Thanks y'all! I appreciate your comments!
Bobbo, you're right, there is more texture. I used a palette knife to paint this one, and it's painted on the rough side of the masonite panel, which has a look similar to canvas, but is a bit more deeply textured.
Zee and Lorijo, there is more variety in the dark of the tree trunk and limbs, but not showing up on this jpg. With the sun almost directly behind the tree, the backlighting created pretty much of a flat silhouette. If you want to, please play with it in your image editing program and show me what you come up with. I'm always open to suggestions!