Treeshelters & Winter Die Back: That Was Then, This Is Now

This 1997 research study appears prominently in web searches for treeshelters. The conclusions reached by Doug Lantagne and Raymond Miller at that time and on that study site were that solid wall treeshelters did not increase height growth and were not successful in helping to regenerate red oak. Naturally, we are often asked about this study and others like it.

Our answer often surprises the questioner: They were right. And then we elaborate: They were right then, but they wouldn't be right today due to the dramatic changes and improvements in treeshelter (tree tube) design.

The Lantagne/Miller paper was the result of six years of testing, meaning that the seedlings were planted and treeshelters were applied either in 1990 or 1991. Keep in mind that the first treeshelters were imported to the USA from the UK only in 1988, and were commercially available only in 1989. These were early days.

The researchers - and everyone using treeshelters back then - were using a product that,
1) Clearly had fantastic potential to solve several problems limiting the success of hardwood regeneration, especially deer browse, weed control (by shielding seedlings from herbicide spray, not to mention clearly marking seedling location amidst the brush), and moisture/drought stress
2) In retrospect were perfectly suited to the moderate, maritime climate of the United Kingdom, but were ill suited in several important respects for the climatic extremes of North America. The moderate climate of the UK was very forgiving on treeshelter design characteristics that our more extreme climate later exposed as design flaws.

The two most important design changes during that period of time have been: Recognizing the importance of tube diameter in promoting thicker stems and balanced root/shoot ratio, and the revolutionary introduction of ventilation. Both topics are covered in more detail here and here.

In the early days of treeshelter use in the USA reports of initial growth acceleration followed by a period of slow growth that allowed un-tubed trees to catch up were common. Why was this? Ironically, it was not until treeshelters were adapted on a large scale for use in commercial vineyards (and were re-dubbed "grow tubes") that we had to controlled & uniform growing conditions necessary to learn the answer: Diameter. In small diameter tubes (and those early treeshelters came in nested groups where the diameter of the inside tubes was too small) the leaves shade each other and the stem to a much larger degree. This in turn triggers a "shade avoidance" growth response in the tree - it shoots upward for light, but invests little growth energy in thickening its stem or developing roots. Upon emergence from the tube and exposure to full sun and wind, the tree then slows or even halts height growth while it reallocates growth energy into stem thickness and root growth... thus allowing un-tubed trees to catch up (provided they hadn't been eaten by deer!).

Plantra Tree Tubes have a much larger diameter - 3.9 inches - than the average diameter of those early treeshelters. The result: Much more balanced growth while inside the tube, so there's no need for the "rebalancing" period upon emerging from the tubes. Growth builds on growth, and there's no chance for un-tubed trees to catch up.

The Michigan State researchers mention winter die back as the main reason un-tubed trees caught up to or surpassed those in solid wall treeshelters, and they were right. This was a real problem throughout the 1990's with solid wall treeshelters. After a summer of rapid growth hardwood seedlings in those early solid wall treeshelters would simply keep right on growing deep into the autumn; they did not get the moisture (drying) and temperature signals they need to initiate dormancy. They were the forestry equivalent of hothouse orchids. Consequently when the first killing frosts of autumn came these trees often suffered significant die back from the tip down. It was better than getting eaten by deer, and eventually the trees would re-sprout and emerge from the tubes early enough in the growing season to properly harden off for winter, but it was far from ideal.

The introduction of the vented treeshelter has solved this. Ventilation has several benefits - increased stem thickness, increased rate of CO2 exchange for optimal growth - but the most immediate and dramatic was the virtual elimination of winter die back of hardwood seedlings in treeshelters. Ventilation equalizes temperatures in & out of the tubes. And while the seedling still enjoys the moisture-stress reducing benefits of wind protection, vented tubes don't create the hothouse climate that leaves seedlings exposed to frost damage.

Since we introduced our Plantra Vented Tree Tubes we have not received a single phone call or email regarding winter die back. It is simply a thing of the past.

Researchers like Lantagne and Miller perform an extremely important role, testing new ideas and casting a spotlight on their shortcomings. This was a very important piece of research, one report among many that caused and encourage those of us who have been involved with treeshelters since the beginning to question long-held assumptions about treeshelter design and performance and try new ideas like ventilation that were once considered to be heresy among treeshelter makers.

The result: A Plantra Tree Tube design that is ideally suited to both hot and cold temperature extremes of North America... with more advancements on the way.

Lantagne and Miller were right about tree tubes at that time, but that was then and this is now!

