Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
1999
Forfattere
E. Grimsrud Halvor SolheimSammendrag
Det er ikke registrert sammendrag
Sammendrag
Within the framework of the Programme for Terrestrial Monitoring (TOV), soil water has been collected from four monitoring plots in 1998 (Fig. 1). Three of the plots are located in birch forest, and one (Solhomfjell) is located in spruce forest. Height above sea level, annual precipitation and growing season temperature show significant variation between plots. Bilberry or bilberry-crowberry are the main vegetation types.Results from 1998 are reported and compared with results from preceeding years. On all plots soil water has been sampled from three soil depths (except Gutulia); the organic layer, the upper and the lower part of the mineral soil (5, 15 and 40 cm soil depth, respectively).The chemical composition of the soil water depends largely on the chemistry of the soil and the amount and quality of the precipitation. The soil chemistry in humic layer and from 5-15 cm depth in the mineral soil is shown in Table 1 and 2, respectively. The concentrations of some of the main elements in soil water from 1998 are shown in Table 3.The pH in soil water increases usually with soil depth. The annual variations in pH from 1991 to 1998, are shown in Figure 2. In Lund there has been a slight decrease in pH in these years, although continous measurements are lacking at 5 cm. Figure 2 also show the same tendencies for Ca2 as for pH in Lund.There is greater annual variation in concentrations of Ca2 and other element in the humic layer than mineral layers. Also other nutrients, such as Mg2 and K, were found with the highest concentrations in the organic soil layer and decreased with increasing soil depth.The concentrations of SO42- were in 1998 below 1 mg/l and only with a few exceptions larger than 1 from 1991 to 1998 (Fig.3). SO42- generally show a decreasing trend in that period. Total Al were lower than 1.0 mg/l for most of the samples. The amount of inorganic Al, which is known to be toxic for plant roots at certain concentrations was first time measuered on the plots in 1998. However, the values were small, well below 1.0 mg/l.That were simular to results from The Forest Monitoring Programme in Norway (OPS) which shows that the concentration of inorganic Al varies between plots and soil depths. Here, however, at some plots there were concentrations of inorganic Al up to 2.0-3.4 mg/l. Results from experiments with Norway spruce seedlings (Picea abies) in nutrient solution show slight decline of the roots at concentrations of unorganic Al at 2.0 mg/l (Eldhuset pers. comm.). This may suggest that even if the concentration of unorganic Al at the TOV-plots were below 1.0 mg/l, there could be periods with higher concentrations that could have effected the plant roots.The concentration of Cl- varied greatly between the plots (Fig. 3), due to the deposition of sea salts. The plot in Gutulia had minimal variation between years and Cl- concentrations were always below 1.0 mg/l. In contrast, the plot in Lund had both the highest concentrations of Cl- and the highest seasonal and annual variation. The between layer differences were usually small each year.Analyses of precipitation show that Lund has the highest supply of acidity, Mg2, SO42-, Na and Cl- of all plots (Trseth og Man 1997). Even if the supply of N also is highest in Lund, soil water from all plots has shown low amounts of N (mostly at detection levels for NH4 and NO3, Table 3) throughout the monitoring period. This may be explained by the low content of plant available nitrogen in Norwegian soils, and plant uptake would minimize any leaching.At present these results give no indication of forest decline in Lund despite decreasing pH and concentration of Ca2 in the soil water. At present it is not possible to confirm that the changes observed in pH and Ca2 are caused by long range air pollution. They may also be due to natural variations in the chemical composition of soil water. It is recommended to continue the soil water monitoring.
Forfattere
Ulrik Bräuner NielsenSammendrag
Det er ikke registrert sammendrag
Forfattere
Peder GjerdrumSammendrag
In pine, heart- and sapwood can in some respect be considered two different timber species, with divergent wood properties. The knowledge of their occurrence has thus been a task for wood scientists ever since the fundamental work of Pilz (1907) a century ago. Close to 1800 observations from all over Scandinavia are analysed. Conclusion is that the physiological conversion from sap- to heartwood in the living tree is under the sole control of time, i.e. years past since activity in the apical. Other factors (height in tree, tree or stand characteristics) seem to be without influence The prediction of heartwood amount in individual trees in a stand of known age is thus attainable. Accordingly, the estimation of age in a log cross-cut, and thus of mean annual ring width, is also feasible, once diameter and heartwood ratio is known. Experiments using IR photography indicate the potential of using such equipment in heartwood detection.
