I've been playing around with base building elements a bit, and chopped some trees (and "bushes") for material, after a while i've been hearing sounds of falling trees without trees falling. Seemed like those were in a loop or so.
when reviewing the video, i noticed, that in both cases there had been like 4-5 min between cutting down a "bush" and the tree sound.
just speculating, but maybe it has something to do with object regeneration (like grass that pops up after a while).