Floating trees... Please help...

[aries_pup]

Hi, i'm doing an island using the visitor tool, but i have a problem...
I already finish planting all the trees and bushes needed in my map, but when i test the game, i realised that some trees are floating... is there anyway to lower the height of the trees in bulk rather den selecting one by one?
Because i have alot of those overlapping squares icons in visitor and its very difficult to click and shift every single tree... Its like a forest...

Please help~
Thanks,
ARies_pup.