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Does exogenous carbon extend the realized niche of canopy lichens? Evidence from sub-boreal forests in British Columbia

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Author

  • Jocelyn Campbell
  • Per Bengtson
  • Arthur L. Fredeen
  • Darwyn S. Coxson
  • Cindy E. Prescott

Summary, in English

Foliose lichens with cyanobacterial bionts (bipartite and tripartite) form a distinct assemblage of epiphytes strongly associated with humid microclimatic conditions in inland British Columbia. Previous research showed that these cyano- and cephalolichen communities are disproportionately abundant and species-rich on conifer saplings beneath Populus compared to beneath other tree species. More revealing, lichens with cyanobacterial bionts were observed beneath Populus even in stands that did not otherwise support them. We experimentally test the hypothesis that this association is due to the interception of glucose-rich nectar that is exuded from Populus extra-floral nectaries (EFN). Using CO2 flux measurements and phospholipid fatty acid (PLFA) analysis with experimental applications of C-13(6)-labeled glucose, we demonstrate that cyano-and cephalolichens have a strong respiratory response to glucose. Lichens treated with glucose had lower net photosynthesis and higher establishment rates than control thalli. Furthermore, lichens with cyanobacterial bionts rapidly incorporate exogenous C-13 into lichen fatty acid tissues. A large proportion of the C-13 taken up by the lichens was incorporated into fungal biomarkers, suggesting that the mycobiont absorbed and assimilated the majority of applied C-13(6) glucose. Our observations suggest that both cyanolichens and cephalolichens may utilize an exogenous source of glucose, made available by poplar EFNs. The exogenous C may enable these lichens to become established by providing a source of C for fungal respiration despite drought-induced inactivity of the cyanobacterial partner. As such, the mycobiont may adopt an alternative nutritional strategy, using available exogenous carbon to extend its realized niche.

Publishing year

2013

Language

English

Pages

1186-1195

Publication/Series

Ecology

Volume

94

Issue

5

Document type

Journal article

Publisher

Ecological Society of America

Topic

  • Biological Sciences

Keywords

  • C-13-glucose
  • cyanolichen
  • fatty acid
  • niche
  • Populus overstory
  • symbiosis

Status

Published

Research group

  • Microbial Ecology

ISBN/ISSN/Other

  • ISSN: 0012-9658