Publication Date
8-2024
Date of Final Oral Examination (Defense)
6-18-2024
Type of Culminating Activity
Dissertation
Degree Title
Doctor of Philosophy in Ecology, Evolution, and Behavior
Department Filter
Biology
Department
Biology
Supervisory Committee Chair
Marie-Anne de Graaff, Ph.D.
Supervisory Committee Member
Kevin Feris, Ph.D.
Supervisory Committee Member
Leonora Bittleston, Ph.D.
Supervisory Committee Member
Julie D. Jastrow, Ph.D.
Abstract
Soil organic carbon (SOC) is an important component for healthy ecosystems, food production, and climate change mitigation, but traditional land management practices have depleted it. Root carbon (C) inputs contribute to both SOC formation and loss through their role in increasing C inputs and impacting microbial community function. Currently, we do not fully understand how root characteristics impacting the quantity and chemistry of root C inputs to the soil influence microbial community function and thus control soil C retention and loss. Gaining a better understanding of the mechanisms at the root-microbe interface will help improve management practices aimed at increasing SOC accumulation. C4 grasses have extensive root systems and have documented genotypic variation in root traits with subsequent effects on SOC accumulation. In this study, we harnessed the natural variation of cultivars from the C4 grass species big bluestem and switchgrass to gain a better understanding of how differences in root traits impact the soil microbial community and SOC storage. We used a field study created by Argonne National Laboratory to investigate how differences in cultivars of big bluestem and switchgrass impacted SOC dynamics after 10 and 14 years of plant growth. In brief, chapter 1 aimed to answer how root morphology affects the quantity and chemistry of C inputs and implications for SOC retention, chapter 2 aimed to answer how microbial communities impact decomposition of plant material and contribute to SOC formation and loss, and chapter 3 aimed to answer how the chemical composition of roots mediates the decomposition and loss of plant material within the soil. To assess how these mechanisms influence SOC formation, we looked at particulate organic matter (POM) and clay associated organic matter fractions, which vary in composition and persistence. The mechanisms contributing to POM formation or loss were related to root traits that influenced both the quantity of C inputs and the decomposition of POM-C. Clay-associated C formation or loss was linked to the interactive effect of cultivar genotype C inputs on microbial function. Despite these different mechanisms governing POM and clay-associated organic matter formation, both pools were vulnerable to C loss. Our data show strong connections between root characteristics at the genotype level and SOC accrual, but incorporating these findings into comprehensive process models is necessary in order to improve SOC predictions. All together these results highlight the importance of needing to select for plant traits that grow both soil organic matter pools in order to increase SOC.
DOI
https://doi.org/10.18122/td.2267.boisestate
Recommended Citation
Kelly-Slatten, Megan Janay, "Harnessing the Power of C4 Perennial Grasses to Understand Soil Carbon Dynamics" (2024). Boise State University Theses and Dissertations. 2267.
https://doi.org/10.18122/td.2267.boisestate
Comments
https://orcid.org/0000-0003-0861-6443