Is this an accurate description of how a tree dies? And of coppicing?

I'm writing an article, and I want to make sure I'm not inventing a mare's nest.

A tree grows ever larger . . . until it dies. Unlike most animals, it does not age at a cellular level; a cutting taken from an ancient tree can be as "youthful" as ever. Instead, new wood and new leaves are constantly being generated, while the old is shed or becomes heartwood.

Assuming that it is not killed off by some marauding fungi or insect, it dies due to "overgrowth". Every year, it must cover every inch of itself with a new layer of wood; this required new wood is a larger amount every year, while the available resources stay fixed. Eventually, it crosses some critical boundary; moisture availability, wind throw resistance, or structural strength under snow load; and it dies, either in a sudden crash, or slowly, branch by branch; each dead branch shed in an effort to economize, but leaving wounds open to infection and ensuring less energy for next year. Nothing grows forever.

We have found a way to keep trees from falling into the overgrowth trap. This is called coppicing. Every so often, woodland managers cut the new woody stems back to a permanent stump, leading to a new flush of growth which can be coppiced again. The tree stays ever vigorous, and can live many times its usual span. It provides a steady, predictable yield in a sustainable fashion.

Both copicing and pollarding increase a trees lifespan, I do not have any references But I believe that some of the hazel coppices in the south of england are over 1000 years old, up from a standard age of 80 for un-cut tress.

I do not know, but I suspect that some trees lives can be extended by coppicing while others can not.  I'm just trying to imagine how a coppiced/pollarded cedar, oak, maple, poplar or white pine would react.

Not a tree but an observation on plant genetics from bamboo....
you can divide, air layer or take cuttings from bamboo and the clones grow better when the "parent" plant is young, eg a few months old.
the clones, dependent on species of bamboo, will live for decades then one year all clones all over the world will flower, seed and die.

This is at least evidence that cuttings in at least one plant family are aware of their genetic age, so it's possible tree cuttings know their "age" too.

Mike Jay wrote:...cedar, oak, maple, poplar or white pine would react.

Not sure about the others, but my father "coppiced" a maple (he backed over it with his pickup) about 8 inches above the ground and it came back seemingly no worse for wear.  It is still going strong and this was 15 or so years ago.

Not a tree but an observation on plant genetics from bamboo....
you can divide, air layer or take cuttings from bamboo and the clones grow better when the "parent" plant is young, eg a few months old.
the clones, dependent on species of bamboo, will live for decades then one year all clones all over the world will flower, seed and die.

This is at least evidence that cuttings in at least one plant family are aware of their genetic age, so it's possible tree cuttings know their "age" too.

Yes, bamboo do age, rather dramatically. Of course, they are a grass; but I guess it is possible that trees also "know" their age. However, with at least many trees, there does not seem to be too many obvious effects of this process.

I do not know, but I suspect that some trees lives can be extended by coppicing while others can not.  I'm just trying to imagine how a coppiced/pollarded cedar, oak, maple, poplar or white pine would react.

Most evergreens can't be coppiced; they just die. Oaks coppice, as do some maples. With many trees, the process has to start when they are young. And some are better then others.

I'm more interested in whether my description of tree death by overgrowth is accurate.

Interesting!

Well it's certainly true that trees don't have a genetic or planned death/senescence.

And it's true that trees always continue to grow, and that in most situations this will result in the tree not having sufficient resources to sustain itself.

But I don't know that I would say that, barring coincidence, trees die of overgrowth. There are a few reasons I say that.

1. Because resource availability is the specific mechanism that you're working off of, and resource availability varies and is dependent on the larger system. It's not possible to say 'this tree died of overgrowth' unless water availability, soil condition and their contributing climactic conditions are totally equal over time. While that may happen, I would say it's more the exception than the rule. Also, I know in a way it goes without saying but those effects are reversible: if water or missing nutrients become available, the damage to the tree is undone.

2. Because as they age there are a number of things trees do to compensate for approaching the limits of their resource availability. Typically as trees age they put more energy into phytochemicals and antioxidants, be it for tree health, insect deterrence or other reasons. Self pruning is common as well, and is, if you think about, a really elegant way to turn the challenges of seasonal variability into a solution. Also few trees stand completely alone, and the transmission of nutrients and sugars from older trees to surrounding, younger trees is a recently discovered but well documented phenomena.

