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Healthy Parks, Healthy Portland

phone: 503-823-7529

1120 SW Fifth Avenue, Portland, OR 97204

Portland Parks & Recreation Urban Forestry News and Activities 

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Event calendar


Learning from History through Irvington’s Trees

Join us for an upcoming history workshop in Irvington on May 20th

By Dave Hedberg, Urban Forestry Community Service Aide II 

When:    10:00 am - 12:00 pm, May 20, 2017 

Where:   Holladay Park Church of God, Fellowship Hall | 2120 NE Tillamook St.

Click here to register!

Trees are an integral part of any neighborhood’s history. The Irvington Neighborhood’s large tree-lined streets and mature yard trees are key features of this Portland Historic District. However, there are several important lessons from Irvington’s history that threaten its defining arboreal assets. 

On a hot sunny day, its easy to stay cool as you stroll through Irvington’s tree-lined streets. Remember these trees are artifacts that were integral to the neighborhood’s design. 

The Irvington Neighborhood gets its name from William and Elizabeth Irving, who obtained a donation land claim here in 1851. Later, developers David P. Thompson, Ellis G. Hughes, John W. Brazee, and eventually Charles Prescott, who are memorialized in the neighborhood’s street names, platted Irvington tract in 1887. The use of restrictive covenants, also called deed restrictions, set the conditions for homebuilding as well as who could live here. Although hard to believe today, early Irvington prohibited the manufacture and consumption of liquor and even forbade Chinese from owning property.  

Like many neighborhoods, the homes in Irvington went in before the trees. Trees graced these large planting strips not soon after this photo was taken in 1905. City of Portland Archives, A2004-002.629. 

By the 1890s, lots with restrictive deeds, large setbacks, and wide 6 – 12 foot planting strips attracted Portland’s upper-class to build their homes here.  Advertisements of the era promoted planting large trees along the streets and in yards. In fact, Irvington’s current mature canopy of maples, elms, horsechestnuts, catalpas, and birches are all artifacts from this early period, as seen in advertisements like this one from the 1913 Oregonian.  

 J.B. Pilkington’s 1913 Oregonian nursery advertisement demonstrates the aesthetic reasons people planted street trees. His tree offerings, for the most part, also match up with the mature canopy we see in Irvington today.  

In turn of the century Irvington, planting street trees and landscaping your yard was both a sign of affluence and part of a much larger tradition of urban beautification called the City Beautiful Movement. Defined broadly, the movement emphasized urban parks and connected parkways to inspire and promote social progress. Yet, Irvington’s early restrictive zoning limited the overall goal of improving social health for all of Portland. 

Irvington’s NE Hancock Street after paving and street tree plantings in 1912. Many of the big leaf maples, Acer macrophyllum, in the neighborhood likely date to this period. City of Portland Archives, A2004-002.2517. 

Encouraging other neighborhoods to plant trees, Florence Holmes, Landscape Architect for the Portland Parks Bureau published a detailed article on how to integrate your street tree to your home landscaping. Published in The Oregonian in 1921, the article outlined aesthetic benefits of trees and that plantings “express the personality of individuals who live in the home.” In selecting a tree, she stressed consideration of the local topography, “Irvington folk are able to accomplish much in the use of velvety lawns and a general open treatment, she wrote.  Further, she stressed uniformity and cooperation between neighbors to achieve single species monocultures. The results of her recommendations led to the mature and homogenous plantings of horsechestnuts, maples, ash, and elm often seen in Irvington today. These recommendations from the past pose significant issues for the future of Irvington’s canopy. 

 

In her 1921 Oregonian article, Florence Holmes promoted planting neighborhood monocultures, an idea we now understand puts the urban canopy at risk for infestation by pests and diseases.  

According to the 2015 Irvington Street Tree Inventory, 54% of all Irvington’s street trees are in the Sapindaceae and Rosaceae families, many of which date to the neighborhoods early plantings. This forest composition means that over 50% of all trees in Irvington are susceptible to emerald ash borer, Asian longhorned beetle, Dutch elm disease, or bronze birch borer—threats which Florence Holmes did not foresee in 1921. If she had, she likely would not have recommended planting only these trees. Moving forward, the Irvington Tree Team is learning from the mistakes inherited from our past and helping promote more diverse tree plantings to ensure a resilient, sustainable urban forest.  

