"Assisted Migration" May Help Trees Being Steadily Pushed From Their Original Range By Growing Heat
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When trees do migrate north, most “species don’t have a smooth transition across the landscape; they will encounter houses, roads, development”, says Landau. Even if trees could find an unobstructed path forward, many studies echo Landau’s conclusion: the Earth’s climate is changing far too rapidly for them to keep pace.
It’s this urgency that is fueling assisted migration projects like the one at Plum Creek Preserve, as well as six sites administered by the Adaptive Silviculture for Climate Change project. A collaborative effort between American and Canadian environmental agencies and universities, ASCC aims to help land managers understand how forests will respond to climate change and how they might play a part in facilitating it. In Minnesota’s Chippewa national forest, for example, where red oak and white spruce are becoming less suited to the climate, ASCC scientists are slowly introducing bitternut hickory and black cherry, species currently found in the climate zone directly south of the forest.
Dr Jim Guldin, one of ASCC’s lead researchers and a 30-year veteran of the USDA Forest Service, says that these trials are backed by “a lot of good science that shows that climatic conditions are going to change”, and when that happens “the species in a given place may no longer be a good fit for that spot”. He’s also quick to point out that the work is “very much an experiment”. It’s the experimental nature of assisted migration that makes some scientists wary about the risks involved. In 2009, the ecologists Anthony Ricciardi and David Simberloff published an op-ed contending that the strategy was “likely to produce myriad unintended and unpredictable consequences” and could profoundly interrupt the established ecosystems and food webs where the new trees are planted. Assisted migration, they said, was tantamount to “ecological gambling”.
Assisted migration can also be a hard sell for the public, especially in communities that have been warned for years about the dangers of non-native plants and invasive species. Guldin reiterates that ASCC’s introductions are done in “very small steps”, and Landau argues that trees like longleaf pine require such specific management –namely, regular burns of the surrounding area that eliminate competing vegetation, enrich the soil, and kill harmful insects – and are so slow-growing that they’re “highly unlikely to escape” the plots where they are grown.
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https://www.theguardian.com/environment/2020/jul/08/planting-trees-assisted-migration-climate-change
