National Geographic : 2015 Apr
YELLOWSTONE NATIONAL PARK MT. RUSHMORE NATIONAL MEMORIAL B lack Hi lls Vancouver Missoula San Francisco Custer Custer Seattle Washington, D.C. Ottawa Edmonton Los Alamos BANDELIER NATIONAL MONUMENT Seeley Lake Yankee Fork Salmon River Wolf Creek Pass ALBERTA B.C. NORTHWEST TERRITORIES SASK. MANITOBA ONTARIO YUKON ALASKA (U.S.) ARIZ. CALIF. COLO. IDAHO MONT. NEBR. N. MEX. NEV. OREG. S. DAK. UTAH WASH. WYO. BajaCalifornia CANADA MEXICO UNITED STATES BorealFores t 0mi 400 0km 400 0mi 1,000 0 km 1,000 Mountain pine beetle occurrence Lodgepole pine range Jack pine range Other pine species THE BEETLE AND ITS HOSTS Historically the mountain pine beetle’s primary host has been lodgepole pine. In the north, where lodgepoles dominate the landscape, cold temperatures helped keep beetle popula- tions in check; down south the insects had far fewer trees to infest. With forests increasingly warmed by climate change, the beetles are thriving in once inhospitable areas, attacking species of pine they rarely touched before—and drastically altering the landscape. Prelude to Disaster A potential epidemic in the mid- 1980s was averted by two particu- larly cold winters in a row. But by the mid-1990s a combination of forestry policies, warmer winters, and dry summers had helped beetle numbers rise dramatically. Infesta- tions erupted in pockets across drought-stricken British Columbia, Washington, and Oregon, sowing the seeds of an epidemic. 1990-1996 The Epidemic Begins Beetle populations swelled to unprecedented numbers as their range expanded north and east. By 2006 beetles had crossed the Canadian Rockies and were in the area around Grande Prairie, Alberta. By 2007 the epidemic in British Columbia was slowing, as the beetles ran out of trees to attack. But from Montana to Colorado it was nearing its peak. 1997-2006 Chronology of an Epidemic ALBERTA BRITISH COLUMBIA ARIZ. CALIF. COLO. IDAHO MONT. NEV. OREG. S. DAK. UTAH WASH. WYO. Chilcotin Plateau Vancouver San Francisco Seattle ROCKYMOUNTAINS Edmonton Cypress Hills Vancouver Seattle Grande Prairie ALBERTA B.C . ARIZ. CALIF. COLO. IDAHO MONT. NEV. OREG. UTAH WASH. WYO. S. DAK.