Redwood Range Shifts

Data Basin is the host for spatial outputs that will be generated as part of the Redwood Climate Change Initiative. A major project of Save-the-Redwoods League, this comprehensive and integrated study of climate impacts on coastal redwoods is being conducted in partnership with researchers from the University of California, Berkeley, Humboldt State University and the California Academy of Sciences.

One important aspect of the initiative is to use a wide range of global climate model outputs to examine the potential future distribution of coastal redwoods. Once finalized, the range shift projections will be used to prioritize land acquisitions for conservation, and to disseminate information to key decision-makers. The findings will contribute to shaping the conservation and restoration strategies of the Save-the-Redwoods League and their partners.

The researchers examined the entire 450-mile native range of the coastal redwood, most of which is now covered with second and third growth forests. Although the study is not yet completed, several important patterns have emerged:

• The southern most part of the current range of coastal redwood is in jeopardy of not being able to maintain redwoods into the future.
• Suitable habitat for coastal redwood may expand into the southern and central coast of Oregon by mid-century.
• There is a large difference in the amount of suitable habitat under different greenhouse gas emission scenarios. Under a scenario involving major global shifts to renewable energy sources (the "B1" scenario), much of the existing habitat for coastal redwoods would likely persist into the future. Under a more business-as-usual scenario of continued high global emissions (the "A2" scenario), the suitable habitat for coastal redwoods is dramatically reduced. We are currently surpassing the A2 scenario assumptions.
• Under either scenario, there are 'climate refuges' for coast redwood that overlap with existing important protected areas. These regions of persistence may become high priority targets areas where Save-the-Redwoods League and their partners work to expand protection and manage for connectivity to other protected areas.

The researchers used species distribution modeling and global climate model data to forecast the distribution of the climate envelope for coastal redwood (Sequoia sempervirens) for several decadal average time slices into the future: the years 2010s (ten year period average), 2050s, and 2090s. The model output is based on a large ensemble of downscaled global climate models (n=16) and four environmental parameters: monthly Tmax, monthly Tmin, monthly Tave, and monthly total precipitation. Localities used to produce the model were resampled from the known current distribution. Data provided by Save-the-Redwood League and Dr. Healy Hamilton from the California Academy of Sciences.