title: Bacterial, fungal, and plant communities exhibit no biomass or compositional response to two years of simulated nitrogen deposition in a semiarid grassland.
abstract: Nitrogen (N) deposition affects myriad aspects of terrestrial ecosystem structure and function, and microbial communities may be particularly sensitive to anthropogenic N inputs. However, our understanding of N deposition effects on microbial communities is far from complete, especially for drylands where data are comparatively rare. To address the need for an improved understanding of dryland biological responses to N deposition, we conducted a two-year fertilization experiment in a semiarid grassland on the Colorado Plateau in the southwestern United States. We evaluated effects of varied levels of N inputs on archaeal, bacterial, fungal and chlorophyte community composition within three microhabitats: biological soil crusts (biocrusts), soil below biocrusts, and the plant rhizosphere. Surprisingly, N addition did not affect the community composition or diversity of any of these microbial groups; however, microbial community composition varied significantly among sampling microhabitats. Further, while plant richness, diversity, and cover showed no response to N addition, there were strong linkages between plant properties and microbial community structure. Overall, these findings highlight the potential for some dryland communities to have limited biotic ability to retain augmented N inputs, possibly leading to large N losses to the atmosphere and to aquatic systems.
authors.affiliation: U.S. Geological Survey, Southwest Biological Science Center, Moab, UT, USA.|Department of Biological Sciences, Colorado Mesa University, Grand Junction, CO, USA.
authors.forename: Theresa A
authors.initials: TA
authors.lastname: McHugh
authors.affiliation: Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV, USA.
authors.forename: Ember M
authors.initials: EM
authors.lastname: Morrissey
authors.affiliation: Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Mueller
authors.affiliation: Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
authors.forename: La Verne
authors.initials: V
authors.lastname: Gallegos-Graves
authors.affiliation: Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
authors.forename: Cheryl R
authors.initials: CR
authors.lastname: Kuske
authors.affiliation: U.S. Geological Survey, Southwest Biological Science Center, Moab, UT, USA.
authors.forename: Sasha C
authors.initials: SC
authors.lastname: Reed
mesh_terms: D001105:Archaea; D018533:Biomass; D003120:Colorado; D017753:Ecosystem; D005658:Fungi / Q000378:metabolism; D065948:Grassland; D009584:Nitrogen / Q000378:metabolism*; D010944:Plants / Q000378:metabolism; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D012987:Soil; D009584:Nitrogen