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Elisabeth C. Miller Library

Keyword: Trees in cities

Urban Forestry & Urban Greening

[Urban Forestry & Urban Greening] cover

One of the more popular periodical publications in the Miller Library is Urban Forestry & Urban Greening, a peer-reviewed, internationally-focused journal published 10 times per year. The publisher (Elsevier) describes the focus as “urban and peri-urban woody and non-woody vegetation and its use, planning, design, establishment and management.”

The editors accept submissions on a wide range of topics under the urban umbrella, including everything from the expected arboriculture and horticulture to urban planning and design, public health, and even environmental psychology. The intended audience includes academics but also policymakers and landscape professionals.

The current and upcoming issues demonstrate this breadth of topics. One report discusses stormwater infrastructure designs, showing that the preferences of professionals and laypeople are often quite different. Another article outlines the challenges of developing “an effective forest therapy program to manage academic stress in conservative societies,” using Malaysia as the model. Closer to home, researchers from the University of British Columbia study “urban green equity on the ground” using Portland (Oregon), Phoenix, and New York City as their models to compare.

Many of the articles are available to download from the journal’s website (linked from the Miller Library’s catalog entry); however, the library maintains a print collection dating from the release of volume 1 in 2002. Visit the library and browse through this impressive journal.

Published in Leaflet for Scholars, Volume 6, Issue 11, November 2019

Mystery trees of Tel Aviv

Sometimes reference librarians ask ourselves questions—especially in times of social isolation! Since libraries are closed, I have been rereading my own collection of books. When I Lived in Modern Times is a novel by Linda Grant, set in 1940s Tel Aviv before Israel became a state. The main character refers several times to unnamed trees that are growing along Rothschild Boulevard (Sderot Rothschild). The trees are noteworthy, yet she cannot identify them. After having read this book twenty years ago, I decided it was time to solve the mystery!

 

[mysterytrees] cover

By searching Google Maps, I could see there were two main types of trees. It’s a mile-long road with a central pedestrian thoroughfare, and in researching sources like Tel Aviv municipal archives and local news, I determined that both Delonix regia and Ficus (F. microcarpa and F. sycomorus) grow there. Delonix, native to Madagascar, was introduced to Israel in the 1920s and may have been planted on the boulevard then or later. The trees are depicted in a 1937 painting by Yehezkel Streichman, “The Kiosk on Rothschild Boulevard.” The ficus trees on Rothschild Boulevard were planted in the 1930s. Although jacaranda trees are mentioned in various historical sources, I did not see contemporary images of them, though a 1946 photo of Rothschild Boulevard at the intersection of Allenby Street (the very corner mentioned in Grant’s novel) shows jacaranda and ficus branches overhanging a photographer’s sidewalk photo-shoot.

Tel Aviv’s founders—with one exception—believed they could ‘make something from nothing’ (yesh me’ayin) of this sandy location. The lone dissenter thought it folly and, in a 1909 photo celebrating the city’s founding, he stands far apart from the others, atop a distant dune, possibly still muttering ‘crazy people, there’s no water here’ (meshuga’im—ayn kan mayim!).

Rothschild Boulevard was built in 1910, utilizing a sand-filled wadi (dry riverbed) which was not stable enough for buildings. The street’s original name was Rehov Ha’Am, Street of the Nation (or the People). Cypresses formed the outline of the boulevard’s edges, with grass and flowerbeds in the middle.

The city’s first mayor Meir Dizengoff had grand and somewhat impractical urban planning ideas. He wanted to impress Winston Churchill (who was due for a visit in 1921) by creating a tree-lined boulevard to rival any in Europe. Mature trees were transplanted from nearby locations, but they did not have time to establish themselves in the arid soil. When people thronged to see Churchill, some climbed the trees, toppling them. Churchill reportedly said, “That which has no roots is bound to wither,” a sly, barbed remark, coming from the man who was Secretary of State for the Colonies during the period of the British Mandate in Palestine.

In 1925, Patrick Geddes, a Scottish botanist and town planner, produced a plan for Tel Aviv. He envisioned a “garden city,” with a blend of “mainways” (for vehicles) and “homeways” (residential interior streets), and a series of east-west green boulevards to connect key urban sites, so the city would have a strong sense of nature.

To this day, Rothschild Boulevard is a well-used tree-lined corridor through the heart of a busy city. Just as we have cherry blossom mania in spring here in Seattle, there is great excitement when the red flowers of Delonix regia (known as flame tree, Royal Poinciana, Flamboyant, Gulmohar, and in Hebrew tze’elon naeh) bloom in early June. The ficus trees with their pale trunks sometimes covered in a net of accessory trunks made of aerial roots, are stately but drop fruit that can be perilous for pedestrians. Still, they are a notable feature of the landscape; Tel Aviv-Yafo municipal agronomist Haim Gavriel even published a recent monograph about the Ficus of Israel’s Boulevards.

