DOI: 10.5061/dryad.98rr457
title: Data from: Nitrogen addition pulse has minimal effect in big sagebrush (Artemisia tridentata) communities on the Pinedale Anticline, Wyoming (USA)

description: Nitrogen additions are known to elicit variable responses in semi-arid
 ecosystems, with responses increasing with precipitation. The response of
 semi-arid ecosystems to nitrogen are important to understand due to their
 large spatial extent worldwide and the global trend of increasingly
 available nitrogen. In this study, we evaluated the impact of a single
 nitrogen addition pulse on a semi-arid big sagebrush (Artemisia
 tridentata) ecosystem in western Wyoming. This is important given that
 sagebrush ecosystems are poorly understood, despite their prevalence in
 the western US. In addition, large-scale nitrogen additions have begun on
 sagebrush landscapes in Wyoming in order to mitigate population declines
 in mule deer (Odocoileus hemionus). The study objectives were (1) to
 evaluate the effectiveness of a nitrogen fertilization pulse in increasing
 sagebrush biomass and forage quality, and (2) to assess effects of
 nitrogen addition on soil biogeochemistry and vegetation community
 structure. We fertilized 15 plots across 5 locations in western Wyoming
 using a single pulse of urea (5.47g N m-2). In addition, we immobilized
 available nitrogen through surface hay treatments (254g hay/m2). Nitrogen
 additions failed to increase growth of sagebrush, alter nitrogen content
 of sagebrush leaders, or alter greenhouse gas efflux from soils. The plant
 community also remained unchanged; total cover, species richness, and
 community composition were all unaffected by our treatment application.
 Over the two years of this study, we did not find indications of nitrogen
 limitation of ecosystem processes, despite a wet growing season in 2014.
 Thus, we have found a general lack of response to nitrogen in sagebrush
 ecosystems and no treatment effect of a single pulse of N to sagebrush
 biomass or forage quality.
description: Carbon and nitrogen
 content of sagebrush leadersDried sagebrush leaders
 were ground and submitted to the University of Wyoming Stable Isotope
 Facility in December 2014. See metadata file for variable
 descriptions.Beltz_2018_Sagebrush.N.Fertilization_CandN.Leaders_CLEAN.csvCarbon and nitrogen content of hay additionThree batches of hay were applied to the hay treatments in 2012. Two samples from each batch were analyzed for carbon and nitrogen content at the Stable Isotope Facility at the University of Wyoming in 2016. See metadata file for variable descriptions.Beltz_2018_Sagebrush.N.Fertilization_CandN.Hay_CLEAN.csvSagebrush inflorescence lengthThe length of sagebrush inflorescences was collected in fall 2014. See metadata file for variable descriptions.Beltz_2018_Sagebrush.N.Fertilization_Inflor.Length_CLEAN.csvSagebrush leader lengthAnnual growth, in the form of sagebrush leaders, was clipped in fall 2014.Beltz_2018_Sagebrush.N.Fertilization_Leader.Length_CLEAN.csvSagebrush plant communityPlant community data and species identification occurred in late summer 2014. See metadata file for variable descriptions.Beltz_2018_Sagebrush.N.Fertilization_Plant.Community_CLEAN.csvSoil nitrogen availabilityFor the 2012-2013 and 2014-2015 soil nitrogen data, plant root simulator (PRS) probes were used to evaluate soil nitrogen availability. PRS data was received directly from Western Agriculture.Beltz_2018_Sagebrush.N.Fertilization_Soil.N_CLEAN.csvSoil textureSoil texture was assessed using the a modified hydrometer method. For variable descriptions see metadata file.Beltz_2018_Sagebrush.N.Fertilization_Soil.Texture_CLEAN.csvSoil trace gasTrace gas was measured in 2013 and examined CO2, CH4, and N2O.Beltz_2018_Sagebrush.N.Fertilization_Trace.Gas.13_CLEAN.csvProject Description and MetadataBeltz_Proj.002_2018_Sagebrush.N.Fertilization_METADATA.txtData Analysis in a Knitted PDF (updated)Knitted PDF of the R Markdown file used to conduct data analysis and figure creation. New version finalized on May 6, 2019.Beltz_2018_Sagebrush.N.Fertilization_Data.Analysis_v5.pdfAnalysis Code (updated)R code for all data analysis and figure creation in Rmd format. New version finalized on May 6, 2019.Beltz_2018_Sagebrush.N.Fertilization_Data.Analysis_v5.Rmd