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Archive for the ‘Trees’ Category

Elm trees are known for their toughness in urban conditions; it’s why so many were planted in the American landscape.  For speed of growth, beauty of form, and wholehearted commitment to growing in all sorts of conditions, almost nothing beats Ulmus americana.  The elm’s Achille’s Heel, of course, is Dutch Elm Disease, which decimated the population of them through the twentieth century.  For the last half of the twentieth century, it was quite unusual to see American elms planted anywhere; they almost entirely disappeared from the market.

It wasn’t impossible to find them, though, and scientists and a few growers continued to work on developing disease-resistant strains of this majestic tree.  The Elm Research Institute grew and distributed clones of elms it believed showed resistance, and in the 1990s Dr. Denny Townsend, a geneticist with the National Arboretum, released two of the first DED-resistant cultivars of American elm, called ‘New Harmony’ and ‘Valley Forge’.  Bit by bit the American elm began to reappear in the landscape.

I was part of the design team for the streetscape restoration of Boston’s downtown area during the Big Dig design and construction phases.  We selected the National Arboretum elm cultivars, among a range of trees, to help fill out the planting palette for what became the Rose Kennedy Greenway.  So far, the trees have been doing swimmingly.

Last week Matt Foti’s crew spent a few days on the Greenway moving a collection of trees bare root from one of the parcels near Quincy Market.  The Rose Kennedy Greenway Conservancy will be building a permanent carousel on that parcel, and they wanted to save and reuse the trees that had been growing where the carousel will be placed.  Matt called to tell me about the work, which involved moving some red maples and some American elms that had been in the ground for the last 6-7 years.

The red maples, about 6″ in diameter, moved quite easily; their roots had readily broken out of the original root balls and grown nicely out into the planting medium.  Blowing them out was a simple process.

The American elms, however, had gargantuan root systems that seemed to go on forever.  Root growth was thick and profuse, and the crew had to keep blowing further and further out, and further and further under the root plate.  Here are photos that Matt sent of the elm roots:

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Tremendous root mass on an elm that had been planted only 6-7 years earlier.

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One elm getting lifted out of its planting hole.  Sinker roots had to be blown off; though the tunnel top is three feet below the surface, it appears that the roots on this tree had grown down to the concrete surface. Note the clean cuts on roots that had to be severed.

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Last spring I posted photos of a lovely little weeping hornbeam that the Foti crew had transplanted bare-root in downtown Boston a month earlier.  Matt Foti just sent me a couple of update photos, taken when his guys had been down on the Rose Kennedy Greenway to move a collection of trees from one of the park parcels near Quincy Market (a couple of photos from that project will show up in my next post).

The hornbeam thrived through the season, and is doing beautifully.  It had fully leafed out after planting, and the foliage looked awfully good.  Take a look:

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Nice dense foliage on the transplanted hornbeam.

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This tree apparently didn’t miss a beat when it was moved.

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…and go back to school for a day.  If anyone in the Massachusetts woody-plants world has not seen the latest in tree- and shrub-planting techniques, here’s your chance:  on September 27, Rolf Briggs and Matt Foti will be giving a workshop entitled At The Root:  Air Tools Workshop at the New England Wild Flower Society’s Garden In The Woods.   Matt and Rolf will discuss and show the best techniques for planting trees and shrubs fresh from the nursery (air tools not necessary for this), as well as how to use air tools to trench under trees, decompact soil, and transplant trees.

I have my reasons to promote this workshop (and it’s next-day partner, At The Root: Understanding and Managing Healthy Soils), and they center on the fact that every planting season I find myself coaching laborers on how to deal with the root balls of plants that we’re planting on my job sites.  The boss, not knowing or having taught his laborers the proper planting techniques, usually has priced the work based on a quick  installation (dig the hole, stick the plant in, cover up the root ball, basket, and burlap), and the laborers, knowing only the quick and dirty method, look sideways at me as I show them what I want them to do.  The guys do the work the way I want it, but really, the process would go much more smoothly, and more landscapes would establish and grow in better, if everyone knew , priced, and carried out the work in what are considered the most plant-friendly ways.

Some of the most effective tools available to see what can be considered plant-friendly, and to work in soil crowded with roots, are pneumatic air tools.  I believe that Rolf and Matt will be transplanting a tree bare-root, using air, which will afford workshop attendees a chance to see what a tree’s roots really look like when the soil is blown away.  It’s an experience that can change how anyone working with plants understands how a plant grows and anchors itself, and for that alone this workshop is worth attending.

Watering in a newly planted tree-form Taxus from Weston Nurseries.

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Last week Matt Foti sent me photos of a bare-root transplant his crew performed on 25 March 2012 in downtown Boston.  They blew soil off the roots of an 8.5″ caliper weeping hornbeam tree (Carpinus betulus ‘Pendula’), and moved it from one end of the city block to the other.  Take a look at this beauty:

This 8.5″ caliper weeping hornbeam tree is getting transplanted from a bed on Summer Street, outside Boston's Federal Reserve Bank building. Note the pigtails on the tree’s near side, and the thick burlap wrapping to protect its trunk.

The tree being moved to its new home in a 3-4′ tall planter on the corner of Atlantic Avenue and Congress Street. Burlap tied under the root mass helps contain loose soil during the move.

Weeping hornbeam in its new location. The Federal Reserve does an excellent job tending its plants, so this one should get the consistent aftercare all transplanted trees need.

With this warm winter and spring, trees have been leafing out several weeks early; this one had just begun to leaf out before it got moved.  The Foti crew has had good success moving trees bare-root even during bud-break; it’ll be interesting to watch this tree and see how it settles in to its new home over the coming year.