This horsechestnut, Aesculus hippocastanum 'Baumannii', is also Heritage Tree #261. It’s surrounded by others of its species on NE Thompson and NE 16th, likely all planted at the same time.  

If you would like to learn more about the history of trees and the people who planted them in Irvington, please come for a free walk and talk exploring Irvington’s heritage trees on Saturday, May 20th (see registration link above). We will view some of the largest and oldest trees in the neighborhood, as well as some new varieties planted in our lifetimes. We’ll not only learn about the past, but we will discuss simple ways to be stewards of our urban forest. 

 

Street Tree Pruning Work Party in Eastmoreland

Join us for our last street tree pruning work party of the season on May 20th - we'll be in Eastmoreland!

By Mason Wordell, Urban Forestry Tree Plan Coordinator and AmeriCorps Member

Join Urban Forestry and the Eastmoreland Tree Team
for a pruning workshop and work party!

When: 8:45 am - 12:00 pm, May 20th, 2017
Where:  Berkeley Park | SE Cesar E Chavez Blvd & Bybee Blvd

Click here to register!

Agenda:
8:45 – 9:00 am – Sign-in, coffee & snacks
9:00 – 9:30 am – Pruning Demonstration
9:30 – 11:45 am – Pruning neighborhood trees in small groups
11:45 – 12:00 pm – Return and wrap up

Portland Parks & Recreation Urban Forestry and the Eastmoreland Tree Team are partnering to offer this street tree pruning workshop to care for young street trees in the neighborhood. The Eastmoreland Tree Team is a well-established tree team and has held two pruning events in the past – this event is an extension of these efforts.  In Eastmoreland, small trees between 0 and 6” DBH (diameter at breast height) account for 20% of the street trees. Clearly, there is a high need to care for these young, small trees as they mature and grow. One important aspect of tree maintenance is structural pruning.

Pruning is an important part of tree care and maintenance, and everyone is welcome to participate in this workshop to learn more about how they can actively care for their trees.  Knowing when to prune and what to look for can help you make successful cuts that will help cultivate beautiful, structurally sound, and long-living trees.  Read our previous blog post to learn more about pruning! View the City’s official pruning standards here.  

Meet us on May 20th at Berkeley Park, next to the Alex Rovello Memorial Tennis Courts! We will be out rain or shine -  we recommend long pants and long sleeves, sturdy shoes and a rain/sun hat and bring a backpack, rain gear, and water bottle. Instruction, tools, gloves, coffee, water and snacks will be provided.

For more information, or if you have something you want to talk about, contact:
Mason Wordell
Tree Plan Coordinator and AmeriCorps member
Mason.Wordell@PortlandOregon.gov
(503) 201-3133

Certified Arborists can receive 3 hours of ISA CEUs for participating and leading small groups. Contact Mason for details!

 

Street Tree Pruning Work Party in Arbor Lodge

By Mason Wordell, Urban Forestry Tree Plan Coordinator and AmeriCorps Member

Join Urban Forestry and the Arbor Lodge Tree Team
for a pruning workshop and work party!

When: 8:45 am - 12:00 pm, May 13, 2017
Where:  Arbor Lodge Park | N Delaware Avenue and N Bryant Street

Click here to register!

Agenda:
8:45 – 9:00 am – Sign-in, coffee, and snacks
9:00 – 9:30 am – Pruning Demonstration
9:30 – 11:45 am – Pruning neighborhood trees in small groups
11:45 – 12:00 pm – Return and wrap up

Portland Parks & Recreation Urban Forestry and the Arbor Lodge Tree Team are partnering to offer this street tree pruning workshop to care for young street trees in the neighborhood. The Arbor Lodge Tree Team is a well established tree team and has held two pruning events in the past – this event is an extension of these efforts. In Arbor Lodge, small trees between 0" and 6” DBH (diameter at breast height) account for 53% of the street trees. Clearly, there is a high need to care for these young, small trees as they mature and grow. One important aspect of tree maintenance is structural pruning.

