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February 24, 2023

Further to previous… 

I forget that I actually do know some scientists, so clearly I should have just done what I eventually did yesterday in my efforts to find out how cedars repair themselves. Instead of wasting time on my frustrated googling or posing a question on a nature board, I should have just asked my friends.

The following, most succinct answer came from one.

“Cedar trees have evolved several mechanisms to heal after being damaged by woodpeckers. The healing process depends on the severity of the damage and the extent of the injury.

“Here are some ways that cedars can heal after being pecked by woodpeckers:

“Natural Resin: Cedar trees produce a sticky resin that acts as a natural antifungal and antibacterial agent. When a woodpecker creates a hole in the tree, the resin oozes out and fills the cavity, protecting the tree from further damage and infection.

“Callus Formation: Cedars can also form a callus around the damaged area, which is a protective layer of new tissue that grows over the wound. The callus helps to seal the wound and prevent further damage or infection.

“Compartmentalization: Another way cedars heal after woodpecker damage is through compartmentalization. The tree creates a physical barrier around the damaged area, which isolates the damaged tissue from the healthy tissue. This prevents the spread of disease and decay, allowing the tree to continue to grow and thrive.

“Overall, cedars have evolved to be quite resilient to woodpecker damage. While the damage may be unsightly, the tree is usually able to heal itself and continue to grow and thrive.”

And from another.

“Looks like a combination of auxin and cytokinin response. I’m interpolating based on animal biology (which I know much more about than plants) but most biological systems regulate themselves in similar ways: cells are continually producing various molecules that regulate each other’s activities. This is sometimes described as ‘signalling’ between cells. 

“When a cell stops getting any signals on one side, the evolved response is generally to go into some kind of repair or scarification mode, where the exposed cell undergoes atypical differentiation to produce more cells that will heal the wound. In mammals (where healing quickly is a priority because we need to eat all the time to keep our body temperature up) this is generally aimed at scarification, which is fast. In reptiles, which can go for much longer without food, this often results in regeneration.

“In trees, only a thin layer is actually living tissue, right under the bark. It’s likely that when cells in this layer find themselves adjacent to nothing (they stop getting signals from one side) they start producing cytokinins, which stimulate cell division, and auxins, which cause cells to elongate. In combination, these produce new growth that covers the wound, as seen in your pictures.

“Dunno if that answers your question in a useful way, but it’s something like how a molecular/cell biologist would explain it.”

For more information he suggested I read this article. (I tried.)

From a marine biologist I know…

“I’m not an expert, but I’m guessing the interior of the tree is rotten. (Woodpeckers know this. How? By pounding it with their pecker). And while the tree may eventually ‘repair’ itself (if it is healthy enough) from damage like this, it also might not due to too much stress from ‘heart rot’.

“I would just encourage you to enjoy the woodpeckers – unless the tree is too close to your home and might blow down anyway.”

And then Joe, inspired by my query and proving himself to be far better than I at figuring out where to ask questions, learnt this from a University of Tennessee paper: “When a tree is wounded, the injured tissue is not repaired and does not heal.” From Purdue University: “Wounding of trees during the growing season results in the formation of callus tissue which develops over the wound surface or parts of it.” And, from a woodlands magazine, which I completely failed to find: “When a cell is damaged, a tree cannot go back and fix or replace it. But it can limit the damage from any given injury by containing it and excommunicating it from the rest of the still-growing tree. “

So, it turns out it’s seal, not heal. And it’s all trees, it seems, not just cedars.

Now you know as much as I do and more, no doubt, that you ever thought you would. 

From → Blog

One Comment
  1. Susan permalink

    Always good to know more about arboreal relatives, thank you!

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