more than 30% of the total population. Downtown does not meet the species diversity guidelines for species, genus, or family. Norway and red maples make up 20.9% and 19.0% of trees, respectively; the Acer genus makes up 43.2% of trees; and the Sapindaceae (soapberry) family makes up 43.3% of trees Downtown. FUNCTIONAL TREE TYPE AND MATURE TREE SIZE DISTRIBUTION Broadleaf deciduous trees dominate the landscape, accounting for 98.5% of all street trees in Downtown (Table 6). Broadleaf evergreen trees comprise 1.0% and coniferous evergreen trees comprise 0.4% of the total. Table 6: Functional tree type and mature tree size Functional Mature Tree Size Tree Type Small Medium Large Total Broadleaf deciduous 4.3% 40.8% 53.4% 98.5% Broadleaf evergreen 0.4% 0.6% 0.0% 1.0% Coniferous evergreen 0.0% 0.1% 0.3% 0.4% Deciduous conifer 0.0% 0.0% 0.1% 0.1% Total 4.7% 41.5% 53.8% 100.0% Figure 3: Tree form sizes 60 feet 40 feet 20 feet SMALL MEDIUM LARGE Mature Tree Size Portland Parks & Recreation 7

12 Mature tree size is determined by the height, canopy width, and general form of the tree at maturity; trees types are classified as small, medium, or large. Generally, small trees grow to 20 in height, medium trees grow to 40 in height, and large trees grow to 60 or greater (Figure 3). Small-sized trees account for 4.7% of the resource, medium-sized trees account for 41.5% of the resource, and large-sized trees account for 53.8% of the resource. Size Class Distribution Although tree species have different lifespans and mature at different sizes, urban forest age can generally be correlated to tree size. Older trees will generally have a larger size, as measured by diameter at breast height (DBH, 4.5 feet above ground). As trees increase in size and age, the value of the tree and the magnitude of the benefits that the tree provides also increases until the tree nears the end of its lifespan and begins to decline. Trees were categorized into diameter size classes (Figure 4; Appendices C, D, E). Trees that are inches in diameter represent young trees. Trees that are inches in diameter and represent midlife trees, as well as mature small form trees. Trees that are 18.1 inches or greater in diameter represent mature trees. Figure 4: Trees by diameter size class 35% 30% 25% Percent of Trees 20% 15% 10% 5% 0% >30 Diameter Class (Inches) An uneven-aged population is desirable for managing tree maintenance costs over time, as age diversity ensures that canopy coverage is not reduced with mortality. Downtown s streets host a wide range of tree sizes from the youngest sapling to the largest, a 56 DBH London plane (Platanus acerifolia). Downtown s trees are unevenly distributed, with more trees in medium diameter size classes. Twenty-four percent of all trees are 6 DBH or less, 28% are between 6.1 and 12.0, 30% are between 12.1 and 18.0 DBH, and 19% are larger than 18.1 DBH. 8 Street Tree Inventory Report Downtown Neighborhood 2013

