Assisted Migration: Saving Trees in Pacific Northwest

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As climate change threatens native trees in the Pacific Northwest, the U.S. Forest Service, Portland, Oregon, and citizen groups in Puget Sound are embracing the innovative strategy of “assisted migration” to protect these endangered species.

Assisted Migration: Helping Trees Adapt to Climate Change

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As tree species face decline, ‘assisted migration’ gains popularity in Pacific Northwest

The Pacific Northwest is facing a significant challenge as native trees struggle to survive due to climate changes. As the world’s climate warms, tree growing ranges are predicted to shift northward and higher in elevation. However, trees cannot simply move on their own. This is where “assisted migration” comes in.

Assisted migration is a strategy that involves humans helping trees keep up with climate change by moving them to more favorable ecosystems faster than they could migrate naturally. It is a deceptively simple solution to a complex problem. However, there is a divide among experts on what type of assisted migration is best for the region.

Assisted Population Migration vs. Assisted Species Migration

One important distinction to make is between assisted population migration and assisted species migration. Assisted population migration involves moving a native species’ seeds and genes within its current growing range. This strategy focuses on helping struggling native trees adapt to climate change without introducing new species to the ecosystem.

On the other hand, assisted species migration involves moving a species well outside its existing range. This could mean introducing non-native trees from the south, such as coast redwoods and giant sequoias, to the Pacific Northwest. While this approach may have its benefits, it also comes with ecological risks and the potential for disrupting the food web.

The Importance of Ecological Risks

When considering assisted migration, it is crucial to weigh the potential ecological risks. Planting non-native species in an area where they are not locally found increases the risk of failure and disturbs ecosystem functions and processes. It can also disrupt the food web if native caterpillars no longer have access to the leaves of migrated nonnative tree species.

For example, the City of Portland is experimenting with the assisted migration of oak species from the south. While oaks are important for supporting wildlife, moving them out of their range could have unintended consequences for the animals that rely on them for food.

Assisted Migration: A Risky Proposition

While the effects of climate change are becoming more evident, the decision to engage in assisted migration is not without risks. Moving species outside their historic range without sufficient experimental results to guide the process can be risky. There is a real possibility of making the situation worse instead of better.

However, with the urgency of climate change, public and private groups in the Pacific Northwest are increasingly assuming this risk. They are exploring different approaches to assisted migration, including population migration and species migration, in an effort to help native trees adapt to the changing climate.

In conclusion, assisted migration is gaining popularity as a climate adaptation strategy in the Pacific Northwest. However, there is a need for careful consideration of the ecological risks involved in moving species outside their historic range. As scientists and policymakers continue to explore this strategy, it is important to prioritize the long-term health and stability of ecosystems in the face of climate change.

SOURCE: As tree species face decline, ‘assisted migration’ gains popularity in Pacific Northwest

https://phys.org/news/2023-12-tree-species-decline-migration-gains.html

FAQ’s

What is assisted migration?

Assisted migration is a strategy that involves humans helping trees keep up with climate change by moving them to more favorable ecosystems faster than they could migrate naturally.

What is the difference between assisted population migration and assisted species migration?

Assisted population migration involves moving a native species’ seeds and genes within its current growing range, while assisted species migration involves moving a species well outside its existing range.

What are the potential ecological risks of assisted migration?

Assisted migration can disrupt ecosystem functions and processes, increase the risk of failure, and disrupt the food web if native species no longer have access to the leaves of migrated nonnative tree species.

Why is assisted migration considered a risky proposition?

Moving species outside their historic range without sufficient experimental results to guide the process can have unintended consequences and potentially make the situation worse instead of better.

What is the importance of considering ecological risks in assisted migration?

Considering ecological risks is crucial to prioritize the long-term health and stability of ecosystems in the face of climate change and prevent potential negative impacts on wildlife and the food web.