This readme.txt file was generated on 2023-11-06 by Talia Michaud Recommended citation for the data: Michaud, Talia J. (2023). Historical plant and fungal nitrogen isotopes and concentrations from Minnesota, USA, 1871–2016. Retrieved from the Data Repository for the University of Minnesota. https://doi.org/10.13020/DRXN-9M88. ------------------- GENERAL INFORMATION ------------------- 1. Title of Dataset: Historical plant and fungal nitrogen isotopes and concentrations from Minnesota, USA, 1871–2016 2. Author Information Author Contact: Talia J Michaud (micha938@umn.edu) Name: Talia J Michaud Institution: Email: micha938@umn.edu ORCID: 3. Date published or finalized for release: 2023-11-06 4. Date of data collection (single date, range, approximate date): 1871 to 2016 5. Geographic location of data collection (where was data collected?): Minnesota, USA 6. Information about funding sources that supported the collection of the data: This work was supported by an NSF RUBC Postdoctoral Fellowship (DEB 1611856) to L. Cline and an NSF grant (DEB 2019518) to P. Kennedy. 7. Overview of the data (abstract): Historical declines in plant tissue nitrogen concentrations and d15N have been interpreted as evidence of declining terrestrial ecosystem nitrogen status. To test whether plant mycorrhizal type influences trajectories of plant nitrogen status, and whether fungi also exhibit declining nitrogen status, we analyzed herbarium collections made in MN, USA, from 1871–2016. -------------------------- SHARING/ACCESS INFORMATION -------------------------- 1. Licenses/restrictions placed on the data: Attribution-NonCommercial 3.0 United States (http://creativecommons.org/licenses/by-nc/3.0/us/) 2. Links to publications that cite or use the data: Michaud, T., Cline, L., Hobbie, E., Gutknecht, J., Kennedy, P. Herbarium specimens reveal that mycorrhizal type does not mediate declining temperate tree nitrogen status over a century of environmental change. New Phytologist. In press 2023. 3. Was data derived from another source? If yes, list source(s): 4. Terms of Use: Data Repository for the U of Minnesota (DRUM) By using these files, users agree to the Terms of Use. https://conservancy.umn.edu/pages/drum/policies/#terms-of-use --------------------- DATA & FILE OVERVIEW --------------------- File List 1. a. MinnesotaAnalysisData.csv b. Description: This file includes the chemical data derived from herbarium specimens, as well as metadata describing the specimens and their collection. -------------------------- METHODOLOGICAL INFORMATION -------------------------- 1. Description of methods used for collection/generation of data: Elemental and isotopic analysis was performed on homogenized tissue samples taken from herbarium specimens from the Bell Museum of Natural History Herbarium to generate tissue nitrogen concentrations and d15N (ratio of 15N to 14N compared to atmospheric standard, expressed in per mille). 2. Methods for processing the data: Tissue d15N and [N] were combined with information about herbarium samples (what kind of organism: fungus, plant, mycorrhizal type; county and year the specimen was collected, etc) in order to run models analyzing temporal trends in tissue [N] and d15N between groups of organisms. 3. Instrument- or software-specific information needed to interpret the data: any statistical software that can read .csv files. 4. Standards and calibration information, if appropriate: Isotopic standards included peach leaves, acetanilide elemental standard, and the USGS40 glutamic acid isotopic standard for d15N. 5. Environmental/experimental conditions: 145 years of historical environmental change in MN. 6. Describe any quality-assurance procedures performed on the data: Isotopic analyses of samples for this dataset were measured at one of two facilities: The University of Minnesota facility in the Gutknecht laboratory using an Elementar Vario Pyrocube (Hanau, Germany) interfaced to an Isoprime 100 isotope ratio mass spectrometer (Cheadle, UK), or at the University of California-Davis (UC-Davis) Stable Isotope facility, using an Elementar Vario EL Cube interfaced to a PDZ Europa 20-20 isotope ratio mass spectrometer (Sercon Ltd., Cheshire, UK). To eliminate concern over consistency of data between these two facilities, twelve herbarium specimens were analyzed at both facilities. To correct for the difference in slopes in N concentrations, N concentration values generated from the University of Minnesota facility in the Gutknecht laboratory were divided by the slope coefficient (1.17). These corrected values were used in further analyses. 7. People involved with sample collection, processing, analysis and/or submission: Sample collection and processing: Lauren Cline, Alex Tang, Erin Andrews. Sample processing: Lauren Cline. Data analysis: Lauren Cline and Talia Michaud. ----------------------------------------- DATA-SPECIFIC INFORMATION FOR: MinnesotaAnalysisData.csv ----------------------------------------- 1. Number of variables: 11 2. Number of cases/rows: 493 3. Missing data codes: No missing data 4. Variable List A. Name: Sample_ID Description: Accession number associated with herbarium specimen at Bell Herbarium B. Name: Genus Description: Genus of herbarium specimen C. Name: Kingdom Description: Kingdom of herbarium specimen D. Name: Species Description: Binomial name of herbarium specimen E. Name: Year Description: Year of specimen collection F. Name: Month Description: Month of specimen collection G. Name: County Description: County specimen collection was made in H. Name: group Description: Ecological group specimen belongs to: AMP = arbuscular mycorrhizal plant, EMP = ectomycorrhizal plant; EMF = ectomycorrhizal fungus; Sap = saprotrophic fungus I. Name: mycorrhizal_type Description: Whether specimen is ectomycorrhizal or not (EM, non-EM) J. Name: xN Description: Tissue nitrogen concentration, expressed in percentage of dry weight K. Name: d15N Description: Ratio of 15N to 14N compared to atmospheric standard, expressed in per mille