13 Tree Condition Tree condition was assessed by assigning trees to one of four categories: good, fair, poor, or dead. These general ratings reflect whether or not a tree is likely to continue contributing to the urban forest (good and fair trees) or whether the tree is at or near the end of its life (poor and dead trees). 43.7% of trees rated good, 50.9% rated fair, 5.0% poor, and 0.4% are dead (Figure 5, Appendix F). Of the most commonly found tree types, the healthiest trees were sweetgum, hawthorn, and tulip poplar, of which 100% were rated good or fair (Table 7). In poorest condition were Norway maple and honey locust, of which at 9% rated poor. Figure 5: Tree Condition Poor 5% Fair 51% Dead 0.4% Good 44% Table 7: Tree condition for the 15 most abundant tree types Common Scientific % of Total Trees (Number of Trees) Name Name Good/Fair Poor ash Fraxinus spp. 98.1% (153) 1.9% (3) elm Ulmus spp. 98.1% (104) 1.9% (2) hawthorn Crataegus spp. 100% (68) 0% (0) honey locust Gleditsia triacanthos 88.9% (64) 11.1% (8) hornbeam Carpinus spp. 97.7% (42) 2.3% (1) linden Tilia spp. 98% (288) 2% (6) London plane Platanus acerifolia 93.4% (310) 6.6% (22) maple, Norway Acer platanoides 90.7% (684) 9.3% (70) maple, other Acer spp. 95.4% (83) 4.6% (4) maple, red Acer rubrum 95.5% (653) 4.5% (31) oak Quercus spp. 98.8% (319) 1.2% (4) pear Pyrus spp. 95.3% (101) 4.7% (5) sweetgum Liquidambar styraciflua 100% (136) 0% (0) tulip poplar Liriodendron tulipifera 100% (53) 0% (0) zelkova Zelkova serrata 97.6% (80) 2.4% (2) Planting Site Composition PLANTING SITE TYPE Planting site locations can be placed into two categories: improved and unimproved rights-of-way. In improved rights-of-way, sidewalks, curbs, and tree planting areas are installed and clearly defined. In these areas, trees may be found in plantings strips between the curb and sidewalk, cut-outs surrounded by concrete, and in swales designed for stormwater capture. Medians, traffic circles, and curb tight areas are also considered improved rights-of-way. In unimproved rights-of-way, tree planting locations are less clearly defined and planting sites include areas without sidewalks and/or curbs. In unimproved rights-ofways, trees were inventoried if they were located within ten feet of the curb. Although they may initially appear to be privately owned trees, these are street trees in the public right-of-way. Portland Parks & Recreation 9

14 Street trees in Downtown are found in 98.8% improved rights-of-way sites and 1.2% unimproved rights-of-way (Table 8). Cutouts are the most common tree planting site. Table 8: Planting site types Site Site Number of Category Type Trees improved planting sites 3,556 sites; 98.8% of total sites unimproved planting sites 61 sites; 1.2% of total sites cutout 2,530 median 132 other 75 planting strip 783 swale 36 curb only 37 no curb or sidewalk 24 PLANTING SITE SIZE Planting site sizes are categorized as small, medium, or large depending upon the presence of overhead high voltage wires and the width of the planting site. Improved planting sites have a clearly defined width while unimproved sites do not. Planting site categories reflect the mature tree size that can be supported by the planting site. In other words, small planting sites can support small trees such as dogwoods and snowbells and large planting sites can support large trees such as oaks and elms. Urban Forestry recommends specific tree planting lists for sites, and further breaks down the small, medium, and large categories to specific width ranges in order to account for the variation in growth form of the many species appropriate for planting in the right-of-way (Table 9). The size, type, and number of planting sites represent the infrastructure currently supporting right-of-way tree planting. Table 9: Planting site sizes Site Size Planting Site Description Figure 6: Size composition for improved planting sites small medium large improved sites wide with or without wires improved sites wide with or without wires improved sites >6.0 wide with wires unimproved sites with wires improved sites >6.0 without wires unimproved sites without wires Note: wires refers to high voltage wires only Large 19.9% 692 sites Small 8.6% 298 sites Medium 71.6% 2,491 sites Because this project did not inventory all available planting sites, but only sites where trees were currently growing, data for planting site sizes include information from an earlier assessment of planting opportunities completed by PP&R Urban Forestry in February In Downtown, 19.9% of existing planting sites are small, 71.6% are medium, and 19.9% are large (Figure 6). 10 Street Tree Inventory Report Downtown Neighborhood 2013

