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SOIL NITROGEN CYCLING UNDER ELEVATED CO 2 : A SYNTHESIS OF FOREST FACE EXPERIMENTS
Author(s) -
Zak Donald R.,
Holmes William E.,
Finzi Adrien C.,
Norby Richard J.,
Schlesinger William H.
Publication year - 2003
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/03-5055
Subject(s) - cycling , mineralization (soil science) , nitrogen cycle , biogeochemical cycle , primary production , environmental science , plant litter , heterotroph , agronomy , nitrogen , ecology , environmental chemistry , litter , ecosystem , chemistry , soil water , soil science , biology , forestry , genetics , organic chemistry , bacteria , geography
The extent to which greater net primary productivity (NPP) will be sustained as the atmospheric CO 2 concentration increases will depend, in part, on the long‐term supply of N for plant growth. Over a two‐year period, we used common field and laboratory methods to quantify microbial N, gross N mineralization, microbial N immobilization, and specific microbial N immobilization in three free‐air CO 2 enrichment experiments (Duke Forest, Oak Ridge, Rhinelander). In these experiments, elevated atmospheric CO 2 has increased the input of above‐ and belowground litter production, which fuels heterotrophic metabolism in soil. Nonetheless, we found no effect of atmospheric CO 2 concentration on any microbial N cycling pool or process, indicating that greater litter production had not initially altered the microbial supply of N for plant growth. Thus, we have no evidence that changes in plant litter production under elevated CO 2 will initially slow soil N availability and produce a negative feedback on NPP. Understanding the time scale over which greater plant production modifies microbial N demand lies at the heart of our ability to predict long‐term changes in soil N availability and hence whether greater NPP will be sustained in a CO 2 ‐enriched atmosphere.