Report: Some yellow cedars to remain healthy through 2100

It turns out polar bears and yellow cedar trees have something common. So do ice seals and red cedars. That commonality: One is negatively impacted by climate change; the other appears to be a climate change “winner.”

Just the same, yellow cedars don’t appear to have it as bad as polar bears. A recent 400-page report from lead author and U.S. Forest Service forest pathologist Paul Hennon, based at the Pacific Northwest Research Station’s lab in Juneau, along with seven other scientists, shows that though the trees have been dying off in large numbers in Southeast Alaska, some large populations should remain healthy for at least the next 100 years.

While some of the impacted areas are wilderness and therefore can only be monitored, others are in managed Tongass landscapes, offering an interesting choice: should managers help yellow cedar along? Or should they help red cedar, which may do better with the changing climate (more research is needed). Or do scientists help other species? (In more northern areas, hemlock appears to be growing best where yellow cedars are dying.)

Or they could do nothing.

“To me, the take home message is that yellow cedar has had this mortality event, populations have been diminished in some places, but the idea that it will be extinct — it doesn’t even look extirpated in certain areas,” Hennon said. “But it can go from a cedar dominant forest to a high percentage (of other trees.) That’s a big change, especially for a high-value tree.” (Hennon defines “high value,” he said, both commercially and culturally.)

Large populations of yellow cedars have been dying — they’ve grown to specialize in wet areas and muskeg, where there’s not much competition from the more prolific Sitka spruce and Western hemlock. They keep their roots shallow, where they find the nitrogen they need to grow, and when they don’t get as much snow as they need to insulate their shallow roots, those roots freeze, killing them.

“I like to think that as we learn about these problems, it may give us a path ahead,” Hennon said.

Impacted areas

For the study, the research team divided yellow cedar’s Alaska range into 33 zones and looked closely at each. They found some interesting things. For one, in highly impacted areas, up to 70 or 80 percent of the cedar trees are dying.

But the other 20 to 30 percent of trees in highly impacted areas are not, and the report’s models don’t predict they will by the year 2100. Scientists aren’t sure if it’s because those trees have deeper root systems, or if those trees have different genetics that will benefit them and be passed on. Both are possibilities, Hennon said.

Other areas, such as those at higher elevations, where the snow pack remains thicker, the report predicts will stay healthy at least until 2100, Hennon said.

In contrast, some areas that are now healthy, especially in the northern part of the panhandle, will become vulnerable as Southeast Alaska’s climate and snowpack change.

“Until we broke the landscape up and reassembled it, we didn’t really understand those patterns,” Hennon said.

Good luck for red cedar?

Red cedar grows in southern Southeast Alaska, south of Petersburg and Kake, Hennon said.

Alaska Coastal Rainforest Center, the Forest Service and the University of Alaska Southeast are working together to test some of those affected areas around Kake, and to better see how red cedar does in places yellow cedar has died and been left standing, or died and been harvested, said Alaska Coastal Rainforest Center Director Allison Bidlack.

The ACRC is also working on providing dead yellow cedar wood to mill owners, in part to determine how viable post-mortality harvest is. Yellow cedar remains harvestable for decades after its death.

Planting red cedar in areas it doesn’t currently grow would in effect be assisted migration, something that can be controversial, Hennon said, though red cedar is already growing domestically some places in northern Southeast Alaska, and will likely move north — though much more slowly — on its own as the climate changes.

“Climate change is likely to happen at a faster pace than a slower growing, slower reproducing tree with great longevity is able to migrate,” Hennon said.

Sealaska has also been planting red and yellow cedars on its land, moving some of its 10,000 yellow cedar plantings to higher elevations and more northern latitudes, Sealaska Forester Brian Kleinhenz wrote in an email. The corporation plans to plant 50,000 red cedars on its land on Prince of Wales Island this spring, he said.

“Our biggest challenge in getting the seedlings to survive is dealing with deer who love to browse on newly planted cedar seedlings,” he wrote.

Endangered species?

Though they began working on the report in 2011, before a petition was filed, the report will also likely inform U.S. Fish and Wildlife’s decision on whether or not to list yellow cedar as endangered, Hennon noted. That petition was filed in June 2014 by the Center for Biological Diversity, The Boat Company, the Greater Southeast Alaska Conservation Community and Greenpeace. The organizations listed both climate change and logging as threats to the trees’ ultimate survival as a species.

“When we first started offering nature-based wilderness cruises in southeast Alaska 35 years ago, the region’s predominant mixed-conifer slopes generally looked healthy, with only a few dead-standing yellow cedars in evidence here and there. But now we see mile after mile of slopes where almost all the yellow cedar trees are dead. We should be protecting remaining healthy stands of this species wherever they may still be found in the region, not clearcutting them,” said The Boat Company’s Joel Hanson in a release April 9 of last year.

On April 10 of last year, FWS announced listing may be warranted; they’re now considering listing, a process that’s usually 12 months or more.

Both the State of Alaska and Sealaska Corp. wrote against listing the trees in their public comments to the 90-day finding.

The Center for Biological Diversity, in a press release, said that 600,000 acres of yellow cedar are visibly dead from the air.

Upcoming research

Next up, Hennon and colleagues are working on a range-wide assessment of yellow cedar, including information from Canada. They hope to have that complete by the summer, Hennon said. The total range stretches from California into Prince William Sound and the Chugach National Forest.

They’re studying how red cedar does when yellow cedars die, and working on trials harvesting dead cedar, which is commercially viable for a long time.

Another next step after modeling the species’ entire range, is to see how other changing factors — like aphids and bark beetles — may play into the Tongass’ future.

As long as Southeast stays wet, which is what climate change models predict for Southeast, “this forest ecosystem isn’t going anywhere,” Hennon said.

For yellow cedar, “I think the big message is, it depends on where you look,” Hennon said.

The report, “A Climate Adaptation Strategy for Conservation and Management of Yellow-Cedar in Alaska,” is available at www.treesearch.fs.fed.us/pubs/50115. (Scientists hyphenate false common names, Hennon said. Yellow cedar is not a “true” cedar.)

John Krapek, a PhD student, will speak about local yellow cedar groves at the Mendenhall Glacier Visitor Center’s Feb. 26 Fireside Chat.

• Contact Juneau Empire Outdoors Editor Mary Catharine Martin at maryc.martin@juneauempire.com.