Insight into genetic variation in trees may provide opportunities to select for genotypes that are better adapted to new locations and future climate conditions. We established a field test at two sites in Humboldt County, California to study the performance of coast redwood (Sequoia sempervirens
(D. Don) Endl.) under assisted migration. Both test sites were near the eastern (inland) limit of coast redwood’s range and had no naturally occurring redwood. Seed were collected from redwood trees on dry, hot ridges and upper slopes from the southernmost populations, and combined with redwood seed from Mendocino County and seed and tissue culture clones from Humboldt County. A total of 34 different clones, open-pollinated families, and commercial seedlots were planted in 27 replicates at each test site using an interlocking hexagonal design. Health, instances of damage, and total height of every seedling was recorded annually since planting in 2010. Caliper (basal diameter) was also measured annually three times beginning in spring 2014, giving basal diameter increment for each tree. Water stress was assessed for each young tree (n ≈ 2000 trees) in the summer of 2015 using a pressure bomb. Performance of progeny planted at each test site varied among regions-of-origin, forest-oforigin, and among families of seedlings from individual open-pollinated parent trees. Results were counter to our expectation that seedlings originating from parents located at the warmer and drier southern extremes of redwood’s range would perform best on the more extreme test site (higher elevation, no fog) in Humboldt County. However, high variances within families and clones suggested that genetic effects may have been obscured by other sources of variability at this early age.
climate change adaptation
Dagley, Christa M.; Berrill, John-Pascal; Johnson, Forrest T.; Kerhoulas, Lucy P. 2017. Adaptation to climate change Moving coast redwood seedlings northward and inland. In: Standiford, Richard B.; Valachovic, Yana, tech cords. Coast redwood science symposium 2016: Past successes and future direction. Proceedings of a workshop. Gen. Tech. Rep. PSW-GTR-258. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 219-227.