To use SimArboreal-Editor with JME… you run the editor. Create a tree… and then save the .j3o.
Then load the j3o in the scene editor. Place it where you want.
Repeat as needed.
There isn’t any scene editor integration and no automatic tree placement from the scene editor.
Though for an example of using SimArboreal trees and a my own grass implementation, you can look at the source code for the IsoSurface-Demo.
(Latest code is really on github: GitHub - Simsilica/IsoSurfaceDemo: Technology demo of the IsoSurface terrain library.)
Note: it currently only works with JME 3.0 unless you make some tweaks.
And here is what it looks like running:
