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
Abstract
Several studies have been conducted on impregnability of the raw material and large variations have been found. The leaching of wood preservatives into nature is a problem, especially agents that consist copper. Leachability of i. e. copper has been studied by several authors. This study tries to set the variation of leachability of Wolmanit CX-8 and Tanalith in system, evaluating the origin of a tree and the origin of a sample. Samples of Scots pine sapwood (Pinus Sylvestris) (20×20×50 mm) were treated with the wood protection agents Wolmanit CX-8 and Tanalith. The variation in leachability within trees, between trees and between different stands of Scots pine (in Norway and Denmark) was studied. The samples were climatized, impregnated with preservatives and leached according to standard EN84. The study indicates differences between the products. Stand location and samples position in a tree play a role in preservative leaching from wood, favouring southern located trees to be more prone to loosing preservative. Also the lowest part of the tree does not fixate preservatives as well as the upper parts.
Authors
Helja-Sisko Helmisaari Kjersti Holt Hanssen Staffan Jacobson Mikko Kukkola Jukka Luiro Anna Saarsalmi Pekka Tamminen Bjørn TveiteAbstract
The aim of this study was to determine the effect of whole-tree harvesting (WTH) on the growth of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) as compared to conventional stem harvesting (CH) over 10 and 20 years. Compensatory (WTH+ CoF) and normal nitrogen-based (CH + F or WTH+ F) fertilisation were also studied. A series of 22 field experiments were established during 1977–1987, representing a range of site types and climatic conditions in Finland, Norway and Sweden. The treatments were performed at the time of establishment and were repeated after 10–13 years at 11 experimental sites. Seven experiments were followed for 25 years. Volume increment was on average significantly lower after WTH than after CH in both 10-year periods in the spruce stands. In the pine stands thinned only once, the WTH induced growth reduction was significant during the second 10-year period, indicating a long-term response. Volume increment of pine stands was 4 and 8% and that of spruce stands 5 and 13% lower on the WTH plots than on CH during the first and the second 10-year period, respectively. For the second 10- year period the relative volume increment of the whole-tree harvested plots tended to be negatively correlated with the amount of logging residue. Accordingly, the relative volume increment decreased more, the more logging residue was harvested, stressing the importance of developing methods for leaving the nutrient-rich needles on site. If nutrient (N, P, K) losses with the removed logging residues were compensated with fertiliser (WTH+ CoF), the volume increment was equal to that in the CH plots. Nitrogen (150–180 kg ha−1) or N+ P fertilisation increased tree growth in all experiments except in one very productive spruce stand. Pine stands fertilised only once had a normal positive growth response during the first 10-year period, on average 13m3 ha−1, followed by a negative response of 5m3 ha−1 during the second 10-year period. The fertilisation effect of WTH+ F and WTH+ CoF on basal area increment was both smaller and shorter than with CH+ F.
Abstract
The aim of this study was to use energy-dispersive X-ray spectroscopy (EDX) to localize chitosan in the cell wall of chitosan-impregnated Scots pine. It was of interest to investigate the concentration of chitosan in wood to gain further knowledge and understanding of the distribution of chitosan in the wooden matrix. After deacetylation, chitosan was re-acetylated with chloroacetic anhydride to achieve a covalent bonding of chloride to the chitosan polymer. Chloride-labelled chitosan was measured by EDX using a scanning electron microscope and described as chloride intensity. Analysis of free chloride anions was performed by dialysis and inductively coupled plasma atomic emission spectroscopy. There was a significant correlation between the molecular weight of chitosan and the intensity of covalentbonded chloride to the chitosan polymer. High molecular weight chitosan showed a better interaction with the cell wall structure than low molecular chitosan.
Abstract
A rapid increase in the frequency of Dutch elm disease (DED), a wilting disease of elm trees caused by bark-beetle vectored fungi, was observed in the early 1990s on several wych elm stands around Oslofjord, southern Norway. To examine the current status of the disease and its impacts on elm population, disease frequency and size distribution of elms were recorded at four locations. Northern parts of Lier, a municipality most affected by DED in Norway 15 years ago, showed in the survey season 4% disease frequency, whereas 13.8% of trees were dead, the dead trees having accumulated over several years in the unmanaged stands. In southern parts of the municipality the mean disease and death percentages were 1.9 and 2.4%. Compatible with their low disease incidence in early 1990s, the other two areas now examined, municipality of Larvik and district of Grenland, showed comparably low frequency of DED. Northern part of Lier showed significantly higher overall density of elm trees per hectare than the other examined areas, and also the small elms below 5 cm in d.b.h. were most frequent in this region. In contrast, the density of large trees was lower in northern Lier than in the other examined areas. These data suggest that regeneration of the tree is not prohibited owing to the disease but that the large trees have been locally reduced in frequency as a result of DED. The superior general density of elm trees in northern Lier, owing to the exceptionally rich soil in the warm southern slopes of the region,> may have contributed to the rapid increase of DED in the area 15 years ago and to the subsequent settlement of the disease outbreak as a chronic stage.
Authors
Holger LangeAbstract
In ecosystem research, data-driven approaches to modeling are of major importance. Models are more often than not shaped by the spatiotemporal structure of the observations: an inverse modeling approach prevails. Here, I investigate the insights obtained from Recurrence Quantification Analysis of observed ecosystem time series. As a typical example of available long-term monitoring data, I choose time series from hydrology and hydrochemistry. Besides providing insights into the nonstationary and nonlinear dynamics of these variables, RQA also enables a detailed and temporally local model-data comparison.
Abstract
Along the succession gradient of the boreal forest ecosystem, black grouse Tetrao tetrix inhabits the early and capercaillie Tetrao urogallus the latest stages. When converting old forest to clearcuts and plantations, commercial forestry has therefore been assumed to affect capercaillie negatively and to be favourable to black grouse. During a 30-year period (1979–2008) we monitored sympatric populations of the two species in a forest in southeast Norway based on annual spring and autumn censuses and radio-marked birds. During this period, the proportion of old, semi-natural forest was halved and clearcuts and young plantations increased accordingly. The grouse populations did not change as predicted. While the trend in August numbers of adult black grouse declined, males more than females, abundance of adult capercaillie remained unchanged. Number of males at leks showed similar patterns. Equally surprising, breeding success (number of chicks per female in August) of both species increased, thus indicating that the populations were regulated more by variation in adult survivorship than by recruitment of young birds. No correlations were found with changing climatic factors (precipitation and temperatures in winter and spring, snow depth and time of snow melt), except that year-to-year breeding success was positively correlated with minimum temperatures during 2 weeks posthatch. The results are explained by a combination of more flexible habitat selection than previously assumed and a changing predator regime: In the early period, nearly all capercaillie leks were located in old, semi-natural forest, but as plantations grew older (>30 years), new leks were established there. Similarly, while young capercaillie broods used old semi-natural forest almost exclusively when the study started, they frequently used middle-aged plantations, especially those with a ground cover of bilberry Vaccinium myrtillus, when these became common in later years. The increasing breeding success could largely be explained by more females rearing chicks successfully, presumably due to a marked decline in the main nest predator, the red fox Vulpes vulpes. A practice of thinning of the old, semi-natural forest some years prior to final harvesting probably facilitated predation of black grouse by goshawks Accipiter gentilis. Contrary to many beliefs, our results indicate that both capercaillie and black grouse are quite tolerant to changes in forest management regimes. In our study, numerical and functional responses of predators (mainly red fox and goshawk) apparently played a more important role in regulating grouse numbers than habitat factors per se.
Authors
Robin Engler Christophe E. Randin Wilfred Thuiller Stefan Dullinger Niklaus E Zimmermann Miguel B. Araujo Peter B. Pearman Gwenaëlle Le Lay Christian Piedallu Cécile H. Albert Philippe Choler Georghe Coldea Xavier De Lamo Thomas Dirnböck Jean-Claude Gegout Daniel Gómez-García John-Arvid Grytnes Einar Heegaard Fride Høistad Schei David Nogues-Bravo Signe Normand Mihai Puscas Maria Teresa Sebastia Angela Stanisci Jean-Philippe Theurillat Mandar R. Trivedi Pascal Vittoz Antoine GuisanAbstract
Continental-scale assessments of 21st century global impacts of climate change on biodiversity have forecasted range contractions for many species. These coarse resolution studies are, however, of limited relevance for projecting risks to biodiversity in mountain systems, where pronounced microclimatic variation could allow species to persist locally, and are ill-suited for assessment of species-specific threat in particular regions. Here, we assess the impacts of climate change on 2632 plant species across all major European mountain ranges, using high-resolution (ca. 100 m) species samples and data expressing four future climate scenarios. Projected habitat loss is greater for species distributed at higher elevations; depending on the climate scenario, we find 36–55% of alpine species, 31–51% of subalpine species and 19–46% of montane species lose more than 80% of their suitable habitat by 2070–2100. While our high-resolution analyses consistently indicate marked levels of threat to cold-adapted mountain florae across Europe, they also reveal unequal distribution of this threat across the various mountain ranges. Impacts on florae from regions projected to undergo increased warming accompanied by decreased precipitation, such as the Pyrenees and the Eastern Austrian Alps, will likely be greater than on florae in regions where the increase in temperature is less pronounced and rainfall increases concomitantly, such as in the Norwegian Scandes and the Scottish Highlands. This suggests that change in precipitation, not only warming, plays an important role in determining the potential impacts of climate change on vegetation.
Authors
Kari Bjørneraas Erling Johan Solberg Ivar Herfindal Bram Van Moorter Christer Moe Rolandsen Jean-Pierre Tremblay Christina Skarpe Bernt-Erik Sæther Rune Eriksen Rasmus AstrupAbstract
Copyright © 2011 The Authors. Published under a CC-BY license.
Abstract
Ungskogpleie anses å være blant de viktigste behandlingsmessige tiltak man kan gjennomføre i skogen og med solid tradisjon i nordisk skogbruk. I denne artikkelen ser vi litt nærmere på hvordan ungskogpleie bidrar til å påvirke skogens langsiktige utvikling. Skogforskningen har siden 1950-tallet drevet systematiske undersøkelser på effektene av ungskogpleie.
Abstract
Epigenetikk er eit ord på veg inn i daglegtalen. No definert som arvelege endringar i framtoninga fenotypen) av eit individ som ikkje skuldast endringar i sjølve sekvensen av arvematerialet (DNA.) Epigenetikk er no eit av dei mest omtala forskingsområda i biologien.