What trees need us to know

Last week at New England Grows, while Toby was manning the table for the Ecological Landscape Alliance (its shiny new name hasn’t made it onto the website yet, but the ELA is an outstanding organization, and so is their material), he struck up a conversation with Jeff Ott, owner of Northeast Shade Tree in Portsmouth, New Hampshire. Jeff told him about a workshop he’ll be giving on March 6 for landscape professionals; it’s called “Tree School for Landscapers; The Built Landscape From An Arborist’s Perspective”.

The Old Elm on Boston Common, 1876
Courtesy Boston Public Library via Flickr; Creative Commons License: http://creativecommons.org/licenses/by-nc-nd/2.0/deed.en

Jeff, who has been an arborist for the last 36 years, had the great good fortune to work with Alex Shigo — probably the most influential tree researcher of the 20th century. Recognizing that more intellectual cross-pollination between arborists and other landscape professionals would benefit the landscapes on which we all work, Jeff decided to put together this workshop. The timing is good, before the spring planting and construction season gets rolling, so I’m aiming to go, and hope that other landscape architects will seize the opportunity as well.

Here’s the Tree School announcement.  Don’t be alarmed about the absence of an address:  you send your registration form and check ($75) to:

166 Clinton Street, Portsmouth, NH  03801

And here’s the Tree School Agenda, which outlines what will be happening through the day.  Contact Jeff if you have further questions; he can be reached at jottphc@gmail.com, or by phone at 603-463-7512.

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And unlevelled places become a plain

In my work doing residential landscape architecture, I have encountered a number of instances where someone has bought a house on a sloping piece of land, getting what seems to be a steal. Usually, the buyer/client first tackles work on the house, revising its interior, and sometimes its exterior, to make it just as he/she wants it to be. House modifications can take years. When the house update is done, the homeowner turns his/her attention to the landscape. Most people want as much usable outdoor space as possible: a patio is a pleasant place to sit, a big, level lawn lets kids play comfortably and within sight, and walking, driving, swimming, or playing sports are all easier on flat surfaces. And it’s when the owner of a sloping site wants to enlarge their usable domain that it becomes clear why the dream house was such a bargain.

Why? Because slopes are expensive to unslope.

For people to use the land immediately around their house with any degree of comfort, it’s necessary to make level areas. A patio typically has a cross-pitch or slope of not more than 2% (just enough to drain water), and a lawn that slopes no more than 5 or 6 percent is best for active kids to organize and play games on. When a house is built on really noticeably sloping ground, the grade can measure anywhere from 8 to 15 percent, or more.

Sometimes earthen banks can hold up a level area; sometimes strategically placed boulders can do the job; often large retaining walls are necessary. Where surface area is scant, retaining walls may be the most efficient way to hold land level. Walls tend to be costly.

To start from a different point: A couple of years ago, I had the good fortune to visit a friend in Konstanz, Germany. While there, we took a number of side trips into Switzerland. We punctuated our train trip to Appenzell, Switzerland (home of many cows and of Appenzeller cheese, a famously stinky but delicious local specialty) with a visit to St. Gallen, home of a UNESCO World Heritage site, the Library of the Abbey of St. Gall.

St. Gallen, Switzerland, from the air. The medieval walled city core is clearly visible among the more regular fabric of later-built streets and buildings. The Abbey and its World Heritage Site Bibliothek can be seen at about four o'clock in the walled part of the city.

The Bibliotek (Library) was closed when we arrived. We were ready to take a rest anyway, so found a spot on the spacious and sunny courtyard lawn and got out a picnic lunch. The day was bright and only slightly cool; though cars puttered by outside the court and a bell nearby clanged the hour and several other people sat on the grass and on nearby benches, the courtyard felt extraordinarily tranquil and pleasant. We munched and chatted, and I tried to put my finger on what made the courtyard feel so different from the surrounding area.

Look closer at the Abbey and its grounds. It takes up a large area within the walled city, and though the surrounding land slopes to the northwest, (that is, toward the photo's top left corner), the huge Abbey courtyard is almost perfectly level.

I had been thinking about the slope/cost issue for a quite some time, and it sprang to mind again in that peaceful abbey close. From the railroad station in the valley bottom, we had climbed winding medieval city streets to get to the Abbey; the walled city around the Abbey sat considerably higher than the station itself. Outside the three-sided Abbey complex, streets bent and sloped against the thick walls of the Roman Catholic enclave. Inside, green grass carpeted an utterly level quadrangle, muffling sound and lying like a tablecloth on a tabletop

Outside the Abbey walls is an orderly but dense fabric of masonry buildings and narrow streets that wind up and down the hilly terrain. Inside the Abbey walls, the utterly level and open ground of this tranquil courtyard puts on display the power and wealth of the Church that built it. Photo by kind courtesy of Galen Frysinger, at http://www.galenfrysinger.com/

In this Swiss city, slope is a fact of life. Buildings themselves do double duty as retaining walls; the back door of a house here can easily be situated a full floor above the front door. The city fabric is tightly woven, to conserve energy and again, because amending long sloping frontages can be expensive. Most homes are built cheek by jowl, with little or no space between houses.

