With the damage and decay so advanced, it now really doesn't matter for the reason and although the tree might live several more years, it's definitely on it's way out sorry to say!

I agree with Frozebudd - Unfortunately that tree really needs to be replaced. But at least, you can think about replacing it with something you really love and taking good care of it for a long life.

I agree it need to be replaced. When we moved into this house 10 years ago there was one nice maple that had beautiful fall foliage. Unfortunate nearly the bark was missing for about a foot for about half the diameter. I did everything I could to save the tree, and the bark seemed to be covering the wound as it grew. It never added more that a couple of feet to its height. After about 8 years it finally started to die and had to cut it down.

Believe me, if we thought you could do something to save that tree, I'm sure someone would have come up with an idea, but as krnuttle has shared her experience when a tree is damaged too much, efforts to try to save it, are just a delay and the next thing you know 8 years have gone by and you could have had a nice new tree established and giving you pleasure.

cut it to about 3 feet.. and start digging out the roots ... you use the 3 foot part to rock it back and forth while digging ... .. you can probably use the truck method also ...

and replant something new.. or maybe 2 ...

there is nothing to be done to help this tree

call miss dig in case there are any utilities under it ...

once the heartwood starts rotting.. then you have no interior structure left.. and there is no 'healing' or fixing that ...

ken