 

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This past summer my good friend, Consulting Arborist Carl Cathcart took me to see an unusual weeping hemlock in a suburb of Boston.  He had shown it to me earlier in the spring, when we got to see it from the road.  This time, he had gotten permission from the owners to examine the tree close up, and so we were very fortunate to be able to stand under and next to it, measuring its stems, its height and width, and generally marveling at its astonishing beauty and size.

The tree’s crown measures approximately 33 -36’ high at its highest point, and approximately 63’ across at its widest spread.  Carl noted that it is averaging 5 1/2 – 6″ of new needled growth all around.

Seven main stems grow from the base.  Their sprawling nature made it impossible to get a diameter at breast height,  but we were able to determine that at roughly 4 ½’ from the ground the stems ranged from 15″ in diameter to 31″ in diameter.  At the tree’s base, we measured a girth of approximately 84″  — this was a tricky measurement to get as some stems grew close to horizontally from the base.  We stood in awe at this magnificent specimen.

Take a look at these photos.  We visited on a cloudy-bright day, the type of day typically good for photographing, but found so much contrast between shadow under the crown and light outside the crown that I resorted to black and white for some photos, the better to show the tree’s form.

It’s not often that we get to see such enormous and grand specimens in this part of the world.  Carl and I appreciated the privilege we had been granted, and hope you enjoy seeing what we saw.

The hemlock from one angle. It sits on a large lawn where it has been allowed to grow in full sun and without competition from other trees.

A slightly different angle. Note Carl's legs under the canopy, just to the right of center.

Carl under the canopy. Note the size of the stems compared the the size of his torso.

Under the canopy.

Underneath, from a different angle.

Not much greenery inside the tree, but plenty outside to make this limb-framed cave.

Magnificent.

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This past week I had occasion to pass the same suburban Massachusetts middle school on two days in a row, and on each of those days my eyes goggled at the sight of a new planting on a slope facing the road.  The array of brown, grey, and coppery-red foliage — on the trees that still had foliage — was stunning.  From what I can tell, over the last month or so more than thirty new oaks, zelkovas, and pears were planted as an understory to a mature oak forest.  Did I say stunning?  Yes — but not in a good way.  Most of the trees are dead, and it’s likely that within a few weeks the few still hanging on will die.

You have to admire the forward thinking that gets a new stand of trees started while an existing stand remains; it’s a principle used more in European landscapes than American ones, and we could stand to practice it more here.  It really makes sense to extend one’s planning horizon beyond the span of one’s own life and think both in terms of tree longevity and of the needs of generations to come after us.  The idea of getting young trees established under a mature stand seems particularly apt at on a school property, where adults are fostering the growth and education of children, and tending the young beings who will one day assume adulthood.

So the failure of this planting, installed with apparently the most admirable of motives, seemed especially poignant and distressing.  The tree species selection seemed fine, but it looked as if almost every other element of a planting — root ball size, soil quality, well construction, mulch used (or lack of it), and watering — was inadequate to fulfill the aim of establishing a planting that would live and thrive.

It was impossible to miss this planting from the road below. Virtually every newly planted tree is either dead or nearly so.

From the school drive above the slope, the view is as disappointing. The pears look like the toughest of the new trees out there. Fall color in July is never a good sign, but at least they still have leaves. The zelkovas are mostly bare.

That pile of soil in the foreground is the native soil on this New England upland slope, thin and sandy, with little organic material evident. It appears that the new trees were planted directly into this soil without amendment -- which is fine, as long as the planting crew worked on the root balls to make a rougher interface between root ball soil and native soil. Because water will only move from soil of one porosity to another when the soil is saturated, and roots follow water, you want to scuff up the walls of a root ball to make a less distinct interface between the two soils, and to encourage water and roots to cross the interface.

Tiny root ball? Perhaps. For a 3" caliper tree like this , ANSI standards call for a 32" diameter root ball. The well on this root ball is about 18" in diameter, so it looks as if the root ball is small -- but it may simply be that the well itself is inadequate. Wells should be built outside the root ball wall, so that water is held over the root ball and over the interface between surrounding soil and root ball soil, and so promotes root growth beyond the root ball. Not to mention that these trees were placed right at the drive edge, where their root cannot spread out under the asphalt, and the weight and pressure of plowed snow can tip them...

Another tiny root ball, with a mini-well. The well is very loosely constructed; water has broken through and run down the sandy slope, leaving the tree high and dry. This photo makes me thirsty.

All of the trees are planted on sloping ground, but hardly look it -- another indication that root balls and water wells are too small. Got mulch, anyone? Particularly in this type of sandy soil, a watering schedule and at least a temporary irrigation system (set up to last and run through the first growing season) would help establish the trees. Planting like this has consigned what were once good trees to the chipper.

Egh. More of the same.

What good can be said of this planting?  Well, again, the idea of starting a new generation of trees in an established stand is an admirable one.  The tree’s root flares appeared to be in the proper relation to the surface of their root balls.  Otherwise, it seems to me that this planting is a cautionary tale:  against contractors who do not know how to plant properly, against too-small root balls, poor soils, substandard planting practices, bad tree wells, the absence of mulch, inadequate provision for watering, and inadequate watering itself.  The information on how to plant and foster trees is readily available, so the question may be how do we broaden people’s awareness of it, and their awareness that trees are living organisms rather than tall pieces of furniture?  Any ideas?

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

Boston ivy uses this dead hemlock tree as a climbing structure; its owners choose to let the tree stand and continue as a feature in their courtyard garden. Mature trees are rare in tiny Beacon Hill gardens; 'repurposing' this one turns it from an eyesore into an asset.

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 whose 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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