DOI: 10.1111/gcb.12849
论文题名: Significant nonsymbiotic nitrogen fixation in Patagonian ombrotrophic bogs
作者: Knorr K.-H. ; Horn M.A. ; Borken W.
刊名: Global Change Biology
ISSN: 13541013
出版年: 2015
卷: 21, 期: 6 起始页码: 2357
结束页码: 2365
语种: 英语
英文关键词: Spaghnum
; 15N
; Acetylen reduction assay
; Cushion plant
; Diazotroph
; Nitrogen cycle
; Nitrogen fixation
; Peatland
Scopus关键词: atmospheric deposition
; mineralization
; moss
; nitrogen cycle
; nitrogen fixation
; ombrotrophic environment
; peatland
; Patagonia
; Bryophyta
; Sphagnum
; Sphagnum magellanicum
; nitrogen
; soil
; chemistry
; Chile
; Embryophyta
; metabolism
; nitrogen cycle
; nitrogen fixation
; plant root
; soil
; Sphagnopsida
; wetland
; Chile
; Embryophyta
; Nitrogen
; Nitrogen Cycle
; Nitrogen Fixation
; Nitrogen Isotopes
; Plant Roots
; Soil
; Sphagnopsida
; Wetlands
英文摘要: Nitrogen (N) nutrition in pristine peatlands relies on the natural input of inorganic N through atmospheric deposition or biological dinitrogen (N2 ) fixation. However, N2 fixation and its significance for N cycling, plant productivity, and peat buildup are mostly associated with the presence of Sphagnum mosses. Here, we report high nonsymbiotic N2 -fixation rates in two pristine Patagonian bogs with diversified vegetation and natural N deposition. Nonsymbiotic N2 fixation was measured in samples from 0 to 10, 10 to 20, and 40 to 50 cm depth using the 15N2 assay as well as the acetylene reduction assay (ARA). The ARA considerably underestimated N2 fixation and can thus not be recommended for peatland studies. Based on the 15N2 assay, high nonsymbiotic N2 -fixation rates of 0.3-1.4 μmol N2 g-1 day-1 were found down to 50 cm under micro-oxic conditions (2 vol.%) in samples from plots covered by Sphagnum magellanicum or by vascular cushion plants, latter characterized by dense and deep aerenchyma roots. Peat N concentrations point to greater potential of nonsymbiotic N2 fixation under cushion plants, likely because of the availability of easily decomposable organic compounds and oxic conditions in the rhizosphere. In the Sphagnum plots, high N2 fixation below 10 cm depth rather reflects the potential during dry periods or low water level when oxygen penetrates the top peat layer and triggers peat mineralization. Natural abundance of the 15N isotope of live Sphagnum (5.6 δ‰) from 0 to 10 cm points to solely N uptake from atmospheric deposition and nonsymbiotic N2 fixation. A mean 15N signature of -0.7 δ‰ of peat from the cushion plant plots indicates additional N supply from N mineralization. Our findings suggest that nonsymbiotic N2 fixation overcomes N deficiency in different vegetation communities and has great significance for N cycling and peat accumulation in pristine peatlands. © 2014 John Wiley & Sons Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/61915
Appears in Collections: 影响、适应和脆弱性
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作者单位: Institute for Landscape Ecology, Hydrology Group, University of Münster, Heisenbergstr. 2, Münster, Germany; Department of Ecological Microbiology, University of Bayreuth, Dr.-Hans-Frisch-Str. 1-3, Bayreuth, Germany; Department of Soil Ecology, University of Bayreuth, Dr.-Hans-Frisch-Str. 1-3, Bayreuth, Germany
Recommended Citation:
Knorr K.-H.,Horn M.A.,Borken W.. Significant nonsymbiotic nitrogen fixation in Patagonian ombrotrophic bogs[J]. Global Change Biology,2015-01-01,21(6)