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Title: Processes regulating progressive nitrogen limitation under elevated carbon dioxide: A meta-analysis

Here, the nitrogen (N) cycle has the potential to regulate climate change through its influence on carbon (C) sequestration. Although extensive research has explored whether or not progressive N limitation (PNL) occurs under CO 2 enrichment, a comprehensive assessment of the processes that regulate PNL is still lacking. Here, we quantitatively synthesized the responses of all major processes and pools in the terrestrial N cycle with meta-analysis of CO 2 experimental data available in the literature. The results showed that CO 2 enrichment significantly increased N sequestration in the plant and litter pools but not in the soil pool, partially supporting one of the basic assumptions in the PNL hypothesis that elevated CO 2 results in more N sequestered in organic pools. However, CO 2 enrichment significantly increased the N influx via biological N fixation and the loss via N 2O emission, but decreased the N efflux via leaching. In addition, no general diminished CO 2 fertilization effect on plant growth was observed over time up to the longest experiment of 13 years. Overall, our analyses suggest that the extra N supply by the increased biological N fixation and decreased leaching may potentially alleviate PNL under elevated CO 2 conditionsmore » in spite of the increases in plant N sequestration and N 2O emission. Moreover, our syntheses indicate that CO 2 enrichment increases soil ammonium (NH 4 +) to nitrate (NO 3 ) ratio. The changed NH 4 +/NO 3 ratio and subsequent biological processes may result in changes in soil microenvironments, above-belowground community structures and associated interactions, which could potentially affect the terrestrial biogeochemical cycles. In addition, our data synthesis suggests that more long-term studies, especially in regions other than temperate ones, are needed for comprehensive assessments of the PNL hypothesis.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3]
  1. Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology
  2. Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology and Oklahoma Biological Survey
  3. Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology; Tsinghua Univ., Beijing (China). Center for Earth System Science
Publication Date:
OSTI Identifier:
1252321
Grant/Contract Number:
SC0008270; SC0004601; SC0010715; DE SC0008270
Type:
Published Article
Journal Name:
Biogeosciences (Online)
Additional Journal Information:
Journal Name: Biogeosciences (Online); Journal Volume: 13; Journal Issue: 9; Journal ID: ISSN 1726-4189
Publisher:
European Geosciences Union
Research Org:
Univ. of Oklahoma, Norman, OK (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; CO2 enrichment; atmospheric CO2; ecosystem responses; dinitrogen fixation; natural ecosystems; plant-growth; water-use; soil-ph; forest; emissions