Graduation Date
Summer 2025
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences
Committee Chair Name
John-Pascal Berrill
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Jim Graham
Second Committee Member Affiliation
Community Member or Outside Professional
Third Committee Member Name
Christopher Looney
Keywords
Redwood, Climate change, Climate transfer distance, Heritability, Provenance study, Humboldt County, Adaptation
Subject Categories
Forestry
Abstract
The climate is changing more rapidly than many species can adapt or migrate. Coast redwood (Sequoia sempervirens) is a unique, long-lived conifer and remains California’s most valuable and economically important timber species. The species is threatened in its natural range due to anthropogenic climate change and human activity. Redwood favors asexual reproduction which restricts its ability to migrate naturally. The consequences of asexual reproduction when faced with a rapidly changing climate may make some form of assisted migration necessary for long-lived organisms like redwood.
This study evaluates drivers of variation in redwood growth and the influence of climate transfer distance by using a common garden experiment involving redwood planted at two test sites outside the species’ natural range in Humboldt County, California. I observed that growth rates (height increment and volume increment) varied according to provenance and that the greatest growth rate occurred with non-local seed sources. Family-within-provenance explained more growth variance than provenance alone, indicating substantial genetic diversity within populations. I found that redwood appears to have moderate narrow-sense heritability (h2 = 0.29 - 0.43) for growth traits. I detected a low genotype–environment interaction, suggesting stable genotype performance across test sites. Surface rock cover was found to be negatively correlated with volume increment, while soil depth was positively correlated with volume increment. Of the 12 climatic variables I tested, the variation in growth between provenances was best explained by differences in extreme minimum temperature (EMT) and summer heat moisture index (SHM). Together, EMT and SHM may prove useful for identifying potential climate-adapted seed sources for future tree improvement programs involving redwood. These findings indicate that assisted population migration of redwood northward to Humboldt County may lead to gains in height and volume growth in young redwood, though performance worsened at greater transfer distances.
Citation Style
APA
Recommended Citation
Murphy, Aidan J., "Can we help coast redwood adapt to climate change? A provenance study on genetic variation and climate transfer distance" (2025). Cal Poly Humboldt theses and projects. 2317.
https://digitalcommons.humboldt.edu/etd/2317