Couple of things happening here in this Bryce3.1 night scene; visible moon, fog laying in the lowlands, 2D trees (needed to place a light high and behind the camera to brighten the trees otherwise they would have a grayish texture and little form). Distant treescape is spiked terrain. By the way, that's a super effect but I can see it could be overused in the future.
All images are copyright © John Rebhun 1999, do not copy without permission.