From the hillsides of extinct volcanoes in Arizona to the jagged peaks of Idaho, aspen trees are falling by the tens of thousands, the latest example of how climate change is dramatically altering the American West.
Starting seven years ago, foresters noticed massive aspen die-offs caused by parasitical insects, one of them so rare it is hardly even written about in scientific literature. But with warming temperatures and the effects of a brutal drought still lingering, the parasites are flourishing at the expense of the tree, beloved for its slender branches and heart-shaped leaves that turn a brilliant yellow in autumn.
Noting the number of other changes to Western vegetation due to warmer, drier temperatures, Wayne Shepperd, an aspen specialist at Colorado State University said: “Everything’s happening all at once. We’re living in interesting times here.”