Street Tree Inventory Report Northwest District Neighborhood

Transcription

1 Street Tree Inventory Report Northwest District Neighborhood November 2012

2 Street Tree Inventory Report: Northwest District Neighborhood November 2012 Compiled by: Angie DiSalvo, Danielle Fuchs, and Christina Schull Portland Parks & Recreation Urban Forestry Northwest District Tree Inventory Organizers Jack Anliker and Mary Anne Pastene Data Collection Volunteers Dorothy Aeto, Mala Aeto, Henry Amick, Darrin Amico, Jack Anliker, Jerry Beatty, Aaron Blumenkron, Greg Bojanowski, Charles Brock, Dan Buri, Nanette Cardon, Susanne Cavicchi, Nick Clark, Alice Corbin, Ronna Craig, Jennifer de Thomas, Bhronwhyn Dean, Peter Del Zotto, Ivy Dunlap, Brooke Geltzeiler, Kelsey Giltz, Fran Goldstein, Mike Goldstein, Estebany Gomez, Teddy Graham, Zach Gustafson, Monica Halka, Bill Harris, Tiffany Harris, Ai Hasada, Nancy Hawver, Judith Henninger, Amick Henry, Lynda Jeffers, Lauren Kael, Kevin Kenaga, Jeff King, Bill Kownacki, Howard Kronish, Landon Lane, Kevin Macquoid, Ali Malekghasemi, Megan Meek, Louis Miles, Andrew Montano, Angela Moos, Tom Myers, Kimanh Nguyen, Susan Oliver, Carol Olwell, Kathy Parkin, Mary Ann Pastene, Ann Pedersen, Nelly Perez, Susan Perez, Olivia Poblacion, Jeff Ramsey, Alison Reddy Abel, Phyllis Reynolds, Bruce Richard, Matt Sanchez, Kathy Sharp, Gail Shibley, Fujiko Shono, Vicki Skryha, Martha Stewart, David Taylor, Erica Timm, Olena Turula, Paul Weaver, Rebecca Wetherby, Barbara Wharton, Alena Wheary, Lilli Wheary, and Ruth Williams Data Entry Volunteers Nanette Cardon, Thom Green, Tren Haselton, Lauren Kael, Natasha Lipai, Dawn McCloud, Jesse Schaefer, Debbie Stoller, and Anne Swinford Arborist-on-Call Volunteers Matt Allen, Kris Day, Rick Faber, Allen Matthew, and Olena Turula GIS Technical Support Josh Darling, Portland Parks & Recreation Financial Support Portland Parks & Recreation Portland Parks & Recreation 1120 SW Fifth Avenue, Suite 1302 Portland, Oregon (503) 823-PLAY Commissioner Nick Fish Director Mike Abbaté

3 Table of Contents Project Overview... 1 Executive Summary Neighborhood Characteristics... 3 Urban Forest Composition Tree type composition Tree type importance values... 5 Species diversity Functional tree type and mature tree size distribution... 6 Relative tree age... 7 Tree Condition... 7 Stocking Level... 8 Right tree in the right place... 9 Replacement Values Environmental and Aesthetic Benefits Recommendations References Appendices A: Methods B: Street trees of Northwest District by tree type C: Street trees of Northwest District 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: Available street tree planting spaces (map) H: Priority street tree planting spaces (map) Portland Parks & Recreation i

4 Volunteers guided by Portland Parks & Recreation Urban Forestry staff collected data on all 5,013 street trees within Northwest District to compile the neighborhood s first complete street tree inventory. Data is being used to inform the creation of a Neighborhood Stewardship Plan to guide volunteers in caring for their community s trees. ii Street Tree Inventory Report Overlook Neighborhood 2011

