Graduation Date
Summer 2026
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences
Committee Chair Name
Matthew Johnson
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Justin Luong
Second Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Third Committee Member Name
Elizabeth Porzig
Third Committee Member Affiliation
Community Member or Outside Professional
Keywords
Rangeland, Soil, Soil carbon, California, Botany, Land management, Carbon sequestration, Working lands
Subject Categories
Rangeland Resources
Abstract
Soil organic carbon (SOC) is central to soil function and an important component of climate mitigation in rangeland ecosystems, but the controls on SOC across California’s working rangelands remain understudied. Using data from Point Blue Conservation Science’s Rangeland Monitoring Network, this study evaluated how soil properties, vegetation structure, and recent climate relate to SOC concentration at depths of 0–10 cm and 10–40 cm across 145 ranches spanning four California regions. Linear mixed-effects models showed that SOC was consistently higher in topsoil than subsoil and highest in coastal sites relative to interior valleys. Bulk density was the strongest negative predictor of SOC, while clay and silt were positively associated with SOC, especially at depth. Interactions between bulk density and both clay and silt indicated that the relationship between bulk density and SOC depended on soil texture. Bare ground was negatively associated with SOC, particularly near the surface, and woody cover moderated the relationship between native herbaceous cover and SOC, making that relationship less negative and in some cases slightly positive where woody cover was greater. Prior-year precipitation was positively associated with SOC. Overall, these findings indicate that SOC in California rangelands is governed primarily by depth and soil physical context, with vegetation structure and recent moisture further shaping carbon retention.
Citation Style
APA
Recommended Citation
Garcia, Dabid Zuniga, "Depth and soil physical context govern soil organic carbon, while woody cover moderates native vegetation relationships in California rangelands" (2026). Cal Poly Humboldt theses and projects. 2599.
https://digitalcommons.humboldt.edu/etd/2599