15 RIGHT TREE IN THE RIGHT PLACE Tree placement is vital for maximizing the benefits trees provide and minimizing avoidable costs. The right tree in the right place will experience fewer obstacles to reaching maturity and will be easier to maintain. For example, large form trees should not be placed under high voltage wires, as they are likely to be subject to heavy pruning by utility companies to maintain clearance standards. Large planting strips without high voltage power lines provide the best opportunity for expanding canopy and maximizing benefits from trees. A small-growing tree in a large planting strip represents a missed opportunity, as it will not live as long or grow as large as a larger-growing tree. In wide planting sites without wires, 8% of trees are undersized for the strip (Table 10). In planting sites 8.5 or great without wires, 31% of trees are undersized for the strip. Table 10: Tree types found in large planting sites Planting Site Tree species planted Tree species planted Code and Description are large enough for site are too small for site without wires 92% (271) 8% (24) >8.5 without wires 69% (272) 31% (125) Stocking Level Street tree stocking level reflects the percentage of planting spaces that are currently occupied by trees. Planting space availability is subject to a number of guidelines, including width of the planting site, presence/absence of high voltage power lines, and distance from conflicts (property lines, stop signs, and underground utilities). Stocking level data were collected by PP&R Urban Forestry for improved sites as well as planting opportunities that would necessitate cutting a tree well in existing concrete. Ideally, stocking level should be near 100%. Downtown s stocking level is 90% for improved planting sites (Table 11). 397 empty spaces have been identified for tree planting (Appendices H and I). Twenty spaces are in existing tree wells or planting strips, and 377 sites would require concrete removal. Table 11: Street tree stocking level in improved right-of-way planting sites Site Size Planting Site Stocking Identified Empty Description Level Planting Spaces small with or without wires 100% 0 small with or without wires 100% 0 medium without wires 78% existing sites 20 sites requiring concrete removal 377 large without wires 100% 0 large >8.5 without wires 100% 0 Totals 90% 397 Portland Parks & Recreation 11

16 Replacement Values A replacement value is an estimate of the full cost of replacing a tree at its current size and condition, should it be removed for some reason. Replacement values are based on the Council of Tree and Landscape Appraisers Guide for Plant Appraisal. This guide bases replacement value on regional species ratings, trunk diameter, and replacement costs. Replacement values were calculated using itree Streets, a software suite from the USDA Forest Service that provides urban forestry analysis and benefits assessment tools. The replacement cost of Downtown s tree population is valued at $14,818,627. The most valuable size classes of trees are those between 12 DBH and 24 DBH (Figure 8). Typically, replacement values are highest for larger, more prevalent tree types. The tree types with the greatest replacement values were Norway maple ($4,034,208), London plane ($2,274,824), red maple ($2,163,999), and oak ($1,682,150). These four tree types account for 68.5% of the total replacement value. Figure 8: Replacement values of trees by diameter class (inches) $6,000,000 $5,000,000 Replacement Value $4,000,000 $3,000,000 $2,000,000 $1,000,000 $ > 42 DBH Class (Inches) Environmental and Aesthetic Benefits Downtown s street tree population was assessed to quantify the dollar value of annual environmental services and aesthetic benefits provided by trees: aesthetic/property value increase, air quality improvement, carbon dioxide reduction, energy savings, and stormwater processing. Calculations were made using itree Streets. The itree model relies on tree size and species from the inventory, as well as Portland s current pricing for electricity and natural gas, regional benefit prices for air quality, regional stormwater interception costs, and the neighborhood s median home resale value (Zillow 2013). Downtown s street trees provide over $560,000 annually in environmental services and aesthetic benefits, as calculated by itree Streets (Table 12). Annual benefits are valued by category at approximately $429,000 in aesthetic and property value increases, $7,800 in air quality improvement, $3,600 in carbon dioxide reduction, $22,800 in energy savings, and $98,800 in stormwater processing. Each tree provides an average of $155 worth of benefits annually. 12 Street Tree Inventory Report Downtown Neighborhood 2013

