Native fungus suggested as another tool for restoring ghostly whitebark pine forests

Siberian slippery jack is a native fungus that may help in the effort to restore whitebark pine forests.
Credit: Cathy Cripps

Cathy Cripps doesn't seem to worry about the grizzly bears and black bears that watch her work, but she is concerned about the ghosts and skeletons she encounters.

The ghosts are whitebark pine forests that have been devastated by mountain pine beetles and white pine blister rust, said the Montana State University scientist who studies fungi that grow in extreme environments. The skeletons are dead trees that no longer shade snow or produce pine cones. The round purple pine cones hold the seeds that feed bears, red squirrels and Clark's nutcracker birds. Shade at the top of watersheds keeps snow from melting too fast in the spring, preventing trout streams from drying up too early in the summer.

Fortunately, she has found hope in a native fungus called Siberian slippery jack, or Suillus sibiricus, said Cripps, a mycologist in MSU's Department of Plant Sciences and Plant Pathology.

Cripps conducted a three-year study in collaboration with Waterton Lakes National Park in Canada that showed a 10 to 15 percent increase in the survival rate of whitebark pine seedlings when Siberian slippery jack spores are injected into the soil around them. The injection takes place in nurseries before the seedlings are transplanted in the mountains.

That increase is significant and good news for those trying to reinstate whitebark pine trees to the north-central Rocky Mountains and Pacific Northwest, Cripps said. The whitebark pine is a keystone species that grows at high elevations where other trees cannot, but it has been declared an endangered species in Canada and awaits the designation in the United States.

"That (jump in survival rates) might not sound like a big difference, but a small amount is a big deal considering the labor-intensive process," Cripps said.

Cyndi Smith, scientist emeritus at Waterton, said "The positive results have encouraged Waterton Lakes National Park to continue inoculating both whitebark and limber pine seedlings, to give them the best opportunity we can to establish and survive to maturity."

Participants in the research project, in addition to Cripps' and Smith's teams, were the U.S. Forest Service, National Park Service and volunteers from the United States and Canada.

Explaining how the collaboration began, Smith said, "Cathy gave a presentation on some of her Yellowstone work at the annual science meeting of the Whitebark Pine Ecosystem Foundation in Hailey, Idaho, in 2006. I was really taken with the idea that the ecosystem may have lost the beneficial fungi because our forests have been dead and dying for so long and that perhaps there was a way to reverse that trend so I approached Cathy with the idea.

"I'm a big believer in collaboration, whether locally or internationally, but certainly working with someone of Cathy's academic stature has been very helpful when I have applied for funding for whitebark and limber pine projects," Smith said, adding that, "Cathy's enthusiasm is very infectious, and it is a delight to work with her."

To carry out the research project, the participants placed cages around whitebark pine trees to collect pine cones without interference from wildlife. Then they tested the cones to see if they were resistant to white pine blister rust, removed seeds by hand from the resistant cones, grew the seeds into seedlings and shipped them to the nursery in Glacier National Park.

Cripps and former graduate student Erin Lonergan drove to Waterton Lakes 

National Park and throughout the Greater Yellowstone area, hiked to the tops of mountains and collected the Siberian slippery jack and other fungi from whitebark pine forests. Then they returned to MSU where they used a coffee grinder to process the spongy outer layer of the fungi. They added water to create a spore slurry, stored the mixture at MSU and later injected about 3 million spores into the soil around each seedling temporarily housed at the Glacier National Park nursery.

A few months later, volunteers planted more than 1,000 seedlings into MSU's test plots. Most of those test plots were located in Waterton, while others were in the neighboring Glacier National Park. The two parks together comprise Waterton-Glacier International Peace Park.

Two years into the study, Lonergan, Cripps and Smith reported success in the journal, American Forests. One year later, they announced their final results in the spring/summer 2014 issue of Nutcracker Notes, a small journal hosted by the Whitebark Pine Ecosystem Foundation.

