Carla R. Reis Ely Steven S. Perakis Cory C. Cleveland Duncan N. L. Menge Sasha C. Reed Sarah A. Batterman Timothy E. Crews Katherine A. Dynarski Maga Gei Michael J. Gundale Sarah E. Jovan Sian Kou-Giesbrecht Mark B. Peoples Emilio Rodríguez-Caballero Verity G. Salmon Fiona M. Soper Anika P. Staccone Benton N. Taylor Bettina Weber Nina Wurzburger 20250408 1 tabular digital data Reis Ely, C.R., Perakis, S.S., Cleveland, C.C., Menge, D.N., Reed, S.C., Batterman, S.A., Crews, T.E., Dynarski, K.A., Gei, M.G., Gundale, M.J., Jovan, S.E., Kou-Giesbrecht, S., Peoples, M.B., Rodríguez-Caballero, E., Salmon, V.G., Soper, F.M., Staccone, A.P., Taylor, B.N., Weber, B., and Wurzburger, N., 2024, A global dataset of terrestrial biological nitrogen fixation: U.S. Geological Survey Data Release. https://doi.org/10.5066/P1MFBVHK https://doi.org/10.5066/P1MFBVHK This dataset includes field measurements of biological nitrogen fixation (BNF) in all major N-fixing niches across natural terrestrial biomes globally. The dataset comprises 32 variables including site location, biome type, N-fixing niche, sampling year, quantification method, BNF rate (in kgN/(ha*y)), the percentage of nitrogen derived from the atmosphere, N-fixer or N-fixing substrate abundance, BNF rate per unit of N-fixer abundance, and species identity. This dataset was created to facilitate synthesis, meta-analysis, upscaling, and model benchmarking of BNF fluxes at multiple spatial scales. The time period is the range of BNF rate sampling years. 1952 2018 See Supplemental Info Complete As needed Global -164.8262 175.3700 79.0000 -69.0000 ISO 19115 Topic Category biota environment None N₂ fixation biogeochemical cycles nitrogen cycle legumes actinorhizal plants symbiotic asymbiotic free-living cryptic rhizobial plants USGS Thesaurus terrestrial ecosystems biochemistry biogeochemical cycling nutrient cycling nitrogen vascular plants nonvascular plants symbiosis mosses lichens bacteria biological soil crusts soil sciences soil chemistry USGS Metadata Identifier USGS:66a97365d34e07a119db3a30 Common geographic areas Earth Land No access constraints. No use constraints. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research. Carla R. Reis Ely Oak Ridge Institute for Science and Education Research Scientist physical

1299 Bethel Valley Rd

Oak Ridge TN 37830 USA (541)231-8608 carlargreis@gmail.com This paper is a contribution from a working group on biological nitrogen fixation supported by the U.S. Geological Survey (USGS) John Wesley Powell Center for Analysis and Synthesis (G19AC00036). This research was supported in part by an appointment to the USGS Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between U.S. Departments of Energy (DOE) and Interior (DOI) under DOE contract number DE-SC0014664. Carla R. Reis Ely Steven S. Perakis Cory C. Cleveland Duncan N. L. Menge Sasha C. Reed Sarah A. Batterman Timothy E. Crews Katherine A. Dynarski Maga Gei Michael J. Gundale Sarah E. Jovan Sian Kou-Giesbrecht Mark B. Peoples Emilio Rodríguez-Caballero Verity G. Salmon Fiona M. Soper Anika P. Staccone Benton N. Taylor Bettina Weber Nina Wurzburger 20250805 publication Scientific Data vol. 12, issue 1 n/a Springer Science and Business Media LLC https://doi.org/10.1038/s41597-025-05131-4 Carla R. Reis Ely Steven S. Perakis Cory C. Cleveland Duncan N. L. Menge Sasha C. Reed Benton N. Taylor Sarah A. Batterman Christopher M. Clark Timothy E. Crews Katherine A. Dynarski Maga Gei Michael J. Gundale David F. Herridge Sarah E. Jovan Sian Kou-Giesbrecht Mark B. Peoples Johannes Piipponen Emilio Rodríguez-Caballero Verity G. Salmon Fiona M. Soper Anika P. Staccone Bettina Weber Christopher A. Williams Nina Wurzburger 20250716 publication Nature vol. 643, issue 8072 n/a Springer Science and Business Media LLC ppg. 705-711 https://doi.org/10.1038/s41586-025-09201-w Data values are as reported in the original publications and converted to standardized units. We checked each data entry against its original publication and conversion calculations at least twice, with particular attention to whether potential outliers represented data entry or conversion errors. We reviewed and removed duplicate studies. If the same data were published in multiple formats, we selected data published as a journal article over other formats. The BNF rates in the dataset show a