LB 19-200 - Mycorrhizal-mediated silviculture: The benefits of mycelial networks for forest regeneration

Thursday, August 18, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

EL

Eva O. Legge

Dartmouth College, United States

Coauthor(s)

AF

Amelia Fitch, MS

PhD candidate
Dartmouth College
Hanover, New Hampshire, United States
SG

Sarah Goldsmith

Dartmouth College, United States
CH

Caitlin Hicks Pries

Assistant Professor
Dartmouth College
Hanover, New Hampshire, United States

Background/Question/Methods:

This project aims to answer two questions driving New England silviculture: How do different types of mycorrhizal networks affect seedling survivorship? And how does the proximity of planted seedlings to “donor” trees affect the amount of nitrogen that a seedling receives from the mycorrhizal network? In 2021, we planted four species of arbuscular (AM)- and four species of ectomycorrhizal(EcM)-associating seedlings in eight quarter-acre clear-cut plots in Corinth, Vermont that were dominated by either AM or EcM trees prior to logging. We assessed seedling growth and survival at the end of the growing season and collected leaf samples to measure plant nitrogen and water status. The leaf samples were ground for 15N and 13C analysis, which can be used as proxies for how much nitrogen the seedling receives from mycorrhizal fungi and seedling water use efficiency. These data will help foresters better understand how forest mycorrhizal networks affect seedling regeneration success.

Results/Conclusions:

Data from the summer of 2021 reveal that AM seedlings planted in AM-dominated clear cuts had a much greater survival rate than AM seedlings planted in EcM plots. These data suggest that arbuscular mycorrhizal networks may play a major role in the recruitment success and vigor of AM-associated seedlings. To tease apart these findings, we will also present the results of in-process research on how nutrient acquisition and water use in AM and EcM trees may vary at the edge of versus the center of a clear cut plot. Finally, we will present a conceptual model and preliminary results of our summer 2022 experiment, in which we are planting clusters AM-affiliated seedlings (Sugar maple, Black Gum, and Black Cherry) in clear cut plots versus smaller canopy gaps allowing either access to mycorrhizal networks or no access to investigate the effects of common mycorrhizal networks on the survival and vigor of AM seedlings. These data will show whether the proximity to potential “donor trees” has a significant effect on AM seedlings survivorship, which will inform future forest management techniques across New England.