5 Project Overview Project Overview This report provides results of a street tree inventory conducted in Northwest District neighborhood in 2012, along with Portland Parks & Recreation (PP&R) Urban Forestry staff recommendations to improve the condition of the urban forest. Street trees were inventoried in Northwest District in summer 2012 by trained volunteers and PP&R Urban Forestry staff. Over the course of three work days, 75 volunteers contributed 379 hours collecting data on 5,013 trees. Street trees at every tax lot in the neighborhood were inventoried; data collected included tree type (species or genus), condition, size (diameter at breast height), planting strip width, and presence of overhead high voltage lines. Data on available planting spaces was collected by PP&R Urban Forestry Staff. 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. Data was later digitized and entered into an ArcGIS geodatabase by volunteers. Residents of the Northwest District were essential to organizing workshops, recruiting volunteers, and promoting the project within the community. A special note of thanks is due to inventory organizers Jack Anliker and Mary Anne Pastene for their tireless dedication to the project. If you would like to get involved with Northwest District s urban forest, contact the Northwest District Association by visiting www. northwestdistrictassociation.org/ or contact PP&R Urban Forestry. Data from the inventory is available to the public in spreadsheet or ArcGIS format by contacting PP&R Urban Forestry. Portland Parks & Recreation 1

6 Executive Summary During summer 2012, the Northwest District neighborhood conducted a street tree inventory with Portland Parks & Recreation Urban Forestry. Seventy-five volunteers contributed 379 hours identifying, mapping, measuring, and assessing every street tree in the neighborhood. Urban Forest structure The street tree population consists of 5,013 trees of 82 types. Fifteen tree types comprise 80% of the resource. Red maple (15.5%), cherry (10.3%), and Norway maple (9.8%) are the most common trees. Thirty-three tree families are represented. 36.3% of trees are in the Sapindaceae (soapberry) family and 31.4% are in the Rosaceae (rose) family. All other families represent less than 5% of the population each. Broadleaf deciduous trees account for 98% of all street trees. Medium form trees account for 39.1% of the population, followed by small (31.3%) and large (29.6%) form trees. Northwest District s trees have an uneven age distribution. Thirty percent of all trees are less than 6 DBH, 30% are between 6 and 12, 25% are between 12 and 18 DBH, and 16% are larger than 18 DBH. 61.5% of trees rated good, 29.0% rated fair, 8.7% poor, and 0.8% are dead. Of the most commonly found tree types, the healthiest trees are hornbeam, sweetgum, paperbark maple, and linden, of which over 98% are rated good or fair. In poorest condition are plum, crabapple, cherry, and ash, of which at least 10% rated poor. stocking level 87% of all street tree planting spaces are currently stocked with trees. 762 available planting spaces have been identified, including 71 high priority spaces in wide planting strips without overhead wires. Replacement Values The replacement cost of the street tree population is valued at $19,119,874. The tree types with the greatest replacement values were red maple ($3,181,453), cherry ($2,614,455), Norway maple ($1,757,144) and elm ($1,651,289): these four tree types account for 48% of the total replacement value. Environmental and Aesthetic Benefits Northwest District s street trees provide over $440,000 annually in environmental services and aesthetic benefits, including $286,000 in property value increases, $9,000 in air quality improvement, $5,000 in carbon dioxide reduction, $27,000 in energy savings, and $113,000 in stormwater processing. Each tree provides an average of $96 worth of benefits annually. 2 Street Tree Inventory Report Northwest District Neighborhood 2012

