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.
2011
Sammendrag
This study is a part of a larger project designed to find out the causes of top dieback symptoms in Norway spruce in SE Norway. Because sapwood tracheids constitute a water transport system while parenchyma serves as a reserve tissue (Sellin, 1991), the separation and quantification of the sapwood and heartwood may contribute to understanding of the healthy tree functioning. As the extent of sapwood is related to tree vitality, it reflects the tree growth, health and effect of environmental factors (Sandberg & Sterley, 2009). Therefore, the sapwood cross-sectional area is widely used as a biometric parameter indicating the tree vitality, although its estimation and evaluation is prone to scaling errors....
Forfattere
Johannes BreidenbachSammendrag
The aim in the analysis of sample surveys is frequently to derive estimates of sub-population characteristics. This task is denoted small area estimation (SAE). Often, the sample available for the sub-population is, however, too small to allow a reliable estimate. Frequently, auxiliary variables exist that are correlated with the variable of interest. Several estimators can make use of auxiliary information which may reduce the variance of the estimate.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Wood protection in the last century has mainly been based on chemical treatments. Additionally, the type of construction of wooden buildings and the choice of wood species play an important role. Degradation of wood is not only caused by fungi or bacteria but also by insects. Termites have been a potential risk to wooden structures not only in the warmer regions of our continents but also beyond the regions of their natural habitat due to transport of wood. A new treatment, Electro osmotic pulsing technology (PLEOT), has been tested in lab termite tests and fungi tests. The two choice and non-choice termite tests were carried out using different duration of exposure and different initial wood moisture content. The results show growth of mould fungi on untreated wood samples with high initial wood moisture content after 4 weeks of termite testing whereas PLEOT treatment strongly reduced the development of moulds. Termite mortality was high on untreated wood samples with high initial moisture content but not on wood samples with low initial moisture content. This is explained by mould growth on the wetter samples, which termites don\"t tolerate in large amounts. The loss of wood mass due to termite attack could be reduced by using PLEOT. The mortality of termites was higher in test systems with protected wood samples than untreated samples. PLEOT could be used successfully against fungal attack. The treatment reduced on the one hand mould growth in a termite test and on the other hand reduced strongly the attack of brown rot fungi in a lab test.
Forfattere
Kjell Andreassen Nicholas Clarke Jørn-Frode Nordbakken Ingvald Røsberg Volkmar Timmermann Tonje ØklandSammendrag
Rapporten presenterer sammendrag av resultatene for 2010 fra tre overvåkingsprogrammer: “Overvåking av langtransportert forurenset luft og nedbør”, ”Overvåkingsprogram for skogskader” (OPS) og “Program for terrestrisk naturovervåking” (TOV). The report presents results for 2010 from three national monitoring programmes on long-range transboundary air pollution.
Sammendrag
A changing climate will likely influence the selection of tree species in the future, and this may in turn affect the size of the pools and fluxes of carbon. Tree species differ in growth rate, fine-root turnover and quality of litter and tend to produce different types of understory vegetation. In Sweden three tree species (Norway spruce [Picea abies] 43%, Scots pine [Pinus sylvestris] 39% and birch [Betula spp.] 11%) dominate. In the present study we used field experiments in southern Sweden to test if these tree species differed in root distribution and turnover.
Sammendrag
Biodiversity is assumed to have high value for many people, but the necessary preservation also incurs a cost for the forest owner. Typically, studies of this cost are at the stand level, and hence, not very accurate as the cost may vary even within the stand. In this work, we use a 1m×1m grid, generated from LIDAR data, to estimate the cost for harvesting and forwarding. The method could be utilized to calculate compensation, and to select between key woodland habitats to minimise the cost. In three of four test cases, the main cost was reduced harvested volume, but in one case the key woodland habitat also made the harvesting operations more expensive.
Forfattere
Kjell Andreassen Bernt-Håvard ØyenSammendrag
Fourteen Nordic increment functions have been validated by use of with a test data set from long-term research plots in Norway of even-aged, pure stands of Scots pine, Birch and Norway spruce. In selected functions from Denmark, Finland, Norway and Sweden measures of site productivity, mean tree size and various stand characteristics are represented. Different models display both strengths and weaknesses in their predicting ability. Some measures of precision and bias have been calculated and the functions are ranked due to their performance. Basal area increment models for spruce and pine from Sweden, and a Finish volume increment model for birch has the best fit to the Norwegian test data. Some of the growth models developed outside Norway estimate the growth with about the same accuracy as the models frequently used and developed in Norway. The results indicate that forest conditions and traditional even-aged forest management practice in the Nordic countries seem to have small influence on the relative growth of even-aged stands. By careful recalibration of existing functions from other Nordic countries with data from Norway, a reasonable accuracy could be achieved in Norwegian forest with a reduction of the bias.
Forfattere
Bruce Talbot Morten NittebergSammendrag
In the coastal region of Norway, large volumes of relatively inaccessible plantation timber are maturing for harvest. The economic feasibility of accessing much of this timber has limited the level of harvesting activity considerably. Harvesting planners are faced with the classic dilemma of finding the appropriate level of investment in infrastructure, as against inoptimal transportation. In this paper, we present results from a simple deterministic simulation carried out to illustrate the efficiency frontiers of three transport methods, one of which requires a substantial investment in road upgrading. Results depend on assumptions made, but clearly show that in these conditions, upgrading roads for truck+trailer transport should be evaluated on a cases by case basis. Forest road length and condition, public road distance to conversion site, and investment level all play important roles in the decision structure. In the coastal regions, road upgrades would generally need to be justified by benefits other than timber harvesting alone.
Sammendrag
Understanding the driving forces affecting species occurrences is a prerequisite for determining the indicator suitability of crenic plants. We analysed 18 environmental variables in a two-step approach, evaluating their ability to explain the species composition of 222 springs on five siliceous mountain ranges, in central Germany and north-west Czech Republic (49.9°–50.8°N, 10.6°–12.8°E). First, we identified the significant environmental variables in three subsets of spatial, hydrophysical and hydrochemical variables using a forward-selection procedure. We then performed a partial canonical correspondence analysis (pCCA) to estimate the influence of each subset alone, as well as in combinations. We also used a multiple response permutation procedure (MRPP) to compare the five regions with respect to the dissimilarity of their vegetation composition and environmental variables. Hydrochemical factors played a fundamental role in determining the plant community of the investigated springs. Spatial factors, in particular altitude, were correlated with the hydrochemical factors, but were less important. Hydrophysical factors played only a marginal role. More precisely, species occurrence was mainly driven by a gradient of nutrient availability, which in turn reflected the acidity status. This gradient was primarily represented by high Al, Cd, and Mn concentrations in acidic crenic waters, high Ca and Mg concentrations were encountered in circumneutral springs. By comparing the five regions we could show that there are spatial patterns in the vegetation of springs, which provide valuable ecological information on the water quality. We therefore suggest that biomonitoring approaches to vegetation are suitable for revealing the acidity status of springs and their forested catchments.