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Posts Tagged ‘Trees’

Last year I worked on a large mall planting project.  A number of trees had to be pulled out to make way for a new parking layout; the islands they had been growing in were removed and paved over, with new islands located in a different configuration.  Most of the trees were hauled away by the landscape contractor, but one ended up in a discard pile next to the mountain of loam that had been excavated for reuse.

I was interested in the root configuration on this six-inch caliper red maple.  A mass of fibrous roots wrapped closely around the tree’s trunk, much like cotton-candy filaments spun around a paper cone.  Looking at it more closely, I found that the fibrous roots grew out of thicker woody roots, some of which had been cut during the tree’s original ball-and-burlapping, and some of which, growing since that operation, were circling the trunk.  Take a look:

Fibrous roots circling the six-inch red maple trunk.

Pulled away from the trunk, the roots clearly are circling it. Over time, as the tree grew in girth, these roots likely would have constricted the flow of nutrients between root mass and crown

This sort of circling root is usually seen when the soil mass in a B&B root ball is of different porosity from the soil surrounding it; moisture will not move from one soil mass to the other until one mass is completely saturated.  Because roots tend to grow where moisture and oxygen are available, they will often stay within the root ball, and circle around the trunk as they grow.  The problem is made worse when burlap is not pulled away from the ball, as the burlap constitutes yet another interface for the moisture to move through.

Here's the tree's underside. Note the girdling root snaking on top of the big torn root facing the camera, and the curiously self-contained look of this root mass. The tree's problems likely began early in its life.

Not every B&B tree has these problems, and in those that do, not every rooting problem can be remedied at planting time.  Judicious treatment — looking for circling roots that can become girdling roots, cutting back girdling roots and cutting or redirecting circling roots, roughing up the sides of the root ball, removing or cutting down wire baskets, pulling down or removing burlap — can go a long way in helping B&B trees establish better in the landscape, and in remedying problems that threaten a tree’s long-term health and viability.  For more discussion on root issues affecting B&B trees, check out this post on Matt Foti’s station at the MAA’s Elm Bank bare-root workshop in September 2009.

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Mark Smith, construction project manager for Belknap Landscape Company in Gilford, NH, sent me photos and a description of the air-tool transplant his company executed with Piscataqua Landscaping recently.  Belknap has been using air tools for transplanting, site preparation (excavating roots at foundation limit lines prior to the foundation excavation), and root forensics, and has also used compressed air to reduce weight in larger B&B-dug root balls being moved.

Here’s what Mark had to say about the Weeping Norway Spruce they recently moved from Baker Valley Nurseries (with light editing):

“We moved a 25+ year old Weeping Norway Spruce that has resided in Baker Valley Nurseries in Rumney for the duration of its life.  This tree stood 10-11 feet tall and at least 12 feet wide on one direction.  The last time this tree was root pruned with a spade was 10 years ago.

Through the spading process we could clearly see where this root pruning occurred.  All said and done we were left with a 25-30′ wide root system…You cannot see that in these pics real well, as we had all the roots coiled up into harnesses and sitting atop the root pan.

I helped Piscataqua with the digging of this and am told so far it looks great in its new home on the coast.  Just to dig and get the tree in the truck took about 4-5 hours with 2 of us spading, and then 4 of us to get the tree in the truck which was actually the worst part.”

The tree before excavation.

Branches tied back to permit easier blowout.

Leader wrapped in burlap to protect it during excavation and moving.

Deepening the excavation.

Root plate covered in wet burlap for the pickup and move.

Guiding the forks for the lift.

Confirming a balanced and firm placement on the forks.

Guiding the lift.

A final spray-down before transport.

No photos yet of the tree in its new location, but when they come in I’ll post them.