7 Neighborhood Characteristics Northwest District neighborhood is located in northwest Portland (Figure 1). The Northwest District neighborhood boundaries are NW Nicolai Street to the north, Interstate 405 to the east, NW Burnside Street to the south and NW Cornell Street and Forest Park to the west. Figure 1: Location of Northwest District neighborhood in Portland The Northwest District is a densely populated commercial and residential neighborhood. Two popular commercial districts run north to south, NW 23rd Avenue and NW 21st Avenue. The areas are popular destinations for dining, entertaining, and shopping. The Alphabet Historic District, named for the alphabetical progression of street names in the area, is in the heart of Northwest and is zoned for historic preservation. The neighborhood is one of Portland s oldest. Craftsman- and old Portland-style houses are packed tightly together with grand old apartment buildings and new condominium developments. The area scores high for walkability and public transport. The Portland Streetcar connects the district to the Pearl District and Downtown Portland. Key neighborhood tree assets include Couch Park, Wallace Park, and neighboring Forest Park. Northwest District is located in the Willamette River watershed. Compared to city-wide averages, Northwest District is a densely populated area with 14 persons per acre (Table 1). Only 31% of homes in Northwest District are owner-occupied. Table 1: Neighborhood and citywide demographics Demographics (2010 Census) NW District Portland Area 976 acres 85,395 acres Population 13, ,776 Density 14 persons/acre 7 persons/acre Race 87% white; 13% non-white 76% white; 24% non-white % of properties occupied by homeowners 31% 58% Portland Parks & Recreation 3

8 Urban Forest Composition TREE TYPE composition Northwest District s public rights-of-way host a diverse array of tree types (trees identified to the species or genus level). The street tree population consists of 5,013 trees of 82 types. Fifteen tree types comprise nearly 80% of the resource, leaving the remaining types to represent less than 2% of the resource each (Table 2). Red maples are the most common tree type, representing 15.3% of all street trees. Cherry, Norway maple, and pear and the next most common tree types, representing 10.3%, 9.8%, and 8.3% of trees, respectively. Table 2: Distribution of the 15 most abundant street tree types in Northwest District Common Species Number % of Mean Name of Trees Total Trees DBH maple, red Acer rubrum % 11.9 cherry Prunus spp % 14.0 maple, Norway Acer platanoides % 11.0 pear Pyrus spp % 9.2 crabapple Malus spp % 10.1 maple, other Acer spp % 10.2 linden Tilia spp % 14.7 plum Prunus spp % 13.5 ash Fraxinus spp % 9.4 sweetgum Liquidambar styraciflua % 17.4 oak Quercus spp % 15.4 maple, Japanese Acer palmatum % 5.0 maple, paperbark Acer griseum % 3.4 hornbeam Carpinus spp % 9.6 birch Betula spp % 12.9 Of the most abundant tree types, the type with the largest average size is sweetgum, with a mean DBH of 17.4 inches. Oak (15.4 inches DBH) and linden (14.7 inches DBH) have the next largest mean diameters at breast height. Thirty-three families are represented in the neighborhood, and the fifteen most abundant families comprise 96% of the resource. Sapindaceae (soapberry) and Rosaceae (rose) are the most commonly found and represent 36.3% and 31.4% of trees, respectively (Table 3). All other families represent 4.2% or less each of the resource. 4 Street Tree Inventory Report Northwest District Neighborhood 2012

9 Table 3: Distribution of the 15 most abundant tree families in Northwest District Family Family Tree Types Included Number of % of Scientific Name Common Name in the Family Trees Total Trees Sapindaceae soapberry boxelder, goldenrain tree, horsechestnut, maple % Rosaceae rose apple, cherry, crabapple, hawthorn, medlar, mountain ash, peach, pear, plum, serviceberry % Oleaceae olive ash, lilac tree, olive % Malvaceae mallow linden % Betulaceae birch alder, birch, hazelnut, hophornbeam, hornbeam % Altingiaceae sweetgum sweetgum % Fagaceae beech beech, chestnut, oak % Ulmaceae elm elm, zelkova % Leguminosae legume amur maackia, black locust, golden chain tree, honey locust, redbud % Styracaceae styrax snowbell % Cornaceae dogwood dogwood, tupelo % Ginkgoaceae maidenhair ginkgo % Magnoliaceae magnolia magnolia, tulip poplar % Cercidiphyllaceae katsura katsura % Cupressaceae cypress arborvitae, cypress, juniper, western red cedar % tree type IMPORtance Values The importance 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) and can range from 0 to 100. The higher the importance value, the more the urban forest relies on a single species to provide functional benefits. Reliance on only a few tree types is risky, as loss from a pest, disease, or a catastrophic event may put excessive strain on a single tree type. Importance values were calculated using itree Streets, an urban forest analysis software suite developed by the USDA Forest Service. Portland Parks & Recreation 5