Mitzi and the Zombie Trees

Last summer my wife and I were on vacation in St. Louis.

We stopped at the gateway arch to take pictures inside and out. While walking around the park under the arch, I noticed a clump of ash that could provide some welcome shade. What I found was a whole stand of zombie trees. The living dead.


The ash above is in a death grip. A death grip of circling roots girdling the tree.

Girdling roots are a common problem transplanted trees such as B&B or balled and burlap trees. Planting large trees like this means you are likely to get a damaged root system and a short life span. Planting small seedlings avoids this problem and grows a tree in place with a natural root structure and the potential for a long life.

The young oak below was planted as a seedling at Lincoln's Tomb in Springfield, IL. Notice the radial root supporting the oak. The folks managing Lincoln's Tomb want oaks and they want oaks that will live well over 100 years.


This oak tree was protected with a tree tube or tree shelter when planted. That is the secret - use a Plantra Tree Tube and plant small seedlings to produce a normal root system that will support your tree for 100 years or more.

If you want more information on trees and root systems in landscapes go to Ed Gilman's web page hosted by the University of Florida.

Beware The Leaf Clot

The top picture is a bur oak leaf clot looking down a tube. You cannot see the shoot and that is bad.










The second is a side view of an Autumn Blaze Maple leaf clot.

Leaf clots are bad. They prevent gas exchange and can trap the shoot. Always prune to a single stem.

Temped to jam the foliage in the tube?

Don't own a pruner?

Don't have time to prune?










Here's more detail.

Have to admit I love the next picture - and not just because the growth and form benefits of Plantra Vented Tree Tubes are so obvious. The other reason is that there are so many lessons from these two trees.

At the bottom you can see the "leaf clot" I want to talk about. The a shoot escaped the clot and screamed to the top of the emerged and formed a new area of dense foliage.

Standard Plantra recommendations are to cut back to a single stem before installing the tube. There are three reasons for this recommendation.


Structure: First is that we want to produce a straight single stem. If you want the tree to live a long productive life, you have to get a sound structure and that means a single straight trunk.

Root System Energy: The most important thing you purchase in a seedling is the carbohydrate stored in the root system. It matters how this energy is used. If there are three shoots the energy is divided between the three and you get three short stems producing leaves that compete for light and CO2. We want one shoot to command that energy. The key to the Plantra Growth Engine is to rapidly fill the tube to the top with an array of spaced out leaves that do not overlap. We want leaves fully expanded and intercepting light through the wall with the stoma on the underside wide open and absorbing CO2 from the humid-CO2 rich air the vents move past the stoma on backside of the leaf.


Leaf Clots: A tangle of leaves can trap the shoots. In the confined space of a tube bunched leaves can form an impenetrable blockage.


Please PRUNE Preventively

This Bud Is For You - If You Want A Straight Tree

On 23 June 2009 this Autumn Blaze Maple was tubed with a 4 foot tall Plantra Vented O-Style Tree Tube.

As you can see in 11 weeks there was a tremendous difference in growth.

The untubed maples are shrubby and about 17-20 inches tall and the tubed maple is 5-1/2 FEET tall with a gun barrel straight stem.

Given the fact that all 1,000 maples in this picture are under two feet and the Plantra maple is well over 5 feet, I think it is safe to say the Plantra Tree Tube made a difference. I would go so far as to claim statistical significance. If the difference is great enough - all you need is one!

Quite a difference - an important difference, but not what I want to call to your attention.

My purpose is to explain some of the hidden mysteries of plant growth in a well designed tube.

The next image is a close-up of the leaves and buds that formed just at the point the maple was emerging from the Plantra Tree Tube into full sun. There is something odd about that picture - it looks upside down. Can you see it?

Notice the dark bark has developed above the younger looking green bark.

Normally you would expect the newer parts to look newer and the older parts to look older. Not in this case.

The lower - older - stem parts were protected from intense sun, strong winds and scouring sand, so the plant kept the protected area photosynthetically active. There is chlorophyll in the stem inside the tube. This effectively increases the leaf surface area and the growth potential of the plant. Not sure if I have every read that observation before.

But that is not what is truly interesting here. Let us look at the next set of leaves below the dark stemmed area.

The first thing you will notice is the angle of the leaf stalk or petiole. It is angled upward because it developed in the restricted space of a tree tube. Next again notice the photosynthetically active green stem.

But wait... there is more.

The most significant difference between the two images is that in the upper picture small branches have emerged between the stem and the leaf stalk. Scroll back up and take a look.