right-skewed frequency distribution across niches, indicating frequent low and episodic high values, typical of BNF fluxes. The dataset includes BNF niches in natural terrestrial biomes for which extensive data were available. However, it does not include all possible BNF sources. There are cryptic niches (e.g., plant endophytes and epiphylls, rhizosphere, and BNF by insects) for which BNF data was too limited and, therefore, not included here. The dataset also does not include grain croplands or pastures intensively managed for forage/livestock production due to more extreme human interference. The location of study sites in the dataset spans across the range of temperature and precipitation in natural terrestrial biomes globally, suggesting the dataset is representative of the heterogeneity of environmental conditions that drive BNF rates in these ecosystems. We performed a literature search using a single systematic Boolean search term to combine nitrogen fixation terms with lists of natural terrestrial biomes, countries, N-fixing taxa, and N-fixing niches. We used this search term in the software Publish or Perish (https://harzing.com/resources/publish-or-perish) to search for BNF publications in the Web of Science, Google Scholar, and Scopus databases. 2020 We screened studies manually and selected those reporting BNF measurements in natural terrestrial biomes. We also used a snowballing approach wherein we inspected the screened studies to help identify additional publications containing BNF measurements that were not located in the primary search. 2020 We extracted data manually into a spreadsheet template. Data published as figures were extracted using the software WebPlotDigitizer (https://automeris.io/). For each study we recorded the site name, country name, geographic coordinates, vegetation type as described by authors, N-fixing niche, sampling year(s), quantification method(s), reported BNF measurements and their units, N-fixer or N-fixing substrate abundance, and species identity. 2021 We harmonized location names so that the same research areas and study sites have the same names across the dataset. We filled gaps using information gathered from sister publications by the same authors or provided directly by authors, or from other publications in the same study site/research area, whenever possible and appropriate. We harmonized the vegetation type within each study site into one of the International Geosphere-Biosphere Program (IGBP; https://doi.org/10.5067/MODIS/MCD12Q1.006) land cover classes based on the reported vegetation descriptions and definitions in the IGBP land cover system. We aggregated reported BNF rates into total rates by niche per site per study and converted them to standardized units (kgN/(ha*y)). We also calculated BNF rates per unit of N-fixer abundance. 2022 We standardized and updated family, genus, and species names in the dataset using The World Flora Online (WFO) database (https://wfoplantlist.org/) and the Taxonomic Name Resolution Service online tool (https://tnrs.biendata.org/) for species of trees, shrubs, herbs, mosses, and lichens. For lichen species not listed in the WFO database, we checked for accepted names in the Consortium of Lichen Herbaria (https://lichenportal.org/portal/). We also used the National Center for Biotechnology Information (https://www.ncbi.nlm.nih.gov/taxonomy) and Algaebase (https://www.algaebase.org/) taxonomy databases to check for accepted names of prokaryotes. 2024 SITE.csv Comma Separated Value (CSV) file containing site location, biome type, and N-fixing niche. Producer Defined record_ID Record identification code that links data across files Producer Defined 1 1529 site_name study site name Producer Defined Similar site names followed by different numbers indicate plots/stands that differ in vegetation composition or dominance, age, disturbance history, N-fixer abundance, elevation/climate, and/or topoedaphic setting within the same study area. country country code ISO 3166-1 alpha-3 3-digit ISO country code. "Multiple" if data spans more than one country lat Latitude coordinate. Coordinates in the data set are taken from the publications, which do not report datum. Producer Defined NA No Data Producer defined -69.0 79.0 decimal degrees lon Longitude coordinate. Coordinates in the data set are taken from the