Symptoms of nitrogen saturation in a riparian wetland

• Published in: Ecological applications Vol. 4; no. 4; pp. 750 - 756
• Main Authors: Hanson, Gay C., Groffman, Peter M., Gold, Arthur J.
• Format: Journal Article
• Language: English
• Published: The Ecological Society of America 01-11-1994; Ecological Society of America
• Subjects: AGUAS SUBTERRANEAS; AZOTE; BOSQUES; CARBON; CARBONE; CARBONO; CONTENIDO DE NITROGENO; COURS D'EAU; CURSOS DE AGUA; DENITRIFICACION; DENITRIFICATION; EAU SOUTERRAINE; FLORA DEL SUELO; FLORE DU SOL; Forest soils; FORESTS; FORET; GROUNDWATER; Highlands; HOJARASCA; LITIERE VEGETALE; METABOLISME DE L'AZOTE; METABOLISMO DEL NITROGENO; MINERALISATION; MINERALIZACION; MINERALIZATION; NITRATE; NITRATES; NITRATOS; NITRIFICACION; NITRIFICATION; NITROGEN; NITROGEN CONTENT; NITROGEN CYCLE; NITROGEN METABOLISM; NITROGENO; PLANT LITTER; POLLUTION DE L'EAU; POLUCION DEL AGUA; RHODE ISLAND; Riparian forests; Riparian soils; RIVERS; SOIL FLORA; soil inorganic nitrogen; Soil microorganisms; Soil water; SOL DE TERRES HUMIDES; SUELO DE TIERRAS HUMEDAS; TENEUR EN AZOTE; TERRE HUMIDE; TIERRAS HUMEDAS; Upland soils; WATER POLLUTION; WETLAND SOILS; WETLANDS
• ISSN: 1051-0761; 1939-5582
• DOI: 10.2307/1942005

Riparian forests are in a unique position in the landscape since they form a transition between uplands and aquatic systems. These ecosystems may be highly susceptible to nitrogen (N) saturation since they may be subject to high inputs of N from upland areas. We measured potential net N mineralization and nitrification, soil inorganic N levels, microbial biomass carbon (C) and N content, and the N content of litter as indicators of N saturation in two riparian zones on the eastern and western sides of a stream. The sites had similar soils, vegetation, and hydrology, but differing upland land use. The eastern or @'enriched@' site was downgradient of a dense residential housing development (built in the 1950s) that produced high groundwater nitrate (NO"3^-) concentrations. The western or @'control@'site had an undeveloped upland. Our objectives were (1) to evaluate if groundwater NO"3^- loading had induced changes in surface soil N-cycle processes that are symptoms of N saturation in the enriched site and (2) to evaluate these changes in relation to inputs and outputs of N to the site. Soil inorganic-N levels, litter N content, and potential net N mineralization and nitrification were significantly higher on the enriched site relative to the control site, suggesting that the enriched site and N saturated. However, input-output analysis indicated that the enriched site was still a sink for upland derived NO"3^-. High rates of denitrification and storage of N in soil organic matter appear to moderate N saturation on the enriched site.