The Church was and is a wealthy and powerful homeowner/landowner, as evidenced by its leveling of a sizable piece of the town’s steep foothill to make a vast piece usable ground. The fact that the courtyard lies in the middle of this densely woven city, and that it is given over to luxurious lawn sends a quiet but clear message of power and wealth. While the elegant and extremely solid buildings convey that message, the carving out of level outdoor space speaks just as definitively about the ability of this particular institution to make unlevelled places plain.

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Thriving live hemlock

That last post made a good point — sometimes the leftovers in a landscape can be used as a feature in and of itself — but I much prefer the photo here. This hemlock is very much alive, and lives outside of Boston on private property. Carl Cathcart, Consulting Arborist, took me to see this wonderful tree last July, and you can see more photos of and information on the tree at Taking Place in the Trees.

To get an idea of the scale of this tree, look just to the right of the tree's center; Carl Cathcart is standing on the ground under the tree's canopy, and his legs are just visible.

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Boston hemlock

The other day I was on Beacon Hill and spotted this mostly dead hemlock tree, completely swathed in Boston ivy:

Though this hemlock tree on Beacon Hill is dead, its stripped-down structure maintains usefulness, as Boston ivy covers it entirely with foliage.

Perhaps the owners were simply neglecting their courtyard garden, but I like to think that they saw the mature tree’s size as an asset to the place, and decided to use the deadwood as an armature for another plant, and to use the resulting ‘hybrid’ as a garden element.

I have seen this strategy used with other trees; an ancient, mostly dead apple through which a vigorous rose climbs and blooms, tiny dead crabapple that hosts a clematis vine, and a couple of thriving Norway maples through whose canopies wind equally thriving wisteria vines.

We see bittersweet and poison ivy taking advantage of the height and sun exposure offered by trees; why not use that principle and foster the growth of ornamental vines over dead trees, or, as in the case of the Norway maples and wisteria, let one aggressive species provide a platform for another aggressive species?

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Hemlock root flare excavation

It has been a while since I’ve written about root flares. I got some photos from my friend Carl Cathcart the other day, showcasing the excavation of a hemlock root flare. This tree is one of a hedge of 7-8′ tall hemlocks planted two years ago. Its owner had noticed that while the hedge wasn’t failing, it wasn’t exactly thriving, either. He called Carl, a Consulting Arborist, in to inspect the situation.

Carl zeroed in immediately on the base of the tree, and with a little hand excavation discovered that the hemlocks were sitting at least four inches too deep in their root balls. It has been customary for years to plant balled and burlapped trees so that the top of their root balls sits at or slightly above the finish grade around them. Cultivation practices in the growers’ nurseries have changed since that technique became the standard, though, and now it is necessary to check each root ball to make sure that root ball soil is not covering a tree’s root flare. A buried root flare — whether it is buried with root ball soil, compost, or an excess of mulch post-planting — spells trouble for a woody plant, and can be the cause of a tree’s failure to thrive. Small leaves, shorter-than-normal annual twig extension, and thin foliage can all be symptoms of a buried root flare. Root flares are not roots and are not adapted to life under the soil surface; they are part of the tree’s aboveground trunk, and typically need to be exposed to the air.

The in-field solution to this problem (should the excess soil not be removed in the nursery) is to excavate the root flare onsite during project planting. This task should be done before the tree is planted, so that the flare is planted at the correct grade; unfortunately, many contractors are not even aware of the issue, and will not have included time for root excavation in their bid. Here’s where landscape architects can make a major difference in the longevity of their project’s woody plants, and where contractors can distinguish themselves from the competition; LAs aware of the need to excavate root flares should include that requirement in their bid sheets for contractors, and contractors aware of that need (whether they are in a bid situation or not) can use this task, and the benefits it brings to the planted landscape, as a compelling selling point.

When root flare excavation doesn’t take place when the plants go in the ground, the signs of tree stress will likely show up within a year or two. At that point, hand excavation is still possible, but air-tool excavation usually will be more efficient.

When Carl identified the problem, he advised the homeowner to have air-tool excavation done. Matt Foti of Matthew R. Foti Tree and Landscape sent over a crew to carry out the work; Carl’s photos illustrate this post-planting process nicely.

The arborist has tied up the hemlock's branches for easier access in to the root ball. In this photo some of the soil has been blown away already.

