Honors Theses
Date of Award
Spring 5-7-2026
Document Type
Undergraduate Thesis
Department
Biology
First Advisor
Jason Hoeksema
Second Advisor
Stephen Brewer
Third Advisor
John Rimoldi
Relational Format
Dissertation/Thesis
Abstract
Invasive Pinus radiata has increasingly spread into native ecosystems in the Southern Hemisphere, including Eucalyptus forests in Australia, where it forms novel hybrid forest systems in which invasive and native tree species coexist. The success of these invasions is closely tied to ectomycorrhizal fungi (EMF) such as Rhizopogon spp., yet the relative roles of pines versus their fungal symbionts in altering soil properties remain poorly understood. This study investigated the independent and interactive effects of soil history (Pinus or Eucalyptus), EMF identity, and pine presence on soil properties using a controlled factorial experiment. Soil from beneath either Pinus or Eucalyptus trees was subjected to three fungal treatments (spore bank, Rhizopogon inoculation, or sterile conditions) and either planted with pine seedlings or left unplanted. EMF identity was a primary driver of variation in soil properties, significantly influencing organic matter (OM), soil texture, moisture, pH, cation exchange capacity (CEC), and several nutrient variables. In contrast, pine presence alone had comparatively limited direct effects on most soil properties. Notably, soils associated with Rhizopogon inoculation generally exhibited lower moisture, OM, and CEC relative to spore bank and sterile treatments, whereas spore bank soils tended to maintain higher moisture and nutrient levels. EMF taxa were also detected on pine roots in some sterile treatments, suggesting incomplete sterilization or minor contamination, which may have contributed to observed soil responses. These findings support the idea that EMF can act as active agents of soil modification rather than passive symbionts, although the direction of these effects does not consistently indicate improved soil conditions for pine establishment. Overall, this study highlights the central role of EMF in shaping soil environments during invasion and provides new insight into the mechanisms underlying pine–EMF co-invasion dynamics in native ecosystems.
Recommended Citation
Watters, Braedan, "Ectomycorrhizal Fungal Identity Strongly Influences Soil Properties Relative to Pine Presence and Soil History in a Pine–Eucalyptus System" (2026). Honors Theses. 3535.
https://egrove.olemiss.edu/hon_thesis/3535
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