caa a22 4500 605516561 CHVBK 20210128100714.0 cr unu---uuuuu 210128e20150501xx s 000 0 eng 10.1007/s10533-015-0107-2 doi (NATIONALLICENCE)springer-10.1007/s10533-015-0107-2 Distinct fungal and bacterial δ13C signatures as potential drivers of increasing δ13C of soil organic matter with depth [Elektronische Daten] [Lukas Kohl, Jérôme Laganière, Kate Edwards, Sharon Billings, Penny Morrill, Geert Van Biesen, Susan Ziegler] Soil microbial biomass is a key source of soil organic carbon (SOC), and the increasing proportion of microbially derived SOC is thought to drive the enrichment of 13C during SOC decomposition. Yet, little is known about how the δ13C of soil microbial biomass differs across space or time, or with the composition of the microbial community. Variation in soil microbial δ13C may occur due to variation in substrates used by soil microorganisms, and variation in how different microorganisms synthesize biomass. Understanding these variations in soil microbial δ13C would enable more accurate interpretation of patterns in the δ13C of SOC. Here, we report the variation in δ13C values of individual phospholipid fatty acids (PLFA) within podzolic soils from mesic boreal forests characterized by steep decreases in fungal to bacterial (F:B) ratios. By comparing trends in δ13C of PLFA indicative of either fungi or bacteria to those PLFA common across both microbial groups, we tested the hypothesis that the enrichment of 13C in bacterial relative to fungal biomass represents a mechanism for the increase of bulk SOC δ13C with depth. We demonstrate that PLFA derived from fungi were consistently depleted in 13C (−40.1 to −30.6‰) relative to those derived from bacteria (−31.1 to −24.6 ‰), but unlike bulk SOC the δ13C of PLFA from either group did not vary significantly with depth. In contrast, the δ13C of PLFA produced by both fungi and bacteria, which represent the δ13C of soil microbial biomass as a whole, strongly increased with depth (increase of 7.6-8.4‰) and was negatively correlated with the fungi/(fungi+bacteria) ratio (R2>0.88). The steep increase of the δ13C of general PLFA with depth cannot be explained by an increase in the δ13C of either fungal or bacterial biomass alone since the PLFA indicative of those groups did not vary with depth. Instead, these data demonstrate that the increase in soil biomass δ13C with depth is driven by a change in the proportion of bacterial relative to fungal biomass. We suggest that the increased proportions of soil bacterial relative to fungal biomass with depth may represent an important mechanism contributing to increasing δ13CSOC with depth via contributions from ‘necromass' to SOC. Springer International Publishing Switzerland, 2015 13C nationallicence Necromass nationallicence Podzols nationallicence Soil organic carbon nationallicence PLFA nationallicence Soil microbial biomass nationallicence Kohl Lukas Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut Laganière Jérôme Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut Edwards Kate Natural Resources Canada, Canadian Forest Service, Atlantic Forestry Centre, 26 University Drive, A2H 6J3, Corner Brook, NL, Canada aut Billings Sharon Department of Ecology and Evolutionary Biology, Kansas Biological Survey, University of Kansas, 2101 Constant Ave., 66047, Lawrence, KS, USA aut Morrill Penny Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut Van Biesen Geert Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut Ziegler Susan Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut Biogeochemistry Springer International Publishing 124/1-3(2015-05-01), 13-26 0168-2563 124:1-3<13 2015 124 10533 https://doi.org/10.1007/s10533-015-0107-2 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 review-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-015-0107-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kohl Lukas Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut NATIONALLICENCE 700 1- Laganière Jérôme Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut NATIONALLICENCE 700 1- Edwards Kate Natural Resources Canada, Canadian Forest Service, Atlantic Forestry Centre, 26 University Drive, A2H 6J3, Corner Brook, NL, Canada aut NATIONALLICENCE 700 1- Billings Sharon Department of Ecology and Evolutionary Biology, Kansas Biological Survey, University of Kansas, 2101 Constant Ave., 66047, Lawrence, KS, USA aut NATIONALLICENCE 700 1- Morrill Penny Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut NATIONALLICENCE 700 1- Van Biesen Geert Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut NATIONALLICENCE 700 1- Ziegler Susan Department of Earth Sciences, Memorial University, 300 Prince Philip Dr., A1B 3X5, St. John's, NL, Canada aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 124/1-3(2015-05-01), 13-26 0168-2563 124:1-3<13 2015 124 10533