Nutrient enrichment typically causes local plant diversity declines. A common but untested expectation is that nutrient enrichment also reduces variation in nutrient conditions among localities and selects for a smaller pool of species, causing greater diversity declines at larger than local scales and thus biotic homogenization. Here we apply a framework that links changes in species richness across scales to changes in the numbers of spatially restricted and widespread species for a standardized nutrient addition experiment across 72 grasslands on six continents. Overall, we find proportionally similar species loss at local and larger scales, suggesting similar declines of spatially restricted and widespread species, and no biotic homogenization after 4 years and up to 14 years of treatment. These patterns of diversity changes are generally consistent across species groups. Thus, nutrient enrichment poses threats to plant diversity, including for widespread species that are often critical for ecosystem functions.

Canadian Centre for Climate Change and Adaptation University of Prince Edward Island St Peter's Bay Charlottetown PE C0A 2A0 Canada

Centre for Applied Ecology 'Prof Baeta Neves' School of Agriculture University of Lisbon Lisbon Portugal

Centre for Ecological Sciences Indian Institute of Science Bangalore India

Centre for Functional Biodiversity School of Life Sciences University of KwaZulu Natal Pietermaritzburg South Africa

Chair of Biodiversity and Nature Tourism Estonian University of Life Sciences Kreutzwaldi 5 51006 Tartu Estonia

Department of Biological Sciences Michigan Technological University Houghton MI 49930 USA

Department of Biological Sciences University of Toronto Scarborough Toronto ON Canada

Department of Biology Texas State University San Marcos TX 78666 USA

Department of Biology University of Prince Edward Island Charlottetown PE Canada

Department of Computer Science Martin Luther University Halle Wittenberg Halle Germany

Department of Ecology Evolution and Behavior University of Minnesota St Paul MN 55108 USA

Department of Entomology University of Maryland College Park MD USA

Department of Environment and Genetics La Trobe University Bundoora VIC 3083 Australia

Department of Environment and Society Utah State University Moab UT USA

Department of Geography King's College London 30 Aldwych London WC2B 4BG UK

Department of Integrative Biology University of Guelph Guelph ON N1G2W1 Canada

Department of Life Sciences Imperial College London Silwood Park Campus Buckhurst Road Ascot SL5 7PY UK

Department of Terrestrial Ecology Netherlands Institute of Ecology Droevedaalsesteeg 10 6708 PB Wageningen The Netherlands

Department of Wildland Resources and the Ecology Center Utah State University Logan UT 84322 USA

Desert Ecology Research Group School of Life and Environmental Sciences ARC Training Centre in Data Analytics for Resources and Environments The University of Sydney Sydney NSW 2006 Australia

Desert Ecology Research Group School of Life and Environmental Sciences The University of Sydney Sydney NSW 2006 Australia

Disturbance Ecology and Vegetation Dynamics Bayreuth Center of Ecology and Environmental Research University of Bayreuth Bayreuth Germany

Ecology and Biodiversity Group Department of Biology Utrecht University Padualaan 8 3584 CH Utrecht The Netherlands

Ecology and Genetics Unit University of Oulu Oulu Finland

Forest Research Centre Associate Laboratory TERRA School of Agriculture University of Lisbon Lisbon Portugal

German Centre for Integrative Biodiversity Research Halle Jena Leipzig Puschstraße 4 04103 Leipzig Germany

Hawkesbury Institute for the Environment Locked Bag 1797 Penrith NSW 2751 Australia

Health and Environmental Sciences Department Xi'an Jiaotong Liverpool University Suzhou Jiangsu China

Helmholtz Center for Environmental Research UFZ Department of Physiological Diversity Permoserstrasse 15 04318 Leipzig Germany

Institute of Biology Leipzig University Puschstrasse 4 04103 Leipzig Germany

Institute of Ecology Leuphana University of Lüneburg Universitätsallee 1 21335 Lüneburg Germany

Institute of Hydrobiology Biology Centre of the Czech Academy of Sciences Na Sadkach 7 Ceske Budejovice 370 05 Budejovice Czech Republic

Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a La Agricultura Facultad de Agronomía Universidad de Buenos Aires and CONICET Buenos Aires Argentina

Instituto de Investigaciones Marinas y Costeras UNMdP CONICET CC 1260 Correo Central B7600WAG Mar Del Plata Argentina

Instituto Nacional de Tecnología Agropecuaria CONICET Río Gallegos Santa Cruz Argentina

Lancaster Environment Centre Lancaster University Lancaster LA1 4YQ UK

Mammal Research Institute Department of Zoology and Entomology University of Pretoria Pretoria South Africa

Martin Luther University Halle Wittenberg Am Kirchtor 1 06108 Halle Germany

School of Climate Change and Adaptation University of Prince Edward Island Charlottetown PE C1A 4P3 Canada

School of Ecosystem and Forest Sciences University of Melbourne Parkville VIC 3010 Australia

School of Environmental and Forest Sciences University of Washington Seattle WA USA

Senckenberg Museum for Natural History Görlitz D 02826 Görlitz Germany

Swiss Federal Institute for Forest Snow and Landscape Research WSL Zuercherstrasse 111 8903 Birmensdorf Switzerland

University of California Santa Barbara Santa Barbara CA 93106 USA

University of Nebraska Lincoln Lincoln NE USA

Vrije Universiteit Brussel Department Biology WILD Pleinlaan 2 1050 Brussels Belgium

Zoology School of Natural Sciences Trinity College Dublin Dublin Ireland

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