Bark development in Coastal Douglas-fir (Pseudotsuga menziesii var. menziesii)

[Cruiser]

Adolescent Bark:

Texture smooth-blistered. Gray, green, brown, silver, or whitish in color. Firm to the touch. Thin. Easily damaged. Resin blisters can be popped to release sap.




Developing Bark:

As tree continues to grow and weather, outermost bark cracks, forming linear vertical fissures. Fissures may show younger brown mottled bark within. Exterior bark develops into hard, rough, grayish-brown ridges. Resin blisters have mostly dried out.




At a distance trunk appears vertically wrinkled or striped. Mosses and lichens take hold, especially at old nodes, around branch stubs, and knot indicators.




Mature-Ancient Bark:

Thickly ridged, plated, and/or mottled-flakey.
Mixed in color: various shades of brown and grey, tan, some green hues from adhering plant life, and sometimes patches of black from charring (previous wildfires).



Internal mottled bark layers build up, adding to and enlarging external ridges. Ridges often broaden into chunky plates with deep fissures in between. Plates are corky, hollow-sounding, and lighter in weight than they appear. Occasionally pot-holed. Roughness is sometimes weathered smooth.



Fissures deep enough for a bird to nest in.

Ridges/plates can get sloughed off and may be absent entirely from lower trunk, leaving only mottled-flakey bark.
Mottled-flakey bark is soft, spongy, and loose-shedding. Does not appear as vertically aligned as ridged bark, more broken in appearance. Flakes small, layered, randomly shaped (puzzle-piece), alternating shades of brown, cream, sometimes greenish or sun-bleached grey. Outer flake layers delaminate, like loose pages of an ancient book. May come off in large chunks. Easily crushed in the hand. There is often a pile of bark fragments with other organic debris at tree base.

The sheltered side (right) of this giant has retained its thick ridged bark. The left side is more exposed which has lead to the ridges sloughing off.

 

[Cruiser]

Other unusual bark characteristics are occasionally encountered..


This fir is popular with local wildlife. Most of its flakey bark has been rubbed off on one side, exeposing papery, spotted, cream-colored bark.


Some trees have been culturally modified. These fir had parts of their bark removed long ago by native peoples. The exposed inner bark develops into a hard, finely wrinkled/sinewy texture.

 

[Cruiser]

Cross section showing the mottled brown bark layers in a younger tree (60ish years). Sometimes referred to as “bacon bark”.

 

[MaciekA]

One question that you might find motivating would be to ask how quickly does a given segment of wood go from smooth to fissured mode, and whether this particular sub-genetic of doug fir does that quicker or slower than others. I've found that paying attention to this transition time is useful in the case of some other species (such as black cottonwood, which goes from bright-and-smooth to JBP levels of rough/fissured in a surprisingly short / usefully short time for bonsai purposes).

 

[Asymetrix]

Thank you for posting. Very interesting to see the stages of development and nicely detailed pictures.

 

[Cruiser]

One question that you might find motivating would be to ask how quickly does a given segment of wood go from smooth to fissured mode, and whether this particular sub-genetic of doug fir does that quicker or slower than others. I've found that paying attention to this transition time is useful in the case of some other species (such as black cottonwood, which goes from bright-and-smooth to JBP levels of rough/fissured in a surprisingly short / usefully short time for bonsai purposes).

For lower trunks of the coastal variety…Based off what I’ve seen in the field, trees growing in plantations with a moderate site index start developing shallow fissures/cracks at 15-20 years. That’s with 11’ tree spacing.
Fissure development probably starts sooner in potted and open grown fir.

It seems that mature bark on the coast variety would develop faster than in other subspecies since they grow so quickly in this environment. But I don’t know for sure. Maybe it’s genetic.

 

[Cruiser]

how quickly does a given segment of wood go from smooth to fissured mode

Here is fissured bark just starting to develop in a plantation grown tree. (13ish years).



How long does fissured bark take to develop in less favorable conditions?

I’ve had the opportunity to sample naturally-growing stunted and confined Douglas-firs to get an idea.
Some were cored with an increment borer, others that had recently died were trunk chopped to count rings.

