Date of Completion

2021

Document Type

Honors College Thesis

Department

Rubenstein School of Environment and Natural Resources

Thesis Type

Honors College

First Advisor

Carol Adair

Second Advisor

Anthony D'Amato

Third Advisor

Aimee Classen

Keywords

soil carbon, above-ground carbon, global, biome-specific, structural equation modeling

Abstract

Mineral soil carbon is an important terrestrial carbon stock, however, the pathway between leaf litter decomposition and mineral soil organic carbon is still undefined. To gain an understanding of this carbon stabilization pathway and the other drivers of mineral soil carbon I addressed the question: (1) is leaf litter decomposition correlated with soil mineral carbon pools within and across forest ecosystems? And more broadly, (2) what are the drivers of mineral soil carbon stabilization at a global and biome specific scale? I answered the first question by conducting a meta-analysis of previously collected litter decomposition data and soil organic carbon (SOC) content in the mineral layer. The data was extracted from data depositories and primary literature. My results showed that mineral SOC was not correlated with litter decomposition rates, or the amount of carbon remaining when the decomposition rate is zero (asymptotic limit value (A)), determined through linear regression. For the second question, I found different drivers of mineral SOC in temperate, tropical, and boreal biomes using structural equation modeling. Including actual evapotranspiration (AET), soil microbial carbon, soil nitrogen, soil clay content, gross primary productivity, litter decomposition rate, and the asymptotic limit value (A), I was able to explain 24.8% of the variation in SOC in the mineral layer globally. This varied in the different biomes; in the temperate biome, 69.2% of the variation in SOC in the mineral layer was explained by the same variables as above, in the boreal system 48.1% of the variation was explained excluding soil N, and in the tropics, 48.5% of the variation was explained excluding AET. Some of the most important drivers of mineral SOC include soil N and AET. However, I found no relationship between mineral SOC and litter decomposition, therefore pushing the scientific community to look at other inputs of stabilized SOC in the mineral layer, such as root inputs.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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