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| Titel |
Nitrogen enrichment enhances the dominance of grasses over forbs in a temperate steppe ecosystem |
| VerfasserIn |
L. Song, X. Bao, X. Liu, Y. Zhang, P. Christie, A. Fangmeier, F. Zhang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 8 ; Nr. 8, no. 8 (2011-08-26), S.2341-2350 |
| Datensatznummer |
250006087
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| Publikation (Nr.) |
 copernicus.org/bg-8-2341-2011.pdf |
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| Zusammenfassung |
| Chinese grasslands are extensive natural ecosystems that comprise 40 % of
the total land area of the country and are sensitive to N deposition. A
field experiment with six N rates (0, 30, 60, 120, 240, and 480 kg N ha−1 yr−1) was conducted at Duolun, Inner Mongolia, during 2005
and 2010 to identify some effects of N addition on a temperate steppe
ecosystem. The dominant plant species in the plots were divided into two
categories, grasses and forbs, on the basis of species life forms. Enhanced
N deposition, even as little as 30 kg N ha−1 yr−1 above ambient N
deposition (16 kg N ha−1 yr−1), led to a decline in species
richness. The cover of grasses increased with N addition rate but their
species richness showed a weak change across N treatments. Both species
richness and cover of forbs declined strongly with increasing N deposition
as shown by linear regression analysis (p < 0.05). Increasing N deposition
elevated aboveground production of grasses but lowered aboveground biomass
of forbs. Plant N concentration, plant δ15N and soil mineral N
increased with N addition, showing positive relationships between plant
δ15N and N concentration, soil mineral N and/or applied N rate.
The cessation of N application in the 480 kg N ha−1 yr−1 treatment
in 2009 and 2010 led to a slight recovery of the forb species richness
relative to total cover and aboveground biomass, coinciding with reduced
plant N concentration and soil mineral N. The results show N
deposition-induced changes in soil N transformations and plant N
assimilation that are closely related to changes in species composition and
biomass accumulation in this temperate steppe ecosystem. |
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