Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 6 4 2009 10.5194/bg-6-623-2009 http://www.biogeosciences.net/6/623/2009/ http://www.biogeosciences.net/6/623/2009/bg-6-623-2009.html http://www.biogeosciences.net/6/623/2009/bg-6-623-2009.pdf 623 631 2009-04-23 Vegetation and proximity to the river control amorphous silica storage in a riparian wetland (Biebrza National Park, Poland) E. Struyf eric.struyf@ua.ac.be W. Opdekamp H. Backx S. Jacobs D. J. Conley P. Meire Lund University, GeoBiosphere Science Centre, Department of Geology, Sölvegatan 12, 22362 Lund, Sweden University of Antwerp, Department of Biology, Ecosystem Management Research Group, Universiteitsplein 1c, 2610 Wilrijk, Belgium Wetlands can modify and control nutrient fluxes between terrestrial and aquatic ecosystems, yet little is known of their potential as biological buffers and sinks in the biogeochemical silica cycle. We investigated the storage of amorphous silica (ASi) in a central-European riparian wetland. The variation in storage of ASi in the soil of an undisturbed wetland was significantly controlled by two factors: dominance of sedges and grasses and distance to the river (combined (<i>R</i>²=78%). Highest ASi storage was found near the river and in sites with a dominance of grasses and sedges, plants which are well known to accumulate ASi. The management practice of mowing reduced the amount of variation attributed to both factors (<i>R</i>²=51%). Although ASi concentrations in soils were low (between 0.1 and 1% of soil dry weight), ASi controlled the availability of dissolved silica (DSi) in the porewater, and thus potentially the exchange of DSi with the nearby river system through both diffusive and advective fluxes. A depth gradient in ASi concentrations, with lower ASi in the deeper layers, indicates dissolution. 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