Climate change alters stoichiometry of phosphorus and nitrogen in a semiarid grassland

Authors

Feike A. Dijkstra, The University of SydneyFollow
Elise Pendall, University of WyomingFollow
Jack A. Morgan, USDA-ARSFollow
Dana M. Blumenthal, USDA-ARSFollow
Yolima Carrillo, The University of SydneyFollow
Daniel R. LeCain, USDA-ARSFollow
Ronald F. Follett, USDA-ARSFollow
David G. Williams, University of WyomingFollow

Date of this Version

2012

Citation

New Phytologist (2012) 196: 807–815; doi: 10.1111/j.1469-8137.2012.04349.x

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 CO₂ 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 CO₂ 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 : Pratios 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 CO₂ and drier conditions with warming can further alter N : P. Although warming may alleviate N constraints under elevated CO₂, warming and drought can exacerbate P constraints on plant growth and microbial activity in this semiarid grassland.