ALBANY, Wyo. (AP) – Vast stands of dead timber in the Western U.S. have forced firefighters to shift tactics, trying to stay out of the shadow of lifeless, unstable trees that could come crashing down with deadly force. U.S. Forest Service statistics compiled for The Associated Press show that about 6.3 billion dead trees are still standing in 11 Western states, up from 5.8 billion five years earlier. The Forest Service says about 20 percent were likely killed by a massive beetle outbreak. Dead trees are an unpredictable threat, prone to blowing over in the wind or getting knocked down by other falling trees. To avoid them, firefighters sometimes have to cut containment lines farther from the flames, and that allows the fires to gobble up more forest before they’re brought under control.