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Dynamics of nitrifying activities, denitrifying activities and nitrogen in grassland mesocosms as altered by elevated CO 2
Author(s) -
Barnard Romain,
Barthes Laure,
Le Roux Xavier,
Leadley Paul W.
Publication year - 2004
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.1469-8137.2004.01038.x
Subject(s) - holcus lanatus , denitrifying bacteria , mesocosm , agronomy , festuca rubra , chemistry , nitrate , environmental chemistry , biomass (ecology) , grassland , denitrification , nitrogen , biology , nutrient , poaceae , lolium perenne , organic chemistry
Summary• The objective of this study was to better identify the mechanisms by which elevated CO 2 ( c . 665 µmol mol −1 ) alters soil nitrifying and denitrifying enzyme activity (NEA and DEA), and the dynamics of plant and microbial N pools. • We measured the effects of elevated CO 2 on plant biomass and N, soil microbial biomass N, soil ammonium and nitrate concentrations, NEA and DEA in monospecific grassland mesocosms ( Holcus lanatus and Festuca rubra ) grown for 15 months in reconstituted grassland soil. • NEA strongly decreased at elevated CO 2 in the Holcus mesocosms, but was not affected in Festuca systems. DEA was less sensitive to elevated CO 2 than NEA. In Holcus mesocosms, microbial N showed an initial growth phase that appeared to limit plant N acquisition, but was only transient. • CO 2 ‐induced changes in NEA and DEA were best explained by factors that could reduce soil [O 2 ] (increased soil water content and organic C). Elevated CO 2 may increase microbial immobilisation in highly disturbed systems, this effect weakening as the system gets closer to equilibrium.