17 Benefit calculations for tree types rely on the size and number of trees within a particular type, as well as the tree type s mature tree form. Thus most benefits are provided by larger, broad-spreading and common trees. Less common, smaller form, and younger trees will provide the fewest benefits. The calculation indicates the benefits that trees currently provide: as trees grow and the population changes, benefits derived from the various tree types will change within a neighborhood. Of the most common tree types, oak, elm, and Norway maple provided the highest annual benefits per tree, at approximately $185 - $257 per tree (Table 13). Sweetgum, linden, London plane, and red maple also provided a high level of annual benefit between $148 and $178. Hawthorn and pear provided the least amount of benefits, ranging from $50 -$61 annually. Table 12: Valuation of the environmental and aesthetic benefits provided annually by Downtown s street trees Benefits Total Total per tree Aesthetic/property value increase $428,883 $ Air quality improvement $7,802 $2.16 Carbon dioxide reduction $3,606 $1.00 Energy savings $22,840 $6.31 Stormwater processing $98,753 $27.30 Total benefits $561,884 $ Table 13: Average annual environmental and aesthetic benefits provided by Downtown s most abundant street tree types Tree Type Aesthetic/ Air CO2 Energy Stormwater Total Prop. Value Quality Reduction Savings Processing per tree ash $72.40 $1.43 $0.37 $0.60 $6.53 $81.32 elm $ $12.65 $1.64 $5.00 $67.93 $ hawthorn $40.00 $2.10 $0.91 $0.75 $5.77 $49.53 honeylocust $83.70 $2.73 $0.62 $0.92 $9.66 $97.63 hornbeam $77.62 $2.12 $0.29 $0.70 $9.54 $90.26 linden $ $5.93 $0.84 $2.01 $27.26 $ London planetree $ $7.05 $1.35 $2.39 $29.54 $ maple, Norway $ $8.45 $1.39 $2.96 $38.14 $ maple, other $97.20 $3.88 $0.66 $1.34 $16.97 $ maple, red $ $6.17 $0.74 $2.08 $22.42 $ oak $ $9.12 $1.51 $3.14 $41.50 $ pear $39.54 $3.71 $0.55 $1.57 $15.59 $60.96 sweetgum $ $8.99 $1.28 $2.18 $39.03 $ tulip tree $87.31 $3.74 $0.78 $1.26 $14.91 $ zelkova $64.39 $2.76 $0.40 $0.67 $11.58 $79.80 Portland Parks & Recreation 13

18 Recommendations Based on street tree inventory data presented in this report, PP&R Urban Forestry staff make the following recommendations for the Downtown neighborhood. PLANTING Reduce dependence on maples by planting a diverse array of species, genera, and families. Plant trees in all available planting spaces. Downtown s street tree stocking level is 90% and 397 spaces have been identified for planting street trees (Appendix G). All but 20 of the identified spaces will require concrete removal to create tree wells. YOUNG TREE ESTABLISHMENT AND MAINTENANCE Properly water and establish young trees. With 24% of trees being 6 DBH or less, special attention should be paid to this vulnerable population (Appendix D). Small trees represent the future generation of street trees, and early care and training will pay off in future benefits. Structurally prune young trees to promote proper form as street trees. This includes removing low limbs for pedestrian and traffic clearance and removing codominate leaders. Structural pruning is critical in the first ten years after planting and can prevent many future problems. MATURE TREE MAINTENANCE Maintain and care for large, mature trees. Nearly 20% of trees in Downtown are larger than 18 diameter. Trees provide the most benefits as they reach maturity, and tree care is also the most expensive for these large trees. Increasing the level of maintenance of large, mature trees will help prolong their lifespan, reduce hazards, and keep these high-value members of the urban forest contributing to the neighborhood. Many mature trees in the Downtown neighborhood have outgrown their sites. Often, grates that were appropriately sized at the time of planting are now obstructing the growth of the tree, which will eventually lead to their failure. Contacting property owners or Urban Forestry staff is the first step in addressing this issue. Retain existing large trees in fair and good condition. Benefits are lost when older trees are removed and replaced with smaller and younger tree species, due to the time it takes for young trees to mature. Promote the importance and benefits of large-form species and mature trees within the community, and advocate for large-form species in the development review process. 14 Street Tree Inventory Report Downtown Neighborhood 2013