10 Red maple has the highest importance value at 17.1 (Table 4). Norway maple (10.6), cherry (9.4), and elm (7.1) also have importance values. Thus, the Northwest District urban forestry is highly reliant on these four species due to their maturity, size, broad leaf area, and prevalence in the neighborhood. All other tree types had importance values of 6.2 or less. Table 4: Tree types with the highest importance values Common Scientific Name Importance Name Value (IV) maple, red Acer rubra 17.1 maple, Norway Acer platanoides 10.6 cherry Prunus spp. 9.4 elm Ulmus spp. 7.1 pear Pyrus spp. 6.2 linden Tilia spp. 5.5 maple, other Acer spp. 5.2 oak Quercus spp. 4.8 sweetgum Liquidambar spp. 4.6 crabapple Malus spp. 3.5 ash Fraxinus spp. 2.9 plum Prunus spp. 2.8 horsechestnut Aesculus spp. 2.5 birch Betula spp. 1.7 maple, Japanese Acer palmatum 1.3 hornbeam Carpinus spp. 1.2 hawthorn Crataegus spp. 1.1 all other trees 12.5 Total Species Diversity 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, no genus should represent more than 20% of the total, and no family should represent more than 30% of the total. Northwest District does not meet the species diversity guideline for individual species, genus, or family. Red maple (Acer rubrum) and cherry (Prunus spp.) are overrepresented at 15.5% and 10.3% respectively. Norway maple (Acer plantanoides) is close to the 10% species threshold at 9.8%. The maple (Acer) genus is overrepresented at 34.9% of the resource. The family Sapindaceae (soapberry), which contains the maple family, is overrepresented at 36.3% and the family Rosaceae (rose) is overrepresented at 31.4% of the resource. Functional tree type and mature tree size distribution Broadleaf deciduous trees dominate the landscape, accounting for 97.9% of all street trees (Table 5). Broadleaf evergreen trees comprise 0.8% and coniferous evergreen trees comprise 0.0% of the total. Mature tree size (small, medium, and large) is determined by the height, canopy width, and general form of the tree at maturity. Medium-sized trees account for 39.1%, small trees account for 31.3%, and large trees account for 29.6% of the resource. 6 Street Tree Inventory Report Northwest District Neighborhood 2012

11 Table 5: Distribution of trees by functional tree type and mature tree size Functional Tree Type Small Medium Large Total Broadleaf deciduous 30.8% 38.0% 29.1% 97.9% Broadleaf evergreen 0.4% 0.5% 0.0% 0.8% Coniferous evergreen 0.0% 0.0% 0.0% 0.0% Palm evergreen 0.2% 0.6% 0.4% 1.2% Total 31.3% 39.1% 29.6% 100.0% Relative Tree Age The relative ages of trees may be approximated using size measured by diameter at breast height (DBH). Generally, trees increase in size with age, along with the value of the tree and the magnitude of the benefits that the tree provides. Trees were categorized into diameter classes to show the proportion of trees at various stages of maturity (Figure 2). Note that an uneven-aged population is desirable for managing tree maintenance costs over time. Age diversity ensures that canopy coverage and community complexity are not reduced with mortality. Figure 2: Relative tree age (tree size by diameter class) Northwest District s streets host a wide range of tree sizes from the youngest sapling to the largest, a 57 DBH elm (Ulmus spp.). Overall, Northwest District s trees are unevenly distributed. Thirty percent of all trees are less than 6 DBH, 30% are between 6 and 12, 25% are between 12 and 18 DBH, and 16% are larger than 18 DBH (Figure 2). 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). 61.5% of trees rated good, 29.0% rated fair, 8.7% poor, and 0.8% are dead (Table 6). Portland Parks & Recreation 7

