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Project ID:

25-1-01-13

Year:

2025

Date Started:

09/30/2025

Date Completed:

Title:

Functions of Fire-Adapted Fungi: A Microbially-Informed Approach to Tree Regeneration Following Severe Fire

Project Proposal Abstract:

Recent research has indicated that while many soil microbes decline following wildfire, certain “pryophilous” taxa, including some root-associated mutualistic ectomycorrhizal fungi (EMF), are actually resistant to or reliant on fire. Importantly, few studies have investigated the role of these pyrophilous EMF in post-fire seedling reestablishment or the specific traits of these fungi which enable them to survive in harsh post-fire soil environments. Particularly in ecosystems where low regeneration rates threaten ecosystem stability, pyrophilous EMF may improve reforestation efforts. The proposed research explores belowground dynamics of post-fire recovery, an understudied dimension of fire effects, and investigates the impacts of shifting fire regimes and water deficit on relationships between growing seedlings and plant-associated fungi.
This project will investigate roles of pyrophilous EMF in post-fire recovery by assessing: 1) effects of inoculation with a pyrophilous EMF on seedling growth and survival in burned and unburned field soils; 2) interacting effects of burned soils and water-limited conditions on seedling ecophysiology and survival; and 3) whether pyrophilous EMF have traits which enable them to grow in burned soils or under water deficit. We hypothesize pyrophilous EMF will improve host performance and that there will be an interaction between burn status and water-availability where mycorrhization will improve host ecophysiological performance and survival in burned soils and under water-deficit, relative to control conditions. Furthermore, burned soils and limited moisture conditions will induce fungal genes involved in mineralization of pyrolyzed organic matter and water uptake, enabling these fungi to thrive in post-fire environments.

Activities to be Performed: A fully factorial design will be used, where seedlings will be assigned to two burn treatments (burned and unburned), four soil microbial treatments (+/- EMF; +/- resident soil microbiota), and two watering conditions (water-limited and well-watered). Seedlings will be grown for six months prior to assessing plant and fungal status, including: host instantaneous water-use, photosynthetic efficiency, leaf water content, total plant biomass, and percent root colonization. Meta-transcriptomic analysis will be used to determine whether particular EMF genes are associated with enhanced seedling growth in burned soils and under water-limitation.

Expected Deliverables: A forest management report will be developed with USFS and WA-DNR colleagues to translate our results into actionable interventions to increase tree reestablishment following stand-replacing fire. If inoculation with pyrophilous fungi appears as a viable strategy, then suggestions for implementation of this method will be included in the report.

Benefits: Through collaborations with the DNR, DFW, USFS, and the Confederated Tribes of the Colville Reservation, I will disseminate our findings and inoculation methods (ex. public reports and workshops) so that this research may be incorporated into forest management plans across US governmental agencies and native tribes. Low-elevation dry forest covers a large portion of federal lands, including sites at high risk of conversion to non-forested ecosystems following stand-replacing fire. Additionally, Ponderosa pine is an important softwood lumber species (USDA) of particular economic, cultural, and ecological value in the Western US. The development of management tools for the US government is necessary to maintain dry-forest ecosystems and enhance forest regeneration, particularly under water deficit. Inoculation of Ponderosa pine seedlings with pyrophilous EMF is a promising strategy for land managers to implement in order to mitigate the effects of water-limitation on tree regeneration following wildfire and accelerate post-fire forest recovery.

Principal Investigator:

Claire Willing

Agency/Organization:

University of Washington

Branch or Dept:

School of Environmental and Forest Sciences

Other Project Collaborators

Type	Name	Agency/Organization	Branch or Dept
Agreements Contact	Debra Callaway	University of Washington	Office of Sponsored Programs
Budget Contact	Debra Callaway	University of Washington	Office of Sponsored Programs
Budget Contact	Jack B Lockhart	University of Washington	School of Environmental and Forest Sciences
Collaborator/Contributor	Daniel C. Donato	Washington	DNR-Department of Natural Resources
Collaborator/Contributor	Joshua S. Halofsky	Washington	DNR-Department of Natural Resources
Student Investigator	Mira Ranganath	University of Washington	School of Environmental and Forest Sciences