Abstract

The interaction networks formed by ectomycorrhizal fungi (EMF) and their tree hosts, which are important to both forest recruitment and ecosystem carbon and nutrient retention, may be particularly susceptible to climate change at the boreal-temperate forest ecotone where environmental conditions are changing rapidly. Here, we quantified the compositional and functional trait responses of EMF communities and their interaction networks with two boreal (Pinus banksiana and Betula papyrifera) and two temperate (Pinus strobus and Quercus macrocarpa) hosts to a factorial combination of experimentally elevated temperatures and reduced rainfall in a long-term open-air field experiment. The study was conducted at the B4WarmED (Boreal Forest Warming at an Ecotone in Danger) experiment in Minnesota, USA, where infrared lamps and buried heating cables elevate temperatures (ambient, +3.1 degrees C) and rain-out shelters reduce growing season precipitation (ambient, similar to 30% reduction). EMF communities were characterized and interaction networks inferred from metabarcoding of fungal-colonized root tips. Warming and rainfall reduction significantly altered EMF community composition, leading to an increase in the relative abundance of EMF with contact-short distance exploration types. These compositional changes, which likely limited the capacity for mycelial connections between trees, corresponded with shifts from highly redundant EMF interaction networks under ambient conditions to less redundant (more specialized) networks. Further, the observed changes in EMF communities and interaction networks were correlated with changes in soil moisture and host photosynthesis. Collectively, these results indicate that the projected changes in climate will likely lead to significant shifts in the traits, structure, and integrity of EMF communities as well as their interaction networks in forest ecosystems at the boreal-temperate ecotone.

Keywords

fungi; climate change; ectomycorrhiza; mycorrhizal interaction network; photosynthesis

Published in

Proceedings of the National Academy of Sciences of the United States of America
2023, Volume: 120, number: 34, article number: e2221619120
Publisher: NATL ACAD SCIENCES

SLU Authors

• Mielke, Louis

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    
  • University of Minnesota

Associated SLU-program

SLU Plant Protection Network
SLU Forest Damage Center


UKÄ Subject classification

Climate Research
Microbiology
Ecology


Publication identifier

DOI: https://doi.org/10.1073/pnas.2221619120

Permanent link to this page (URI)

https://res.slu.se/id/publ/126905