12 Table 6: Trees by condition class Condition % of Total Trees Good 61.5% Fair 29.0% Poor 8.7% Dead 0.8% Of the most commonly found tree types, the healthiest trees were hornbeam, sweetgum, paperbark maple, and linden, of which over 98% were rated good or fair (Table 7). In poorest condition were plum, crabapple, cherry, and ash of which at least 10% rated poor. Table 7: Condition class percentages and numbers of trees for the 15 most abundant tree types Common Species % of Total Trees (Number of Trees) Name Good Fair Poor maple, red Acer rubrum 74.3% (576) 21.8% (169) 3.9% (30) cherry Prunus spp. 43.5% (225) 36.2% (187) 20.3% (105) maple, Norway Acer platanoides 53.2% (260) 37.2% (182) 9.6% (47) pear Pyrus spp. 58.6% (245) 33% (138) 8.4% (35) crabapple Malus spp. 27.6% (81) 48.1% (141) 24.2% (71) maple, other Acer spp. 56.5% (143) 38.7% (98) 4.7% (12) linden Tilia spp. 66.3% (136) 32.2% (66) 1.5% (3) plum Prunus spp. 45.3% (86) 28.9% (55) 25.8% (49) ash Fraxinus spp. 68.6% (127) 21.1% (39) 10.3% (19) sweetgum Liquidambar styraciflua 80.1% (117) 19.2% (28) 0.7% (1) oak Quercus spp. 76.7% (99) 20.2% (26) 3.1% (4) maple, Japanese Acer palmatum 84.7% (94) 11.7% (13) 3.6% (4) maple, paperbark Acer griseum 81.1% (77) 17.9% (17) 1.1% (1) hornbeam Carpinus spp. 86.3% (82) 13.7% (13) 0% (0) birch Betula spp. 64% (57) 32.6% (29) 3.4% (3) Stocking Level 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 strip, presence/absence of high voltage power lines, and distance from conflicts (property lines, stop signs, and underground utilities). Stocking level data was provided by PP&R Urban Forestry. Ideally, stocking level should be near 100%. Northwest District s stocking level is 87% (Table 8). 762 empty spaces have been identified for tree planting. Planting spaces are categorized into planting strip categories based upon width and overhead wire presence. The lowest stocking levels are found in the smallest planting strip size of Street Tree Inventory Report Northwest District Neighborhood 2012

13 Table 8: Street tree stocking level data Planting Strip Available Existing Total Stocking Code and Description Planting Spaces Trees Spaces Level A with or without wires % B 3-4 with or without wires % C 4-6 without wires % D 4-6 with wires % E without wires % F >6 with wires % G >8.5 without wires % Totals % 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. 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 strips without wires, 59% of trees are undersized for the strip (Table 9). In planting strips 8.5 or great without wires, 37% of trees are undersized for the strip. Table 9: Percentage and number of adequately sized trees growing in large planting strips without wires Planting Strip Tree species planted Tree species planted Code and Description are large enough for strip are too small for strip E without wires 41% (192) 59% (277) G >8.5 without wires 63% (94) 37% (56) 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. The replacement cost of Northwest District s tree population is valued at $19,119,874 (Figure 3). The most valuable size classes of trees are those between 12 DBH and 18 DBH (Figure 5). Typically, replacement values are highest for larger, more prevalent tree types. The tree types with the greatest replacement values were red maple ($3,181,453), cherry ($2,614,455), Norway maple ($1,757,144) and elm ($1,651,289). These four tree types account for 48% of the resource s total replacement value. Portland Parks & Recreation 9