In the lower picture all we have are two leaves. This two leaves only pattern continues exactly the same down the stem for all of the new growth in the tube.


Why is this significant?

• It means the grower has a labor-free method to control the height of the first branches
  
• It means the plant has not wasted energy producing useless branches
• It means the grower has far fewer branches to prune
• It means the stem it straighter
• It means the stem is stronger - no narrow crotches or included bark
  
• It means the stem has a more appealing form for a veneer or landscape buyer
• It means more growth due to excellent air flow within the tube to replenish CO2 consumed in growth
• It means no excess of fungus harboring moisture trapped by over crowded leaves and branches
  

There will of course be a dormant bud at the leaf site, but it will not form a branch under normal conditions.

Branches do not form readily in the tube because of the absence of blue light and a surplus of red light. Not all tubes take this important plant response to account when designing products. At Plantra we try to think of everything.

Best Un-Natural Forest Regeneration Ever

In July the Northern Nut Growers had their 100th meeting and scheduled it at Purdue University. Purdue has a national reputation for work on black walnut. My wife Mitzi & I live in Minnesota. There are many innovative hardwood tree planters between Indiana and Minnesota. On our way back, we drove through Iowa to meet John Olds of One-Stop Forestry. We wanted to see for ourselves the directing seeding magic we had heard so much about. John was at his office in Postville, IA behind the Northeast Iowa RC&D. By the way, Mitz took most of these pictures.

John Olds and Gary Beyer of the Iowa DNR were unsatisfied with the results from traditional low-density seedling planting and decided to see if they could take an old method of reforestation called direct seeding and modernize it to make it work for hardwoods in the Driftless Area where Iowa, Illinois, Wisconsin and Minnesota come together.

John and Gary reasoned that trees know how to grow from seed. Seed is cheap. And the highest quality timber is produced when the trees are crowded and forced to grow clean straight boles in competition for sunlight. By direct seeding a large volume of nuts, seeds and acorns, they hoped to germinate and grow over 10,000 stems per acre. Competition, the site and natural selection would sort out which trees grew where. With help from three years of weed control and Plantra Tree Tubes the landowner would have an incredible stand of hardwoods.

We followed John in his pickup out to Daryl Landsgard's farm. Every forester has his favorite client. You know the type. The grower willing to try new ideas and the one who can be counted on to do his part. No planting succeeds without an involved landowner. Daryl is an enthusiastic deer hunter and wants improve habitat. He doesn’t mind if he produces some high quality hardwood timber along the way. Even though there were seedlings every two feet in this planting, I think Daryl knew the status of every single one.

A typical planting with seedlings has about 700 stems per acre. As I wrote above, John’s goal is to over produce an incredible 10,000 or more stems per acre. It was originally thought this many plants would overwhelm the deer. It would be more than they could eat.

That is only partially true. Although deer do appear to randomly browse as they walk around, in fact deer have strong species preferences for browsing. That means with so many stems nip, the deer get selective and nip what they prefer. In John’s plantings, if there is enough oak, the walnut grows free. Walnut is a fast grower and even excretes the phytotoxic chemical Juglone to control competition. So, even though there is plenty to eat, the deer browse the defenseless oaks. John has found that he needs to use tree tubes to protect the oaks and give them an advantage over the walnut.

At Plantra we are always looking for new and improved methods to establish trees. We have the luxury of working with the best of the best. Not surprisingly, John Olds is truly one of the best. After leaving Daryl’s farm we followed John back to his house. The Olds Estate (It doesn’t have a name yet, but is more than impressive enough to deserve one) sits on the crest of a hill with a commanding view of an immense valley. John wanted to show us what Daryl’s planting would look like in a few years.

The regeneration is so dense you have work up a little courage to enter. John’s biggest problem is deciding what to thin. With so many high quality stems to choose from the choice can be a difficult one.

Darn, too much black walnut!

Direct seeding is not a new concept and has many variations. Arlyn Perkey, author of Crop Tree Management has written about a direct seeding acorns in Tree Farmer Magazine and has a photo journal on direct seeding chestnut. By the way, John Olds says he reads his copy of Crop Tree Management every year. While written for the forestry professional, Arlyn’s clear prose and minimal use of jargon make it very easy to read for anyone. Every woodlot owner should have a copy.

For direct seeding in Iowa and the Driftless Area call:

John Olds

One-Stop Forestry

101 E. Green Street

Postville, IA 52162

563-864-3586