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• 1. [Article] Spreading the Green and Sharing the Wealth

  Examines the effects and benefits of trees for the urban environment, and looks at recent studies that have attempted to define the benefits of urban trees. Discusses the implications of trees for city ...

  Citation × Citation Citation Abstract Copy Title: Spreading the Green and Sharing the Wealth Author: White, Rachel Year: 2009 Examines the effects and benefits of trees for the urban environment, and looks at recent studies that have attempted to define the benefits of urban trees. Discusses the implications of trees for city planning. Title: Spreading the Green and Sharing the Wealth Author: White, Rachel Year: 2009 Examines the effects and benefits of trees for the urban environment, and looks at recent studies that have attempted to define the benefits of urban trees. Discusses the implications of trees for city planning. Close

• 2. [Article] Integrating High-Resolution Datasets to Target Mitigation Efforts for Improving Air Quality and Public Health in Urban Neighborhoods

  Reducing exposure to degraded air quality is essential for building healthy cities. Although air quality and population vary at fine spatial scales, current regulatory and public health frameworks assess ...

  Citation × Citation Citation Abstract Copy Title: Integrating High-Resolution Datasets to Target Mitigation Efforts for Improving Air Quality and Public Health in Urban Neighborhoods Author: Shandas, Vivek, Voelkel, Jackson, Rao, Meenakshi, George, Linda A. Year: 2016 Reducing exposure to degraded air quality is essential for building healthy cities. Although air quality and population vary at fine spatial scales, current regulatory and public health frameworks assess human exposures using county- or city-scales. We build on a spatial analysis technique, dasymetric mapping, for allocating urban populations that, together with emerging fine-scale measurements of air pollution, addresses three objectives: (1) evaluate the role of spatial scale in estimating exposure; (2) identify urban communities that are disproportionately burdened by poor air quality; and (3) estimate reduction in mobile sources of pollutants due to local tree-planting efforts using nitrogen dioxide. Our results show a maximum value of 197% difference between cadastrally-informed dasymetric system (CIDS) and standard estimations of population exposure to degraded air quality for small spatial extent analyses, and a lack of substantial difference for large spatial extent analyses. These results provide the foundation for improving policies for managing air quality, and targeting mitigation efforts to address challenges of environmental justice. Title: Integrating High-Resolution Datasets to Target Mitigation Efforts for Improving Air Quality and Public Health in Urban Neighborhoods Author: Shandas, Vivek, Voelkel, Jackson, Rao, Meenakshi, George, Linda A. Year: 2016 Reducing exposure to degraded air quality is essential for building healthy cities. Although air quality and population vary at fine spatial scales, current regulatory and public health frameworks assess human exposures using county- or city-scales. We build on a spatial analysis technique, dasymetric mapping, for allocating urban populations that, together with emerging fine-scale measurements of air pollution, addresses three objectives: (1) evaluate the role of spatial scale in estimating exposure; (2) identify urban communities that are disproportionately burdened by poor air quality; and (3) estimate reduction in mobile sources of pollutants due to local tree-planting efforts using nitrogen dioxide. Our results show a maximum value of 197% difference between cadastrally-informed dasymetric system (CIDS) and standard estimations of population exposure to degraded air quality for small spatial extent analyses, and a lack of substantial difference for large spatial extent analyses. These results provide the foundation for improving policies for managing air quality, and targeting mitigation efforts to address challenges of environmental justice. Close

• 3. [Article] From Stumptown to Treetown: A Field Guide for Interpreting Portland’s History though its Heritage Trees

  Portland’s urban forest is rooted in the city’s history. This guide is the first of its kind to use historic literature, archival collections, and living trees as evidence to interpret Portland’s history. ...

  Citation × Citation Citation Abstract Copy Title: From Stumptown to Treetown: A Field Guide for Interpreting Portland’s History though its Heritage Trees Author: Hedberg, David-Paul B. Year: 2015 Portland’s urban forest is rooted in the city’s history. This guide is the first of its kind to use historic literature, archival collections, and living trees as evidence to interpret Portland’s history. Trees are some of our city’s oldest living artifacts and this guide will show you some of the many ways to see and interpret both history and nature in Portland. Title: From Stumptown to Treetown: A Field Guide for Interpreting Portland’s History though its Heritage Trees Author: Hedberg, David-Paul B. Year: 2015 Portland’s urban forest is rooted in the city’s history. This guide is the first of its kind to use historic literature, archival collections, and living trees as evidence to interpret Portland’s history. Trees are some of our city’s oldest living artifacts and this guide will show you some of the many ways to see and interpret both history and nature in Portland. Close

• 4. [Article] Street Trees in the Urban Forest Canopy: Portland, Oregon

  Attempts to identify the contribution of street trees to the overall urban forest of a city have been rare and lack consensus on how to measure that contribution – percentage of trees, percentage of canopy ...

