When looking through the 382 "Aspen" images at Acclaim Images.com this Abstract of Aspen Trees was a favorite.
All of their pictures are hand picked, availiable in a number of formats, and you can even get custom prints and posters.

Description:
Abstract of Aspen Trees
Abstract of aspen trees created by panning the camera vertically during exposure.

Some related terms for more images:
aspen,  texture,  blur,  aspens,  abstract scene,  natural,  sharon day,  summer trees,  background,  forest,  camera effects,  woods,  rocky mountains,  colorado,  wooded,  nature,  blurring,  textures,