I had two trees close together that were struck by lightning. I sawed the elderberry that did not get blown apart for my wife's projects. The wood is beautiful – it's black speckled mid way down to a fine line towards the butt. Does the lightning destroy the structure of the wood and make it unstable in any way? The tree did not crack or completely die.
(Sawing and Drying Forum)
From Professor Gene Wengert, forum technical advisor:
I have never heard of lightning hurting the structure of the tree. But right at the lightning streak (1/2" wide zone) that runs down the tree, I would expect that the heat may have weakened the wood. So, I really do not know, but my thoughts are "no problem."
Each little strand of the multiple flashes is about the size of a pencil, but the flickering that we perceive is actually because these pulses are only a few thousandths of a second, and they dance around a little, which makes it look like it may be as big around as a foot or even more than a yard across.
The temperature is around 30,000* C or six times as hot as the surface of the Sun. When this discharge travels down the side of a tree, the sap instantly turns to steam, which usually blows a strip of bark off of the outside of the tree. A good healthy tree can recover from these scars in a year or two. Some may die from insects and pathogens attacking the injury as an after-effect. But I don't think it kills a tree by destroying the cells.