title: Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability.
abstract: Ratios of nitrogen (N) isotopes in leaves could elucidate underlying patterns of N cycling across ecological gradients. To better understand global-scale patterns of N cycling, we compiled data on foliar N isotope ratios (delta(15)N), foliar N concentrations, mycorrhizal type and climate for over 11,000 plants worldwide. Arbuscular mycorrhizal, ectomycorrhizal, and ericoid mycorrhizal plants were depleted in foliar delta(15)N by 2 per thousand, 3.2 per thousand, 5.9 per thousand, respectively, relative to nonmycorrhizal plants. Foliar delta(15)N increased with decreasing mean annual precipitation and with increasing mean annual temperature (MAT) across sites with MAT >or= -0.5 degrees C, but was invariant with MAT across sites with MAT < -0.5 degrees C. In independent landscape-level to regional-level studies, foliar delta(15)N increased with increasing N availability; at the global scale, foliar delta(15)N increased with increasing foliar N concentrations and decreasing foliar phosphorus (P) concentrations. Together, these results suggest that warm, dry ecosystems have the highest N availability, while plants with high N concentrations, on average, occupy sites with higher N availability than plants with low N concentrations. Global-scale comparisons of other components of the N cycle are still required for better mechanistic understanding of the determinants of variation in foliar delta(15)N and ultimately global patterns in N cycling.
authors: Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
authors: Joseph M
authors: JM
authors: Craine
authors: University of Maryland Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, MD 21532, USA.
authors: Andrew J
authors: AJ
authors: Elmore
authors: Department of Plant Physiology and Biochemistry, Institute of Botany, PB 4005 CEP 01061-970 São Paulo, Brazil.
authors: Marcos P M
authors: MPM
authors: Aidar
authors: Departamento de Ecologia, Universidade de Brasília, Brasília, DF, Brazil.
authors: Mercedes
authors: M
authors: Bustamante
authors: Division of Ecosystem Sciences, Mulford Hall, University of California, Berkeley, CA 94720, USA.|Center for Stable Isotope Biogeochemistry, Department of Integrative Biology, University of California, Valley Life Sciences Building, Berkeley, CA 94720, USA.
authors: Todd E
authors: TE
authors: Dawson
authors: Institute for the Study of Earth, Oceans, and Space, Morse Hall, University of New Hampshire, 39 College Road, Durham, NH 03824, USA.
authors: Erik A
authors: EA
authors: Hobbie
authors: Center for Stable Isotope Biogeochemistry, Department of Integrative Biology, University of California, Valley Life Sciences Building, Berkeley, CA 94720, USA.
authors: Ansgar
authors: A
authors: Kahmen
authors: Department of Botany, University of Florida, PO Box 118526, Gainesville, FL 32611, USA.
authors: Michelle C
authors: MC
authors: Mack
authors: Department of Geography, Kansas State University, Manhattan, KS 66506.
authors: Kendra K
authors: KK
authors: McLauchlan
authors: Department of Terrestrial Ecology, Institute of Biology, Oester Farimagsgade 2D, DK-1353 Copenhagen K, Denmark.
authors: Anders
authors: A
authors: Michelsen
authors: Lab. Ecologia Isotópica - CENA/USP, Universidade de São Paulo, Av. Centenário, 303, Piracicaba SP 13416-000, Brazil.
authors: Gabriela B
authors: GB
authors: Nardoto
authors: USDA Forest Service, PO Box 968, Burlington, VT 05402, USA.
authors: Linda H
authors: LH
authors: Pardo
authors: Unitat d'Ecofisiologia CSIC-CREAF-CEAB, Centre de Recerca Ecològica i Aplicacions Forestals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors: Josep
authors: J
authors: Peñuelas
authors: Department of Forest Resources, University of Minnesota, 115 Green Hall, 1530 Cleveland Avenue North, St Paul, MN 55108, USA.
authors: Peter B
authors: PB
authors: Reich
authors: Department of Botany, University of Florida, PO Box 118526, Gainesville, FL 32611, USA.
authors: Edward A G
authors: EAG
authors: Schuur
authors: Centre for Ecosystem Management, School of Natural Sciences, Edith Cowan University, Joondalup 6027, Western Australia, Australia.
authors: William D
authors: WD
authors: Stock
authors: Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.
authors: Pamela H
authors: PH
authors: Templer
authors: Environmental Studies, Dartmouth College, Hanover, NH 03755, USA.
authors: Ross A
authors: RA
authors: Virginia
authors: Environment and Natural Resources Institute, University of Alaska, 707 A Street, Anchorage, AK 99501, USA.
authors: Jeffrey M
authors: JM
authors: Welker
authors: Department of Biological Sciences, Macquarie University 2109, Sydney, Australia.
authors: Ian J
authors: IJ
authors: Wright
mesh_terms: D002980:Climate; D017753:Ecosystem; D005658:Fungi; D038821:Mycorrhizae; D009584:Nitrogen / Q000378:metabolism; D009587:Nitrogen Isotopes / Q000032:analysis* / Q000378:metabolism; D010758:Phosphorus / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D018521:Plant Physiological Phenomena; D011891:Rain; D013696:Temperature
chemical_list: D009587:Nitrogen Isotopes; D010758:Phosphorus; D009584:Nitrogen