The airplane sustained a loss of engine power at about 1240 Eastern time while climbing to cruise altitude. The Private pilot made a forced landing at the airport in Fort Pierce, Fla., from which he had just departed. Visual conditions prevailed. The Private pilot received minor injuries and the airplane incurred substantial damage. According to the pilot, about eight to 10 minutes after takeoff, while still climbing and at an altitude of about 5000 feet, the airplane lost engine power. The gauges showed about 1000 rpm and the manifold pressure remained at 25 inches. The pilot could not regain power or determine the reason for the power loss. As the airplane glided toward the airport, the pilot said he became uncertain he would reach it and selected a clearing in which to execute a forced landing. While landing in the clearing, the right wing impacted a tree and the airplane pancaked during the landing.