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Effects of Riparian Forest Buffers on In‐Stream Nutrient Retention in Agricultural Catchments
Author(s) -
Weigelhofer Gabriele,
Fuchsberger Jennifer,
Teufl Bernadette,
Welti Nina,
Hein Thomas
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/jeq2010.0436
Subject(s) - riparian zone , streams , environmental science , nutrient , biogeochemical cycle , riparian forest , riparian buffer , hydrology (agriculture) , eutrophication , ecology , biology , geology , computer network , geotechnical engineering , habitat , computer science
In northeastern Austria, marshlands have been turned into the most productive arable land of the country. As a result, most headwater streams show structurally degraded channels, lacking riparian buffer zones, which are heavily loaded with nutrients from the surrounding crop fields. The present study examines whether longitudinally restricted riparian forest buffers can enhance the in‐stream nutrient retention in nutrient‐enriched headwater streams. We estimated nutrient uptake from pairwise, short‐term addition experiments with 15 NH 4 , NH 4 , PO 4 , and NaCl within reaches with riparian forest buffers (RFB) and degraded reaches (DEG) of the same streams. Riparian forest buffers originated from the conservation of the pristine vegetation or from restoration measures. Hydrologic retention was calculated with the model OTIS‐P on the basis of conductivity break‐through curves from the salt injections. A significant increase in surface transient storage was revealed in pristine and restored RFB reaches compared with DEG reaches due to the longitudinal step‐pool pattern and the frequent occurrence of woody debris on the channel bed. Ammonium uptake lengths were significantly shorter in RFB reaches than in DEG reaches, resulting from the higher hydrologic retention. Uptake velocities did not differ significantly between RFB and DEG reaches, indicating that riparian forest buffers did not affect the biochemical nutrient demand. Uptake of 15 NH 4 was mainly driven by autotrophs. Net PO 4 uptake was not affected by riparian forest buffers. The study shows that the physical and biogeochemical effects of riparian forest buffers on the in‐stream nutrient retention are limited in the case of highly eutrophic streams.