Resources that were useful in researching this mystery include:

  • Mann, Barbara. A Place in History: Modernism, Tel Aviv, and the Creation of Jewish Urban Space. Stanford University Press, 2006. [accessed online 4/25/2020]
  • Mann, Barbara. “Tel Aviv’s Rothschild: When a boulevard becomes a monument.” Jewish Social Studies, New Series, Vol. 7, No. 2 (Winter, 2001), pp. 1-38. [accessed online 4/24/2020]
  • Rosenberg, Elissa. “Tel Aviv never stops.” Landscape Architecture Magazine 107 (11), 120-128
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Narrow or fastigiate trees

Can you recommend some narrow or fastigiate trees for the space between our house and the house next door? The space is about 14 feet wide. Will Cornus kousa ‘National’ work?

From what the experts say, Cornus kousa grows 20-30 feet high and wide in cultivation. They can grow to twice that size in the wild.

I found this and other information that might help you in the sources below:
1. Trees and Shrubs for Pacific Northwest Gardens, by J. Grant, 1990, p. 71
2. Trees & Shrubs Hardy in the British Isles, by W.J. Bean, 1976, p. 703
3. Manual of Woody Landscape Plants, by M. Dirr, 1998, p. 260
4. North American Landscape Trees, by A. Lee Jacobson, 1996, pp. xiii, 144

The Seattle City Arborist’s Office recommends the following narrow trees:
1. Magnolia grandiflora ‘Little Gem’ – 15 ft. high, 10 ft. wide. White flowers, evergreen.
2. Malus ‘Adirondack’ – 18 ft. high, 10 ft. wide. White flowers, red fruit, excellent scab resistance.
3. Malus ‘Red Barron’ – 18 ft. high, 8 ft. wide. Red flowers, red fruit, yellow fall color.
4. Malus ‘Golden Raindrops’ – 18 ft. high, 13 ft. wide. White flowers, yellow fall color, abundant yellow fruit.
5. Prunus serrulata ‘Amanogawa’ – 20 ft. tall, 6 ft. wide. Pale pink double flowers, bronze fall color.

Here are additional sources:

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planting and caring for new Magnolia trees

How do I go about planting a new Magnolia tree this fall?

 

The City of Seattle’s Department of Transportation has perhaps the best set of instructions and tips for planting trees in the Pacific Northwest. It includes a diagram of how to plant a tree. This same site also has guidelines for care of young trees.
If your tree is a “street tree” (planted in a parking strip), then be sure it is appropriate. The left-hand menu here gives lists of trees that are and are not appropriate, under Street Trees.

The current consensus is that you do not need to amend the hole with new or superior soil from another source when you fill in the hole, as this just creates an environment the roots do not want to leave. In order for a tree to become established, the roots need to grow outward, into the native soil. Washington State University Extension professor Linda Chalker-Scott discusses this subject as well as whether or not to disturb the root ball, how to handle balled and burlapped trees(remove the wire basket!), and whether staking is necessary.

The University of British Columbia Botanical Garden Forums includes the following comments about planting some varieties of magnolias:

“I would only use a well seasoned compost for a Magnolia as a top dress at planting time. We advised people to dig the hole three times the width of the root ball and place the dug out soil back in the hole with no other soil additives. Providing a root shock preventer such as liquid Vitamin B1 at a rate of one fluid ounce per gallon of water is optional. A good choice to use when planting these Magnolias on a warm day in a warm climate but generally not needed in the Pacific Northwest. What we have to guard against is planting this and others of this series too low in the ground. We like to plant these in a raised mound for a yard planting. Never plant these trees with the graft union at soil level, try to plant them about six inches to a foot above the soil level and allow
for settling in later. A Spring planting is regarded as being best for these Magnolias but in the warmer climates can be planted almost year round as our soils here seldom ever
are frozen.”

I would add to this that planting too deeply is a common mistake, but another mistake is to plant “too high” (as is suggested above, when the writer mentions planting in a “raised mound”). Some people think that such a mound can be buried in mulch; it is much better to plant at the proper depth and use mulch from about 6 inches away from the trunk to the outer edge of the root ball, creating a ‘dam’ as described by Seattle Department of Transportation.Then you can turn the hose on low and let the water fill the ‘moat’ created by the dam. During the winter, be careful that your mulch is not too deep, as it can actually keep water from getting into the soil (3-4 inches of mulch is plenty). Mulch in the spring through fall is much more important for keeping water from evaporating from the soil surface, as well as for slowing down the weeds. Be careful not to pile mulch against the trunk of the tree, as this can cause rot.

One more thing, as mentioned below on University of British Columbia Botanical Gardens Forum, do not fill the planting hole with water, as this may contribute to root rot.

Pacific Madrone and fungal diseases

We recently bought a house on San Juan Island with lots of beautiful madronas (Arbutus menziesii) on the property. Two of them show no signs of life… others have the occasional dead branch here and there. We have been advised that this is likely caused by a fungus and that it can spread rapidly. We have been shown blackened excavated areas on the trunks of the dead trees.. and similar though less extensive areas on some of the others. What can be done to save our beautiful madronas?

 

It is possible your trees are suffering from canker fungus (Nattrassia mangiferae), or some other type of fungal disease. Here is a link to a file called “The Decline of the Pacific Madrone” edited by A. B. Adams (from a symposium held here at the Center for Urban Horticulture in 1995).