19 REPLACEMENTS Encourage removal and replacement of dead trees and trees in poor condition. 5.4% of Downtown s trees are dead (16 trees) or in poor condition (181 trees) (Appendix F). Further assessment of trees for hazards by a certified arborist can help with prioritization for replacement. Encourage replacement of underperforming species, including undersized trees in large rights-ofway, with higher functioning, appropriately sized trees. In large planting sites without high voltage wires, 149 trees have been identified as being too small for their respective site. These trees should be evaluated on an individual basis for replacement. Portland Parks & Recreation 15

20 References City of Portland Office of Neighborhood Involvement. Accessed 10/3/ Portland Neighborhood Demographic Data. Metro State of the Watersheds Monitoring Report. watersheds_2008_revised_ pdf Portland Parks & Recreation Portland s Urban Forest Canopy: Assessment and Public Tree Evaluation. Santamour, Frank S., Jr Trees for Urban Planting: Diversity, Uniformity, and Common Sense. Proceedings of the 7th Conference of Metropolitan Tree Improvement Alliance (METRIA) 7: US Census Bureau. Accessed 10/3/2012. Portland, Oregon, State and County Quick Facts. census.gov/qfd/states/41/ html US Forest Service. itree Streets (version 5.0). Zillow Home Value Index. Accessed 8/11/ Street Tree Inventory Report Downtown Neighborhood 2013

21 Appendix A: Methods Street trees were inventoried in summer 2013 by trained volunteers and PP&R Urban Forestry staff. Street trees at every tax lot in the neighborhood were inventoried. Street trees are located in the public right-of-way, typically between the sidewalk and curb. DATA COLLECTED Data collected included tree type identified to species or genus, condition, size (diameter at breast height), planting strip width, planting site type, and presence of overhead high voltage lines. Tree type: Trees were identified to the genus or species. Six maple species were identified to the species level: bigleaf (Acer macrophyllum) Japanese (A. palmatum), Norway (A. platanoides), paperbark (A. griseum), red (A. rubrum) and silver (A. saccharinum) maple. All other maple species were identified as maple, other. Tree types of dead trees were listed as unknown, as identification was difficult. Tree condition: Trees were rated as either good, fair, poor, or dead. These general ratings reflect whether or not a tree is likely to continue contributing to the urban forest (good and fair trees) or whether the tree is at or near the end of its life (poor and dead trees). The following guidelines were used. Good: Tree is healthy and vigorous with no apparent problems. Roots are sound, trunk is solid with no bark damage, and crown is full. No wounds, decay, conks, cavities, root heaving or other symptoms. Fair: Tree is in average condition. Tree may need some pruning and have some dead branches. Wounds are minimal but there is no major decay. Other signs and symptoms are minimal. Poor: Tree is in a general state of decline as indicated by the presence of cavities, decay, conks, root heaving, or significant dead crown areas. Dead: Tree is dead or close to dying. Dead trees were excluded from data analsysis, with the exception of tree condition analysis. Tree size: Diameter at breast height (4.5 above ground) was measured with a diameter tape. Measurements of trees with branches, forks, or swelling at 4.5 were taken lower on the tree. Trees with multiple stems were measured individually and PP&R staff made final diameter calculations in the office. Trees with many low multiple stems (>3 were measured near ground level). Planting strip width: Planting strip width was measured from the inside of the curb to the sidewalk. Planting site type: Planting site types were placed into one of the following categories: Curb No Sidewalk: The site has a curb but no sidewalk. Cutout: The site is a concrete cutout, also called a tree pit or tree well. Portland Parks & Recreation 17

