Isotopic evidence for oligotrophication of terrestrial ecosystems

Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (δ 15 N) from more than 43,000 samples acquired over 37 years, here we show that foliar N concentration declined by 9% and foliar δ 15 N declined by 0.6–1.6‰. Examining patterns across different climate spaces, foliar δ 15 N declined across the entire range of mean annual temperature and mean annual precipitation tested. These results suggest declines in N supply relative to plant demand at the global scale. In all, there are now multiple lines of evidence of declining N availability in many unfertilized terrestrial ecosystems, including declines in δ 15 N of tree rings and leaves from herbarium samples over the past 75–150 years. These patterns are consistent with the proposed consequences of elevated atmospheric carbon dioxide and longer growing seasons. These declines will limit future terrestrial carbon uptake and increase nutritional stress for herbivores. Fil: Craine, Joseph M.. Jonah Ventures; Estados Unidos Fil: Elmore, Andrew J.. University of Maryland; Estados Unidos Fil: Wang, Lixin. Indiana University; Estados Unidos. Purdue University; Estados Unidos Fil: Aranibar, Julieta Nelida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Bauters, Marijn. University of Ghent; Bélgica Fil: Boeckx, Pascal. University of Ghent; Bélgica Fil: Crowley, Brooke E.. University of Cincinnati; Estados Unidos Fil: Dawes, Melissa A.. Swiss Federal Institute for Forest, Snow and Landscape Research; Suiza Fil: Delzon, Sylvain. Universite de Bordeaux; Francia. Institut National de la Recherche Agronomique; Francia Fil: Fajardo, Alex. Centro de Investigación en Ecosistemas de la Patagonia; Chile Fil: Fang, Yunting. Chinese Academy of Sciences; República de China Fil: Fujiyoshi, Lei. Research Institute for Humanity and Nature; Japón Fil: Gray, Alan. North American Electric Reliability Corporation. Centre for Ecology and Hydrology; Estados Unidos Fil: Guerrieri, Rossella. Consejo Superior de Investigaciones Científicas. Centre de Recerca Ecológica I Aplicacions Forestals; España Fil: Gundale, Michael J.. Swedish University of Agricultural Sciences; Suecia Fil: Hawke, David J.. Ara Institute of Canterbury. Department of Science and Primary Industries; Nueva Zelanda Fil: Hietz, Peter. University of Natural Resources and Life Sciences. Institute of Botany; Austria Fil: Jonard, Mathieu. Université Catholique de Louvain; Bélgica Fil: Kearsley, Elizabeth. University of Ghent; Bélgica Fil: Kenzo, Tanaka. Forestry and Forest Products Research Institute. Department of Plant Ecology; Japón Fil: Makarov, Mikhail. Moscow M.V. Lomonosov State University; Rusia Fil: Marañón Jiménez, Sara. Universidad de Granada; España. Consejo Superior de Investigaciones Científicas. Centre de Recerca Ecológica I Aplicacions Forestals; España Fil: McGlynn, Terrence P.. University of California; Estados Unidos. Natural History Museum of Los Angeles County. Department of Entomology; Estados Unidos Fil: McNeil, Brenden E.. West Virginia University. Department of Geology and Geography; Estados Unidos Fil: Mosher, Stella G.. University of Cincinnati; Estados Unidos Fil: Nelson, David M.. University of Maryland; Estados Unidos Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de la Patagonia Austral; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Roggy, Jean Christophe. Institut National de la Recherche Agronomique; Francia. Ecologie des Forêts de Guyane; Francia Fil: Sanders Demott, Rebecca. Boston University; Estados Unidos Fil: Song, Minghua. Chinese Academy of Sciences; República de China Fil: Szpak, Paul. Trent University. Department of Anthropology; Canadá Fil: Templer, Pamela H.. Boston University; Estados Unidos Fil: Van der Colff, Dewidine. South African National Biodiversity Institute; Sudáfrica Fil: Werner, Christiane. Albert Ludwigs University of Freiburg; Alemania Fil: Xu, Xingliang. Chinese Academy of Sciences; República de China Fil: Yang, Yang. Chinese Academy of Sciences; República de China Fil: Yu, Guirui. Chinese Academy of Sciences; República de China. University of Chinese Academy of Sciences. College of Resources and Environment; República de China Fil: Zmudczyńska Skarbek, Katarzyna. University of Gdańsk; Polonia