I'm not surprised by the tree ring theory. What's that old saying, "Plant them low, they grow slow; plant them high, they'll never die" ? By the same token, I doubt burying the roots deeper with a tree ring on an established tree does it any good. Sounds like a good way to deprive the roots of oxygen; to crush roots (those stacked blocks are HEAVY, and if driving a car over the roots damages the tree, imagine what those blocks do); to drown, suffocate or otherwise kill off mycorrhizae colonies; and in general to do all sorts of other things that are Not Recommended®...
On the lightning thing and GFCI: My mother had lightning destroy not one but TWO submersible well pumps (and these pumps were something like 100 feet deep in the ground) within one or two years. If lightning can get down there and wipe stuff out, I doubt GFCIs are going to do much more to protect against lightning than liberate Magic Smoke at best on a good day...