Tree rings are said to show how old a tree is. So showing tree rings that indicates an older tree, it could either depict you as an old soul or that you are strong enough to grow. But it could definitely depend on your own story.
Could do a dead oak and a small baby oak next to the dead one, or on branch of life on the dead oak. Meaning she's been through a lot of things in her life that have killed her spiritually but she will always over come her trials in life.