By Times Staff Writer Bettina BoxallThere would be more backcountry trails open to off-road vehicles in Southern California's four national forests under a plan that also recommends that about 100,000 additional acres be given wilderness protection.The proposal, released Thursday by the U.S. Forest Service, is a blueprint for managing some of the most intensely used public forests in the nation.It emphasizes recreation and does not suggest any radical departures from current operation of the four forests, which cover 3.7 million acres, extend from Big Sur almost to the Mexican border, and offer remote retreats at the doorstep of the second-largest metropolitan area in the country.The brushy slopes and wooded peaks of the Angeles, Cleveland, San Bernardino and Los Padres national forests are beset by growing recreational demands and increasing urbanization and habitat loss at their borders. Total visitation approaches 8 million people a year and is expected to grow by 20% during the next 15 years.Tom White, an assistant project leader who helped draw up the proposal, said the blueprint recognizes and attempts to manage the increased use. "We're increasing the level of control," he said.Under the plan, total backcountry acreage in the four forests zoned for motorized use would increase by about 2% to nearly 1.6 million acres. Some new trails would be constructed to connect existing routes, but for the most part, White said, these areas have informal networks of roads."It's moving to a higher level of regulated use, recognizing that use is going to be there," White said.Don Amador, California representative of the Blue Ribbon Coalition, an off-road group, said the Forest Service was going in the right direction."Blue Ribbon is certainly happy that the Forest Service is going to work to better develop and manage their recreation program by looking at connecting trails that are now disconnected . . . and overall improving their program," he said. "So, at this time, we're pleased and looking forward to working with the Forest Service."The Sierra Club, which has a large Southern California chapter that leads hundreds of hikes in the forests, found the plan wanting on a number of counts."I've got to tell you, it is a very, very disappointing plan that doesn't reflect what the public wants for its national forests," regional representative Bill Corcoran said. "It has missed a great opportunity to permanently protect large areas of the forest for future generations, and it increases activities like off-road vehicle use that the Forest Service recognizes are harmful and can't manage currently. It's pretty remarkable how weak the document is."Corcoran particularly criticized the amount of acreage recommended for wilderness protection and noted that the forests are home to 470 plant and animal species that are in some level of biological peril."The Forest Service has a responsibility to balance recreational use of the forest with protecting the natural integrity of the forest," Corcoran added. "This forest plan doesn't provide that balance."About one-third of the forests, or roughly 1.1 million acres, is protected as federally designated wilderness. There are about another million acres without roads that have been deemed eligible for wilderness protection. The management proposal recommends that about a tenth of that land actually be protected.White said forest managers believed there was, for the most part, enough existing wilderness. And he noted that access was limited in non-wilderness areas because Southern California forests have a lower density of roads than other national forests in the state because of the rugged terrain and the relative lack of logging."A lot of the wilderness character is actually inherent in the non-wilderness because it's so steep," White said.The proposal, outlined in a draft environmental impact statement, includes various other management options the Forest Service can draw on in making its final decision.The plan would not preclude pending proposals for utility corridors and a toll road in the Cleveland National Forest.The Forest Service will take public comments on the plan for the next three months at www.fs.fed.us/r5/scfpr.