Tree and equipment supplier:   Baker Valley Nurseries, Inc., Wentworth, NH

Moved by:

Piscataqua Landscaping Company, Inc., Eliot, ME  (Booth Hemingway and Travis Wright) and

Belknap Landscape Company, Inc., Gilford, NH (Mark Smith)

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Last week I drove to Wellesley College to see the Dwarf Alberta Spruce that Jim Doyle and Don Garrick had moved bare-root last November.  Fritz Hoffman, an Alaska contractor in town to learn about bare-root transplant work, accompanied me, and we walked and walked along the lakeshore looking for the Spruce.

Well, it wasn’t there.  We turned around, backtracked along the pathway, and came upon a grounds crew working on a plaza installation.  We stopped and met John Olmsted, Manager of Landscape Operations, who told us that the Spruce had died.  He said that despite its loss, the arborists had recently transplanted a Sugar Maple, two Kousa Dogwoods, and an American Smokebush bare-root.

The Dwarf Alberta Spruce didn't make it, but this spring-transplanted Kousa Dogwood may well thrive in this spot.

Later, Jim Doyle told me that he thought they had moved the Spruce to a too-exposed location.  It seemed to fare well through the winter, but in March had turned brown and had to be removed.  We speculated that the move from a very sheltered spot to an open waterfront location might have placed too high a demand on the plant.  It might have survived the dangerous phenomenon of frozen soils and warm air had it been wrapped in burlap, but it’s impossible to know.

Nice trunk flare on the newly transplanted Sugar Maple at Wellesley College.

What is heartening is that the Spruce move came about because Jim and Don took a chance — and though the risk didn’t pan out, the College believed in the possibility of success, and authorized the bare-root moving of four more plants.  When it comes down to a choice, especially on a large campus, between moving or destroying a tree, the opportunity to move and save the tree may make sense.   Actively managing a landscape — especially one with valuable mature trees —  requires this kind of decision-making, and newly available technologies can give greater flexibility in the move-save debate.

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A reader, Mark Vanderwouw from Shady Lane Expert Tree Care, Inc. wrote a comment on the post titled Another Air-Tool Bare-Root Transplanting (cross-posted from TakingPlace.net, the other blog I co-write for landscape architects).  His company is excavating out several large specimen trees for a one-year storage period, after which they will plant the trees in their new home.  I answered his questions in the Comments section of that post (click on the link above and scroll down to the Comments), but they, and the questions I’ve been asked quite a bit in the last few months, need airing and discussion in a larger format.  So here goes:

Q:  How long did it take to excavate the Taxus and the Kousa Dogwood that were  growing next to each other?

A:  It took the better part of a day to excavate and transplant these trees.  Because their roots were intertwined, the process took longer than it would have had they been stand-alone specimens.

Interwoven roots of two trees to be moved makes the excavating process more time-consuming.

Q:  Is it necessary to keep the roots moist during the excavation?

A:  It is a good idea to do so, as compressed air tends to dry soil and roots.  Having a hose on hand to spray down the exposed roots every so often makes sense.  There has been some discussion among the arborists doing this work that because such a large volume of root mass gets saved, the tree is much more resilient and adaptable to the short period of drying caused during air-tool work.  Compressed air will blow off quite a lot of the tiny feeder roots — but they tend to regenerate pretty quickly once planted in the new site, and the ‘reservoir’ of moisture and nutrients in the remaining large roots helps sustain the tree during the excavation and move.

I don’t know of any scientific experiments that have been done to date to test this hypothesis — right now, the results are anecdotal — but I’m guessing that we will be hearing in the next few years about controlled experiments that prove or disprove this idea.  In the meantime, if you have been transplanting trees bare-root with air tools, feel free to write in and share your experience, and join the community that’s pushing into this new territory.

Q:  Do you use hydrogel on the roots of air-excavated trees?

A:  If a tree is being moved from one location on a site to another within a relatively short period of time (say, within a day), then hydrogel is probably not necessary.  If the tree is being moved from one site to another, and trucking or trailering is involved, a hydrogel spray and a secure tarp covering are probably advisable.  The following pictures come from Bransfield Tree Company LLC, which moved a large Beech tree last fall (subject of post next month):

Jonathan Bransfield spraying down the root plate of a tree with water and a 1% solution of Wilt-Pruf before tarping. Hydrogel was used in the backfill at planting.