22 Median: The site is in the middle of the street. No Curb No Sidewalk: The site is unimproved with no curb or sidewalk. Strip: The tree is a planting strip between a curb and a sidewalk. Swale: The tree is in the middle of a bioswale designed for stormwater capture. Other: Traffic circles and other miscellaneous scenarios. High voltage wires: The presence of voltage wires was recorded. Stocking level: Inventory data were supplemented with available planting space data collected by PP&R Urban Forestry and the Bureau of Environmental Services in 2012 and These data were compared with existing tree data collected at the same time and used to calculate stocking level. Some industrial, commercial, and multi-family residential areas may be excluded in the analysis. DATA COLLECTION METHODS Volunteer neighborhood coordinators recruited volunteers to conduct street tree inventories during four work days. Volunteers interested in being inventory team leaders attended a half-day training to learn to identify tree species and site conditions, and how to collect and record data. During work days, team leaders were paired with novice volunteers to collect data in a three to four block area. Groups were given a clipboard containing a map, data entry sheets, tree type abbreviations, and a list of trees planted by Friends of Trees in the neighborhood. Volunteers wore safety vests and carried a diameter tape, tree identification book, and bags for collecting samples. In addition to PP&R staff, one or more volunteer arborists-on-call was available on inventory work days to assist volunteers with questions. Accuracy was stressed as highly important, and volunteers utilized the arborist-on-call to verify species identification as questions arose. Data were collected on paper maps and forms, and later digitized in ArcGIS by PP&R staff and trained volunteers. Accuracy of volunteer-collected data was checked by PP&R staff and corrections were made as necessary. Remaining areas not completed during inventory work days were inventoried by volunteer team leaders. In Downtown, 74% of the inventory data were collected by volunteers. Spot-checks of the final data set found species identifications to be over 95% accurate. 18 Street Tree Inventory Report Downtown Neighborhood 2013

23 Appendix B: Street trees of Downtown by tree type Common Scientific Number % of Mean Name Name of Trees Total Trees DBH ash Fraxinus spp % 6.1 beech Fagus spp % 11.8 birch Betula spp % 10.6 black locust Robinia pseudoacacia 3 0.1% 15.3 cherry Prunus spp % 14.1 crabapple Malus spp % 9.3 cypress Chamaecyparis spp % 4.8 dawn redwood Metasequoia glyptostroboides 2 0.1% 8.7 dogwood Cornus spp % 6.1 elm Ulmus spp % 19.5 ginkgo Ginkgo biloba % 10.5 hackberry Celtis occidentalis % 3.9 hawthorn Crataegus spp % 7.8 holly Ilex spp % 13.7 honey locust Gleditsia triacanthos % 8.3 hornbeam Carpinus spp % 9.9 horsechestnut Aesculus spp % 23.7 incense cedar Calocedrus decurrens 8 0.2% 19.2 katsura Cercidiphyllum japonicum % 6.0 linden Tilia spp % 12.6 London plane Platanus acerifolia % 15.3 magnolia Magnolia spp % 1.2 magnolia, Southern Magnolia grandiflora % 6.5 maple, bigleaf Acer macrophyllum 1 0.0% 44.2 maple, Japanese Acer palmatum % 7.6 maple, Norway Acer platanoides % 15.2 maple, other Acer spp % 7.8 maple, paperbark Acer griseum % 3.0 maple, red Acer rubrum % 10.5 mountain ash Sorbus spp % 8.1 oak Quercus spp % 13.7 pear Pyrus spp % 8.1 Persian ironwood Parrotia persica 9 0.2% 5.0 plum Prunus spp % 8.5 poplar Populus spp % 8.1 redbud Cercis canadensis 4 0.1% 1.6 serviceberry Amelanchier spp % 2.8 snowbell Styrax spp % 3.3 sweetgum Liquidambar styraciflua % 17.1 tulip poplar Liriodendron tulipifera % 9.6 Portland Parks & Recreation 19

24 Common Scientific Number % of Mean Name Name of Trees Total Trees DBH tupelo Nyssa sylvatica % 4.0 unknown (dead) unknown % 4.7 Western redcedar Thuja plicata 4 0.1% 8.8 willow Salix spp % 5.2 yellow wood Cladrastis lutea 3 0.1% 4.5 zelkova Zelkova serrata % 7.2 Grand Total 3, % Street Tree Inventory Report Downtown Neighborhood 2013

