I cant find this movie that I watched as a kid

There's this movie that I can't find it's anime styled and is post apocalyptic where I think in a futuristic version of the world some bombs get shot at the moon btw I might be wrong on that but some sort of dragon comes down the the earth and starts growing a forest that if you spend to much time in it you'll start turning into a tree anyway there these colonies and the main character is living in one of them his father is very far into the process of turning into a tree and he soon turning into a tree but he is still semi conscious but is not in pain or anything like that anyway the kid and his friend are going to steal some water the reason they are stealing it is because it's ment for the tree's and some sort of druid cult are protecting them anyway he and his friend get seen and scared by the druids btw the druids are good I think and after that he goes to see his father and his father turns into a tree that and some sort of nation attacks and the current chief/mayor fights them and he had silver hair and in this world people who have silver hair are like really strong and it turning and the main character has silver hair to but when he uses his power he starts turning into a tree.  Anyway that is all I remember for now!  Pls help I think it released in the the 2000s I think it was from 2008