Publication Date:
2012-09-08
Description:
Increased atmospheric carbon dioxide (CO 2 ) concentrations and nitrogen (N) deposition induced by human activities have greatly influenced the stoichiometry of N and phosphorus (P). We used model forest ecosystems in open-top chambers to study the effects of elevated CO 2 (ca. 700 μ mol mol −1 ) alone and together with N addition (100 kg N ha −1 yr −1 ) on N to P (N:P) ratios in leaves, stems and roots of five tree species, including four non-N 2 fixers and one N 2 fixer, in subtropical China from 2006 to 2009. Elevated CO 2 decreased or had no effects on N:P ratios in plant tissues of tree species. N addition, especially under elevated CO 2 , lowered N:P ratios in the N 2 fixer, and this effect was significant in the stems and the roots. However, only one species of the non-N 2 fixers showed significantly lower N:P ratios under N addition in 2009, and the others were not affected by N addition. The reductions of N:P ratios in response to elevated CO 2 and N addition were mainly associated with the increases in P concentrations. Our results imply that elevated CO 2 and N addition could facilitate tree species to mitigate P limitation by more strongly influencing on P dynamics than N in the subtropical forests. © 2012 Blackwell Publishing Ltd
Print ISSN:
1354-1013
Electronic ISSN:
1365-2486
Topics:
Biology
,
Energy, Environment Protection, Nuclear Power Engineering
,
Geography
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