“Adaptive management strategies may assist plants in adapting to future climate changes, but will be challenged by the long life-cycles of many Oregon tree species.”
– Oregon Climate Assessment Report
By Lee Anna Sherman
BEND, Oregon – The seedlings are barely visible among the tufts of lupine, balsamroot and bunchgrass dominating the study plot in the Deschutes National Forest. Matt Horning tramps over the uneven ground, naming each tiny tree as he goes — Douglas fir, Ponderosa pine and a dozen other species whose survival rates, growth patterns and genetic makeup are under scrutiny for a joint study by Canadian and American scientists.
Out beyond the Cyclone fence enclosing the hilltop site, acres of charred forest march across the landscape, thousands of blackened trunks etched eerily against the Three Sisters peaks. “We’re still replanting from the B&B Complex fire of 2003 because the burned area was so huge,” notes Horning, a geneticist for the U.S. Forest Service. “Seedlings not only have to be adapted to the local climate, they also have to compete with existing vegetation and withstand nibbling by deer and other browsers. Replanting on some of the units has not been as successful as it has on others.”
Understanding the optimal growing conditions for trees and other vegetation helps foresters ensure good outcomes when they replant burned-out, pest-infested or logged-over stands of timber. “My role is to help identify the most appropriate plant materials that will be used in reforestation and revegetation,” says Horning, who has studied genetic diversity and adaptation of flora and fauna ranging from the American robin to a threatened prairie lily.
“So if there’s a big fire or some other disturbance, and the Forest Service decides to revegetate the area, land managers will be able to use the best plant materials to create a healthy, sustainable forest.”
Scientists with the Forest Service and OSU’s College of Forestry have collected legions of data on Northwest species over the decades. They have mapped which plants thrive in each local mix of geography, elevation and climate. These maps are called “seed-zone” maps — they pinpoint places where each seed type is best suited.
But the climate defining those zones is shifting fast. As forests get wetter or drier, warmer or cooler, vegetation migrates in response. For short-lived plants, the shifts are quick. Grasses can adapt nearly overnight. But for the giants of the Northwest’s boreal and temperate forests, which take decades to mature, a rapidly changing climate can be catastrophic. A seedling that takes root during one climatic period may suffer stress or die in another. Its genetic code, written over eons of evolutionary adaptation, no longer matches the world it lives in.
“Some species can migrate more readily than others,” says Horning, who collaborates not only with OSU forestry researchers but also with crop and soil scientists on rangeland studies. “Species that are generalists, like western red cedar or bluebunch wheatgrass, are more broadly adaptable. Species that are specialists, like whitebark pine, are more susceptible to climate change.”
In fact, more than half of the evergreen species across northwestern Canada and the U.S. already are losing their competitive edge, according to a new study led by Richard Waring, an emeritus professor in the OSU College of Forestry. “Some of these changes are already happening, pretty fast and in some huge areas,” says Waring.
Seeding the Future
That’s why the Forest Service and OSU recently created a Seedlot Selection Tool — a public website built with GIS mapping technology and climate modeling software — to help land managers adapt to change. (A “seedlot” refers to seeds of a certain plant collected at one time and likely to have similar germination rates and other traits.) Horning’s Forest Service colleague Brad St. Clair at the Pacific Northwest Research Station in Corvallis and OSU tree geneticist Glenn Howe led the project with funding from the U.S. Forest Service’s Global Change Research Program.
“Because forest trees are genetically adapted to their local climates, local seed sources are generally recommended for reforestation,” St. Clair, Howe and their colleagues explain. “These recommendations, however, assume that climates are stable over the long term, an assumption that we now know is unlikely.” The Seedlot Selection Tool is one of several projects undertaken in recent years by OSU’s Taskforce on Adapting Forests to Climate Change, whose mission is to provide science-based management options for public and private forest landowners. At a genetics workshop for researchers in 2010, Horning highlighted the user-friendly tool during a presentation on seed-transfer guidelines. “We sat down in Corvallis — the genetics community in the Forest Service along with a lot of researchers from OSU and elsewhere — and said: ‘What sort of management recommendations can we make to folks to help mitigate climate change?’”
Matching seeds with sites is one key strategy. To get the free, online tool into the hands of stakeholders, the OSU taskforce brought potential users together in 2010 for a workshop. Among the attendees were members of OSU’s Tree Improvement Research Cooperative, which includes Starker Forests, Stimpson Lumber Co., Weyerhauser Co. and a dozen other private firms and public agencies.
With a few clicks on the computer, users can try out various seedlots on a selected planting site (or they can map various planting sites onto a selected seedlot) under a range of climate scenarios. In places where precipitation has dropped and temperatures have risen, for instance, they might discover that drought-tolerant Ponderosa pine is a better fit than moisture-craving Douglas fir. “The best way to learn about the tool,” notes Howe, “is to try it.”