  Citation × Citation Citation Abstract Copy Title: Street Trees in the Urban Forest Canopy: Portland, Oregon Author: Poracsky, Joseph, Banis, David Year: 2005 Attempts to identify the contribution of street trees to the overall urban forest of a city have been rare and lack consensus on how to measure that contribution – percentage of trees, percentage of canopy cover, or percentage of leaf area. The actual numeric values presented in the literature also vary over a broad range and often are based on estimates, extrapolations from aggregated data, or simply stated with no empirical data referenced. This study was undertaken to evaluate the contribution of street trees to canopy in Portland, Oregon. The study involved both visual and digital analysis of multi-band aerial images, field observation, and GIS analysis involving several ancillary data themes. The strategy was to calculate the street tree component (STC) of the urban forest canopy within a sample of areas in the city and generalize that pattern to the whole city. The analysis indicates that street trees constitute 3.4% of the whole study area. In commercial / industrial areas the value drops to only 1.1% and in residential areas rises to 4.8%. For the overall study area the STC of the canopy is 17.2%, a value in the middle of the range of values found in the published literature. In commercial / industrial areas we found a value of 23.7% and a value of 16.6% for residential areas. Residential areas are overall better treed than commercial / industrial areas, but do not rely on street trees to contribute as large a percentage to overall canopy as do commercial / industrial areas. Available planting space in the right-of-way (ROW) is much more nearly constant (or independent of land cover) than the amount of planting space available inside a block. Therefore, the STC tends to vary inversely with the total amount of vegetated area. As the vegetated (read, plantable) area decreases, the ROW becomes a more significant space for planting and the STC increases. Conversely, as the vegetated area increases, the ROW becomes a less significant space for planting and the STC decreases. For both residential and commercial / industrial areas, the percentage of street tree area within the total canopy varies from locale to locale. The relatively small sampling used in this study suggests that neighborhood age and physical characteristics influence the STC in a given neighborhood, particularly for residential areas. Analysis allowed division of the study area into five residential neighborhood groups that attempt to reflect local differences. A larger / more detailed sampling would allow for improved delineation, perhaps below the level of neighborhood. Three generalized spatial patterns emerge for Portland. Street tree canopy as a percent of area seems to follow an east-west gradient, with lower values to the east and higher values to the west. Street trees as a component of the total canopy takes on an inverted-U shape, with higher values in the Inner Eastside and lower values to the east and to the west. The overall tree canopy category takes on just the opposite pattern – a standard-U – with lower values in the Inner Eastside and higher values to the east and west. This study represents a useful starting point for understanding the dynamics of an important and highly visible component of the urban forest. Title: Street Trees in the Urban Forest Canopy: Portland, Oregon Author: Poracsky, Joseph, Banis, David Year: 2005 Attempts to identify the contribution of street trees to the overall urban forest of a city have been rare and lack consensus on how to measure that contribution – percentage of trees, percentage of canopy cover, or percentage of leaf area. The actual numeric values presented in the literature also vary over a broad range and often are based on estimates, extrapolations from aggregated data, or simply stated with no empirical data referenced. This study was undertaken to evaluate the contribution of street trees to canopy in Portland, Oregon. The study involved both visual and digital analysis of multi-band aerial images, field observation, and GIS analysis involving several ancillary data themes. The strategy was to calculate the street tree component (STC) of the urban forest canopy within a sample of areas in the city and generalize that pattern to the whole city. The analysis indicates that street trees constitute 3.4% of the whole study area. In commercial / industrial areas the value drops to only 1.1% and in residential areas rises to 4.8%. For the overall study area the STC of the canopy is 17.2%, a value in the middle of the range of values found in the published literature. In commercial / industrial areas we found a value of 23.7% and a value of 16.6% for residential areas. Residential areas are overall better treed than commercial / industrial areas, but do not rely on street trees to contribute as large a percentage to overall canopy as do commercial / industrial areas. Available planting space in the right-of-way (ROW) is much more nearly constant (or independent of land cover) than the amount of planting space available inside a block. Therefore, the STC tends to vary inversely with the total amount of vegetated area. As the vegetated (read, plantable) area decreases, the ROW becomes a more significant space for planting and the STC increases. Conversely, as the vegetated area increases, the ROW becomes a less significant space for planting and the STC decreases. For both residential and commercial / industrial areas, the percentage of street tree area within the total canopy varies from locale to locale. The relatively small sampling used in this study suggests that neighborhood age and physical characteristics influence the STC in a given neighborhood, particularly for residential areas. Analysis allowed division of the study area into five residential neighborhood groups that attempt to reflect local differences. A larger / more detailed sampling would allow for improved delineation, perhaps below the level of neighborhood. Three generalized spatial patterns emerge for Portland. Street tree canopy as a percent of area seems to follow an east-west gradient, with lower values to the east and higher values to the west. Street trees as a component of the total canopy takes on an inverted-U shape, with higher values in the Inner Eastside and lower values to the east and to the west. The overall tree canopy category takes on just the opposite pattern – a standard-U – with lower values in the Inner Eastside and higher values to the east and west. This study represents a useful starting point for understanding the dynamics of an important and highly visible component of the urban forest. Close

• 5. [Article] Interception in Open-grown Douglas-fir (Pseudotsuga menziesii) Urban Canopy

  I hypothesized that Douglas-fir trees (Pseudotsuga menziesii) standing apart from other trees ('open-grown') will intercept more rainfall than Douglas-fir trees standing near other trees ('closed-canopy'). ...

