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The City of Portland’s Urban Forestry program is currently experimenting with the assisted migration of 11 tree species, including three oak species to the south: California black oak, canyon live oak and interior live oak. Asked via email about potential ecological disruptions Portland’s City Forester Urban Forestry Manager Jenn Cairo responded: “We use research from universities, state and federal sources, and local and regional field practitioner experience.” Another advocate for species migration is the Puget Sound-based, citizen-led PropagationNation. The organization has planted trees in several parks in the Seattle area and has the ambitious goal of “bringing a million coast redwoods and giant sequoias to the Northwest,” according to its website. The PropagationNation website also recommends planting redwoods in areas where native western red cedar, western hemlock, Sitka spruce and big leaf maple already grow. Western red cedar, western hemlock and big leaf maple have all seen die-offs and growth declines in recent years tied to climate. Philip Stielstra, PropagationNation’s founder and president, and a retired Boeing employee, declined to comment for this story. David Milarch, founder of the Michigan-based Archangel Ancient Tree Archive, which has supplied PropagationNation with redwoods and sequoias, says his trees aren’t intended to replace Pacific Northwest native species. “All we are doing is extending the range (of redwoods and sequoias) north in the hopes that they will still be here in 100 to 200 years and not join the list of trees that are going extinct,” said Milarch. Robert Slesak, research forester at the Pacific Northwest Research Station, runs the Forest Service’s Experimental Network for Assisted Migration and Establishment Silviculture, or ENAMES project, which oversees population migration sites in Washington, Oregon and California. Slesak called moving redwoods north a “risky proposition.” He said he has serious concerns about both assisted species migration and assisted migration efforts that lack experimental rigor. “Widespread assisted species migration without a lot of experimental results to guide it is risky,” said Slesak. “Everyone knows we need to do some kind of action related to climate, but there’s a real risk of making it worse.” Nevertheless, with the effects of climate change increasing, it’s a risk increasingly being assumed by public and private groups around the Pacific Northwest.
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