Root work

Contractors, arborists, and landscape architects in Massachusetts would do well to check out the Ecological Landscaping Association’s September events list.  The ELA is offering a number of really good workshops, on topics ranging from Boston-area restoration projects to the use of fire in landscape management, as well as a two-part, two-day workshop on root issues.  

One day of the root work will focus on soils(f you’ve read any of this blog, or Taking Place In The Trees, you’ll know that I’m interested in roots.)  In the air tool workshop, entitled At The Root: Air Tools Workshop, Rolf Briggs and Matt Foti will be talking about using air to work in the root zone, to decompact soils, to transplant trees and shrubs and also about how to plant nursery-grown stock properly.  

Matt and Rolf have done a similar workshop for the Mass. Arborists Association in the past, and Matt holds an annual workshop on proper planting techniques.  Being able to see what a root system looks like is eye-opening.  Learning — not just from written specs or a generic tree-planting detail — how a tree or shrub should be planted is essential, and well worth the price of admission.  I have been to at least three of these workshops, and learn something new at each one, and so can say that this workshop is one every landscape architect who designs plantings, and every contractor who sells plantings should attend.

Michael waters in a hemlock whose root flare has been excavated with air.

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Weeping willow — the nature of the beast

A year ago I wrote a post on dappled willows (Salix integra ‘Hakuro Nishiki’), comparing one rigorously maintained specimen and one planted-and-forgotten specimen. Two takeaway points from that post (I hope): 1) plants in a garden usually require at least some maintenance — more or less, depending on the genus and its role in the garden; and 2) willows really want to grow.

Here’s a photo illustrating the second point. This willow — I think it’s an old weeping willow (Salix babylonica) — clearly had started to break apart, and had apparently become fairly hazardous. Its owner whacked the entire top off, and the willow responded with this explosion of shoots. Willows grow fast and grow weak, but they’re vigorous enough to continue growing even if they break up, fall over, are pruned to the nth degree, or are cut down, which is what makes them such great coppicing plants. But that’s a topic for another post…In the meantime, enjoy the photo, which I took in a New Hampshire seacoast town.

Cartoon character or tree? Weeping willow growing into a new form after having been topped.

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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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Herbie

I just wrote a post on Herbie, the champion American elm in Yarmouth, Maine, that was taken down last week after a life that spanned more than two centuries. The post, at Taking Place In The Trees, included several photos I took the day before Herbie came down. In his prime, Herbie was the largest American elm in New England — 110′ high, 120′ wide at the crown’s widest point, and 20′ in girth. When I saw him, more than half of his largest limbs had been removed, but the tree’s presence and majesty were unmistakable.

Herbie the American Elm, in his prime.

A field count of the rings on Herbie’s trunk indicated that the tree was at least 212 years old. This was a tree that largely defined the genius loci of its neighborhood. It filled the corner of a private yard and marked the intersection of two streets; it cast high shade over a wide and fortunate area.

It’s not difficult to extrapolate lessons from Herbie’s presence and longevity, lessons that might inform how landscape architects design and advocate for planting spaces. I can think of these lessons:

1. Plant trees! They provide cover, coolness, oxygen, and identifiability to a place.

2. Plan for the long term — aim to foster a tree’s growth for decades, not just for years.

3. Design for root space — bare-root transplanting of large trees shows us how trees benefit from space in which to grow, and how far from the trunk their roots need to grow to add crown growth. Push those developers, homeowners, and city agency officials to allocate more space for subgrade growth; it’ll pay off in happier, healthier trees, and broader shade canopies.

4. Remember how big trees want to get. Putting a large-scaled canopy tree in a slot of soil better used for skinny grasses won’t give you the tree you’re looking for; it’ll give you a tree that whimpers for a few years, declines, and then dies. Scale your trees to your site (aiming for as big a planting site as possible — see 2. and 3.)

5. Shoot for size. People love the giant, and are more apt to preserve and take what they love. A large tree builds its own constituency, which helps when you’re trying to keep nature from being overtaken by pavement. If you want people to engage with nature, give them something with which it’s easy to engage. (Keeping in mind 4.)

That’s for starters. What other lessons do you see in Herbie’s story?

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Air tool transplant video

I just got a rough cut today of the video, shot last summer, of the moving of a very large (about 14″ caliper, 30′ height) London Plane Tree in Wellesley, MA. It’s taken a while to edit several hours of footage down to a half an hour, but it’s about done, and in the next few weeks I hope to have added commentary. This video is from the project run by Matt Foti’s crew, aided by Mike Furgal, and it showcases the techniques used in air-tool transplanting. I hope to be able to preview the rough cut at New England Grows, and have the final version completed by the end of February; if there’s enough interest in the landscape architecture, architecture, or arboriculture communities I’ll sell copies. Stay tuned.

The first of five 12-14' caliper London Plane trees being excavated with air tools and transplanted bare root in August 2009.

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Massachusetts Arbor Day of Service

The Massachusetts Arborists Association has a new volunteer initiative starting in 2010. They aim to build on the traditional Arbor Day celebration by instituting a statewide volunteer service day on that day, which falls on April 30, 2010.

To get the ball rolling, the MAA is inviting anyone to identify potential tree care projects in their own communities, and then to post those project ideas on the Arbor Day link at www.MassArbor.org. They hope to get ideas from all 351 Massachusetts cities and towns by January 15. From that list, MAA members and member companies will choose projects for their own Arbor Day of Service volunteer effort.

This is a great way for landscape architects to elect projects and for professional arborists to make a contribution, both for the civic good, and for cities and towns to reap the benefits of a concerted professional effort. Safety pruning, tree planting, hazard tree removal, ornamental pruning — a community you drive through daily may have the project that’s perfect for your company to tackle on Arbor Day. To submit a project for Arbor Day of Service consideration by the MAA arborists, visit www.MassArbor.org by January 15, and click on Arbor Day.

Arbor Day is a great way to get all generations involved in plant care.

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Honey Locust in the suburbs

Well, this town outside of Boston can’t be considered ‘the country’ these days, but still, there’s plenty of room for a tree to grow. This Gleditsia, unlike the two in the previous post, has plenty of room to grow, and shows what form and size a Honey Locust really wants to take:

Plenty of rooting room translates into plenty of canopy.

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Honey Locusts in the city

I was recently on Newbury Street in Boston. Turning away from the nifty pay-for-parking machine (these things have replaced meters on the street, and they couldn’t be more convenient, or more helpful for reducing street furniture clutter), I spotted this valiant little Gleditsia, working hard to stay alive:

A little way down the street was another Gleditsia, this one growing in a similarly sized tree pit, but intact from the saw:

Both trees work hard under severe limitations. The far tree shows what the nearer tree could have looked like.

How well these characters are doing is a direct consequence of how well they’re being cared for, and of their native vitality. The far tree is impressive for its growth despite the tiny volume of root space available for it; the near tree admirable for its persistence.

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