Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
1999
Authors
O. Janne KjønaasAbstract
Mixed bed ion exchange resin bags have previously been used in studies of soil N transformation rates with NH4-N and NO3-N being adsorbed from the solution percolating through the incubated soil core. An evaluation of the in situ adsorption efficiency of mixed bed resin bags was performed by comparing dissolved inorganic nitrogen (DIN, sum of NH4-N NO3-N) accumulated in resins with DIN fluxes in throughfall (TF) and with DIN concentrations in soil water. A significant correlation was found between DIN fluxes in TF and accumulated DIN in resins placed at the soil surface (r2= 0.92 for NO3-N, r2=0.86 for NH4-N, p0.001). The ratio of accumulated DIN in resins to DIN flux in TF was significantly affected by season. A low but significant correlation was found between NO3-N concentrations in soil water and NO3-N contents in resins deployed in the bottom of soil cylinders (r2=0.34, p0.01), however, when only the winter periods were taken into account, the correlation improved (r2=0.72, p0.001). As little water and few nutrients are removed from the soil water by the vegetation during the dormant season, the conditions inside and outside the core were more comparable. For NH4-N there was no correlation between accumulated amounts in the resins and concentrations in soil water sampled at 13 cm and 20 cm depth, respectively, probably due to the strong depth gradient in the NH4-N concentrations of the soil. Although the resin bags were unable to adsorb all the incoming DIN, they gave valuable information on small scale input of N and small scale differences in NO3-N leaching.
Authors
A. FriesAbstract
No abstract has been registered
Authors
Kari Anne Sølvernes Gunnar OgnerAbstract
The impact of climate change on a mini forest ecosystem was studied for three years in an open-top chamber (OTC) experiment with an outside control plot. Clones of Silver birch (Betula pendula Roth.) and Norway spruce (Picea abies (L.) Karst) were grown in monolithic lysimeters containing undisturbed profiles of podsolic forest soil. The original understory was also present.The soil temperature was increased with 2-3 C. The atmospheric CO2 concentration in the OTCs was ambient (380mol mol-1 CO2), approximately 500 and 700 mol mol-1 CO2. The leachates from the lysimeters was collected, and the solute concentration was analysed monthly.Increased soil temperature increased the mineralisation of soil organic matter, and large amounts of nitrate, dissolved organic nitrogen (DON) and aluminium were released. In the leachates from the 500 mol mol-1 CO2 birch lysimeters, high concentrations of Al were recorded during the second and third growth seasons.The high concentrations of Al were correlated with high concentration of total organic carbon (TOC) and increased pH. Large amounts of Al was organically bound in these leachates. The origin of the organic ligands could have been products of the birch roots, e.g. root exudates.
Authors
Gunnar Ogner Kari Anne SølvernesAbstract
The impact of elevated CO2 and increased temperature on the soil of a mini forest ecosystem was investigated in an open-top chamber experiment. The CO2 treatments of the OTCs were ambient, 500 and 700 mmol CO2 mol-1 with an ambient outdoor control. All soils were warmed by natural air flow and radiation to a temperature 2-3 C above a corresponding forest soil site. Overheating was prevented by a cooling system. Silver birch and Norway spruce were planted in undisturbed soil monolithic profiles, with their original understory, in lysimeters and compared to a lysimeter control with understory only. Soil samples were collected in the forest at the end of the experiment and used as reference samples. Increased temperature was found to cause the greatest effect on soil. All data clearly indicated increased breakdown of the soil organic matter with increased temperature. The breakdown of raw humus gave a decrease in concentration of total C, total N, and in the exchangeable plus extractable elements (org.-C, Ca, K, Mg, Mn, t-P and t-S) relative to the original forest reference soil in the range of 18 - 57 %. The exchangeable plus extractable elements (Al, Fe, Si, NH4-N and org.-N) from the raw humus layer increased in concentration relative to original forest soil by 28 - 96 %. The effect of different vegetation on soil quality was less than for the temperature increase. Birch had the strongest effect by decreasing soil acidity and the concentration of exchangeable Al throughout the soil profile relative to spruce. Birch also increased weathering of mineral soil relative to spruce. The effects of CO2 treatment on the soil were clearly smaller than for the temperature and vegetation parameters. Elevated CO2 gave increased concentrations of exchangeable plus extractable Zn, organic C and organic N for the raw humus layer of the understory and spruce vegetation relative to the raw humus of the birch lysimeters. Principal component analysis of the complete data set indicated an effect of elevated CO2 on the humus layer relative to the ambient treatments. This effect was seen most clearly in the lysimeters with understory vegetation.
Abstract
No abstract has been registered
Authors
M.J. Latkowska Harald Kvaalen M. AppelgrenAbstract
No abstract has been registered
Authors
Geir I. Vestøl Francis Colin Michel LoubéreAbstract
No abstract has been registered
Authors
Geir Wæhler GustavsenAbstract
No abstract has been registered
Authors
A. Sigurgeirsson Thröstur EysteinssonAbstract
No abstract has been registered
Authors
Fred MidtgaardAbstract
No abstract has been registered