Forfattere
Svein SolbergSammendrag
Det er ikke registrert sammendrag
Forfattere
O. Janne KjønaasSammendrag
Det er ikke registrert sammendrag
Forfattere
P.K. Egeberg Morten Eikenes E.T. GjessingSammendrag
In Norwegian lakes, organic nitrogen typically constitutes about 60% of the total dissolved pool of nitrogen. However, evaluation of its effect on aquatic ecosystems and its role as promoter of heterotrophic growth in water distribution systems is difficult because of restricted knowledge about the various forms of organically-bound nitrogen in water. On line standard wet chemical analysis of total nitrogen was combined with high-performance size exclusion chromatographic (HPSEC) separation of natural organic matter (NOM) for investigation of the distribution of nitrogen between size classes of NOM. It was found that the high molecular weight (HMW) size fractions (humic acids) are enriched in nitrogen relative to the low molecular weight (LMW) size fractions (fulvic acids, nominal molecular weights of about 1000 Daltons) by a factor of up to 10. The low molecular weight size fractions (a few hundred Daltons) are interpreted to be of autocthonous origin based on their low C/N ratios, and correlation with the eutrophic status of the source waters. It was observed that NOM from water sources surrounded by large catchments contains relatively more nitrogen in HMW size fractions than NOM from small catchments, except that bog-derived NOM is particularly enriched in HMW nitrogen.
Sammendrag
Studies were undertaken in forest ecosystems of the northwestern Kola Peninsula, Russia and South-Varanger, Norway in the zone affected by the Pechenganikel smelter. The soils consist mainly of shallow sandy iron-humus-illuvial and iron-illuvial podzols on highly bouldery unsorted morainic deposits of course texture, fluvioglacial sands and bedrocks.Plant specimens were collected from 16 plots located at different distances from the source of emissions: Pinus sylvestris needles, bark and wood, dwarf shrub (Empetrum hermaphroditum, Vaccinium myrtillus and Vaccinium vitis-idaea ) leaves, wavy-hair grass (Deschampsia flexuosa), green mosses (Hylocomium splendens and Pleurozium schreberi) and lichens (Cladina rangifirina [Cladonia rangiferina], and Cladina stellaris [Physcia stellaris]) were collected at the end of the growing season.Results showed that the elemental composition of the dominants of the tree, grass-shrub, and moss layers was affected by the sulfur and heavy metals from the source of pollution. The content of nickel and copper in pine needles near the smelter exceeded control levels by an order of magnitude and the content of sulfur exceeded it twofold, reaching toxic levels.In addition to the direct input of pollutants from the atmosphere, soil contamination by nickel and copper within a 30 km radius of the smelter will have adverse effects on mineral nutrition of plants.It is concluded that the disturbance of biological cycles because of the active involvement of pollutants and the decreased availability of nutrients results in retardation of plant growth, a reduction in forest biomass and alterations in plant succession and species composition that leads to simplification and death of forest ecosystems.
Sammendrag
This study describes how crown density changes were distributed within monitoring plots, in order to determine whether the reduced crown density observed could be explained as a worsening of a limited number of unhealthy or small and slightly suppressed trees.Crown density, yellowing, coning and stem diameter data were available from 447 selected plots comprising 22560 single trees all having a complete 1990-97 series of crown condition data.The eight years series of crown density for each tree were recalculated to two median values, for 1990-93 and 1994-97, in order to reduce the influence from short time variations including random errors. The scores for yellowing and amounts of cones were averaged over the years 1990-93. These variables, and diameter, were recalculated to rank indices within each plot.Relationships between variables were described by graphs and examined by correlation analyses of the indices. The trees tended to retain their internal ranking. Generally, when crown density for a plot has changed, most of the trees were affected. The most defoliated trees in each plots had the least negative changes, but except from that the trees were equally affected regardless of their yellowing, amount of cones, and their size.The results demonstrates that any effects from competition between the trees were sufficiently removed in the assessments, even in densely stocked stands.
Forfattere
Kari Anne SølvernesSammendrag
The impact of climate change, i.e. elevated atmospheric CO2 and increased temperature, on a mini forest ecosystem was studied for three years in an open-top chamber experiment at s, Norway. Clones of Norway spruce (Picea abies L. Karst.) and one clone of Silver birch (Betula pendula Roth.) were grown in monolithic lysimeters containing undisturbed profiles of boreal forest soil. Seedlings and clones of Norway spruce were also grown in pots with fertilised peat. The atmospheric CO2 concentration was increased with 50 and 100 % of the present CO2 concentration, i.e. to approximately 500 and 700 mol mol-1 CO2. Ambient CO2 (380 mol mol-1 CO2) in chambers and at outside control plots (chamber control) were also included. There were two replicates of each treatment.The soil temperature was increased by 2 - 3 C. Growth and chemical composition of plants, leachates and soil chemistry were measured. Elevated CO2 caused a limited growth increase in Norway spruce and Silver birch. The CO2 effect was largest when the plants received good nutrient supply. The effect of CO2 on height increment was probably depended on growth pattern. When the plant exhibited free growth the stimulation of top shoot elongation was larger than when the plant exhibited predetermined growth. The benefit of elevated CO2 was also probably larger for Silver birch than for Norway spruce. The chemical composition of the plants were almost unaffected by elevated CO2. Increased soil temperature caused an increased mineralisation. Increased amounts of N and Al were released and leached from the soil. The data obtained from the leachates from the 500 mol mol-1 CO2 birch lysimeters during the two last growth seasons were surprisingly and not expected. In these leachates the pH and the concentrations of Al and TOC were increased in both replicates compare to the other treatment with birch. It was hypothesised this could be caused by increased exudations of organic compounds from Silver birch roots induced by elevated CO2