Long-term N-addition alters the community structure of functionally important N-cycling soil microorganisms across global grasslands

Author(s)
Beat Frey, Barbara Moser, Bjorn Tytgat, Stephan Zimmermann, Juan Alberti, Lori A. Biederman, Elizabeth T. Borer, Arthur A.D. Broadbent, Maria C. Caldeira, Kendi F. Davies, Nico Eisenhauer, Anu Eskelinen, Philip A. Fay, Frank Hagedorn, Yann Hautier, Andrew S. MacDougall, Rebecca L. McCulley, Joslin L. Moore, Maximilian Nepel, Sally A. Power, Eric W. Seabloom, Eduardo Vázquez, Risto Virtanen, Laura Yahdjian, Anita C. Risch
Abstract

Anthropogenic nitrogen (N) input is known to alter the soil microbiome, but how N enrichment influences the abundance, alpha-diversity and community structure of N-cycling functional microbial communities in grasslands remains poorly understood. Here, we collected soils from plant communities subjected to up to 9 years of annual N-addition (10 g N m−2 per year using urea as a N-source) and from unfertilized plots (control) in 30 grasslands worldwide spanning a large range of climatic and soil conditions. We focused on three key microbial groups responsible for two essential processes of the global N cycle: N2 fixation (soil diazotrophs) and nitrification (AOA: ammonia-oxidizing archaea and AOB: ammonia-oxidizing bacteria). We targeted soil diazotrophs, AOA and AOB using Illumina MiSeq sequencing and measured the abundance (gene copy numbers) using quantitative PCR. N-addition shifted the structure of the diazotrophic communities, although their alpha-diversity and abundance were not affected. AOA and AOB responded differently to N-addition. The abundance and alpha-diversity of AOB increased, and their community structure shifted with N-addition. In contrast, AOA were not affected by N-addition. AOA abundance outnumbered AOB in control plots under conditions of low N availability, whereas N-addition favoured copiotrophic AOB. Overall, N-addition showed a low impact on soil diazotrophs and AOA while effects for AOB communities were considerable. These results reveal that long-term N-addition has important ecological implications for key microbial groups involved in two critical soil N-cycling processes. Increased AOB abundance and community shifts following N-addition may change soil N-cycling, as larger population sizes may promote higher rates of ammonia oxidation and subsequently increase N loss via gaseous and soil N-leaching. These findings bring us a step closer to predicting the responses and feedbacks of microbial-mediated N-cycling processes to long-term anthropogenic N-addition in grasslands.

Organisation(s)
Department of Botany and Biodiversity Research
External organisation(s)
Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft, Ghent University , Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Iowa State University, University of Minnesota, Mineapolis, University of Manchester, Universidade de Lisboa, University of Colorado, Boulder, German Centre for Integrative Biodiversity Research (iDiv), Universität Leipzig, Helmholtz-Zentrum für Umweltforschung, University of Oulu, United States Department of Agriculture USDA, Utrecht University, University of Guelph, University of Kentucky, Monash University, Western Sydney University, Universität Bayreuth, Universidad de Buenos Aires
Journal
Soil Biology and Biochemistry
Volume
176
No. of pages
11
ISSN
0038-0717
DOI
https://doi.org/10.1016/j.soilbio.2022.108887
Publication date
01-2023
Peer reviewed
Yes
Austrian Fields of Science 2012
106008 Botany, 106012 Evolutionary research, 106042 Systematic botany
Keywords
ASJC Scopus subject areas
Soil Science, Microbiology
Portal url
https://ucris.univie.ac.at/portal/en/publications/longterm-naddition-alters-the-community-structure-of-functionally-important-ncycling-soil-microorganisms-across-global-grasslands(64005051-ae1d-4f62-a15e-3e5faee4347b).html