Some rotting on Chinese elm. Should I be worried?

[Bonds Guy]

Last year I girdled my chinese elm with a sheet of copper and today I wanted to review the results and remove the root below the girdle. After removing the soil, I noticed some rotting on the face and bottom of the root base. The face rot was soft so I scraped most of off. The rot on the bottom was much harder and though I was capable of scratching it off, it took some force to remove and at times I would dig too deep so I left it alone. I thought maybe the rot is from the copper sheet, because all the other seedling I girdle didn't have any rot and the copper sheet had blue spots on it. This tree has survived a lot of abuse (in fact that's why it's a clump) so I figured it might not be a something to worry about, but just in case, is this rot something to be worried about?

 

[TomB]

It’s just exposed wood rotting away due to constant damp. Normal with layers. I’d cut away whatever is soft or loose, the rest will eventually be callused over by live wood.

 

[Shibui]

I agree. looks completely normal and unlikely the copper has caused this.
Chinese elm should be able to overcome this and heal the holes without any help apart from normal care. Even if some wood does rot that won't usually kill a tree. many old trees live for centuries with completely hollow trunks. All the activity takes place in the outer layers so the center wood is just for strength.