Here is a piece of the in-game fiction about this character:
"As with any other one of the Deathless Forests, there
are many who would rise up to defend Forest Green: some great, some small, all
respectful toward the woods they call home. But they act for their own reasons,
their own benefit. They merely live in the Forest, they are not a part of it,
they are not born of it. Thus, when it is threatened, Forest Green fields its
own champion: bark of its bark, sap of its sap - the clenched fist of Nature.
And it may believe that all life is sacred, but some deserve to live as trees
and people, while others only as mulch to feed and fertilize the ground. And it
means to enforce this belief."