how did you loop those tree animations
modeling>simulate the three >blend shape the cached animation with the same animation with a time offset.
with 200 frames simulated
for 99 looped frames
start the first blendshape input at frame 100
start the second blendshape input at frame 50
blend shape at time 0 to 50 : full input 1
Blend input 2 from time 50 to 100
Works great with smoke, fire, clouds, tree...