The speaker seems to feel less than fully alive when away from the woods, and the poem is about going back to them. The title, "Root or die," borrows a phrase about pigs having to dig for their food or starve, and the speaker takes that on directly, going back to nature "like a hog" with a "great mouth." There's something greedy and unembarrassed in that image. The speaker doesn't tiptoe into the wild but eats, digs, and takes it all in.
The last lines turn the poem in a surprising direction. Being more alive means being more open to pain: "now I can hurt / in so many places." That isn't quite a complaint. It reads as a trade the speaker accepts, since feeling sharply comes bundled with feeling hurt. The mood is raw and blunt, a little wry, but also oddly satisfied. Judging by the imagery, aliveness here is physical and messy, not peaceful or pretty.