You may want to call a certified arborist to look at the trees, determine the extent of the disease, and help you decide whether the trees can be salvaged. (Search the Pacific Northwest Chapter of the International Society of Arboriculture for a local arborist.)

Below is a response to a question similar to yours from the
University of British Columbia Botanical Garden and Centre for Plant Research:

“What you describe are the classic symptoms of ‘Arbutus decline,’ which is postulated in the literature as being caused by mostly naturally-occurring, weakly pathogenic fungi, made more virulent by the predisposition of Arbutus to disease, caused by urban stresses, especially root disturbance.” (see also: “Arbutus Tree Decline” from Nanaimo. B.C.’s Parks, Recreation and Culture department)

Nevertheless, I am convinced that much of the die-back we are seeing on established Arbutus trees stems not from disease, but primarily from the complications of damage, competition, shading and especially, drought stress (we have had a run of very droughty summers). Typically, the most affected natural stands of Arbutus are very dense, with poor air-circulation, internal shading and intense competition for resources (characteristic of rapid growth after clearing). And because this region is becoming increasingly urbanized, with more vehicular and marine traffic (marine traffic evidently accounts for a huge proportion of the pollution in the Fraser Basin air-shed), I would not discount atmospheric pollution as a contributor to the decline (one more stress).

I think the reason your shaded trees are not as affected is that their roots are probably deeper and less exposed, and there is reduced evaporative demand on the leaves. However, as the shade increases, these plants, or at least their shaded branches, will succumb.

What to do? I do not think there is anything you can do to save the existing trees, except, perhaps, to minimize human influence around them. You should avoid both disrupting roots and damaging above-ground portions of the trees (with pruning, for example), as any wound is an open invitation to disease-causing micro-organisms. Interestingly, a friend of mine who kayaks has seen black bears foraging for fruit in the tops of Arbutus trees on Keats Island (he should have told them they are not helping the situation any).

Irrigation of established plants is nearly always counter-productive because it encourages surface rooting (which is typically short-lived and considerably less resilient than deep rooting), and summer irrigation is worse, as Arbutus are well adapted to our conditions (at least, where we find them growing naturally) and normally somewhat dormant in summer.

You can plant more Arbutus, as a previous correspondent in this thread has, to replace what you are losing, but there is no guarantee that these plants will survive the next drought or indeed, your well-intentioned meddling. (I suspect his plant was lost for the same reason most young Arbutus are lost–by root damage from saturated or compacted soil conditions). The natural succession on your island is probably (as elsewhere in similar places along the coast) tending toward open Douglas fir forest with a few scattered Arbutus in the more inhospitable places. In other words, you can plant what you will, but the larger the Douglas firs, the fewer Arbutus will be able to survive around them. Neither species is particularly shade tolerant and resources are pretty limited on rocky ground, where both prefer to grow locally. Expect change.

tree topping as a solution to landscape problems

We just moved into a new house that has a beautiful 20-foot-tall Colorado blue spruce planted too close to the house. Can it be topped and shaped so it could be left in that spot? If we wanted to remove it and plant it somewhere else could we do that? Or will it just die anyway? What to do?

 

I would not recommend topping the tree. Since this tree can reach mature heights of 30 to 60 feet or more, it may not be the right tree for the site. Here is a page about Colorado blue spruce (Picea pungens) from University of Illinois Extension’s Selecting Trees For Your Home.

Here is information (now archived) from a local organization, Plant Amnesty, on why topping trees is not a good solution to your landscaping problem.

This organization has an “Adopt-a-Plant” service, if you think you would like to give the tree away. There are also referral services available from Plant Amnesty if you need the tree removed or moved to another location. You could also contact a certified arborist through the
International Society for Arboriculture.

I also suggest looking at resources like Great Plant Picks, which lists trees and shrubs which will do well in our area, and includes information on their growth habits and ultimate size at maturity.

 

 

 

Trees of Greater Portland

Trees of greater Portland cover Phyllis Reynolds co-wrote “Trees of Greater Portland”, published in 1993. Twenty years later, she has written the second edition of this worthy guide to urban trees, narrowing her definition of “Greater Portland” so that most of the subjects now included are within the city limits. The Miller Library has both editions.

She revisited and re-photographed all the trees from the first edition, sadly removing the ones that are gone, but adding some that are new. Most interesting is comparing the photographs of the same tree in the two editions after twenty years more growth. One of the most remarkable is a Malus x domestica ‘Yellow Bellflower’, a winter apple with pale yellow fruit. Thought to be planted in 1848, it still blooms and bears fruit.

For the Portland resident or visitor, the nine tree tours at the end of each book will be of the most interest. These are in neighborhoods especially rich with notable trees, many profiled earlier in the book. To sharpen your recognition skills, the author only identifies one example of each species on the walk, as she explains, “This should be a learning experience.”

Excerpted from the Fall 2017 Arboretum Bulletin.

Friends of the Trees

A Portland-based non-profit organization, Friends of Trees advocates for urban forestry issues. They provide education about greening urban areas and caring for existing trees in the urban forest.