Date of Award
2025
Document Type
Open Access Dissertation
Degree Name
Doctor of Philosophy in Forest Science (PhD)
Administrative Home Department
College of Forest Resources and Environmental Science
Advisor 1
Molly A. Cavaleri
Advisor 2
Andrew J. Burton
Committee Member 1
Carsten Külheim
Committee Member 2
Trista J. Vick-Majors
Abstract
Forests are increasingly considered for their carbon sequestration value, but their ability to store carbon is dependent on a close balance between carbon fluxes into and out of ecosystems. Nutrient uptake of roots and associated symbiotic communities results in respiratory carbon release, which is projected to increase with warming and represents a substantial uncertainty in earth system modeling. Traits that are functionally related to nutrient uptake can be used to estimate carbon fluxes, but our understanding of the trade-offs that govern root, and especially fungal, traits is limited. Fine roots in surface soils are responsible for the bulk of plant nutrient uptake and therefore C release, and are thought to vary along two trade-off dimensions that describe their nutrient uptake and soil foraging capacities. Multiple hypotheses have been proposed to explain the second dimension, including differences in ectomycorrhizal collaboration. In this dissertation, I investigated fine root and ectomycorrhizal trait coordination across Quercus rubra populations, as well as relationships between these traits and environmental factors across a Midwest, U.S. latitudinal gradient. In addition, I measured these traits in an established common garden experiment to assess their potential for adaptive plasticity and relationships to aboveground growth. Intraspecific root traits were governed by similar trade-offs as those across species, and the second dimension was related to ectomycorrhizal traits. Fine root carbon fluxes did relate to root traits, but the total root respiratory flux was heavily dependent on fine root biomass variation. In a replicated common garden experiment, root activity-related traits, but not root respiration, showed strong potential for adaptive plasticity. Root foraging traits related to aboveground growth and showed moderate evidence of plasticity, while ectomycorrhizal community traits appeared to adjust to common garden site. Though there were some potential growth rate reductions mediated by fine root and fungal traits between populations and common garden sites, the generalist ectomycorrhizal community and relatively strong potential for adaptive plasticity suggests that nutrient uptake of Q. rubra populations may be resilient to a moderate degree of environmental change, though reductions in fine root biomass would likely be needed to offset carbon loss from increased root respiration rates.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Shedd, Emma L., "FINE ROOT AND ECTOMYCORRHIZAL FUNCTIONAL TRAITS OF QUERCUS RUBRA POPULATIONS FROM ACROSS A LATITUDINAL GRADIENT", Open Access Dissertation, Michigan Technological University, 2025.