The pilot was practicing takeoff and landings at night. Due to his lack of night experience, he had a commercial pilot act as his safety pilot. The pilot stated that on final approach, he noted his altitude was 250 feet, the airspeed was 85 knots, and the flaps were at the second notch. He stated that he realized his altitude was low, so he attempted to add power. He reported that the engine did not produce full power and this he attributed to the possibility of a magneto failure. Subsequently, the aircraft collided with the ground 900 feet short of the runway and nosed over. The safety pilot reported that he was distracted during the turn from base to final; however, on final when he lifted his head and looked out the window, he noticed trees in front of the aircraft. The right wing struck the trees, and the aircraft veered to the right. Examination of the aircraft by the FAA did not disclose any evidence of malfunction.