I made a walkway for another image, decided I liked it and duplicated it twice with the idea of making a kind of mechanical, industrial scene. The idea was to have the scene lit from above by shafts of light filtered through a grid. This didn't really work, so I tried using a foliage texture as a texture gel.
The tree trunks are terrains, built loosely according to the principles described in Jonathon Allen's forest tutorial (loosely because I didn't have a copy to hand when I was making the scene). The hanging vines or mosses are symmetric lattices with a foliage texture applied. The lattices are based on threadlike structures output from KPT Texture Explorer, a technique which didn't really work very well. A better and simpler solution might just have been to hand-paint them.