14 Figure 3: Replacement values of trees by diameter class (inches) Environmental and Aesthetic Benefits Using itree Streets, Northwest District s street tree population was assessed to quantify the dollar value of annual environmental services and aesthetic benefits provided by trees: energy conservation, air quality improvement, carbon dioxide reduction, stormwater control, and property value increase. The model relies on tree size and species, as well as current pricing for electricity rates, median home resale value, regional stormwater interception costs, and costs of tree maintenance. Northwest District s street trees provide over $440,000 annually in environmental services and aesthetic benefits, as calculated by itree Streets (Table 10). Annual benefits are valued by category at approximately $286,000 in property value increases, $9,000 in air quality improvement, $5,000 in carbon dioxide reduction, $27,000 in energy savings, and $113,000 in stormwater processing. Each tree provides an average of $88 worth of benefits annually. Table 10: Valuation of the environmental and aesthetic benefits provided annually by Northwest District s street trees Benefits Total ($) $ / Tree Aesthetic/other (property value increase) $285,921 $57.00 Air quality improvement $9,240 $1.84 Carbon dioxide reduction $4,513 $0.90 Energy savings $27,187 $5.42 Stormwater processing $113,445 $22.62 Total benefits $440,306 $87.78 Of the most common tree types, elms provided the highest annual per tree benefits, at $303 per tree (Table 11). Oak and horsechestnut also provided a high level of annual benefit, at $202 and $178, respectively. Snowbell, dogwood, crabapple and hawthorn provided the least amount of benefits, ranging from $12 to $49 annually. 10 Street Tree Inventory Report Northwest District Neighborhood 2012

15 Table 11: Average annual environmental and aesthetic benefits provided by Northwest District s most abundant street tree types Tree Type Aesthetic/ Air CO2 Energy Stormwater Total ($) Other Quality Reduction Savings Processing per tree maple, red $75.87 $2.37 $0.80 $7.25 $25.70 $ cherry $25.52 $1.77 $0.65 $4.68 $19.11 $51.75 maple, Norway $75.46 $2.01 $0.97 $6.03 $26.05 $ pear $26.61 $1.79 $0.64 $4.39 $17.73 $51.17 crabapple $30.90 $0.97 $1.32 $2.73 $7.77 $43.69 maple, other $73.60 $1.83 $0.90 $5.51 $23.78 $ linden $87.56 $2.45 $0.97 $7.48 $34.22 $ plum $41.18 $1.45 $1.96 $3.98 $11.97 $60.54 ash $60.21 $1.26 $0.68 $3.21 $14.87 $80.23 sweetgum $83.82 $2.29 $1.37 $9.86 $41.30 $ oak $ $3.63 $1.67 $10.78 $51.09 $ maple, Japanese $56.48 $0.70 $0.39 $2.21 $9.12 $68.89 maple, paperbark $49.81 $0.34 $0.22 $1.12 $4.54 $56.03 hornbeam $68.35 $0.70 $0.36 $2.23 $9.64 $81.29 birch $47.13 $1.74 $0.44 $5.18 $22.31 $76.81 elm $ $8.87 $2.80 $22.39 $ $ hawthorn $34.05 $1.09 $1.55 $3.04 $8.90 $48.63 snowbell $9.35 $0.23 $0.23 $0.69 $1.64 $12.14 dogwood $21.39 $0.18 $0.10 $0.76 $2.86 $25.29 ginkgo $42.43 $1.12 $0.66 $3.41 $14.21 $61.85 horsechestnut $92.05 $4.55 $2.32 $13.49 $65.84 $ Portland Parks & Recreation 11

