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
Jørund RolstadAbstract
No abstract has been registered
Authors
Knute J. Nadelhoffer Bridget A. Emmett Per Gundersen O. Janne Kjønaas Chris J. Koopmans Patrick Schleppi Albert Tietema Richard Frederic WrightAbstract
Humans have altered global nitrogen cycling such that more atmospheric N2 is being converted (\"fixed\") into biologically reactive forms by anthropogenic activities than by all natural processes combined. In particular, nitrogen oxides emitted during fuel combustion and ammonia volatilized as a result of intensive agriculture have increased atmospheric nitrogen inputs (mostly NO3 and NH4) to temperate forests in the Northern Hemisphere.Because tree growth in northern temperate regions is typically nitrogen-limited, increased nitrogen deposition could have the effect of attenuating rising atmospheric CO2 by stimulating the accumulation of forest biomass. Forest inventories indicate that the carbon contents of northern forests have increased concurrently with nitrogen deposition since the 1950s. In addition, variations in atmospheric CO2 indicate a globally significant carbon sink in northern mid-latitude forest regions. It is unclear, however, whether elevated nitrogen deposition or other factors are the primary cause of carbon sequestration in northern forests. Here we use evidence from 15N-tracer studies in nine forests to show that elevated nitrogen deposition is unlikely to be a major contributor to the putative CO2 sink in forested northern temperature regions.
Authors
D. LindgrenAbstract
No abstract has been registered
Authors
O. Janne KjønaasAbstract
Mixtures of cation and anion exchange resins are used as part of the resin core technique to determine nitrogen transformation in forest soils as they adsorb the NH4-N and NO3-N from soil solution percolating through the incubated soil cores. In the field, the exchange resins may be subjected to a variety of conditions, involving drying, rehydration, freezing, and thawing. This paper examines how these processes affect adsorption of NH4-N and NO3-N and the stability of the resins. Lab tests were performed on the anion resin Amberlite IRA-93, the cationresin Amberlite IR-120, and a mixture of IRA-93 and IR-120, and the commercially-mixed bed resin Amberlite MB1. The background content of NO3-N and NH4-N on the resins was large and highly variable between different batches of resins in spite of a 2 M NaCl pre-rinse. The IR-120 cation resin that was subjected to 48 hours air-drying contained significantly less NH4-N than the most resins, while the drying of the IRA-93 anion resin caused a significant release of NO3-N from resins with no N addition. Although the variation was large, the mixed bed resin MB1 indicated a release of NH4-N, which supports results from long term in situ deployments. A reduced adsorption of NO3-N was found on the IRA-93 anion resins and the MB1 mixed bed resins that were dried prior to N addition while the dry IR-120 cation resins adsorbed significantly less NH4-N than the control resin. No effect of freezing the thawing efficiency was observed on resin stability or N adsorption efficiency. Sufficient blanks that have been subjected to similar moisture changes are necessary in N limited systems with low levels of avialable NH4-N and NO3-N.
Authors
Gunnar HaugAbstract
No abstract has been registered
Authors
M. Lavoie Peder GjerdrumAbstract
The aim of this study has been to investigate the effects of high temperature drying on the equilibrium moisture content, to verify the presence of hysteresis and to screen the effects of high temperature on timber quality. Further, we wanted to utilise the laboratory kiln at Forestia Sokna in a pilot project, to learn more about the experimental possibilities connected to this equipment. The hypothesis was that the equilibrium moisture content will decrease as the drying temperature increase. Five series of twelve spruce wood samples each were prepared to verify this hypothesis: air-dried (green samples), moist samples for desorption and dry samples for adsorption for the ordinary-progressive (72 C) and for the high temperature kilns (115 C). The tension has been measured to compare the timber quality between ordinary-progressive and high temperature kilns. The conclusion is that there was too much stochastic noise to verify the initial hypothesis. Consequently it was impossible to confirm the presence of hysteresis. There are interesting observations to make in further research on how fast the equilibrium moisture content is reached according to the drying temperature. This experiment has been accomplished using Norway spruce, and further research should include Scots pine or other coniferous species.
Abstract
Potential response of forest soils to sulphur deposition in the Norwegian-Russian border area in the surroundings of the Pechenganikel smelters, the major sulphur emitters in the northern Europe, has been assessed with the PROFILE model. The release rate of base cations due to weathering range from 0.05 to 0.28 kmol(c)/ha/yr in the 0 - 50 cm soil layer, thus demonstrating the high sensitivity of the coarse and thin podzols studied. Calculated steady-state BC/Al values are significantly lower than the presumed critical value of 1, which indicate possible negative effect on vegetation through soil acidification. According to the model calculations future sulphur deposition have to be very low in order to stop the ongoing acidification and prevent vegetation damage. However, model assumptions, uncertainty in input data and critical chemical values applied implies that modelling results must be interpreted carefully
Authors
A. TigerstedtAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Ketil KohmannAbstract
Side effects of the permethrin formulations Gori 920 and Gori 920 L, the fenvalerate formulation Sumicidin 10 FW and the emulsifier of the Gori formulations have been studied in seedlings of Norway spruce. Whole plant treatment with the Gori formulations in early autumn resulted in a 5 - 10 C poorer frost tolerance (TDI) later in the autumn. Moreover, this treatment increased mortality by 30 % within two years of testing in field trials. A basal part treatment with the Gori formulations and whole plant treatment with Sumicidin 10FW containing 10 % fenvalerate, gave on the other hand no negative effects during two years of field testing. Late autumn treatment with Gori 920 and Gori 920 L. followed by cold storage for six months revealed poorer frost tolerance (3-4 C) in the spring than the control. These treatments also reduced leader shoot growth in the first year, and increased the frequency of plants lacking a dominant leader after two years by 20-40 %. The detrimental agent in Gori 920 L was found to be the emulsifier, ethoxylated nonylphenol, alone and in combination with the dispersal agent, the linseed oil. The linseed oil gave no significant additional negative effect on frost resistance and growth after the cold storage during the winter. The investigation demonstrates the necessity of testing for possible side effects before practical use of any commercial pesticide formulation. The experiments were conducted in Norway at the nursery of Buskerud Forestry Society and at The Norwegian Forest Research Institute at s