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Contrasting effects of elevated CO 2 and warming on nitrogen cycling in a semiarid grassland
Author(s) -
Dijkstra Feike A.,
Blumenthal Dana,
Morgan Jack A.,
Pendall Elise,
Carrillo Yolima,
Follett Ronald F.
Publication year - 2010
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2010.03293.x
Subject(s) - cycling , grassland , carbon cycle , nitrogen cycle , carbon sequestration , nitrogen , global warming , environmental science , agronomy , productivity , ecosystem , soil carbon , chemistry , environmental chemistry , soil water , ecology , climate change , soil science , biology , forestry , macroeconomics , organic chemistry , economics , geography
Summary• Simulation models indicate that the nitrogen (N) cycle plays a key role in how other ecosystem processes such as plant productivity and carbon (C) sequestration respond to elevated CO 2 and warming. However, combined effects of elevated CO 2 and warming on N cycling have rarely been tested in the field. • Here, we studied N cycling under ambient and elevated CO 2 concentrations (600 μmol mol −1 ), and ambient and elevated temperature (1.5 : 3.0°C warmer day:night) in a full factorial semiarid grassland field experiment in Wyoming, USA. We measured soil inorganic N, plant and microbial N pool sizes and NO 3 − uptake (using a 15 N tracer). • Soil inorganic N significantly decreased under elevated CO 2 , probably because of increased microbial N immobilization, while soil inorganic N and plant N pool sizes significantly increased with warming, probably because of increased N supply. We observed no CO 2 × warming interaction effects on soil inorganic N, N pool sizes or NO 3 − uptake in plants and microbes. • Our results indicate a more closed N cycle under elevated CO 2 and a more open N cycle with warming, which could affect long‐term N retention, plant productivity, and C sequestration in this semiarid grassland.