This looks so much like our dry creek bed with our little apple tree in the middle. Maybe adding large rocks around the other side of the tree will make it feel more balanced. Also, I like the itty bitty rocks along the outside of the larger rocks.
"In the steady gaze of the horse shines a silent eloquence that speaks of love and loyalty, strength and courage. It is the window that reveals to us how willing is his spirit — how generous his heart." Eye of the Horses www.