New West Feature
Grizzlies Only Scratch the Surface of What It Will Mean to Lose the Whitebark Pine
The twisted, threatened symbol of high elevation connects an entire ecosystem. As one biologist puts it, "We don't know what's going to happen without whitebark."By Shauna Stephenson, 8-31-10
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Blame it on their large stature or America's obsession with bears, but when it comes to the decline of the whitebark pine, the grizzly may be the least of our worries.
"Everyone is thinking grizzly bear, and there's no question there is going to be some impact on grizzly food supply," says whitebark expert Diana Tomback. "What they don't understand or what really hasn't been well-emphasized is there is a bigger issue here. Whitebark pine is a species that plays a number of important ecological roles in high elevation communities."
A recent report by the Natural Resources Defense Council (NRDC) says the tree could become functionally extinct within the next decade due to an increase in mountain pine beetle infestation. The increase is attributed to a warming trend that allows beetles to reach areas formerly off-limits due to harsh weather. Surveys conducted by the group showed that in the Yellowstone area, 82 percent of the forests are dead or dying. That report echoes its lawsuit against the U.S. Fish and Wildlife Service to list the tree on the Endangered Species Act, a review the service is currently looking at.
"Whitebark pine is basically a sitting duck to pine beetle," says Louisa Willcox of NRDC.
However, even if the beetle were to disappear tomorrow, trouble would be looming on the horizon for the species says Tomback, a professor and acting chair of the Department of Integrated Biology at the University of Colorado Denver. She says that rates of blister rust are high enough across its range to pose a serious threat. Blister rust, she notes, attacks all age classes of whitebark, not just mature ones.
"Pine beetle outbreaks settle down," she says. "Blister rust doesn't give trees a chance. … Everything is vulnerable."
With the two working in tandem, whitebark is getting hit on both sides. Trees that might have survived the blister rust are now being attacked by mountain pine beetle, causing a trickle down effect in the ecosystem as a whole.
But in the time since that report was released, very little has been said about the bigger picture. While the fateful tree has dominated the news, the explanation of what that actually means has been largely ignored. Perhaps it is because these things make for less than sexy headlines – indeed, who can get excited about words like sublimation or evapotranspiration? But it is these changes that will eventually be felt by the populations as a whole.
It is hard to gauge the specifics of how this change will occur. The fact of the matter is we have never experienced this type of shift on this scale. While there have been both pine-beetle and blister-rust outbreaks in the past, they have not been as broad as this one appears to be. Add to that the multiple other fronts America's forests seem to be fighting on, and it can become quite hard to comprehend, let alone predict. That said, what is out there, isn't pretty.
"We don't know what's going to happen without whitebark," Tomback says.
WHITEBARK ECOLOGY
Whitebark is a trailblazer, a trendsetter, an ass-kicker of a tree—a tree Westerners can really relate to, one of the oldest and toughest broads out there. As one of the last trees before the tree line, the widely distributed whitebark leads a harsh and harrowing life.
Given its precarious perch, it serves a few very important functions. It acts as a snow fence in the winter and it provides shade in the spring, slowing runoff and parsing out water to lower-elevation communities well into the summer. After fires, it is one of the first to regenerate in compromised soil, blazing the way for other species to take root behind it.
It is a food source to multitudes of wildlife. Clark's nutcrackers enjoy a symbiotic relationship with the tree, dispersing its seeds while using them throughout the year as a food source. Red squirrels cache cones in middens, feeding both themselves and the occasional grizzly bear fattening up for winter. Other species such as the Golden-mantled squirrel, chipmunk species, the hairy and white-headed woodpeckers, Williamson's sapsucker, mountain chickadee, white- and red-breasted nuthatches, Stellar's jay, raven, pine grosbeak, red crossbill and Cassin's finch all dabble in whitebark seed consumption at various times of year.
But it also has a softer side. It is individualistic. Unlike the lodgepoles and Douglas firs of the world, each tree has its own personality, twisting and carving its unique niche. It is a long-lived tree: reaching ages old enough to have been around when the Magna Carta was signed, there when Christopher Columbus sailed the ocean blue, when America declared its independence, and when Lewis and Clark ventured west.
"They're kind of symbols of the high elevation. As they decline, we lose their beauty," Tomback says. "As they're lost, we lose a sense of ancient presence."
WATER, WATER EVERYWHERE...
For years, fights over water and water rights have raged throughout the West. With the decline of whitebark, those fights are only bound to increase.
As trees die, their ability to both capture snowpack and shade it is reduced. On the other end, live trees also take up a huge amount of water, taking up the most when they are young and then tapering off as they mature. With large stands of trees dying, that ratio is bound to play a role as well.
"It's going to vary depending on watershed and percentage of tree cover in that water shed," says Greg Pederson, research scientist with USGS at the Bozeman-based Northern Rocky Mountain Science Center.
He says some areas may see lower snowpacks and earlier runoff, meaning longer, drier summers. Other areas may experience more water in the system, leading to flooding downstream. As trees begin to grow back, short term gains may turn into losses as young trees take up more water.
Some areas may even benefit from the canopy being opened up a bit, allowing more snow to accumulate during the winter. Factors such as erosion and fire will play a role, as will wind.
"At the end of the day the hard part is picking apart what's happening among those processes," he says.
