The private pilot reported that while in level cruise flight, the airplane's engine began to lose power, and then lost all power. He said he was unable to restart the engine, and selected a snow and tree-covered area as a forced landing site. During the forced landing, the airplane's left wing collided with a tree, resulting in substantial damage to the fuselage, empennage, and left wing. The pilot said that at the time of the accident the outside air temperature was minus 22 degrees F, and that during his postaccident inspection of the airplane he discovered that the engine fuel gascolator filter had become blocked by ice crystals. The pilot indicated in his written report to the NTSB that there were no preaccident mechanical problems with the airplane, and noted that the accident might have been prevented if he had removed the gascolator during his preflight to check for ice crystals, or preheated the engine, and then drained the water from the gascolator.