In 14 samples, the average time to acquire a fissured bark appearance is about 28 years. This is for trees growing in the wild.

This dead fir was found on a large mossy rock at 2800’.


It was cut at a point along the trunk where the bark starts showing cracks and signs of thickening.


Miniscule rings reveal that it took 29 years to reach this stage of bark development. Proportionally, it is thick and the bacon pattern is starting to show.


Tiny plate.


A few inches above root flair. 2” diameter. 43 years. Thicker, more developed bark.




This tree is growing on a dry site near Twisp, WA.
It’s about 5’ tall and 3” wide at ground line. The trunk was cored at a place with fissured bark. Light brown coloration is peeking through cracks in the sun-bleached grey exterior. Immature bark is seen above.



It took this tree around 40 years to develop the bark shown.

 

[RKatzin]

Terrific expose! Thanks for taking the time to share this most interesting info.

 

[Cruiser]

It would be nice to get some data for how long mature or fissured bark takes to develop in container grown Douglas-fir. I suspect that drought plays a role in the process for natural confined trees. A container grown tree could control for that variable…

 

[0soyoung]

Just a bit of pedantry to start:
Bark grows from a separate bark or cork cambium that is created every year along with new phloem. As such a new layer of cork cells are created annually just like a new layer of wood (xylem) is --> there are growth rings in the bark analogous to growth rings in the wood. Further, bark made from the products of photosynthesis just as is wood and everything else in a tree, which means that anything that restricts growth also restricts bark growth. The sugars must be off-loaded from the phloem and moved via a ray connection to the cork cambium in order to create a new layer of cork cells. We label trees that do this well with the name 'cork bark' (I note that generally corkers are 'slow growing', meaning their wood stems thicken relatively slowly). I have it in my mind that this is because the available raw materials (carbohydrates from photosynthesis) are allocated more strongly to the cork cambium than 'the cambium' (that produces new wood).

Anyway, my point is that it will take longer to grow bark in container growing just as it takes longer to thicken stems/trunks in container growing. Likewise, a tree growing in restrictive conditions will be thinner as a consequence and will also have thinner bark. This isn't to say that there are not additional factors that can lead to thicker/gnarlier bark sooner than normally happens.


Regarding data, I am still container growing most of the trees I used in my Douglas fir Repotting Experiment. Some of these I've not tried to make bonsai of (yet) and have simply let them grow. They were about 2 years old when I acquired them from ArborDay, so they are all now less than 15 years old. The ones I let go are now 6+ feet tall. They have the characteristic smooth, shiny blistered bark of young Douglas firs. The ones I diverted into bonsai styling efforts have a duller bark and very few resin blisters and are far from fissured in any way.

I have applied a treatment that successfully induced the enhanced bark growth evident in this photo



The same treatment's effects on the smaller 'bonsai-ish' pseudotsugas failed to produce much of an effect (hence part of my pedantry, above).


Grow the trunk, grow the bark, then make the bonsai as not a whole lot of growth (including bark growth) is going to occur once it is a bonsai. Just as in the forest, my bit of data indicates that it will take far more than 15 years to create gnarly fissure bark on a Douglas fir in normal container growing.

 

[Cruiser]

Just a bit of pedantry to start:
Bark grows from a separate bark or cork cambium that is created every year along with new phloem. As such a new layer of cork cells are created annually just like a new layer of wood (xylem) is --> there are growth rings in the bark analogous to growth rings in the wood. Further, bark made from the products of photosynthesis just as is wood and everything else in a tree, which means that anything that restricts growth also restricts bark growth. The sugars must be off-loaded from the phloem and moved via a ray connection to the cork cambium in order to create a new layer of cork cells. We label trees that do this well with the name 'cork bark' (I note that generally corkers are 'slow growing', meaning their wood stems thicken relatively slowly). I have it in my mind that this is because the available raw materials (carbohydrates from photosynthesis) are allocated more strongly to the cork cambium than 'the cambium' (that produces new wood).

