Every year around this time, “leaf peepers” from all over the world descend on Colorado’s mountain towns to gape at the white-trunked aspen trees as they don their fall colors, setting the hillsides ablaze with bright swaths of yellow and orange foliage. But a mysterious syndrome may leave the Rocky Mountains aspen-free by 2090.


Scientists with the federal Rocky Mountain Research Station (RMRS) in Moscow, Idaho, have predicted the near total disappearance of aspen in the Rocky Mountain region by 2090, when they say up to 94 percent of Western forests will be unable to support the trees. Their research is set to be published in the journal Forest Ecology and Management.

Trees’ Roots are Dying
“Most aspen forests have some dead trees in them, and that’s perfectly normal, but this is an accelerated rate of death, in some cases without replacement by new trees, as would normally happen following a disturbance,” RMRS aspen expert Wayne Shepperd told KCFR’s Colorado Matters news show back in 2006, not long after the problem was first observed. Most disturbing, Shepperd said at the time, the trees’ parent root systems are dying, and, he added, “if the roots are dead, that means aspens will not be occupying that site in the future.”

Since then, the acreage in Colorado with sick aspens has quadrupled to more than 850 square miles, writes Laura Snider of BigGreenBoulder in a piece about the troubling phenomenon known as “sudden aspen decline,” or SAD. Afflicted trees “drop their leaves, are ravaged by insects, and can’t reproduce.”

Drought and Global Warming Possible Culprits
The cause or causes behind the problem remain frustratingly unclear, though scientists have some theories. The dying trees could be over-aged, living longer than they would normally due to fire suppression and thus, much like elderly people, becoming more prone to various ailments. The severe drought of recent years is thought to be playing a significant role, and the impacts of the changing climate may also be adding to the stress that leaves the trees vulnerable to various pests and diseases.

The loss of aspen threatens species such elk and deer, which eat the trees’ early shoots, as well as local sawmills and cities and businesses that rely on tourism, reports Reuters. Says Aspen Mayor Mick Ireland: “A large die-off could be devastating.”

Via Treehugger