Saving the trees: Coeur d’Alene Nursery plays major role in whitebark pine conservation

It starts with the cones. They’re usually gathered in the wild, from whitebark pine trees several thousand feet above sea level somewhere in the West. The cones get shipped to the U.S. Forest Service’s Coeur d’Alene Nursery, where they’ll sit on drying racks for a few months. Once the moisture is out, the cones are cracked by hand to extract the seeds. The seeds are stratified – three days soaking in water, 19 days in a warm chamber, then 100 days in a cooler.

After all that, the seeds are ready to be planted in nursery boxes.

That’s how some 300,000 whitebark pine seedlings came to be in two greenhouses at the Coeur d’Alene Nursery, a sea of green on waist-high tables. White tags are interspersed throughout, relaying the details for each tree. It’s how nursery workers tell the difference between trees bound for forests in Idaho and those for places farther afield, like Yellowstone National Park.

“If you don’t know what they are, they all look the same,” said Aram Eramian, the nursery’s manager.

The vast collection of whitebark seedlings is just a fraction of the output of this nursery, which has been growing all manner of plants for public land agencies for more than 60 years. But the whitebark pine program has become more significant in the past couple of years.

In 2022, the U.S. Fish and Wildlife Service listed whitebark pine as threatened under the Endangered Species Act. The decision came after decades of die-offs and massive declines in tree numbers driven by climate change, insect infestations and an invasive fungal disease called white pine blister rust.

Diana Tomback, a professor at the University of Colorado-Denver and the policy and outreach coordinator for the Whitebark Pine Ecosystem Foundation, said blister rust in particular has decimated stands in the Northern Rockies, killing off trees in Glacier National Park and the Bob Marshall Wilderness of Northwest Montana.

Tomback and other scientists are working on a recovery plan for the species. Many details still need to be worked out, but one piece is clear.

“It’s going to take a lot of planting to restore these landscapes,” Tomback said.

That makes this sprawling government farm on the western edge of Coeur d’Alene a key player in conserving the trees. Of all the Forest Service’s nurseries, it produces the most whitebark seedlings. It’s also been involved in scientific efforts aimed at identifying the best trees to propagate and developing the next generation of whitebark pine seeds.

In other words, the road to recovery runs through Coeur d’Alene.

Decline

Whitebark pine trees exist in most Western states, including Washington and Idaho. They’re found in the highest and most unforgiving parts of the forest, between elevations of 4,300 feet and 12,100 feet, according to the National Park Service.

They grow slowly. It takes 25 to 30 years for a tree to produce cones, and they don’t normally reach peak cone production until they’re over 60. That’s still a relatively young tree – researchers have found individuals between 500 and 1,000 years old.

Their cones are food for a number of animals, such as birds, squirrels and grizzly bears. The Clark’s nutcracker eats the seed and helps spread them, allowing the trees to take root in more places.

Over the past few decades, scientists have watched the trees die in large numbers. Official estimates put the decline at about 50%. In some stands, up to 90% of the trees have been killed.

“The decline is pretty substantial,” said Anna Schoettle, a research plant ecophysiologist for the Forest Service. “In some areas, it’s enough to jeopardize the sustainability of populations.”

Climate change and insect infestations have played roles in the decline, but white pine blister rust is widely considered the greatest threat. It’s a fungal disease that was introduced to western North America more than 100 years ago, and it affects all of the five-needled pine trees.

The spores that cause the disease move between two hosts: ribes species, such as goooseberries, and trees. In trees, the infection can cause cankers and callouses, and it gets worse and worse until it kills the tree, Schoettle said.

Spores move through the air, and those tracking the disease have seen it move from forest to forest. It’s still moving, Schoettle said, and it can’t be eradicated.

“It’s a permanent resident now,” she said. “We can expect that it will continue to kill trees.”

While the disease can wreck entire stands of trees, often a few survive. For one reason or another, they are able to either ward off the infection or simply survive it.

Those trees have some form of natural resistance to the infection. In that resistance, scientists see a way they can fight the whitebark’s decline – by increasing the numbers of trees on the landscape that can resist the disease.

“The only way we’re going to build resilience into the trees is by planting seedlings that have resistance,” Tomback said.

The right seeds

The Coeur d’Alene Nursery began growing whitebark pine in the early 1990s. Eramian said there weren’t any guidelines for growing them, and some machines and techniques they used for other trees didn’t work on whitebark pine. Eventually, they figured it out, and they started growing a few thousand trees per year.

As concern over the decline increased through the 1990s and into the 2000s, so did demand for seedlings. For the past eight years or so, Eramian said, the nursery has grown 300,000 to 350,000 whitebark seedlings each year. They end up in national parks and national forests in several states, including Idaho, Montana and Wyoming.

Seedlings are grown at a couple of other Forest Service nurseries, Eramian said, but they don’t grow nearly as many as Coeur d’Alene.

Crucial to the effort is growing seedlings with genetic resistance to blister rust, giving them the best possible chance to survive in the wild. Through rust screenings – an intensive process of exposing seedlings to rust spores and ensuring they don’t die – officials have identified several families of trees with natural resistance, making them good seed sources.

That’s good, but it means there are a limited number of trees to gather cones from, and the massive planting effort that recovery would require will call for more options.

Tomback said that’s important in terms of volume and in maintaining genetic diversity among whitebark pines. Rust screenings take years to confirm resistance in an individual tree, however, so identifying new seed sources is a slow process.

“This whole process has got to be sped up, and we’ve got to identify more trees because we don’t want to bottleneck the species,” Tomback said.

Last year, researchers sequenced the genome for whitebark pine, an advancement that allows them to analyze a tree’s DNA. By comparing the genomes of trees with and without resistance, they might discover a way to confirm rust resistance in trees in the wild without putting the tree through screenings.

Seed orchards are another part of the picture. The Forest Service has established a few of them, using trees known to have rust resistance. Because the trees grow so slowly, orchards get grafted trees – material from an older, cone producing tree attached to the rootstock of a younger tree.

Kelsie Grover, the tree improvement program manager at the Coeur d’Alene Nursery, said the material from the older tree retains its ability to produce cones, so grafted trees are able to produce cones sooner.

“We’re basically cheating time,” Grover said.

Time can’t be cheated completely. Seed orchards aren’t producing large numbers of cones. Nearly all of the seedlings in Coeur d’Alene are still coming from the forest, gathered by crews hiking deep into the woods at just the right time to collect them.

Work is also being done to see if the orchards could produce a new and improved generation of whitebark pine seeds. In an orchard behind the Coeur d’Alene Nursery, Grover is working with a geneticist on a study of cross pollination – pairing two parents with different forms of rust resistance to produce offspring with multiple layers of protection. In early May, the first cones produced from the study had bloomed.

When they’re ready, those cones will go through the same process as every other that arrives at the nursery. That’s where most of the work in whitebark pine conservation leads – finding more cones to put on drying racks and eventually plant in greenhouses before replanting them in the woods.

Schoettle, the Forest Service ecophysiologist, said that while genetic resistance and finding the right seedlings is important, the work to get seedlings into their natural habitat is a massive commitment.

“We still gotta get it out there,” she said.