Couple all of that with changing temperatures and the difficulty of prediction increases exponentially. Over the years, Steve Gray, Wyoming state climatologist, has seen a trend in the average temperatures going up in the northwestern part of the state. While he says it's too early to tell if this is a long-term trend, or short-term variability, one thing is for certain:
"The bottom line is that the best guess we have, the majority or all of the forecast predictions we have, say it's going to be warmer," he says. "It's just a matter of how fast that happens and the magnitude of that warming. Even a seemingly small shift in average temperature is going to have significant consequences of regional ecosystems."
As that shift occurs, it gets passed down the line.
"Lower elevations are intimately connected to what happens up in the high country," he says. "Changes will have definite and significant consequences for everything that happens downstream. That includes a huge part of the U.S. population."
ADAPTATION AS A LIFESTYLE
As whitebark declines, the wildlife that depends on it will have to adapt as well.
Grizzlies tend to be at the center of this polarizing debate. While their use of whitebark pine seeds is well-documented, they are also known as a highly adaptable creature, switching over to other food sources when one becomes unavailable. Lawsuits and politics aside, there is no doubt a change in whitebark pine will have an impact on the bear. The question is: To what extent?
Chuck Schwartz, leader of the Interagency Grizzly Bear Study Team, says when whitebark pine crops are low, the impact doesn't necessarily affect bears across the entire population.
"Our data show that bears drop down in elevation about 200 meters in poor-versus-good whitebark pine years in autumn," Schwartz wrote in an e-mail. "There seems to be some confusion on this movement. All the bears don't pack their suitcase and move from the mountain tops to the valley bottoms where people live.
"Bears that live in secure habitats--areas with few roads, developments and homes--shift in elevation and use alternate foods and continue to survive just fine. It's the bears that exist on the edge of the ecosystem that tend to shift closer to humans."
While it's the mortality levels in those populations that concern environmentalists, Chris Servheen, grizzly bear recovery coordinator for the U.S. Fish and Wildlife Service, says populations have been increasing for years and continue to increase. It is just the rate of that increase that will be impacted.
"There's not enough mortality to change the overall increase," he says. "(It is just) a slower increase during the poorer whitebark years."
But with Clark's Nutcrackers—the main dispersant of whitebark seeds—a change in behavior could have major consequences.
"Nutcrackers won't go extinct," Tomback says. They'll continue to eat seeds and it's likely they'll simply shift to some of the other species in the forest. That shift, however, may have some longer-term implications for their carrying capacity and could spell further disaster for the tree.
This is where things get more complex. Think of the entire system as a business. You have a set number of employees, which is like your carrying capacity, and you have a budget of food that fluctuates based on a number of factors. A reduction in carrying capacity is like nature's version of layoffs: If there's not enough money in the budget to pay 10 employees, it will reduce that number to five.
But that number turns around and takes a bite out of the overall health of whitebark pines. Just like layoffs, if there are only five nutcrackers supported by the forest, then there are only five to do the work. And while "do more with less" is all the rage, it doesn't really work for this tree. As seeds decline, red squirrels get desperate and begin targeting the trees, harvesting entire crops before they are mature and hiding them away in their middens, leaving little for the nutcrackers to cache. Immature seeds won't germinate and the problem is compounded. Essentially, less work gets done.
As that continues to trickle down, other species will be impacted. While many of the other small mammals and birds, including chipmunks and blue grouse, don't depend on the tree as a main food source, that contribution is still part of their annual food budget and they have to turn to other sources. Thus, we begin to rob Peter to pay Paul.
"The point is what's going to happen when we don't have that many whitebark pine seeds," Tomback says. "Whenever you remove a food source, there's always an impact on the rest of the ecosystem.
THE DREADED E-WORD
The forecast for the entire situation has some putting the nails in the coffin for whitebark pine.
Tomback says with climate change being the 900-pound gorilla in the room, this notion that trees will just shift north isn't as simple as it seems. There have to be viable seeds to do that and processes to distribute them.
"Some people say, well, 50 years from now if the range moves north, what difference is it going to make?" she says. "I need to point out that unless there are healthy populations of whitebark, it can't move north."
While solutions have been identified, there is a significant lack of funding in implementing them. Blister-rust-resistant seedlings are being collected and grown in greenhouses to be replanted in their native habitats. But this solution tends to be both difficult and costly.
In the mean time, Tomback is avoiding the big "E" (extinction) and instead, opting for the little "e."
"At this point, I don't want to sound alarmist, but from what I've seen I can, with confidence, say expatriation from many parts of its range is a real possibility."
While the fundamental premise of an ecosystem revolves around its ability to evolve and adapt, it's hard to see how forests are going to adapt their way out of this one – true, they will go on. But picturing that end result is a stretch.
With the introduction of invasive species, change in climate, change in fire regime and countless other factors, ecosystems seem to be facing bigger problems on larger scales more and more often. When blister rust came to America in the early 1900s, it was only the beginning.
"It could have been considered the harbinger of what we're dealing with today," Tomback says.
Forests everywhere seem to be at war and, while change is part of the natural process, keeping faith that everything will be O.K. is difficult, even for the most optimistic.
"We are just going to be in a crisis mode," Tomback says. "I don't know what else we're going to do to deal with this [while] struggling to keep our native ecosystems in tact."
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