A compressed air tool blows off the root mass. Just visible behind the tree is a plywood barrier that helps keep airborne soil from covering the surrounding plants.

The root flare has been uncovered; note the soil line about four inches up from the root mass. When you see side branches at, just above, or even emerging from below the soil level you can suspect a buried root flare. Carefully scraping away soil at the tree's trunk will indicate if further excavation is necessary. Now that the root flare is exposed, it is possible to see the girdling root that has formed on the trunk's left side.

The girdling root has been cut off, preventing any further vascular constriction in the root coming off the trunk and heading toward the photo's lower left corner.

With the root flare exposed and girdling roots removed, planting soil is blown or shoveled back into the excavated area at the correct grade.

The last step, before untying the branches, is to water the excavated area thoroughly, to rehydrate roots and to eliminate any air pockets in the root mass.

Project site: Private Residence, Sudbury, MA

Consulting Arborist: Carl Cathcart, A Plant Healthcare Consultant
Arborist for root flare excavation: Matthew R. Foti Landscape and Tree Service, Inc.

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Dappled willow

About ten years ago, I noticed a mild fad rev up in the gardening world; all the garden centers around here started carrying Salix integra ‘Hakuro Nishiki’, usually trained into standard form with a 3-4′ high stem and a pompom of foliage at top. Hakuro Nishiki, also known as Dappled Willow, is a fast-growing, twiggy large shrub/small tree with variegated white and light green to pink leaves, and it lights up a garden with its foliage, which is profuse and almost aggressively healthy-looking.

I’m fond of these plants, though they certainly need to be placed with care. They like full sun, but can deal with some shade. Because they grow so vigorously, it’s a good idea to commit to pruning them every year or so, to keep them in bounds. Actually, I can see how sculpting them in various ways each year might be an interesting exercise — not something you’d want to do with most plants, but this one seems malleable enough to allow some experimentation.

I have written earlier about L. and A., my excellent clients on the North Shore, who enjoy developing and fostering their landscape. Several years ago L. bought a Dappled Willow for her perennial garden. It’s not a standard form; instead, she’s keeping it pruned low, to keep it in scale with other elements in the garden. Here’s a photo of it in leaf:

This plant is about thirty inches high and wide, and is kept as a mounded shrub with pruning.

And here’s a photo of how L. prunes it to keep it contained to this form:

Every year L. cuts this Dappled Willow back hard, to keep its vigorous growth contained in a form that works for her perennial garden.

I have wondered what these plants look like unpruned, and last week got to see one. If the willow in L.’s garden looks like a contained explosion, this one looks as if the top blew off the container:

Perhaps the owner of this plant didn't realize what level of attention Hakuro Nishiki was going to require annually.

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Renaissance view

Don’t you love this photo? Toby Wolf took it at the Crane Reservation in Ipswich, a property of The Trustees of Reservations. He said that for him it has the quality of an oil painting; I agree completely. It has that same dark/light/dark sequence, that same frame/focal point/background flavor as a painting by an Italian Renaissance painter.

At the Crane Reservation, Toby writes, “It looks like The Trustees have deliberately maintained the opening to the view, and that the late-afternoon light, raking across the marshes and the bark of the trees, is what makes it work. I like the light on the ground-layer plants.”

The whole ravishing photo.

Here’s an example of landscape management supporting a design intention. Sometimes we design places with stone, wood, earth, metal, and plants; sometimes we design views, and tweak a visitor’s perception of a place by what we leave in, what we remove, and how we frame and focus what they see. Obviously, a photograph can be manipulated to do these things, but sometimes a photograph simply records a perception that has been shaped by others, as The Trustees have apparently shaped the Crane Reservation view.

A view framed by dark elements, a view into a light space, a view toward water, a view toward curves — what a pleasing combination. I want to take a bite out of this photo.

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If a tree falls in a garden…

The massive four-stem Norway maple that blew down in high winds last week.

Following up on the list post item from June 9, about what to use to replace a lost Norway maple: it will be a honey locust (Gleditsia triacanthos inermis ‘Shademaster’), placed slightly upslope from the Norway stump.

Last week I visited the North Shore seaside site (where last year we revamped the drive court planting and added bamboo and holly for property line screening; to read about those projects, see Refinement and Air Spade In Action) and saw the spatial effect of losing this tree.

Surprisingly, the loss wasn’t as bad as I had thought it would be. The tree’s canopy had taken up a huge amount of space and cast deep shade over quite an area. It had screened my clients from an unappealing view of the corner of their neighbor’s house — but also from a wider view of the Boston skyline in the distance. Now the horizon is wider; they’re going to have a spectacular view of the city’s July 4 fireworks. While the neighbor’s house is unfortunately visible for the moment, the honey locust will mitigate that view. A younger specimen maple just over the property line, which had been hidden by the larger tree, looks healthy, and helps provide a perspective-focusing foreground to the far horizon.

