Thursday, March 3, 2011

Study Suggests the Pacific Northwest Could Lose All Lodgepole Pine Trees Due to Global Warming

A new study in the journal Climatic Change by scientists at Oregon State University suggests that the Pacific Northwest, a cherished old-growth forest region of the US, could lose virtually all lodgepole pine trees by 2080.  Researchers say that warming temperatures have changed the ecosystem dynamics such that conditions favor increased infestations by bark beetles.  The combined effects of global warming appear to be driving the effects already seen, and continuing warming is likely to make conditions even worse.

Part of the problem is that warming temperatures have reduced the spring frosts that inhibited the growth of competing trees.  Without them the soil has less moisture and more adaptable trees like Douglas fir are able to move into the areas previously dominated by lodgepole pines. For centuries lodgepole pines have dominated higher elevations in the Cascades (along the Pacific US) and the Rocky Mountains (further east).  This may not be the case a century from now.

The researchers estimate that lodgepole would cover "less than 6,000 square miles in America" by the year 2080, which is only "about 17 percent of its current range."  This change in ecosystem dynamics is important, as lodgepole pine is one of the first species to repopulate areas that have been decimated by fire.  They also can get a start growing in post-volcanic soil, a critical attribute in the active volcanic region that characterizes the Cascade range. [Remember Mount St. Helens, anyone?]  But now the trees are being hard hit by both soil conditions and bark beetle infestations.  Recently the Agriculture Secretary, Tom Vilsack, had "to allocate $35 million for tree removal" in the Rocky Mountains because beetles had killed more than 5,000 square miles of lodgepole pine and spruce forest."  And that is just since the late 1990s.

The abstract of the study in Climatic Change can be viewed here.

Source article by Jeff Barnard in the Seattle Times.

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