I rather like that, myself.Godmy dixit:I thought of a neologism such as "arborāx, arborācis" that just sounds like a badass tree.
As for gigens, that has the added bonus of looking like a portmanteau of gigas and gens, 'huge folk', which I think Tolkien would have loved. We remember that, while he loved to pull old words like 'ent' up out of obscurity, he liked also to grind the old words into snappier modern ones, such as 'hobbit' from OE holbytla 'hole-builder'.
I was thrilled to see (what I think is) a Russian neologism Средиземье for 'Middle-earth'. What would the Czech be, do you suppose?