Pruning is an important part of tree care and maintenance, and everyone is welcome to participate in this workshop to learn more about how they can actively care for their trees. Knowing when to prune and what to look for can help you make successful cuts that will help cultivate beautiful, structurally sound, and long-living trees. Read our previous blog post to learn more about pruning! View the City’s official pruning standards here.  

Meet us on May 13, at Arbor Lodge Park, at the west baseball diamond! We will be out rain or shine -  we recommend long pants and long sleeves, sturdy shoes and a rain/sun hat and bring a backpack, rain gear, and water bottle. Instruction, tools, gloves, coffee, water and snacks will be provided.

For more information, or if you have something you want to talk about, please contact:

Mason Wordell, Tree Plan Coordinator and AmeriCorps member
mason.wordell@portlandoregon.gov
(503) 201-3133

Certified Arborists can receive three hours of ISA CEUs for participating and leading small groups. Contact Mason for details!

Dutch Elm Disease Update

by Kasey M. Yturralde, Botanic Specialist II

Proportion of elm inventory by property type (N=4767 elms)

Portland Elms

PP&R Urban Forestry has a new tool in their elm management arsenal, data. This summer, with the help of 1400 tree inventory volunteers (and about 17,000 volunteer hours), Urban Forestry (UF) completed an inventory of Portland’s street trees, which included elms. UF staff inventoried private elms as well, resulting in the first complete assessment of Portland’s elm population to date. This inventory data is critical in managing elms, which are in a constant battle with Dutch elm disease and meeting the challenges of living in an urban environment.

Dutch elm disease (DED) is caused by a fungus (Ophiostoma spp.), which spreads via adjacent elm roots and may also be transmitted by bark beetles. DED may spread by roots, in a process called root grafting. Root grafting may occur when DED positive elms are in close proximity to other elms and there is contact between roots below ground. DED spores are also spread via an insect vector, elm bark beetles. Understanding where elms are located across the city and where elm mortality occurs is a first step to understanding how DED spreads through Portland’s elm population.

Elms and Dutch elm disease management

Fortunately, there is a treatment used to prevent the growth of the DED fungus. The treatment consists of a special fungicide that is injected at the base of elms, into their water-conducting system, or xylem. Healthy elms that are good candidates for treatment are treated every three years. The tree itself also helps propel the protective fungicide up the tree, throughout the canopy. In 2016, UF treated 129 park elms with the Arbotect fungicide. Neighborhood groups, such as Save Our Elms, also joined the effort and treated 115 elms with either Arbotect or Alamo.

Figure 1. Neighborhood elm inoculation by microinjection.

Elm loss

In 2016, 55 elms (approximately 1% of our elm population) tested positive for DED and were removed- of these, Urban Forestry removed 45 out of the 55 (82%).  Most of the Urban Forestry removals (29 out of 45) were in the public right-of-way (ROW).

Analysis of elm loss reveals interesting spatial patterns. In some areas with high elm density, such as Ladd’s Addition, adjacent elms are lost in each subsequent year as DED progresses down a block, likely via root grafting (see Figure 2).

Figure 2. Map of elm trees in Ladd’s Addition. The light green buffer around elms shows the 25-foot distance within which DED can be transmitted via root grafting. DED can spread up to a distance of 50-feet.

However, in other areas of high density, the pattern of annual loss may not occur via root grafting, or may occur in combination with transmission via elm bark beetles. For example, in Eastmoreland there isn’t a clear spatial progression of elm loss along blocks (Figure 3). However, there are other potential factors that could explain the differences between elm loss in the two neighborhoods. For example, the neighborhoods differ in their use of fungicide used to prevent growth of DED.

Figure 3. Map of elm trees in Eastmoreland neighborhood.

