In the early 1900s, an average forested acre in California supported fewer than 50 or so trees. After a century of efforts to fight wildfires, the average has risen to more than 300 (albeit mostly smaller) trees. Some might reckon such growth wonderful, but it is a problem far more serious than, say, the fact that horses can no longer trot through areas where they once could. The extra fuel turns today’s wildfires into infernos hot enough to devastate the landscape, torching even the big older trees that typically survived fires in the old days.