The concept of this piece is very interesting. I read it as the contemplation of once origins, the questioning about who we really are. This is my interpretation, and I think everyone can see himself in it in a different way.
I really like the suggested fusion between the first plan and the background, with the roots appearing on her back. However, I think it would have a stronger impact if the roots were precisely drawn in the continuity of the tree. We can notice that the trunk in the background is deviating on the left side, and is not connecting with the roots on the model's back.
The bluish color of the scene might be a little overused, but you did a great job creating a coherent and cold atmosphere.
Concerning the Technique, there are some issues with the lighting of the scene. I see strange black spots on the bottom half of the wall, and some areas are too dark for no apparent reason.
Also, the model looks like she's floating above the ground. The floor on the edge of her dress should be practically black ; however, within the shadow you drew, there's a slight halo coming from underneath the dress that gives the wrong impression.
Besides the small technical flaws, you did the most important thing : creating an emotion that reaches the viewer.