improper planning/decision by the pilot, which led to flight into icing conditions; and his failure to use all anti-ice and deicing equipment, as specified by the airplane operator's manual for inadvertent flight into icing conditions. This resulted in loss of engine power due to ice, a forced landing, and subsequent collision with trees during the forced landing. Factors relating to the accident were: the adverse weather (icing) condition, failure of a FAA Flight Service Station briefer to provide adequate icing advisories to the pilot, and low ceiling and trees in the emergency landing area.