"We wanted to get the word out that results after three years showed that inoculation with these native fungi significantly improved the survival of rust resistant seedlings, especially when inoculated seedlings were planted in burned areas near shelter objects such as stumps and logs," Cripps said.

High nitrogen fertilizations and fungicides prevent the inoculations from working, Cripps said. The age of the seedlings is important because they need to grow plenty of side roots before being inoculated.

When successful, the injected fungi slip like tiny socks over the ends of every root of the whitebark pine seedling and form a relationship that benefits both the tree and the fungi, Cripps said. The fungi help the seedling take in more nutrients and water from the soil. The tree produces the sugars that feed the fungi.

"Instead of being bad guys, these fungi are beneficial," Cripps said of the Siberian slippery jack. "They help plants take up nitrogen and phosphorus from the soil. That's a big deal."

Her study is one of many research projects involving whitebark pine forests, but it's unique because it focuses on beneficial native fungi, Cripps said. She added that land managers might want to incorporate MSU's findings into their overall strategy for restoring whitebark pine forests. She noted that large-scale inoculations are already planned for nurseries in Canada. She said inoculating beneficial fungi into nursery stock is common in Europe.

"As we work to save the vital whitebark pine from disappearing from the landscape, it is essential to use all available tools," Cripps said. "Ectomycorrhizal fungi are an integral part of forest integrity, ecology and health. Showing respect for these mighty microbes might just mean the difference between the restoration and death of a forest."

"Ectomycorrhizal fungi" refers to beneficial fungi that form a symbiotic relationship with the roots of trees. Siberian slippery jack is one of those fungi, and it only associates with five-needle pines. White pine blister rust is another type of fungus, one of the "bad guys."

Source: Montana State University

Mountain pine beetles get bad rap for wildfires, study says

Following wildfires in 2011, a UW-Madison research team studied lodgepole pine trees in the Northern Rocky Mountains to examine whether earlier outbreaks of mountain pine beetles changed the ecological impact of the wildfires. Credit: Turner Lab

Mountain pine beetles get a bad rap, and understandably so. The grain-of-rice-sized insects are responsible for killing pine trees over tens of millions of acres in the Western U.S. and Canada over the last decade.

But contrary to popular belief, these pests may not be to blame for more severe wildfires like those that have recently swept through the region. Instead, weather and topography play a greater role in the ecological severity of fires than these bark-boring beetles.

New research led by the University of Wisconsin-Madison and the Washington State Department of Natural Resources provides some of the first rigorous field data to test whether fires that burn in areas impacted by mountain pine beetles are more ecologically severe than in those not attacked by the native bug.

In a study published this week in the Proceedings of the National Academy of Sciences, UW-Madison zoology professor Monica Turner and her graduate student, Brian Harvey, show pine beetle outbreaks contributed little to the severity of six wildfires that affected more than 75,000 acres in the Northern Rocky Mountains in 2011. They also show that the beetle outbreaks, which occurred from 2000 through 2010, have not directly impacted post-fire recovery of the forests. The study does not, however, address fire behavior, such as how quickly fires spread or how dangerous they are to fight.

While the findings may exonerate the insect scapegoats, they should also help ecosystem managers better respond to changes in the face of climate-driven disturbances, like drought and warmer temperatures.

Large, severe fires are typical in the lodgepole pine forests found throughout the region, even without mountain pine beetle outbreaks. However, as the climate has warmed, outbreaks and big fires have both become more common. The phenomenon of more beetles has meant more dead trees, and some have grown concerned about how beetle attacks and wildfires may interact.

"The conventional wisdom is that a forest of dead trees is a tinder box just waiting to burn up," says Turner, who has long studied the forest landscape of the Mountain West. "There were very little data out there but a lot of concern."

Forests attacked by bark beetles -- which burrow into the bark of lodgepole pines to mate and incubate their larvae -- can seem nothing more than ample kindling for a raging blaze, with their dead wood and dry, reddish-brown needles.