The newly tarped root plate getting sprayed down with water before the tree's drive to another site.

Q:  Have you seen any mortality from this method of moving trees?

A:  There is some evidence that trees with particularly tender bark don’t do well with direct pressure from compressed air.  Matt Foti notes that two cherry trees he moved last year died; a few weeks ago he moved a cherry on his own property, and had his crew blow soil out from under the tree, aiming the air in toward the trunk from the blowout trench.  He has planted the tree out in his nursery and will watch it for the next year, to see how it respond to the more sensitive treatment.   Here’s an instance where the technology is available to do the work, but our knowledge is still catching up with the technology.  If anyone wants to do a controlled, scientific study, this species-specific question would be a great one to explore.  In the meantime, arborists doing this work will report in as they learn more.

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Yesterday I drove through Yarmouth, Maine, and stopped by the site where Herbie the New England Champion American Elm (Ulmus americana) had lived for over two hundred years before meeting his end this past January (see this post for the story).  I wanted to see Herbie’s stump and get a better idea of what 217 years of tree age looked like in plan view.

It was hard to get a clear measure of the stump.  It was cleanly cut across the root flare, and there were no signs of internal decay at the cut line, which indicates that no root damage — or none of the kind that travels up the trunk and compromises it —  had affected the tree in its life.

This tree was big.  A slice from the bottom of the butt, mounted on table-height legs, would be big enough to seat at least a dozen people quite comfortably, if a bit irregularly.  The following photos show my attempts at comparative scale.

From a distance, the spot where Herbie stood looks like a small paved dais in a big open space.

A pair of Felcos and a water bottle for scale, and still it's hard to fathom the stump's size.

Hmm. This yellow nursery caliper gauge, maxed out at 4 1/4", doesn't come close to an appropriate scale. The school bus in the background ran past before I could catch its image right in front of the stump, but it begins to suggest a comparison.

This angle doesn't help much either, though it certainly illustrates how Herbie dealt with grade change -- he just grew over it.

People walking by help with scale.

Eureka! The handy measuring tape, laid across the stump's widest part, gives at least some numeric sense of size.

Here's a crop from that last photo, showing the stump measuring at its widest point 9'-2". Herbie had plenty of root room, among other advantages, so he could grow to this size.

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Another question asked at last week’s New England Grows about bare-root transplanting was “How do you make sure the roots don’t dry out?” The answer, of course, is that you water the tree you’re moving.  You water it thoroughly a couple of days before the transplant, to insure that the tree’s tissues have good turgor pressure and moisture reserves for the bare-rooting.  You take a break every now and again during the blow-out (if you’re using compressed air) and spray down the exposed roots with water.  You may spray more water on the roots — the top, bottom, and inside of the root mass — when you pick the tree up on forks to deliver it to its new home.  You ‘mud in’ the tree as you backfill, saturating the backfill soil with water to eliminate any air pockets and again, to combat root dessication.   And once you have mulched the tree well, you water still more.

Water in all phases of the operation is key to tree transplanting.

Cornell’s Urban Horticulture Institute advocates using a hydrogel slurry to hold water on the bare roots during planting.  Their excellent Creating the Urban Forest:  The Bare-Root Method describes the process of planting young trees bare-root, and is well worth reading.  The challenge of using a slurry for large-tree transplanting would be in getting a consistent coating of hydrogel on the roots (you can’t dip the root plate in a tub, the way you can with a sapling root mass) — but there must be a solution (so to speak) to that problem. And finally, aftercare is critical.  Moving a large specimen tree bare-root takes time and effort, and it would be folly to follow all the steps, get the tree in the ground, and then leave its re-establishment and survival up to chance.  Some arborists add fertilizer and bio-stimulants to the backfill, some don’t.  What is essential, again, is water.  Consistent and adequate water for the first growing season is the best way to make sure that a transplanted tree makes the transition to its new home, survives, and thrives.

