Sorry, but i guess Max doesn't include any procedure to save a global parameter with the scene. This also would introduce some instability issues in the Forest behaviour.
You can try disabling the camera clipping options, so the Forest objects have not to be rebuilt when camera moves: Uncheck 'Auto assign to camera view', click 'Clear' camera and use the 'Copy' button to assign this configuration to all the objects.
Alternatively, you can move all Forest objects to a hidden layer.