The burrows the beetles carve under the bark of pines, called galleries, choke off water and nutrient circulation in the trees. The trees die and, for the first couple of years, they hold on to their dry, lifeless needles. Scientists call this the "red stage," and some believe these trees could fuel more severe fires.

By year three, most beetle-attacked trees have entered the "gray stage," dropping their once green pine foliage, becoming needleless wood carcasses.

Earlier studies from Turner's group suggested that beetle outbreaks would not lead to more severe fires. But without actual fires, the interaction could not be tested.

However, in 2011, wildfires throughout eastern Idaho and western Montana -- in forests that had experienced varying mountain pine beetle outbreak impacts -- provided opportunity for the research team to begin to answer the question: Do the two disturbances, beetle attacks and wildfire, together change the ecological response of the forest to fire?

Fortunately for the team, among the burned areas studied were pine stands that had not been attacked by beetles. These areas served as controls. Others suffered a range of mortality from the beetles; in some stands, beetles killed nearly 90 percent of the trees prior to wildfire. The fires that raged also ran the spectrum of severity, allowing the researchers to compare a number of variables.

Some study plots comprised mostly live trees, while others contained mostly red-stage or gray-stage trees -- allowing the researchers to assess whether plots with red-stage trees (with dry needles) experienced greater levels of fire severity than plots with mostly gray-stage trees (no needles), as they and others had expected.

The study team examined ecosystem indicators of fire severity, such as how many trees were killed by fire and how much char covered the forests.

Engaging in what Harvey calls "post-fire detective work," in 2012, the scientific team evaluated fire severity in each study plot and stripped sections of bark from over 10,000 trees to determine what killed them, beetles or fire. Beetle galleries can remain visible under the bark even after fire.

As they sifted through the blackened trees and forest floor, the team became covered with ash and soot.

"We looked like coal miners when we were done," says Harvey.

They found that the severity of the outbreak and whether trees were in the red or gray stage had almost no effect on fire severity under moderate burning conditions.

Only under more extreme fire-burning conditions -- when it was hot, dry and windy -- did areas with more beetle-killed trees show signs of more ecologically severe fires, such as more deeply burned trunks and crowns (the part of the tree that includes its limbs and needles). The presence of more gray-stage trees actually had a stronger impact on fire severity than the amount of red-stage trees, to the surprise of the scientists.

Overall, however, Turner says the effects of beetle outbreaks on fire severity took a back seat to stronger drivers -- primarily weather and topography. Fire severity increased under more extreme weather, regardless of pre-fire outbreaks, and forest stands higher in the landscape burned more severely than those at lower elevation as fires moved uphill, building momentum.

"No one says beetle-killed forests won't burn," says Turner. "The data set looks at whether they burn with different severity compared to unattacked forests burning under similar conditions."

The team was also interested in whether beetle outbreaks slowed the recovery of the forests after fires. Lodgepole pines are adapted to fire, containing two types of seed-carrying cones: those that release seeds as soon as they mature and those that require fire to open, blanketing the forest floor with potential new life following a blaze.

By counting the number of post-fire tree seedlings in their plots, the researchers found very little beetle-related impact. Tree seedlings were most numerous where more of the fire-killed trees bore the fire-adapted, or serotinous, cones. Beetle-killed trees likely contributed to post-fire seedling establishment, too, as their seeds remain viable in cones if they are not consumed in fire. Only high-reaching char from tall flames reduced the number of seed-spreading cones.

The scientists emphasize the results may differ in other forest types or with different lengths of time between beetle outbreaks and fire.

"These are both natural disturbances, fire and beetle outbreaks," says Turner. "It's not surprising the ecosystem has these mechanisms to be resilient. What we as people see as catastrophes are not always catastrophes to the ecosystem."

Source: University of Wisconsin-Madison