title: Climate change alters stoichiometry of phosphorus and nitrogen in a semiarid grassland.
abstract: Nitrogen (N) and phosphorus (P) are essential nutrients for primary producers and decomposers in terrestrial ecosystems. Although climate change affects terrestrial N cycling with important feedbacks to plant productivity and carbon sequestration, the impacts of climate change on the relative availability of N with respect to P remain highly uncertain. In a semiarid grassland in Wyoming, USA, we studied the effects of atmospheric CO(2) enrichment (to 600 ppmv) and warming (1.5/3.0°C above ambient temperature during the day/night) on plant, microbial and available soil pools of N and P. Elevated CO(2) increased P availability to plants and microbes relative to that of N, whereas warming reduced P availability relative to N. Across years and treatments, plant N : P ratios varied between 5 and 18 and were inversely related to soil moisture. Our results indicate that soil moisture is important in controlling P supply from inorganic sources, causing reduced P relative to N availability during dry periods. Both wetter soil conditions under elevated CO(2) and drier conditions with warming can further alter N : P. Although warming may alleviate N constraints under elevated CO(2) , warming and drought can exacerbate P constraints on plant growth and microbial activity in this semiarid grassland.
authors.affiliation: Department of Environmental Sciences, The University of Sydney, Eveleigh, NSW, 2015, Australia.
authors.forename: Feike A
authors.initials: FA
authors.lastname: Dijkstra
authors.affiliation: Department of Botany and Program in Ecology, University of Wyoming, Laramie, WY, 82071, USA.
authors.forename: Elise
authors.initials: E
authors.lastname: Pendall
authors.affiliation: Rangeland Resources Research Unit, USDA-ARS, Fort Collins, CO, 80526, USA.
authors.forename: Jack A
authors.initials: JA
authors.lastname: Morgan
authors.affiliation: Rangeland Resources Research Unit, USDA-ARS, Fort Collins, CO, 80526, USA.
authors.forename: Dana M
authors.initials: DM
authors.lastname: Blumenthal
authors.affiliation: Department of Environmental Sciences, The University of Sydney, Eveleigh, NSW, 2015, Australia.
authors.forename: Yolima
authors.initials: Y
authors.lastname: Carrillo
authors.affiliation: Rangeland Resources Research Unit, USDA-ARS, Fort Collins, CO, 80526, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: LeCain
authors.affiliation: Soil, Plant, and Nutrient Research Unit, USDA-ARS, Fort Collins, CO, 80526, USA.
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Follett
authors.affiliation: Departments of Botany, Ecosystem Science and Management, Program in Ecology, University of Wyoming, Laramie, WY, 82071, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Williams
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D057231:Climate Change; D017753:Ecosystem; D006358:Hot Temperature; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D006109:Poaceae / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D014867:Water / Q000378:metabolism; D014959:Wyoming
chemical_list: D000644:Quaternary Ammonium Compounds; D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen