PARENT SESSION
Organized Oral Session 26: From microbes to ecosystems: How do we really make the connections?
Organizer(s): J Schimel and S Frey
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 510a, Level 5, Palais des congrès de Montréal
Linking fungal identify to function: Approaches using radioisotope signatures of mushrooms and nucleotide analog labeling of DNA.
Treseder, Kathleen *,1, Lansing, Jennifer2, Turner, Katie1, Choi, Nathan1, 1 University of California Irvine, Irvine, CA, USA2 University of Pennsylvania, Philadelphia, PA, USA
ABSTRACT- Several fundamental questions remain regarding the role of fungal communities in ecosystem dynamics. For instance, do fungal groups differ in terms of biogeochemical function? And how does global change alter fungal diversity and activity? We addressed these questions by linking fungal identity to function in decomposition along a fire chronosequence in Alaska. Our approach integrated molecular and radioisotope analyses. Specifically, we collected mushrooms and used RFLP analyses to sort mushrooms by species. Radiocarbon isotope signatures reflected the average age of organic matter used by each fungal species. We found that species of saprotrophic fungi target different types of organic matter, ranging from recalcitrant to labile forms. In particular, the average age of carbon used by individual species ranged from over 50 years old to 1 year old or less. Recalcitrant users became progressively less common during 80 years of recovery from forest fire. In addition, we found that nucleotide analog labeling of DNA can be a useful tool to delineate ecological niches of fungal groups. We used nucleotide analogs to isolate and identify DNA from active fungal groups in aspen litter from a 17-year old site and an 80-year old site after decomposition in a common site. Litter from the younger site had better litter quality than did that of the older site, and it harbored 426 ±16 fungal groups. In comparison, litter from the older site contained 495 ±40 fungal groups (P = 0.07). Altogether, our results suggest that global change may alter the composition of fungal communities in Alaskan boreal ecosystems, with potential consequences for ecosystem dynamics.
Key words: forest fire, radiocarbon, BrdU, diversity