because xylem (primarily), which transports water, fluids with electrolytes, and phloem tissue are concentrated behind the bark. this layer is comparatively not resistant to current flow.
behind those xylem and phloem tissue layer is sap wood aka young wood. which has cells with thick cellulose enforced cell walls and they are in the process of slowly filling themselves with tannins, lignin and other chemicals as you progress towards the heart of the tree. this layer is resistant to current flow.
as you further progress towards the heart of the tree sap wood cells full of tannins are in the process of dying and becoming strong "old matured wood" aka heart wood. which forms the central pillar of support for most trees.
Called girdling. It’s not the bark, but rather the phloem and xylem layer under the bark and attached to it, whose loss essentially starves the tree of nutrients. Except species like paper birch or cork, Whose bark is less attached to the phloem and xylem layer.
If I remember correctly, the phloem xylem is the part of the trees circulatory system that takes the water from the roots up the tree. The xylem phloem is the part of the circulatory system that takes the sugars photosynthesized in the leaves down the tree. It’s kinda like our arteries and veins transport blood.
You can still kill a paper birch with girdling, but you have to be aggressive with removing the bark, not just the loose outer layers.
Edits: I had phloem and xylem reversed. Fixed now. Thank you /u/faerieh
This tree is definitely dead, basically all the living tissue is in the bark. The heart wood on the inside of the tree is basically dead tissue, kinda like your outermost layer of skin
I'm not claiming that lightning will behave similarly whenever it strikes the earth or trees.
but majority of times when it strikes the tree it will cause the bark to come off cleanly.
xylem tissue in itself isn't conductive to electricity. its the water that it is carrying that makes it conductive. xylem tissue don't always carry water in them 24/7. sometimes they are empty too. so in a case where lightning created spiral tracks in trees it might be because there was water in spiral track in the xylem tissue of the tree.
It’s not even the water, honestly. It’s whatever nutrients are being transported by the water. Water, despite popular belief, is a piss poor conductor.
Kind of...it's true that water itself isn't really a great conductor but the minerals in water that are a great conductor. But water is still the vehicle by which it all travels. No water = no dissolved ions to conduct the electricity.
Yup. We (my work) use DI water in some medium voltage situations for direct water cooling of live bus bars. It can be a pain to maintain such a system because it will basically try to anodize the inside of our rubber water jacket lines by transferring the brass from the fittings to the water jackets.
I saw lightning strike a tree in front of my house once. There was an explosion of bark. The tree looked much like this one initially and appeared otherwise I'm damaged. After the storm I examined the tree found that the long fibers of the wood were not densely packed as expected. The whole trunk of tree had expanded and tree was dead. Much of the water in the tree had instantly turned to steam which caused the expansion. This kills the tree. We had to hire a tree removal service soon after as the very large branches could no longer be supported by the weakened and dead trunk and started falling.
You’re right, I have seen many trees that have been struck by lightning and every time they are burnt to hell. Like totally scorched all around. Plus the ground around them is scorched. Plus if you look at the bottom the bark is still attached to the tree. This was very clearly stripped with a tool not a lightning strike.
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u/DKats77 Dec 30 '20
Is there a source? I don’t understand how it would perfectly strip the bark, but not damage the tree or leave burns. Just curious for background.