publications, which do not report datum. Producer Defined NA No Data Producer defined -164.8262 175.37 decimal degrees IGBP International Geosphere-Biosphere Program land cover class Producer Defined NA No Data Producer defined ENF Evergreen Needleleaf Forests Producer defined EBF Evergreen Broadleaf Forests Producer defined DBF Deciduous Broadleaf Forests Producer defined MF Mixed Forests Producer defined Shrub Closed Shrublands or Open Shrublands Producer defined Sav Woody Savannas or Savannas Producer defined Grass Grasslands Producer defined Bare Barren Producer defined Wet Permanent Wetlands Producer defined Snow Permanent Snow and Ice Producer defined niche N-fixing niche Producer Defined Trees trees Producer defined Herbs herbaceous plants Producer defined Soil mineral and/or organic soil, including humus Producer defined Litter all non-woody litter, usually leaf litter Producer defined Lichens lichens Producer defined Dead wood logs > 7.5 cm diameter Producer defined Mosses mosses Producer defined Biocrusts biological soil crusts Producer defined Shrubs shrubs Producer defined Woody litter dead branches and stems ≥ 7.5 cm diameter Producer defined ecological_level ecological organization level the data refer to Producer Defined NA No Data Producer defined Community community-level data Producer defined Species species-level data Producer defined ref_code Source reference code. Refer to REFERENCES.csv for full citation Producer Defined Source reference code in the form of "First author's last name_year of publication" BNF_AREA.csv Comma Separated Value (CSV) file containing sampling year, quantification method, and BNF rates in reported and standardized units. Producer Defined record_ID Record identification code that links data across files Producer Defined 1 1529 year The calendar year that BNF was measured. The mean was entered if BNF was measured over multiple years Producer Defined NA No Data Producer defined 1952 2018 BNF_central Central BNF rate reported. Value is exactly as reported, or the mean or sum of reported group values Producer Defined NA No Data Producer defined 0.0 9432.6 varies, as reported. See "BNF_unit" BNF_min Minimum BNF rate reported Producer Defined NA No Data Producer defined 0.0 282.0 varies, as reported. See "BNF_unit" BNF_max Maximum BNF rate reported Producer Defined NA No Data Producer defined 0.13 363.0 Varies, as reported. See "BNF_unit" BNF_unit The unit BNF_central, BNF_min, and BNF_max are expressed Producer Defined Values vary, as reported method The method(s) used to quantify BNF rates Producer Defined 10 Acetylene Reduction Assay (ARA) Producer defined 11 ARA + 15N2 incorporation Producer defined 12 ARA + N accretion Producer defined 13 ARA + N accumulation Producer defined 20 15N2 incorporation Producer defined 21 15N2 incorporation + N accretion Producer defined 30 15N natural abundance Producer defined 31 15N natural abundance + 15N dilution Producer defined 32 15N natural abundance + N accretion Producer defined 40 15N dilution Producer defined 50 N accretion Producer defined 60 N accumulation Producer defined 70 Mass balance of other N fluxes Producer defined BNF_final Final BNF rate in standardized units based on BNF_central or BNF_min and BNF_max, and local N-fixer or N-fixing substrate abundance. If BNF_central is not available, BNF_final is based on the mean of BNF_min and BNF max values Producer Defined NA No Data Producer defined 0.0 361.6 kilograms of nitrogen per hectare per year BNF_final_type Indication on whether BNF_final was reported in the original publication, converted from similar temporal and/or spatial units, or converted from other types of BNF data. It also indicates whether rates were adjusted for local N-fixer of N-fixing substrate abundance in the original publication or here Producer Defined NA No Data Producer defined 1 reported in the original publication and already adjusted for local N-fixer or N-fixing substrate abundance Producer defined 2 reported in the original publication and adjusted here for local N-fixer or N-fixing substrate abundance Producer defined 3 converted from similar temporal and/or spatial units already adjusted for local N-fixer or N-fixing substrate abundance Producer defined 4 converted from similar temporal and/or spatial units and adjusted here for local N-fixer or N-fixing substrate