What is killing these maples?

[A1920sCitizen]

I have included some pictures of the two maples in my yard. I am not sure what their issue is, but they are rotting out. One has rings of rot along the base of the tree, and at the base of many branches. The other has some of the same, as well as a large section of bark on the trunk that is gone. I was just curious what you think this is. They still leaf out fine, although one does have a small section of dead in the top middle area. I am thinking it would be good to get them down in the near future.

Thanks for any information you can provide!
grant

 

[ronnyb]

looks like a girdling root on one

 

[diezelsmoke]

IMO ....... 1) Trees coming to the end of life expectance. 2) 0 tree maintenance over the years. 3) Root girdling.