Recommendations

Currently, Urban Forestry removes DED-infected elms in the public ROW, which requires a full crew of arborists and lasts an average of three days per tree, not including stump removal. This service, however, is not offered to residents for the removal of other tree species located in the ROW. In the interest of equity, Urban Forestry recommends that removal of DED-infected elms becomes the responsibility of the adjacent homeowner. This change in policy would then comply with the Title 11 Tree code, which requires adjacent homeowners to maintain and remove street trees. In addition, this change would lead to more equitably distributed city services as Urban Forestry would then dedicate more time to maintenance and care of park trees across the city, as well as continuing to monitor elms for DED.

Given potential changes in the removal policy of DED-infected elms, Urban Forestry could reallocate time and effort to DED prevention. For example, patterns of DED-related elm loss seem to indicate that the mode of DED transmission may vary across Portland. Formally investigating the spread of DED through Portland’s elms could help inform future management decisions.

Portland also manages for DED through the planting of DED-resistant cultivars. The size distribution of such elms is heavily skewed toward smaller elms (Figure 4). Proper tree pruning will be critical to ensuring a healthy future for these young elms. As neighborhood groups continue their care of elms, they may want to incorporate young-tree pruning in their elm management, of course with the proper tree pruning permits.  

Figure 4. Size class distribution of DED-resistant elms (DBH-diameter of tree at 4.5 feet high)

Currently a moratorium on elm pruning is implemented from April 15th through October 15th, to avoid pruning when elm bark beetles are most active, as elms with injuries, such as those made by pruning, are especially attractive to elm bark beetles. To further prevent DED, Urban Forestry is considering adjusting the moratorium window each year, dependent on springtime temperatures, which predict onset of beetle activity.

For more information on Dutch elm disease:

How to Identify and Manage Dutch Elm Disease

Dutch elm disease

Fungicide Injection to Control Dutch Elm Disease: Understanding the Options

Questions? Kasey.Yturralde@portlandoregon.gov

 

Pruning Workshop with the Hillsdale Tree Team

Portland Parks & Recreation Urban Forestry and the Hillsdale Tree Team are partnering to offer this street tree pruning workshop to care for young street trees in the neighborhood.

By Mason Wordell, Urban Forestry Tree Plan Coordinator and AmeriCorps Member

Join Urban Forestry and the Hillsdale Tree Team
for a pruning workshop and work party!

When: 8:45 am - 12:00 pm, April 29, 2017
Where:  Rieke Elementary School | 1405 SW Vermont St.

Click here to register!

Agenda:
8:45 – 9:00 am – Sign-in, coffee & snacks
9:00 – 9:30 am – Pruning Demonstration
9:30 – 11:45 am – Pruning neighborhood trees in small groups
11:45 – 12:00pm – Return and wrap up

Portland Parks & Recreation Urban Forestry and the Hillsdale Tree Team are partnering to offer this street tree pruning workshop to care for young street trees in the neighborhood. The Hillsdale Tree Team is in their first year of tree stewardship, and this is their first pruning workshop in the neighborhood.  In Hillsdale, small trees between 0" and 6” dbh (diameter at breast height) account for 37.9% of the street trees. Clearly, there is a high need to care for these young, small trees as they mature and grow. One important aspect of tree maintenance is structural pruning.

Pruning is an important part of tree care and maintenance, and everyone is welcome to participate in this workshop to learn more about how they can actively care for their trees.  Knowing when to prune and what to look for can help you make successful cuts that will help cultivate beautiful, structurally sound, and long living trees.  Read our previous blog post to learn more about pruning! View the City’s official pruning standards here.  

Meet us on April 29th at Rieke Elementary School, near the main parking lot! We will be out rain or shine -  we recommend long pants and long sleeves, sturdy shoes and a rain/sunhat and bring a backpack, rain gear and water bottle. Instruction, tools, gloves, coffee, water and snacks will be provided.

For more information, or if you have something you want to talk about, contact:
Mason Wordell
Tree Plan Coordinator and AmeriCorps member
Mason.Wordell@PortlandOregon.gov
(503) 201-3133

Certified Arborists can receive 3 hours of ISA CEUs for participating and leading small groups. Contact Mason for details!