abundance Producer defined 5 converted from other types of BNF data already adjusted for local N-fixer or N-fixing substrate abundance Producer defined 6 converted from other types of BNF data and adjusted here for local N-fixer or N-fixing substrate abundance Producer defined ABUNDANCE.csv Comma Separated Value (CSV) file containing N-fixer or N-fixing substrate abundance. Producer Defined record_ID Record identification code that links data across files Producer Defined 1 1527 variable N-fixer or N-fixing substrate abundance variable Producer Defined pct_BA N-fixer relative basal area Producer defined pct_stems N-fixer relative stem density Producer defined pct_cover N-fixer percent ground cover Producer defined AGB N-fixing substrate aboveground biomass Producer defined value N-fixer or N-fixing substrate abundance value Producer Defined 0.0 296.2 percent for pct_BA, pct_stems, and pct_cover; Mg/ha for AGB BNF_ABUNDANCE.csv Comma Separated Value (CSV) file containing BNF rates per unit of N-fixer abundance. Producer Defined record_ID Record identification code that links data across files Producer Defined 1 1527 variable BNF per unit of N-fixer abundance variable Producer Defined BNF_BA BNF rate per unit of N-fixer relative basal area Producer defined BNF_stems BNF rate per unit of N-fixer relative stem density Producer defined BNF_cover BNF rate per unit of N-fixer percent ground cover Producer defined value BNF per unit of N-fixer abundance value Producer Defined 0.0 11.2 kgN/(ha*y*%BA) for BNF_BA, kgN/(ha*y*%stems) for BNF_stems, and kgN/(ha*y*%cover) for BNF_cover NDFA.csv Comma Separated Value (CSV) file containing the percentage of nitrogen derived from the atmosphere for N-fixing herbs. Producer Defined record_ID Record identification code that links data across files Producer Defined 9 1418 year The calendar year that Ndfa was measured. The mean was entered if Ndfa was measured over multiple years Producer Defined NA No Data Producer defined 1991 2017 calendar year method The method(s) used to quantify Ndfa Producer Defined 30 15N natural abundance Producer defined 31 15N natural abundance + 15N dilution Producer defined 40 15N dilution Producer defined Ndfa Percentage of nitrogen derived from atmosphere Producer Defined 0.63 100.0 percent SPECIES.csv Comma Separated Value (CSV) file containing species identity. Producer Defined record_ID Record identification code that links data across files Producer Defined 5 1527 family Taxonomic family Producer Defined family name genus Taxonomic genus Producer Defined genus name species Taxonomic species Producer Defined NA No Data Producer defined Species name. "sp" indicates one and "spp" indicates more than one unidentified species AUXILIARY_DATA.csv Comma Separated Value (CSV) file containing auxiliary data. Producer Defined record_ID Record identification code that links data across files Producer Defined 13 1529 variable Auxiliary data variable Producer Defined soil_depth soil depth sampled for BNF Producer defined habit habit of sampled N-fixing mosses and lichens Producer defined bulk_density soil bulk density Producer defined value Auxiliary data value. For N-fixer habit, 1 = on the ground, or 2 = epiphyte Producer Defined 2.41e-06 40.0 cm for soil_depth; g/cm³ for bulk_density REFERENCES.csv Comma Separated Value (CSV) file containing source references. Producer Defined ref_code Source reference code Producer Defined Source reference code in the form of "First author last name_year of publication" ref_complete source reference Producer Defined complete source reference METADATA.csv Comma Separated Value (CSV) file containing metadata description. Producer Defined file Data file name Producer Defined data file name in the dataset field Variable name Producer Defined variable name in the corresponding data file description Variable description Producer Defined variable description values Variable values Producer Defined << empty cell >> No Data Producer defined List of values and/or additional description GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. CSV https://doi.org/10.5066/P1MFBVHK None 20250808 Data Manager Forest and Rangeland Ecosystem Science Center mailing and physical

777 NW 9th Street, Suite 400

Corvallis OR 97330 USA 541-750-1030 fresc_outreach@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999