Wonderful work, I think any other technique wouldn't do this idea justice. I like the way the tree bends, almost in the shape of a crescent Moon. Excellent work. 
Thank you for putting so much thought into it. I was just randomly drawing as the flow seemed to take me at the time. The original image is very large, it was drawn for a gallery in highschool, it won first place in a state tree drawing competition and was on display at the Oklahoma State Capitol for a while. I never learned what happened to the original, sadly. But I have a full scan of it, thankfully!