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17 Recommendations Based on street tree inventory data presented in this report, PP&R Urban Forestry staff make the following recommendations for the Northwest District neighborhood. Planting Reduce dependence on maples and cherries by planting a diverse array of species, genera, and families. Red maple is highly overrepresented at 15.5% of all trees and PP&R recommends not planting additional red maples. Plant trees in all available planting spaces. Northwest District s street tree stocking level is 87% and 762 spaces have been identified for planting street trees (Appendix G). Prioritize planting opportunities to plant large, high performing trees that will provide high levels of benefits over their lifetime. These trees are best planted in large planting strips (>6 ) without overhead wires. In these planting strips, 71 spaces have been identified for planting (Appendix H). Plant in the smallest planting strips last. Trees in small planting strips provide fewer benefits and are more likely to cause sidewalk and clearance problems in a shorter time frame than if they were planted in larger spaces. However, all plantings help contribute to a neighborhood tree ethic and encourage others to plant and maintain street trees. Take advantage of existing planting programs, such the Friends of Trees neighborhood planting program. Currently, Northwest District does not participate in the program. Young Tree Establishment and Maintenance Properly water and establish young trees. With 30% 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. Educate property owners on how to properly care for young street trees (branch and root pruning, watering, and mulching) in order to reduce and delay future problems and conflicts with infrastructure. Mature Tree Maintenance Maintain and care for large, mature trees. Sixteen percent of trees in Northwest District 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 Portland Parks & Recreation 13

18 help prolong their lifespan, reduce hazards, and keep these high-value members of the urban forest contributing to the neighborhood. Seek funding or assistance for low-income property owners to care for their mature trees. 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. Replacements Encourage removal and replacement of dead trees and trees in poor condition. 9.5% of Northwest District s trees are dead (41 trees) or in poor condition (440 trees). 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 strips without high voltage wires, 333 trees are identified as being too small for their respective strip. These trees should be evaluated on an individual basis for replacement. 14 Street Tree Inventory Report Northwest District Neighborhood 2012

19 References City of Portland Office of Neighborhood Involvement. Accessed 10/3/ Portland Neighborhood Demographic Data. 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 3.1). Portland Parks & Recreation 15

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21 Appendices Appendix A: Methods Street trees were inventoried in summer 2012 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, 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. Bark is undamaged, trunk is sound and solid, and crown is full. Fair: Tree is in average condition. Tree may need some pruning and have some dead branches. Damage to bark is minimal and there is no decay on trunk. Other problems are minimal. Poor: Tree is in a general state of decline as indicated by the presence of cavities, conks, decay, and many dead branches. 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 close to ground level were measured individually, and PP&R staff made final diameter calculations in the office. Planting strip width: Planting strip width was measured from the inside of the curb to the sidewalk. High voltage wires: Only high voltage wires were recorded. Stocking level: Inventory data was supplemented with available planting space data collected by PP&R Urban Forestry and the Bureau of Environmental Services in 2011 and This data Portland Parks & Recreation 17

22 was 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 three Saturday 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 was 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 and PP&R staff. In Northwest District, 88% of the inventory was collected by volunteers and 12% by PP&R staff. Spot-checks of the final data set found species identifications to be 95% accurate. 18 Street Tree Inventory Report Northwest District Neighborhood 2012

23 Appendix B: Street trees of Northwest District Association by tree type Common Scientific Number % of Mean Name Name of Trees Total Trees DBH alder Alnus spp % 8.8 American sycamore Platanus occidentalis % 22.6 amur maackia Maackia amurensis 9 0.2% 2.8 apple Malus domestica % 7.0 arborvitae Thuja arborvitae % 2.4 ash Fraxinus spp % 9.4 beautyberry Callicarpa spp % 0.5 beech Fagus spp % 8.0 birch Betula spp % 12.9 boxelder Acer negundo 1 0.0% 9.3 camellia Camellia spp % 16.8 catalpa Catalpa spp % 36.7 cedar Cedrus spp % 23.7 cherry Prunus spp % 14.0 chestnut Castanea spp % 7.6 crabapple Malus spp % 10.1 crape myrtle Lagerstroemia indica % 2.6 cryptomeria Cryptomeria spp % 12.4 cypress Cupressus % 2.4 dogwood Cornus spp % 3.3 Douglas fir Pseudotsuga menziesii 2 0.0% 11.1 elm Ulmus spp % 32.9 empress tree Paulownia tomentosa 2 0.0% 2.2 fig Ficus spp % 9.0 giant sequoia Sequoiadendron giganteum 1 0.0% 28.2 ginkgo Ginkgo biloba % 8.4 glorybower Clerodendron spp % 4.6 golden chain tree Laburnum anagyroides 3 0.1% 4.3 golden rain tree Koelreuteria paniculata % 10.8 hawthorn Crataegus spp % 10.7 hazelnut Corylus spp % 7.8 hophornbeam Ostrya spp % 3.1 hornbeam Carpinus spp % 9.6 horsechestnut Aesculus spp % 25.7 juniper Juniperus spp % 5.1 katsura Cercidiphyllum japonicom % 13.0 larch Larix spp % 39.0 lilac tree Syringa reticulata % 3.9 linden Tilia spp % 14.7 locust, black Robinia pseudoacacia 5 0.1% 18.5 Portland Parks & Recreation 19

