The pilot stated that en route to her destination, she was practicing low-altitude ground reference maneuvers. The last maneuver ended with the airplane in a box canyon. The airplane had insufficient altitude, airspeed, and distance from the canyon walls to turn around. As the airplane approached the end of the canyon, she realized the airplane would not be able to out-climb the rising terrain. She looked for a clear spot to land and reduced the throttle to idle while shutting off the fuel. The pilot tried to maneuver to avoid taller terrain and touched down in between trees with the wings impacting them. During the accident sequence, the airplane incurred substantial damage to the wings. The pilot reported that there were no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.