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

  • Jocelyn Campbell
  • Per Bengtson
  • Arthur L. Fredeen
  • Darwyn S. Coxson
  • Cindy E. Prescott
Publishing year: 2013
Language: English
Pages: 1186-1195
Publication/Series: Ecology
Volume: 94
Issue: 5
Document type: Journal article
Publisher: Ecological Society of America

Abstract 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.


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


  • ISSN: 0012-9658
Per Bengtson
E-mail: per [dot] bengtson [at] biol [dot] lu [dot] se



+46 46 222 37 60


Sölvegatan 37, Lund


Research group

Microbial Ecology


Doctoral students and postdocs

PhD students, main supervisor


PhD students, assistant supervisor

Jian Li

Experimental setup