Mapping Nature With a Pen.
Originally I found this artist, Tim Knowles, from Inhabitat and their little blurb about Tim's work with trees creating drawings. He pretty much sticks some pens on some branches and puts a canvas/paper in front of it and let the tree do the work, but then I went to his webpage and there is a lot of very interesting works that he has done. In particular are the ones in which he used apparatus of some description, looks like a richter scale, to map a journey through the Alps, and also another one where he placed a pen in a homemade drawing box thing that would draw as it was posted from one place to another...have a look...

Link Tim Knowles
Link via Inhabitat