german 88mm gun flak diorama

Don't know what kind of trees you are shooting for , but here is a tutorial on pine trees http://www.digitaldioramas.com/2002/issue5/dd_pinetrees.htm

Another good book is how to build armor dioramas. I have heard good thing about the lichen and root technique. I Havent tried this, but you can buy herb leaves used for cooking, and then gather some roots. Why roots for trees? roots for some reason hold scale bark. Go figure?! Then glue the roots into a tree shape. then use a fiber cleaning pad, available from an isdustrial cleaning supply store, and cover some parts of the basic shape made by the roots. Cover Small areas with white glue at a time and sprinkle on the herbs. and your done.
You can also buy trees from woodland scenics, but they dont look quite as real.
hope that helps just a little, sounds kinda confusing when i read it. Be sure TO show us pics when U r finished!!!!!

If you can get your hands on it try and get Shep Paines Diorama book... it is VERY helpful... I haven't had much experience with trees but the time or two I have used them I made them from roots and lichten but it wasn't that pleased. Do a google search and see what turns up... also try posting this in the diorama forum if you haven't already..

Good luck