Anyway, my point is that it will take longer to grow bark in container growing just as it takes longer to thicken stems/trunks in container growing. Likewise, a tree growing in restrictive conditions will be thinner as a consequence and will also have thinner bark. This isn't to say that there are not additional factors that can lead to thicker/gnarlier bark sooner than normally happens.


Regarding data, I am still container growing most of the trees I used in my Douglas fir Repotting Experiment. Some of these I've not tried to make bonsai of (yet) and have simply let them grow. They were about 2 years old when I acquired them from ArborDay, so they are all now less than 15 years old. The ones I let go are now 6+ feet tall. They have the characteristic smooth, shiny blistered bark of young Douglas firs. The ones I diverted into bonsai styling efforts have a duller bark and very few resin blisters and are far from fissured in any way.

I have applied a treatment that successfully induced the enhanced bark growth evident in this photo

View attachment 543363

The same treatment's effects on the smaller 'bonsai-ish' pseudotsugas failed to produce much of an effect (hence part of my pedantry, above).


Grow the trunk, grow the bark, then make the bonsai as not a whole lot of growth (including bark growth) is going to occur once it is a bonsai. Just as in the forest, my bit of data indicates that it will take far more than 15 years to create gnarly fissure bark on a Douglas fir in normal container growing.

What treatment did you apply to the tree with the enhanced bark growth?

 

[yashu]

Great thread @Cruiser ! Glad I noticed it. Did you take all the photos?

 

[Cruiser]

Great thread @Cruiser ! Glad I noticed it. Did you take all the photos?

Thanks! Yes, I did.

 

[0soyoung]

What treatment did you apply to the tree with the enhanced bark growth?

Ethylene. I've noted in another thread or two that ethylene enhances radial growth of stems. Blocking the flow of auxin causes natural ethylene production. This is why there is a flare in the stem at the top of a girdle or above a tourniquet. Likewise, this is why stems rapidly thicken once our spiral wrapped wire begins to 'bite in'.
Ethylene is also produced as part of damage response. Some practitioners have noted that they can enhance growth in specific areas by repeatedly piercing the bark or by 'gently' peening an area with a hammer. While I don't think they are the beast of techniques, they do work (to a certain extent) because the damage to the cambium induces ethylene production and enhanced growth of the undamaged cambium cells in the immediate area. It has also been suggested (for some time now) that the root flare of ground planted trees is due to damage (microcracks) of the cambium just above the root collar similarly affecting enhanced radial growth (known as 'reaction wood' to lumbermen). The Telperion method for growing pine bonsai exploits this phenomenon which is effect of endogenous ethylene, IMO.

What I've shown you is that exogenously applied ethylene enhances the growth of the bark cambium.


You have that lovely coring tool. I think it would be interesting to see if the bark is proportionally thicker in/near the root flare than at 'chest height' of forest trees.

 

[Cruiser]

Ethylene. I've noted in another thread or two that ethylene enhances radial growth of stems. Blocking the flow of auxin causes natural ethylene production. This is why there is a flare in the stem at the top of a girdle or above a tourniquet. Likewise, this is why stems rapidly thicken once our spiral wrapped wire begins to 'bite in'.
Ethylene is also produced as part of damage response. Some practitioners have noted that they can enhance growth in specific areas by repeatedly piercing the bark or by 'gently' peening an area with a hammer. While I don't think they are the beast of techniques, they do work (to a certain extent) because the damage to the cambium induces ethylene production and enhanced growth of the undamaged cambium cells in the immediate area. It has also been suggested (for some time now) that the root flare of ground planted trees is due to damage (microcracks) of the cambium just above the root collar similarly affecting enhanced radial growth (known as 'reaction wood' to lumbermen). The Telperion method for growing pine bonsai exploits this phenomenon which is effect of endogenous ethylene, IMO.

What I've shown you is that exogenously applied ethylene enhances the growth of the bark cambium.


You have that lovely coring tool. I think it would be interesting to see if the bark is proportionally thicker in/near the root flare than at 'chest height' of forest trees.

Very interesting. How was the ethylene applied and in what dosage?

Bark does get thicker the lower you go on a DF because it gets older. (unless it gets rubbed off/shed).
Though it sounds that the microcracking and associated ethylene production would also play a role.