Watering in a root-washed pin oak at Cavicchio's Nursery. Photo courtesy of Carl Cathcart.

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Thousands of people showed up at New England Grows this past week.  One of the conference’s principal speakers, Bonnie Lee Appleton, unfortunately fell ill and had to cancel her Wednesday talk; for a while the day before the conference it looked as if one of the two convention center ballrooms would be empty for a couple of hours.  At the last minute, NE Grows asked Matt Foti to take Ms. Appleton’s place with a talk on bare-root planting.

The talk was great — packed with information — and sent a steady stream of people to the Foti Tree and Landscaping booth to learn more about bare-root transplanting.  Matt teamed with Teddy and Mike, two of his arborists, to field questions at the booth, which had a good set of air-tool transplant photos, a continually running rough cut of my London Plane video, and two 3-inch caliper Zelkovas from Matt’s nursery. One of the Zelkovas had been dug, balled, and burlapped; the other sat with its bare roots splayed on a sheet of plastic, showing off their extension (they extended about 3-4′ on all sides from the tree trunk), uncut tapers, and web of water-collecting and nutrient-storing capacity.  Every now and again one of the arborists would spray the roots with water.

It was cool to watch visitors to the booth stop and take in what they were seeing.  Some of them shook their heads and moved on; most, though, would watch the video for a few moments, or peer at the photos and the trees and start asking questions.  Matt and Timmy and Mike rarely had a moment in the three days when they weren’t answering questions.

A couple of questions popped up over and over.   Arborists, landscape architects, designers, and contractors all wanted to know how much air-tool transplantation costs.  The answer, based on labor requirements, species, condition, and size of tree, as well as on site conditions, was that bare-rooting a tree for transplant may cost more than digging it with a tree spade, but less than digging it with the more traditional drumlaced B&B method.  Bare-rooting a tree for transplant typically preserves at least 90% of the tree’s roots, though, a claim that cannot be made for the other methods.  The more roots you save, the less transplant stress and the shorter the tree’s reestablishment period — and all other factors being equal, the healthier the tree tends to be after transplant.

The other question, also coming from arborists, landscape architects, designers, and contractors, was about taproots.  How did bare-root transplant affect a taprooted tree?  The answer is that taproots are rarely an issue, at least in this part of the world.  In New England, soils tend to be shallow.  As we know, trees tend to develop their roots in the top 18″ of soil; the larger the tree, the deeper that zone may go, but typically it extends no more than 3 or 4 feet below grade.  Some thick roots do extend vertically down in this zone, but many more run horizontally away from the tree’s trunk.

It’s helpful to keep in mind another factor when thinking about taproots and transplanting trees.  More often than not, a large tree being transplanted was planted out years earlier as a B&B plant, or possibly moved into place with a tree spade.  Both methods would have cut any taproot in the initial planting.  When the end of a root is cut, the tree tends to send shoots out from just above the cut end.  In a vertically oriented root, the new shoots are apt to extend horizontally from the cut end, and feeder roots would similarly extend out horizontally.  The situation may well be different for a tree that has grown from seed in one place, that someone now wants to transplant bare root, but for most landscape trees the taproot issue is moot — whatever taproot may have existed when the tree seed germinated has already been cut, and the tree has adjusted for its loss.

A carrot grows downward, with rootlets out to the side and foliage above ground. A tree is not a carrot. Photo by obenson in Flickr.

This beech tree was moved last fall, having been transplanted once about 20 years ago. See how the root mass extends far out horizontally, with a relatively shallow depth.

This is one of the thickest roots extending vertically from the beech's trunk. This root was cut in the earlier (20 years previous) transplant; note the resultant root growth just above the cut.

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I was in Maine last week, and planned to stop in Yarmouth on Monday to watch the removal of Herbie, the champion American Elm (Ulmus americana) that had finally become too compromised to stay standing.

