What’s killing the whitebark pine forests?

Kari Grover-Wier, Michele Crist and Pete Wier walk through lupine flowers in a fire-burnt forest near Red Moutain, Idaho.

On a hot summer day last week, a group of forest scientists and managers hiked up a cool Idaho mountain ridge to look at trees in trouble. Whitebark pines are hardy, gnarly and long-lived trees at high elevations across the Pacific Crest, western Canada and the Northern Rockies of Idaho, Wyoming and Montana. While these trees have long withstood wind, snows and freezing temperatures for millennium, on slopes from 5,000 to over 12,000 feet — today, a combination of conditions puts the species at risk.

An introduced pathogen from Europe called blister rust is weakening and killing whitebark pine forests in an expanding geography. Two other factors also stress whitebark pines. Climate change has resulted in longer fire seasons with conditions often hotter and drier. And mountain pine beetles, a natural host of Rocky Mountain forests have moved upslope to higher elevations, again influenced by warmer conditions.

The day we hiked up a ridge leading to Red Mountain, in the roadless area of the same name in southern Idaho, the thermometer hit 106 degrees back home in Boise. Along the ridge where we walked above 8000 feet, snow-banks lingered where cornices piled deep through seven months of winter. The temperatures in the high 70s felt refreshing.

Three years before, about a month later in the summer, the landscape where we walked was a rolling inferno. An unattended campfire blew up in a wind, sparking a forest fire that ran over more than 35,000 acres.

“When I started working with the Forest Service in the 1980s, a 10,000 acre fire was really big,” said Peter Wier, silvaculturist for the Lowman Ranger District. “Now these fires 30 or 40,000 acres are common and we get fires more than 100,000 acres.”

Although only about 295 acres of whitebark pine burnt in the Red Mountain fire, the flames were lethal resulting in approximately 98% mortality of whitebark pine.

In an attempt to re-establish the whitebark pines along the ridge, forester Wier and hydrologist Kari Grover-Wier, who happen to be married, propose to plant seedlings using seeds from trees on nearby ridges that demonstrate blister rust resistance.

“Normally I wouldn’t favor planting, because natural regeneration is best and usually happens eventually,” said Michele Crist, landscape ecologist for The Wilderness Society in the Idaho office. “But after seeing very few seed trees surviving the Red Mountain fire and seeing the loss of other nearby whitebark pine populations because of blister rust – planting may be the best option to keep whitebark pine in the ecosystem.”

The use of local, blister rust resistant seedlings and plans to mimic natural regeneration patterns by planting in clumps and irregular spacing added to the appeal..

While some scientists doubt the efficiency of keeping whitebark pine on life support, when so many factors pose threats, Crist also found Wier’s interest in treating it as an experiment to be compelling. Monitoring test plots for comparisons are already set up on neighboring, un-burnt ridges of whitebark pine. And the vast Frank Church-River of No Return Wilderness visible across Bear Valley to the north offers many opportunities to compare sites that have burned but won’t ever be planted.

Michele, Kari and Pete also liked the idea of joining forces to set up protocols for monitoring plots and to seek funding to hire university students to collect the data in future years.

At the end of the day, we’d shared a lot of information and ideas, and we’d escaped the heat.

photo: Forest scientists Kari Grover-Wier, Michele Crist and Pete Wier walk through lupine flowers in a fire-burnt forest near Red Mountain in southern Idaho. Photo by John McCarthy.