Fortunately too, while the tree provided shade over a wide area of the site, much of its underplanting consisted of junipers and taxus, which should benefit from having more sunlight. The redtwig dogwood, azaleas, and hydrangea will think a bit about how much they like being exposed, but I think they’ll adapt. Even the little spring shade garden should fare all right, protected as much of it by a dense shrub planting from full sun exposure. Many of the herbaceous plants in it are ephemeral anyway, showing up in early spring before any trees leaf out, and fading back as foliage emerges above them.

Shade cast by the now-gone Norway maple protected the little spring garden and its ligularia circle at the path's end.

Our biggest concern for this newly sunny area is the ligularia bed. This bed, banded with a circle of bluestone, makes the southern terminus of a sightline through the tiny spring garden. The ‘Britt Marie Crawford’ ligularia, with its chocolate-brown foliage and golden spikes of flowers, makes a ravishing dot at the bottom of the exclamation point. And it’s a shade lover.

Ligularia 'Britt Marie Crawford' in its circle bed.

It may not be at all happy to be getting sun all day every day. My hope is that it can handle it well enough for long enough to feel relief from the kinder, more dappled shade that the new honey locust will eventually cast.

This site has seen several mature trees come down since last year; neighbors next to the drive court removed a large maple and a lovely S-shaped pine, an ailing ash tree got taken out, and a graceful Russian olive specimen, some 20 feet tall, blew down in the same storm that took the big Norway maple.

Each subtraction has shifted the sun/shade proportions, and each will affect the growth and health of the surrounding area. This kind of change requires adaptation both by the plants and by the owners, and provides opportunities for new ways of seeing a familiar place.

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My phone applications

Voice.  That’s it.  My phone lets me talk, and listen to someone on the other end; if I’m working, I can plug a headset in or hit the speaker phone button.  And use the ‘Mute’ button if necessary.

I opened Toby’s iPhone app post with reservations, having felt saturated recently with iPhone app ‘articles’ that seem little more than ways for a newspaper or blog to fill space.   (In the Boston Sunday Globe Magazine recently I mistook a piece on phone apps for an advertisement, because it was largely a collection of photos of phones, each one showing a different app, with a weblink below.  It was not poor beleaguered print journalism’s finest hour.)

I’ve been a dedicated voice-only phone user forever.  Low-to-the-ground technology is what I like to use, knowing how easy it is for me to get lured in to a moving display and find myself sidetracked for an hour or four.  And I just got a new phone contract last week, turning down the chance to get a new phone because the one I have works just fine.  So a post about phone apps?  Argh.

But the apps Toby shows are making my dialing finger (so to speak) itch.  It would be hugely helpful to be able to place dimensions directly on a photo in the field.  My field notes tend to be scratchy and blobby, and while I’ve developed a method for keeping straight what numbers go with what dimension line, that dimensioning app holds out the promise of more organized field dimensioning.  So tempting.  And stitching together a bunch of photos a la David Hockney would simplify my reference photo printing, too.  Even the number converter looks inviting, though I keep a handy cheat sheet with me for quick and dirty conversions.

An excerpt from a recent set of field notes.

Still, colored pencil and paper are quick, and while they’re not beautiful they do give me the information I need, in exactly the way they’ll be useful when it’s time to draw a base plan and work out the details.  You can’t beat the price.  So far, the end results  over the last couple of decades have been successful.

Stay tuned.  I’m betting that I’ll stick with a voice-only phone, but if the iPad adds a camera and a UWB port and can use those apps I may turn into a technology maven yet.

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Ceci n’est pas un arbre

Or, ‘This is not a tree’.

Thinking again about, and then past the pollen issue, I wonder if humans had such strong allergic reactions in pre-industrial times. In much the same way that we have been using the world’s oceans as a dumping ground for every substance we don’t want to deal with, we have been pumping fine particulates into the atmosphere in ever-increasing quantities since the start of the Industrial Revolution.

Maybe pollen's not the real problem. Photo courtesy of The Library Of Congress, via Flickr.

We breathe oxygen. Oxygen shares atmospheric space with pollen and with myriad other particulates; our bodies work to filter out the particulates as we draw in oxygen.

Certainly, pollen poses challenges to the smooth operation of the human body. And planting fewer pollen-abundant trees might help breathing conditions to some extent. But really, now — shouldn’t we also look at the overload of particulates continuously (not only seasonally) streaming into our breathing space from coal-fired power plants, miscellaneous smokestacks, vents, trains, trucks, buses, and cars? And act to place more stringent limits on emissions from all those sources?

Making the natural world the culprit is easy. Calling ourselves to account for the consequences of our much more harmful actions may, as painful as it is, may be the more responsible and fruitful response.

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