For several months,  stories about Herbie and his long-time steward, Yarmouth tree warden Frank Knight (at 101 years old, he is now retired) had been appearing in the news — Knight had cared for Herbie for over 50 years, and had treated the elm in repeated battles with Dutch Elm Disease.  He had succeeded for decades, but in recent years the disease and old age had been catching up, infecting whole limbs and making it necessary to remove large chunks of the tree’s crown.  Last summer, the town’s current tree warden, Debra Hopkins, determined that Herbie should come down, and Knight concurred.   The date of removal was set for January 18.

There were reports that arborists and Herbie-fans from around New England would show up to watch the proceedings.  As I would be driving past Yarmouth that day, I decided to join them.  Work was slated to begin at 7:30 a.m.

Fortunately or not, a heavy snowstorm started on Sunday night, and when I awoke at 5 on Monday morning several inches had already fallen, with no end in sight.   A couple of tasks delayed my departure by several hours, and as it seemed unlikely that the work would proceed that day anyway, I didn’t arrive in Yarmouth until about 2:30 p.m.  Herbie still stood.  As I drove up, several people were snapping photos of the tree; more showed up when they left, and still more arrived as I was leaving.  Lots of people wanted to get a last look at this giant.

Herbie the American Elm, on the day scheduled for his removal.

Herbie was massive — in his prime, he stood 110′ tall, with a crown spread of 120′ and a girth of 20′.  Disease and age had diminished him, and it was clear that this was a tree under serious stress, but it was impossible to stand next to or near him without feeling awe.

To get a sense of the tree's scale, note the people standing to the left of Herbie.

Someone had tied a red, white, and blue ribbon around the tree, and people had attached cards and well wishes and information on this champion to it.

The placard in the middle is an 8.5" x 11" sheet of paper, with facts on Herbie's size and life.

The tree had quite a lot of evidently viable growth in the canopy, but the canopy itself had been hugely compromised, with several very large limbs removed.  I remember hearing Alex Shigo talk about how and when to make the decision to remove a tree; he spoke eloquently about the native dignity of trees, and about how at some point the act of removal shows more respect for the tree than leaving it in place.

There comes a point in a tree's life where removal of this much of its crown is a removal of dignity, as well. Though the tree's trunk appeared to be sound, and the limb removals had eliminated hazard wood, Herbie's time had come.

For about 15 minutes, I ran around in the cold photographing Herbie from different angles.  As I did, I saw carloads of people arrive, jump out, snap photos of themselves with the tree, put a hand out to feel its bark, and then gaze up at it reverently before they left.  And then I went over, put my hand on the craggy, lichen-speckled bark, and also said a silent goodbye.

Herbie in his heyday. This was a classic American elm.

Herbie was taken down the following day, with Frank Knight in attendance.  To see removal photos and videos, as well as how the wood from this elm will be used, click on this link.

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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.  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 arborist community 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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Say you’re a growing country club in a nicely-treed community, and you need to enlarge your parking lot. And perhaps you want to lower its grade. The lot has some mature oak trees in it, and they add a certain je ne sais quoi to the scene, so you decide to save the trees by keeping the grade as is around the base of their trunks. You retain the roots and soil with a mortared stone wall. Voila!

Good idea – but woops! The minimum standard for root preservation is to keep 10 inches of root mass diameter per caliper inch of tree. For these trees, that would spell at least 360-inch diameter root masses. Because the trees are so close together, their roots overlap significantly — but still, 360 inches is thirty feet of diameter.

This 18-footish enclosure takes a tad too much root; the country club will almost certainly be watching these trees decline and die over the next few years (and they may well drop dead branches onto the parking lot, or cars in it, in the process).

The idea of saving a mature tree is a good one, as long as the tree’s actual requirements for continued healthy life are met.   Now that we have the tools to see how large a tree’s root mass really is, it’s much easier to see how big the unimpeded area around it has to be for the tree to survive happily and to thrive.

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