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.
If you are looking for cool Polynesian tattoos, then here are some themes and ideas that should get you thinking. The Polynesian culture has some definite elements which have a deeper significance to them, and these will be reflected in tattoo designs.