Climate warming causes photobiont degradation and carbon starvation in a boreal climate sentinel lichen

Abigail R. Meyer, Maria Valentin, Laima Liulevicius, Tami R. McDonald, Matthew P. Nelsen, Jean Pengra, Robert J. Smith, Daniel Stanton

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Premise: The long-term potential for acclimation by lichens to changing climates is poorly known, despite their prominent roles in forested ecosystems. Although often considered “extremophiles,” lichens may not readily acclimate to novel climates well beyond historical norms. In a previous study (Smith et al., 2018), Evernia mesomorpha transplants in a whole-ecosystem climate change experiment showed drastic mass loss after 1 yr of warming and drying; however, the causes of this mass loss were not addressed. Methods: We examined the causes of this warming-induced mass loss by measuring physiological, functional, and reproductive attributes of lichen transplants. Results: Severe loss of mass and physiological function occurred above +2°C of experimental warming. Loss of algal symbionts (“bleaching”) and turnover in algal community compositions increased with temperature and were the clearest impacts of experimental warming. Enhanced CO2 had no significant physiological or symbiont composition effects. The functional loss of algal photobionts led to significant loss of mass and specific thallus mass (STM), which in turn reduced water-holding capacity (WHC). Although algal genotypes remained detectable in thalli exposed to higher stress, within-thallus photobiont communities shifted in composition toward greater diversity. Conclusions: The strong negative impacts of warming and/or lower humidity on Evernia mesomorpha were driven by a loss of photobiont activity. Analogous to the effects of climate change on corals, the balance of symbiont carbon metabolism in lichens is central to their resilience to changing conditions.

Original languageEnglish (US)
Article numbere16114
JournalAmerican journal of botany
Volume110
Issue number2
DOIs
StatePublished - Feb 2023

Bibliographical note

Funding Information:
The authors thank the U.S. Department of Energy (DOE) SPRUCE site's personnel, notably R. Kolka, S. Sebestyen, D. Kyllander, R. Nettles, J. Burdick, and others for logistical support of fieldwork. B. McCune provided helpful feedback on early stages of experimental design and again on early drafts of the manuscript. Earlier rounds of field sampling were made possible by contributions from B. McCune, P. Muir, K. Spickerman, P. Nelson, and E. DiMeglio. P. Kennedy provided valuable insights and support for the extractions and sequencing of photobionts. M.V. was supported by an Undergraduate Research Award from the University of Minnesota College of Biological Sciences. A.R.M. and J.P. were supported by startup funds from the University of Minnesota to D.S. R.J.S. was supported in part by an appointment to the Research Participation Program at the USDA Forest Service administered by the DOE's Oak Ridge Institute for Science and Education. Evernia

Publisher Copyright:
© 2022 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.

Keywords

  • Evernia mesomorpha
  • Trebouxia
  • boreal forest
  • climate change
  • lichen physiology

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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