DURING CRUISE FLIGHT, THE PILOT EXPERIENCED A NON MECHANICAL ENGINE FAILURE. THE FORCED LANDING AREA CONTAINED SCRUB TREES AND DURING THE LANDING, THE AIRPLANE STRUCK THESE TREES CAUSING SUBSTANTIAL DAMAGE. EXAMINATION OF THE AIRPLANE'S FUEL SYSTEM REVEALED THAT THE GASCOLATOR AND FUEL LINES CONTAINED DIRT AND DEBRIS FROM AN UNDETERMINED SOURCE. NO OTHER MECHANICAL DIFFICULTIES WERE FOUND.