title: Temporal variation overshadows the response of leaf litter microbial communities to simulated global change.
abstract: Bacteria and fungi drive the decomposition of dead plant biomass (litter), an important step in the terrestrial carbon cycle. Here we investigate the sensitivity of litter microbial communities to simulated global change (drought and nitrogen addition) in a California annual grassland. Using 16S and 28S rDNA amplicon pyrosequencing, we quantify the response of the bacterial and fungal communities to the treatments and compare these results to background, temporal (seasonal and interannual) variability of the communities. We found that the drought and nitrogen treatments both had significant effects on microbial community composition, explaining 2-6% of total compositional variation. However, microbial composition was even more strongly influenced by seasonal and annual variation (explaining 14-39%). The response of microbial composition to drought varied by season, while the effect of the nitrogen addition treatment was constant through time. These compositional responses were similar in magnitude to those seen in microbial enzyme activities and the surrounding plant community, but did not correspond to a consistent effect on leaf litter decomposition rate. Overall, these patterns indicate that, in this ecosystem, temporal variability in the composition of leaf litter microorganisms largely surpasses that expected in a short-term global change experiment. Thus, as for plant communities, future microbial communities will likely be determined by the interplay between rapid, local background variability and slower, global changes.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA, USA.
authors.forename: Kristin L
authors.identifier: http://orcid.org/0000-0003-2642-9406
authors.initials: KL
authors.lastname: Matulich
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Weihe
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA, USA.|Department of Earth System Science, University of California-Irvine, Irvine, CA, USA.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Allison
authors.affiliation: Department of Botany, University of Hawaii, Honolulu, HI, USA.
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Amend
authors.affiliation: Department of Earth System Science, University of California-Irvine, Irvine, CA, USA.
authors.forename: Renaud
authors.initials: R
authors.lastname: Berlemont
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA, USA.|Department of Earth System Science, University of California-Irvine, Irvine, CA, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Goulden
authors.affiliation: Center for Environmental Biology, University of California-Irvine, Irvine, CA, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Kimball
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA, USA.|Department of Earth System Science, University of California-Irvine, Irvine, CA, USA.
authors.forename: Adam C
authors.identifier: http://orcid.org/0000-0003-2829-4314
authors.initials: AC
authors.lastname: Martiny
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California-Irvine, Irvine, CA, USA.
authors.forename: Jennifer B H
authors.initials: JB
authors.lastname: Martiny
mesh_terms: D001419:Bacteria / Q000145:classification*; D018533:Biomass; D002140:California; D057486:Carbon Cycle; D002980:Climate; D055864:Droughts; D017753:Ecosystem; D005658:Fungi / Q000145:classification*; D009584:Nitrogen / Q000737:chemistry; D018515:Plant Leaves / Q000382:microbiology*; D010944:Plants; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D012621:Seasons; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D012339:RNA, Ribosomal, 28S; D009584:Nitrogen