OOS 2-6 - Mycorrhizal community dynamics and drivers after glacier retreat across the globe

Monday, August 15, 2022

2:45 PM – 3:00 PM EDT

Location: 520D

Presenting Author(s)

AC

Alexis Carteron

Università degli Studi di Milano, Italy

Co-author(s)

AC

Alexis Carteron

Università degli Studi di Milano, Italy
AG

Alessia Guerrieri

University of Milan
milano, Italy
IC

Isabel Cantera

Università degli Studi di Milano, Department of Environmental Science and Policy, Italy
SM

Silvio Marta

Università degli Studi di Milano, Department of Environmental Science and Policy, Italy
AB

Aurélie Bonin

Argaly, Bâtiment CleanSpace, France; Università degli Studi di Milano, Department of Environmental Science and Policy, Italy
SG

Simone Giachello

Università degli Studi di Milano, Department of Environmental Science and Policy, Italy
RA

Roberto Ambrosini

Università degli Studi di Milano, Department of Environmental Science and Policy, Italy
MC

Marco Caccianiga

Università degli Studi di Milano, Department of Environmental Science and Policy, Italy
PT

Pierre Taberlet

Universite Grenoble Alpes, CNRS, Laboratoire d'Ecologie Alpine (LECA), France; UiT The Arctic University of Norway, Norway
GD

Guglielmina Adele Diolaiuti

Università degli Studi di Milano, Department of Environmental Science and Policy, Italy
JP

Jérôme Poulenard

Université Savoie Mont-Blanc, Environment Dynamics and Territories of Mountains (EDYTEM), France
DF

Diego Fontaneto

CNR - Water Research Institute, Italy
WT

Wilfried Thuiller

Senior Research Scientist
Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, LECA
38400 Saint-Martin-d'Hères, France
GF

Gentile Francesco Ficetola

Università degli Studi di Milano, Department of Environmental Science and Policy, Italy

Background/Question/Methods
Mountain and high-latitude glaciers have been retreating around the world since the Little Ice Age. However, the rate has increased dramatically in recent decades and is predicted to accelerate further. Large areas of newly deglaciated substrates are exposed to biotic colonization and soil development, but changes in habitat and climatic conditions could influence the formation of these young ecosystems. Thus, there is an urgent need to predict the evolution of these deglaciated areas, which requires fine-scale analyses of current patterns and common factors that call for global studies in glacier forelands around the world. Ecosystem development in these nutrient-poor and harsh environments is limited, with primary production heavily dependent on symbiotic associations such as mycorrhiza.

To evaluate the effects of time and local microhabitats on mycorrhizal fungal community, we conducted a comprehensive inventory of 1862 plots in 266 forelands of 48 mountain and high-latitude glaciers around the globe, with sites spanning from 1 to 520 years since the retreat of ice sheets. For each plot, we assessed the richness and composition of fungal communities using metabarcoding of soil environmental DNA. For a subset of 32 glaciers, the microhabitat conditions were determined by measuring soil chemistry, temperature and humidity.

Results/Conclusions
We showed that the overall fungal richness increases rapidly after glacier retreat, although a delay is observed for mycorrhizal fungi. Ectomycorrhizal fungi were virtually absent in the early stages of soil development but increase rapidly after ~ 50 years. Arbuscular mycorrhizal fungi were present soon after glacier retreat and appeared to reach their greatest richness after 200 years. Even after accounting for microhabitat variation, time since glacier retreat remained the strongest predictor of mycorrhizal diversity, but the rate of colonization differed strongly by glacier location. Furthermore, local temperature also had an impact, with ectomycorrhizal fungi achieving greater diversity in cold environments and the opposite for arbuscular mycorrhizal fungi. Community composition was also largely influenced by time since glacier retreat and soil pH for arbuscular mycorrhizal fungi, while moisture was the strongest parameter influencing community composition for ectomycorrhizal fungi.

Although mycorrhizal fungi rapidly colonize areas after glacier retreat, their expansion is strongly influenced by microhabitat parameters that locally interact. Therefore, changes in climatic conditions could disrupt biotic colonization, potentially by causing a mismatch between symbiotic partners. This could slow ecosystem development, but further analyses using multi-trophic surveys is needed to predict ecosystem-level impacts.