The U.S. Forest Service would get new rules to help fight wildfires in some of its most at-risk areas under a bipartisan plan introduced Thursday by Northwest senators. The proposal would try to reduce the catastrophic wildfires that have plagued Western states in recent years by concentrating on federal forests with ponderosa pines, which some studies show are the most likely to be involved in expensive fires. It tries to walk the line between concerns expressed by environmentalists and supplies sought by the timber industry. Sen. Maria Cantwell, D-Wash., the bill’s prime sponsor, called it way to give the Forest Service new ways to reduce fires and protect communities. “This science-based pilot program gives the Forest Service tools to address wildfire in our most vulnerable forests and prioritizes cross-laminated timber.”