The pilot/owner stated that during the takeoff from his private airstrip, the airplane was unable to gain sufficient altitude to clear the trees at the end of the grass runway. The left wing and landing gear struck the top of a tree; the airplane impacted the ground nose first, and came to rest inverted. A post-accident examination conducted by a Federal Aviation Administration inspector revealed substantial damage to the wings, engine, firewall, and fuselage. The pilot reported there were no mechanical malfunctions or anomalies with the airplane that would have precluded normal operation. In addition, he stated that he did not complete performance planning calculations prior to takeoff.