Our forests are withered
Anyone who’s ever looked up from his Blackberry or iPod for a
moment while driving around the American West already knows this,
but a lot of our trees are dying.
From the Monterey pines that define the peninsula they share a
name with to the great forests across the West, our vast legacy of
native timber is dying.
Our forests are withered
Anyone who’s ever looked up from his Blackberry or iPod for a moment while driving around the American West already knows this, but a lot of our trees are dying.
From the Monterey pines that define the peninsula they share a name with to the great forests across the West, our vast legacy of native timber is dying.
And it’s not just one species or one group of trees. Conifers closer to the Pacific, Aspens in Colorado, it’s widespread.
Earlier this month, scientists published a report in the journal “Science” that points to rising regional temperatures and the resulting combination of early snowmelt, drought, forest fires and insect infestations (the plague that affects those Monterey pines).
The research leading to the report involved leading forest ecologists who studied forests in 76 unmanaged areas, mostly in California, Oregon, Washington and southwest British Columbia, with some study going on in interior states of the West.
“Pervasive” is the way Phillip J. van Mantgem, a forester with the U.S. Geological Survey’s Western Ecological Research Center in Arcata described it.
“The same way that in any group of people a small number will die each year, in any forest a small number of trees die each year,” van Mantgem said. “But our long-term monitoring shows that tree mortality has been climbing, while the establishment of replacement trees has not.”
The study’s authors ruled out a number of possible sources of the increasing tree deaths, including air pollution, long-term effects of fire suppression, and normal forest dynamics. In contrast, increasing regional temperature was correlated with tree deaths.
“Average temperature in the West rose by more than 1 degree F over the last few decades,” van Mantgem said. “While this may not sound like much, it has been enough to reduce winter snowpack, cause earlier snowmelt, and lengthen the summer drought.”
“The ultimate implications for our forests and the environment are huge,” said Mark Harmon of Oregon State University, one of the report’s authors and a member of the team that authored the report.
If forest dieback grows widespread enough, it could diminish their capacity to absorb carbon dioxide, further accelerating the concentration of greenhouse gases in the atmosphere.
Van Mantgem led the team tracking 20,000 trees in Yosemite and Sequoia National Parks, two of our nation’s jewels. In the last 25 years, death rates doubled.
In the Sierra, the increasing frequency of drought is believed to be a significant influence, accrding to Nathan L. Stevenson of the USGS.
“The droughts are lasting longer, and they’re helping all those things that like to eat trees,” Stevenson said.