24 Appendix B continued Common Scientific Number % of Mean Name Name of Trees Total Trees DBH locust, honey Gleditsia triacanthos % 8.0 London plane Platanus acerifolia 3 0.1% 16.2 madrone Arbutus menziesii 1 0.0% 6.4 magnolia Magnolia spp % 4.7 magnolia, southern Magnolia grandiflora % 4.7 maple, other Acer spp % 10.2 maple, bigleaf Acer macrophyllum 4 0.1% 22.4 maple, Japanese Acer palmatum % 5.0 maple, Norway Acer platanoides % 11.0 maple, paperbark Acer griseum % 3.4 maple, red Acer rubrum % 11.9 maple, silver Acer saccharinum % 14.5 medlar Mespilus spp % 1.5 mountain ash Sorbus spp % 10.7 mulberry Morus spp % 13.6 myrtlewood Umbellularia californica 1 0.0% 4.0 oak Quercus spp % 15.4 olive Olea spp % 3.0 peach Prunus persica 2 0.0% 1.8 pear Pyrus spp % 9.2 Persian ironwood Parrotia spp % 3.3 persimmon Diospyros spp % 1.3 pine Pinus spp % 12.5 plum Prunus spp % 13.5 poplar Populus spp % 17.6 Prunus, other Prunus spp % 10.6 redbud Cercis canadensis % 7.6 serviceberry Amelanchier spp % 0.9 smoketree Cotinus spp % 3.3 snowbell Styrax spp % 3.9 spruce Picea spp % 8.3 stewartia Stewartia pseudocamellia % 2.0 strawberry tree Arbutus spp % 7.2 sweetgum Liquidambar styraciflua % 17.4 sycoparrotia Sycoparrotia X sycoparrotia 1 0.0% 11.0 tree of heaven Ailanthus altissima 5 0.1% 4.2 tulip poplar Liriodendron tulipifera 6 0.1% 27.3 tupelo Nyssa sylvatica 1 0.0% 3.1 walnut Juglans spp % 19.1 western red cedar Thuja plicata 3 0.1% Street Tree Inventory Report Northwest District Neighborhood 2012

25 Appendix B continued Common Scientific Number % of Mean Name Name of Trees Total Trees DBH willow Salix spp % 10.0 zelkova Zelkova serrata % 3.9 Grand Total 5, % 11.4 Portland Parks & Recreation 21

26 Appendix C: Street trees of Northwest District Association by size 22 Street Tree Inventory Report Northwest District Neighborhood 2012

27 Appendix D: Small street trees (trees 6 DBH) Portland Parks & Recreation 23

28 Appendix E: Large street trees (trees > 24 DBH) 24 Street Tree Inventory Report Northwest District Neighborhood 2012

29 Portland Parks & Recreation 25 Appendix F: Poor and dead street trees

30 Appendix G: Available street tree planting spaces 26 Street Tree Inventory Report Northwest District Neighborhood 2012

31 Appendix H: Priority street tree planting spaces Portland Parks & Recreation 27