MORE THAN A DOZEN VOLUNTEERS GATHERED IN WATSONVILLE YESTERDAY (SUN) TO CELEBRATE NATIONAL TRAILS DAY.    THE WETLAND WATCH GROUP LED VOLUNTEERS TO HELP RESTORE NATIVE SPECIES AND PICK UP TRASH ON TRAILS NEAR THE WATSONVILLE NATURE CENTER.    THE CITY WILL BE LAUNCHING ITS FIRST ADOPT-A-TRAIL PROGRAM NEXT MONTH.  WATSONVILLE HAS MORE THAN SEVEN MILES OF TRAILS WITH ANOTHER THIRTY IN PROGRESS.