3. Because there is such a thing as aging in trees, it's just not a matter of genetic degradation. Trees age physically- phloem pathways are disrupted, destroyed, collapse or bust, are rerouted or abandoned. Scars reshape and reorient the tree, affecting its hydraulic patterns, growth patterns and efficiency in moving sugars, minerals and water. Older trees put less energy into root growth than younger trees, even after the addition of soil nutrient and/or water. Older trees grow their foliage slower, and individual leaves are usually bigger, likely as a result of these and similar things.

It's certainly not wrong to say that trees die of overgrowth. I just don't know that it's necessarily the full story. To me it seems more accurate to say that trees don't age at a cellular level, when they die it is due to the cumulative effects of the circumstances of life.

Great resource on this topic: http://www.isa-arbor.com/education/onlinelearning/podcastDetail.aspx?ID=7&EP=1365

In my opinion you could look at the question from an evolution perspective. After all, a chicken is the way an egg makes more eggs. I don't remember whose quote this is but i think you can extrapolate from that.

Anything living is affected by evolutionary pressures. The organism invests in repair if this somehow advantageous to its reproduction later on.


As long as it is more advantagious for a plant to regenerate and thus reproduce better later the plant will 'invest' energy and time to reproduce. A tree is basically a structure of plants to compete for light. Given good conditions a tree will continue to grow but the tree hits a barrier. Chance events (storm, drought, wildfire, logging, fungi, etc...) will sooner or later topple it. A single event is probably survivable but eventually one or more chance events will occur simultaneously and bring the tree down. By that time the tree has hopefully produced enough fruit to succesfully reproduce.
To regenerate a tree 'stores' energy in its tissue - f.e. in underground roots. If you remove the fruit from a tree, it will invest the incoming nutrients and energy into its growth. Growers remove fruit from damaged trees they hope to save in order to improve the chances of the tree. So trees 'invest' solely in their structure in order to reproduce 'better' that is MORE competitive later.

True annual plants follow a different strategy. They put everything in their seeds at the end of their growing cycle. At the end they are nothing but dry stalks. They aim to cover a large area fast in order to harvest 'light and energy' before the competition.

I think this explains partially what i observe when harvesting leafs and such. Say lemon balm, most kinds of mint, etc.... if you let the plant follow its normal cyclus it will flower early in the year - say between june and august. A stem with flowers on top typically has mostly big leafs that are in a bad shape. The plant does not invest any more in the bottom leafs that are eventually shaded out by higher leafs, damaged by sun and climate, attacked by insects etc.... It puts everything in the flowers and their seeds.
I take advantage of this mechanism when harvesting.
I typically pinch the top leaves of lots of herbs. Many react to this by form 2 new stems from the base of the remaining top leafs. I effectively take away the flower buds already there.  So the plant is forced to invest in one or more stalks with fresh leaves and new embryonic flower buds. So i get a plant that is bushier, greener and produces a lot more fresh folliage for a lot longer than it would do otherwise. The harvest is also spread out over a longer period so it's easier to process - less loss after harvest.
The plant stems/stalks that survive this treatment become stronger more cellulos and lignine i suppose.

I even have the distinct impression that some of the plants take some of their 'proceeds' and put them in their roots. Lemon balm roots of plants treated like this become thicker and can survive a lot of brutal treatment.



So i don't think that a tree dies of overgrowth. Remember half or more of the tree is underground. It can form runners and spread out much as a mycelium does. These articles illustrate the point.

https://www.pri.org/stories/2015-05-05/earths-biggest-living-thing-might-be-tree-thousands-clones

The original tree mentioned in the article must have sprouted from a seed. Its original stem and roots are probably long gone but it still is not dead. Coppiced trees can have very lare diameters after a few hundred years - how big would it be after 80000 years ?



https://en.wikipedia.org/wiki/Fortingall_Yew

This is kind of similar to coppicing i suppose



https://en.wikipedia.org/wiki/Old_Tjikko


Last but not least. We have restrictions on tree logging here. Alas we also have boneheads who want to cut trees frivolously 'to much leafs in fall' etc.... There are cases known of idiots who killed the trees by poisining the roots.