The private pilot reported he was landing his tailwheel-equipped airplane on a soft, rough and uneven gravel runway at the conclusion of a local personal flight operated under Title 14, Code of Federal Regulations Part 91. He said immediately upon touchdown, the airplane veered to the right, and the right wing struck trees, which pivoted the airplane 180 degrees to the right. The left wing struck the ground and sustained substantial damage. The pilot reported that there were no preaccident mechanical problems with the airplane. In his written report to the NTSB the pilot noted that the accident might have been avoided if he had landed on the first part of the airstrip where the runway was wider.