25 SW HALL ST SW 10TH AVE SW 9TH AVE SW 3RD AVE Appendix C: Street trees of Downtown by size Downtown Street Tree Inventory 2013 Trees by Size SW WASHINGTON ST SW 14TH AVE SW 13TH AVE SW 12TH AVE SW 11TH AVE SW PARK AVE SW PARK AVE SW BROADWAY SW 6TH AVE SW 5TH AVE SW 4TH AVE W BURNSIDE ST SW ALDER ST SW YAMHILL ST SW TAYLOR ST SW SALMON ST SW MAIN ST SW MORRISON ST SW ANKENY ST INTERSTATE 405 SW 2ND AVE SW PINE ST SW 1ST AVE SW OAK ST SW STARK ST SW MADISON ST SW JEFFERSON ST MORRISON SW COLUMBIA ST SW CLAY ST SW MARKET ST SW MILL ST SW NAITO PKWY HAWTHORNE SW HARRISON ST Diameter at Breast Height (4.5 feet) in inches: SW COLLEGE ST SW JACKSON ST SW LINCOLN ST INTERSTATE 405 SW WATER AVE SW HARBOR DR SW RIVER WALK SW HARBOR PL SW RIVER PKWY SW RIVER DR INTERSTATE 5 MARQUAM Miles $ Portland Parks & Recreation 21

26 SW HALL ST SW 10TH AVE SW 9TH AVE SW 3RD AVE Appendix D: Small street trees (trees 6 DBH) Downtown Street Tree Inventory 2013 Small Trees SW WASHINGTON ST SW 14TH AVE SW 13TH AVE SW 12TH AVE SW 11TH AVE SW PARK AVE SW PARK AVE SW BROADWAY SW 6TH AVE SW 5TH AVE SW 4TH AVE W BURNSIDE ST SW ALDER ST SW YAMHILL ST SW TAYLOR ST SW SALMON ST SW MAIN ST SW MORRISON ST SW ANKENY ST INTERSTATE 405 SW 2ND AVE SW PINE ST SW 1ST AVE SW OAK ST SW STARK ST SW MADISON ST SW JEFFERSON ST MORRISON SW COLUMBIA ST SW CLAY ST SW MARKET ST SW MILL ST SW NAITO PKWY HAWTHORNE SW HARRISON ST Diameter at Breast Height (4.5 feet) in inches: SW COLLEGE ST SW JACKSON ST SW LINCOLN ST INTERSTATE 405 SW WATER AVE SW HARBOR DR SW RIVER WALK SW HARBOR PL SW RIVER PKWY SW RIVER DR INTERSTATE 5 MARQUAM Miles $ 22 Street Tree Inventory Report Downtown Neighborhood 2013

27 SW HALL ST SW 10TH AVE SW 9TH AVE SW 3RD AVE Appendix E: Large street trees (trees > 24 DBH) Downtown Street Tree Inventory 2013 Large Trees SW WASHINGTON ST SW 14TH AVE SW 13TH AVE SW 12TH AVE SW 11TH AVE SW PARK AVE SW PARK AVE SW BROADWAY SW 6TH AVE SW 5TH AVE SW 4TH AVE W BURNSIDE ST SW ALDER ST SW YAMHILL ST SW TAYLOR ST SW SALMON ST SW MAIN ST SW MORRISON ST SW ANKENY ST INTERSTATE 405 SW 2ND AVE SW PINE ST SW 1ST AVE SW OAK ST SW STARK ST SW MADISON ST SW JEFFERSON ST MORRISON SW COLUMBIA ST SW CLAY ST SW MARKET ST SW MILL ST SW NAITO PKWY HAWTHORNE SW HARRISON ST Diameter at Breast Height (4.5 feet) in inches: SW COLLEGE ST SW JACKSON ST SW LINCOLN ST INTERSTATE 405 SW WATER AVE SW HARBOR DR SW RIVER WALK SW HARBOR PL SW RIVER PKWY SW RIVER DR INTERSTATE 5 MARQUAM Miles $ Portland Parks & Recreation 23

