The private pilot reported he and the sole passenger were on a personal Title 14 CFR Part 91 flight en route to a hunting site. While maneuvering at a low altitude to assess weather conditions and determine the viability of flying through a pass, he said he encountered turbulence and a strong downdraft. He immediately added engine power to climb, but the downdraft pushed the airplane below the tops of tall Spruce trees. The pilot said he was unable to avoid the trees, and struck trees with the right wing and then the nose of the airplane. The airplane continued to fly, and he was able to return to his home airport, where the right main landing gear collapsed on landing. The airplane sustained substantial damage to the right wing and right horizontal stabilizer. The pilot stated that there were no preimpact mechanical problems with the airplane.