I have been hesitant to include these because there are more settings specific to your printer/filament that you'll need to modify than there are necessary to printing the trees. So PLEASE be aware that these are not magic files that will allow you to print these trees properly according to your unique setup. Use them only as a reference if you're unfamiliar with how to tune slicer settings.
As far as the troubles people have had with other slicers, such as Cura, unfortunately, I can't help you there, since I use Simplify3d. I have, however, included the .gcode file for the 160mm tree as a reference for those not using Simplify3d.