28 SW 10TH AVE SW 9TH AVE SW 3RD AVE Appendix F: Poor and dead street trees Downtown Street Tree Inventory 2013 Poor and Dead Trees SW WASHINGTON ST SW ALDER ST SW 14TH AVE SW 13TH AVE SW 12TH AVE SW 11TH AVE E SW PARK AVE SW PARK AVE SW BROADWAY SW 6TH AVE SW 5TH AVE SW 4TH AVE W BURNSIDE ST E E SW ANKENY ST SW MORRISON ST SW YAMHILL ST SW TAYLOR ST SW SALMON ST SW MAIN ST INTERSTATE 405 E E E SW 2ND AVE SW PINE ST SW 1ST AVE SW OAK ST SW STARK ST E SW MADISON ST SW JEFFERSON ST MORRISON SW COLUMBIA ST SW CLAY ST SW MARKET ST SW MILL ST E E SW NAITO PKWY E E HAWTHORNE SW HARRISON ST Diameter at Breast Height (4.5 feet) in inches: SW HALL ST SW COLLEGE ST SW JACKSON ST E Dead Trees SW LINCOLN ST INTERSTATE 405 E E E SW WATER AVE SW HARBOR DR SW RIVER WALK SW HARBOR PL SW RIVER PKWY SW RIVER DR INTERSTATE 5 MARQUAM Miles $ 24 Street Tree Inventory Report Downtown Neighborhood 2013

29 SW HALL ST SW 10TH AVE SW 9TH AVE SW 3RD AVE Appendix G: Planting site types Downtown Street Tree Inventory 2013 Site Type SW WASHINGTON ST SW 14TH AVE SW 13TH AVE SW 12TH AVE SW 11TH AVE SW PARK AVE SW PARK AVE SW BROADWAY SW 6TH AVE SW 5TH AVE SW 4TH AVE W BURNSIDE ST SW ALDER ST SW YAMHILL ST SW TAYLOR ST SW SALMON ST SW MAIN ST SW MORRISON ST SW ANKENY ST INTERSTATE 405 SW 2ND AVE SW PINE ST SW 1ST AVE SW OAK ST SW STARK ST SW MADISON ST SW JEFFERSON ST MORRISON SW COLUMBIA ST SW CLAY ST SW MARKET ST SW MILL ST SW NAITO PKWY HAWTHORNE SW HARRISON ST SW COLLEGE ST Small: improved sites wide with or without wires SW JACKSON ST Medium: improved sites wide with or without wires, improved sites >5.9 wide with wires, unimproved with wires Large: improved sites >5.9 without wires, unimproved without wires SW LINCOLN ST INTERSTATE 405 SW WATER AVE SW HARBOR DR SW RIVER WALK SW HARBOR PL SW RIVER PKWY SW RIVER DR INTERSTATE 5 MARQUAM Miles $ Portland Parks & Recreation 25

30 SW HALL ST SW 10TH AVE SW 9TH AVE SW 3RD AVE Appendix H: Available street tree planting spaces Downtown Street Tree Inventory 2013 Available street tree planting spaces SW WASHINGTON ST SW 14TH AVE SW 13TH AVE SW 12TH AVE SW 11TH AVE SW PARK AVE SW PARK AVE SW BROADWAY SW 6TH AVE SW 5TH AVE SW 4TH AVE W BURNSIDE ST SW ALDER ST SW YAMHILL ST SW TAYLOR ST SW SALMON ST SW MAIN ST SW MORRISON ST SW ANKENY ST INTERSTATE 405 SW 2ND AVE SW PINE ST SW 1ST AVE SW OAK ST SW STARK ST SW MADISON ST SW JEFFERSON ST MORRISON SW COLUMBIA ST SW CLAY ST SW MARKET ST SW MILL ST SW NAITO PKWY HAWTHORNE SW HARRISON ST SW COLLEGE ST SW JACKSON ST SW LINCOLN ST SW HARBOR DR SW RIVER WALK SW HARBOR PL SW RIVER DR Available street tree planting spaces: INTERSTATE 405 SW WATER AVE SW RIVER PKWY INTERSTATE 5 MARQUAM Miles $ 26 Street Tree Inventory Report Downtown Neighborhood 2013