September 5, 2014--Forests dying as Rocky Mountains heat up (Beacon)

Nobody paid much attention at first when pine beetles started multiplying in the montane forests of Colorado in the late 1990s. Old-timers had seen it all before; a few years of beetle kill, then a long, hard early winter freeze that killed most of the bugs during their winter larval phase, suppressing numbers back down to an endemic background level. It’s an aeons-old cycle that works at a basic evolutionary level. Lodgepole-killing mountain pine beetles and their many relatives have always been part of the forest cycle, clearing away older stressed or diseased trees to make room for new growth. But this time, there was no slowdown. There was no cold snap, and the bugs kept coming. The average temperature across the Rockies has gone up 2 degrees Fahrenheit in the past four decades, taking the edge off the winter chill that used to kill the bugs in the bark of trees, and also giving them a longer breeding season. Studies have documented a remarkable shortening of the reproductive cycle that allows the insects to multiply exponentially, and a warmer climate also enables them climb higher and kill trees like whitebark pines. The dying forests are one of the most visible signs of climate change in any ecosystem, many researchers say. pointing to a global pattern of forest die-offs that suggest a response to human-caused global warming. If temperatures rise to projected levels in the next 100 years, entire forests will vanish, while others may appear in new areas. 

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