The pilot reported that he was overflying a mountain plateau about 100 ft. As he overflew the plateau with 2 or 3 notches of flaps and about 60 kts, he noticed that the terrain was rising on both sides and ahead of the flight path. The pilot increased the throttle to full power and initiated a climb; the angle of attack indicator began to alert the pilot to an impending stall. The pilot estimated that the airplane would not be able to clear trees in front of the flight path and began a slow turn to the right. The airplane then struck a tree, impacted the terrain, and came to rest upright on its nose. The airplane sustained substantial damage to both wings. The pilot stated that the accident could have been prevented if he had assessed the density altitude and airplane performance for the flight and flown at a higher airspeed and altitude. The pilot reported that there were no preimpact mechanical malfunctions or failures that would have precluded normal operations.