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Soil Nitrogen Dynamics in a River Floodplain Mosaic
Author(s) -
Shrestha J.,
Niklaus P.A.,
Frossard E.,
Samaritani E.,
Huber B.,
Barnard R. L.,
Schleppi P.,
Tockner K.,
Luster J.
Publication year - 2012
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0059
Subject(s) - nitrification , denitrification , environmental science , floodplain , nitrogen cycle , nitrogen , nitrate , blackwater , environmental chemistry , hydrology (agriculture) , soil water , ecology , soil science , chemistry , environmental engineering , geology , geotechnical engineering , organic chemistry , biology
In their natural state, river floodplains are heterogeneous and dynamic ecosystems that may retain and remove large quantities of nitrogen from surface waters. We compared the soil nitrogen dynamics in different types of habitat patches in a restored and a channelized section of a Thur River floodplain (northeast Switzerland). Our objective was to relate the spatiotemporal variability of selected nitrogen pools (ammonium, nitrate, microbial nitrogen), nitrogen transformations (mineralization, nitrification, denitrification), and gaseous nitrogen emission (N 2 O) to soil properties and hydrological processes. Our study showed that soil water content and carbon availability, which depend on sedimentation and inundation dynamics, were the key factors controlling nitrogen pools and processes. High nitrogen turnover rates were measured on gravel bars, characterized by both frequent inundation and high sediment deposition rates, as well as in low‐lying alluvial forest patches with a fine‐textured, nutrient‐rich soil where anaerobic microsites probably facilitated coupled nitrification–denitrification. In contrast, soils of the embankment in the channelized section had comparatively small inorganic nitrogen pools and low transformation rates, particularly those related to nitrate production. Environmental heterogeneity, characteristic of the restored section, favors nitrogen removal by creating sites of high sedimentation and denitrification. Of concern, however, are the locally high N 2 O efflux and the possibility that nitrate could leach from nitrification hotspots.