  Citation × Citation Citation Abstract Copy Title: Interception in Open-grown Douglas-fir (Pseudotsuga menziesii) Urban Canopy Author: Bixby, Mitchell Year: 2011 I hypothesized that Douglas-fir trees (Pseudotsuga menziesii) standing apart from other trees ('open-grown') will intercept more rainfall than Douglas-fir trees standing near other trees ('closed-canopy'). Open-grown trees differ structurally and are more common in urban settings, yet have been infrequently studied. Existing literature, based primarily on closed-canopy trees, suggests Douglas-fir trees in Pacific Northwest forests intercept approximately 25% of rainfall annually. Because open-grown trees have more vertical leaf area than individual trees in closed-canopy forests, I expected to find higher interception by open-grown trees. I collected throughfall under four open-grown Douglas-firs using six static collectors ('buckets') per tree, and two closed-canopy Douglas-firs using six buckets per tree. I compared their throughfall to the incident rainfall in two adjacent open-field buckets. Gross interception was measured in 53 collections during rainy weather from 16Nov07 to 31Mar08. Over the same period, rainfall per hour, wind speed, gust speed, wind direction, temperature and relative humidity were collected at a weather station located within 1 km of the site. For comparison, average hourly rainfall at Portland International Airport from 1950 to 2005, for the same months of the collection period, showed a comparable number of medium- to high-intensity storms, but more low-intensity storms. I found that incident rainfall for the adjacent open-field buckets totaled 65.6cm and 71.6cm over the study period. Interception values for closed-canopy trees averaged 26%, corresponding to the literature, with results of 22 and 30%. Interception values for open-grown trees averaged 31%, with results ranging from 15 to 45%. Three of the 24 buckets returned overall negative interception rates over five months. Given the lower storm intensity of 2007-08, interception rates may be somewhat high, compared to the historical average. The negative interception rates at three buckets were likely due to their locations under high drip points, as has been observed in other studies. Considering the wide range of canopy architecture among open-grown trees, the high variability in interception was not surprising. My hypothesis was supported by the data, but requires more testing to better generalize these results. Future studies that link open grown tree canopy morphological characteristics to interception are warranted. Title: Interception in Open-grown Douglas-fir (Pseudotsuga menziesii) Urban Canopy Author: Bixby, Mitchell Year: 2011 I hypothesized that Douglas-fir trees (Pseudotsuga menziesii) standing apart from other trees ('open-grown') will intercept more rainfall than Douglas-fir trees standing near other trees ('closed-canopy'). Open-grown trees differ structurally and are more common in urban settings, yet have been infrequently studied. Existing literature, based primarily on closed-canopy trees, suggests Douglas-fir trees in Pacific Northwest forests intercept approximately 25% of rainfall annually. Because open-grown trees have more vertical leaf area than individual trees in closed-canopy forests, I expected to find higher interception by open-grown trees. I collected throughfall under four open-grown Douglas-firs using six static collectors ('buckets') per tree, and two closed-canopy Douglas-firs using six buckets per tree. I compared their throughfall to the incident rainfall in two adjacent open-field buckets. Gross interception was measured in 53 collections during rainy weather from 16Nov07 to 31Mar08. Over the same period, rainfall per hour, wind speed, gust speed, wind direction, temperature and relative humidity were collected at a weather station located within 1 km of the site. For comparison, average hourly rainfall at Portland International Airport from 1950 to 2005, for the same months of the collection period, showed a comparable number of medium- to high-intensity storms, but more low-intensity storms. I found that incident rainfall for the adjacent open-field buckets totaled 65.6cm and 71.6cm over the study period. Interception values for closed-canopy trees averaged 26%, corresponding to the literature, with results of 22 and 30%. Interception values for open-grown trees averaged 31%, with results ranging from 15 to 45%. Three of the 24 buckets returned overall negative interception rates over five months. Given the lower storm intensity of 2007-08, interception rates may be somewhat high, compared to the historical average. The negative interception rates at three buckets were likely due to their locations under high drip points, as has been observed in other studies. Considering the wide range of canopy architecture among open-grown trees, the high variability in interception was not surprising. My hypothesis was supported by the data, but requires more testing to better generalize these results. Future studies that link open grown tree canopy morphological characteristics to interception are warranted. Close