What do you suggest or how do people usually light an outdoor scene (forest) at night:
1.) moon light comes from above. so how would you light trees (in BG or FG)? is there a really talllll lightstand to use or would you have to use some sort of lift or ladder or ?!
It's usually done with a condor lift. Faking it on a lower budget would consist of just trying to get the tallest light stand you can, like the mambo gonzo suggests, but depending on the size of the area of the forest you hope to see that might not be enough.
The question is how big of a shot are you making? . . . and from what angle? The need is to keep the instrument (or instruments) out of your shot. Then use a stand that is high enough to clear the shot and come from the angle you that want. We've put large HMIs on an adjacent structure, hung them from a tall tree limb (without damaging the tree), on mambos, etc.; anything that will hold them safely. Also, if you are shooting from a high angle you will see less height of the background.
Additionally, the moon doesn't necessarily come from high above. It can come from horizon to horizon. Generally the reason for moon light is for effect and to give background definition and depth. A high side angle might be easier to control and create the desired effect since high overhead isn't necessary to emulate moon light. You probably would want to blue it up a bit to enhance the effect and maybe a cookie to break it up some.
Good Luck,
Ken