Check out Ramah's TreeThing application, which will rapidly create forests in the style of the LoTR map.
I'm currently working on a map for a fantasy world and need help creating a appealing and clean forest for the terrain. I'm somewhat inexperienced in making my own maps and am using GIMP for all my processes. I'm looking for a style of trees that are not very realistic, as the entire map is black and white and consists of mostly outlined textures. I'm following the theme somewhat of this LOTR map posted below. I'm not looking for a style similar to those created in Gidde's "Textured Forests in GIMP" tut, but rather ones that are not quite as realistic. I've posted a sample of mountains from my map below, created using the Aberron Brush Set. Thanks for any help that is given.