Board Thread:Naruto Discussions/@comment-24847491-20140921145042/@comment-5407586-20140924102750

Well, Naruto in order to enter Nine-Tails Chakra Mode has to shelve his own chakra to use the fox's chakra, and only then the trees near him develop. Yamato stated that this was due to Naruto emanating life force. So, either Naruto or Kurama's life force was what caused this event. Since Naruto was using Kurama's chakra, it's more likely that it was due to the fox's power.