Elevation alters ecosystem properties across temperate treelines globally

• Published in: Nature
• Main Authors: Mayor, Jordan R., Sanders, Nathan J., Classen, Aimée T., Bardgett, Richard D., Clement, Jean-Christophe, Fajardo, Alex, Lavorel, Sandra, Sundqvist, Maja K., Bahn, Michael, Chisholm, Chelsea, Cieraad, Ellen, Gedalof, Ze’ev, Grigulis, Karl, Kudo, Gaku, Oberski, Daniel L., Wardle, David A.
• Other Authors: Department of Forest Ecology and Management, Swedish University of Agricultural Sciences = Sveriges lantbruksuniversitet (SLU), Center Macroecology, Evolution and Climate, Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Health and Medical Sciences, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), School of Earth and Environmental Sciences Manchester (SEES), University of Manchester Manchester, Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry ), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Universidad Austral de Chile, Umeå University = Umeå Universitet, Institute of Ecology, Technical University of Berlin / Technische Universität Berlin (TUB), Manaaki Whenua – Landcare Research Lincoln, Institute of Environmental Sciences Leiden (CML), Universiteit Leiden = Leiden University, University of Guelph, Faculty of Environment Earth Science, Hokkaido University Sapporo, Japan, Department of Methodology and Statistic, Universiteit Utrecht / Utrecht University Utrecht, Asian School of the Environment (ASE), Nanyang Technological University Singapour, Wallenberg Scholars Award; Fondecyt 1120171; Carlsberg Fund; Danish National Research Foundation; US Department of Energy, Office of Science, Office of Biological and Environmental Research DE-SC0010562;UK Natural Environment Research Council;BiodivERsA project REGARDS ANR-12-EBID-004-01; REGARDS FWF-I-1056; Netherlands Organization for Scientific Research VENI 451-14-017; Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.EE.BIO]Life Sciences [q-bio]/Ecology; environment/Bioclimatology; Tundra
• Online Access: https://hal.science/hal-01606591; https://hal.science/hal-01606591/document; https://hal.science/hal-01606591/file/view.pdf; https://doi.org/10.1038/nature21027

Temperature is a primary driver of the distribution of biodiversity as well as of ecosystem boundaries(1,2). Declining temperature with increasing elevation in montane systems has long been recognized as a major factor shaping plant community biodiversity, metabolic processes, and ecosystem dynamics(3,4). Elevational gradients, as thermoclines, also enable prediction of long-term ecological responses to climate warming(5-7). One of the most striking manifestations of increasing elevation is the abrupt transitions from forest to treeless alpine tundra(8). However, whether there are globally consistent above-and belowground responses to these transitions remains an open question(4). To disentangle the direct and indirect effects of temperature on ecosystem properties, here we evaluate replicate treeline ecotones in seven temperate regions of the world. We find that declining temperatures with increasing elevation did not affect tree leaf nutrient concentrations, but did reduce ground-layer community-weighted plant nitrogen, leading to the strong stoichiometric convergence of ground-layer plant community nitrogen to phosphorus ratios across all regions. Further, elevation-driven changes in plant nutrients were associated with changes in soil organic matter content and quality (carbon to nitrogen ratios) and microbial properties. Combined, our identification of direct and indirect temperature controls over plant communities and soil properties in seven contrasting regions suggests that future warming may disrupt the functional properties of montane ecosystems, particularly where plant community reorganization outpaces treeline advance.