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Ancient trees

If we can clone crabapples, maples, and chamaecyparis, why can’t we clone the enormous redwoods that stand as the world’s tallest trees?  Well, apparently we can. This article in Sunday’s New York Times (4/10/2011) explains how a group of arborists dedicated to propagating and planting clonal stands of coastal and giant sequoias, using tissue and cuttings harvested from the sprouting stumps of sequoias that have been cut down.   It’s a compelling read, has good pix, and might leave you with something to chew on.

 

 

 

 

Yesterday I swung by the site where Herbie, the American Elm in Yarmouth, Maine, had stood for over two centuries.  Herbie was taken down last January; to read the tale see this post, and to see photos of Herbie’s stump, click on this link.

I hadn’t planned to stop and see the stump — what more could be said about a stump?  As the exit from Rte. 95 neared, though, I wondered if anyone might have put up any signs, or even if some of the woodwork from Herbie’s wood might be displayed on the site.

It wasn’t though, and in fact all that remained of the stump was an area, approximately 12′ x 18′,  of wood chips.  Herbie’s stump had been ground.  The adjacent road has been undergoing repaving, and stakes and markers dot the roadside and the edge of the chipped area.  We’ll have to wait and see what takes place now where Herbie once stood.

All that remains are wood chips, an open space, and a view of the utility pole.

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.

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)

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.

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.

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.

At New England Grows, I met Jim Doyle, one of Wellesley College‘s team of arborists. He told me about an air-tool transplant that he and a colleague performed last November at the College.  He was kind enough to send photos, and with them included this text, which I have edited only slightly:

“My colleague Don Garrick and I performed the transplant on Nov. 3rd 2009.  The reason for the transplant was that the tree, a Picea glauca ‘Conica’ (Dwarf Alberta Spruce), had outgrown its current location and was providing too much shade to the greenhouse.  An old accession tag we found told us that the tree had been planted in 1956.

The tree in its original location, quite close to the greenhouse.

Jim using the airspade to locate the root zone's outer limits.

Don digging a trench outside of the root zone.

In this and in the next two pictures, Jim removes soil from the Picea's roots.

  

Working in from the perimeter toward the trunk.

Don lifts the tree out of the hole.

Transporting the tree to its new home across campus. The tree has been laid down for stability.

The tree in its new location, with plenty of room for continued growth up and out.

During the whole process we watered the roots every 5 to 10 min.  We wrapped the roots in wet burlap for the transport.  Once we had placed it in its new home, I sprayed the tree with with anti-transpirant and we then staked it, as its new home was a very windy location on the lake.  The stakes and guys will probably be removed this summer once we can confirm that the tree has settled well enough in its new hole.”

Here’s an example of the thoughtful management of plants on a property.  This Dwarf Alberta Spruce was in good shape, but had grown out of its original location, tucked behind the greenhouse.  Moving it was a fine way to save the tree, preserve the antique greenhouse glass adjacent to it, eliminate the greenhouse interior shading problem, and revamp the area — and now the tree, in its new spot, has room to grow and is visible to the Wellesley College community.

Project site:  Wellesley College campus, Wellesley, MA

Project arborists:  Jim Doyle, ISA-Certified Arborist; Don Garrick, MA-Certified Arborist

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.

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.