HIKE THE SANTA BARBARA BACK COUNTRY by Dennis Gagnon (Western Tanager Press: $9.95, illustrated). This unusually practical guide details a variety of excursions that range from a two-mile afternoon hike to a 65-mile backpacking trip in the southern Los Padres Forest, an area roughly bounded by Highway 166, Highway 126 and Interstate 5. Gagnon carefully keys his descriptions of trails and byways to the recreation and topographic maps issued by the U.S. Forest Service--and emphasizes the importance of carrying these maps at all times, even on a short excursion into the back country. He separates necessary and optional equipment in his lists, and outlines practices that ensure the maximum safety of both the hiker and the surrounding environment. A handy, inexpensive way to escape the noise and smog of L.A. for a few hours or a few days.