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.
2012
Authors
Mette Thomsen Bertalan Galambosi Zsuzsanna Galambosi Marja Uusitalo Ruth Mordal Alpo HeinonenAbstract
In the present study we evaluated the effect of phenological stage at harvest and drying temperature on the content of secondary metabolites in six year old cultivatedclones of Rhodiola rosea. The experimental work was performed in cooperation between MTT in Finland and Bioforsk in Norway. In spite of the differences in growing season, we found similar development in biomassproduction and content of secondary metabolites in the two field experiments.During the period with intensive shoot growth the dry weight of the rootdecreased until budding / full flowering followed by an increase towards thelast harvest after wilting. The % dry matter followed the same development. The content of total rosavins in the dry rhizomes was highest at flowering at both sitesand the average content for spring was 24 % respectively 21% higher than inautumn in Finland and Norway (P=0,002). In Finland the average content of salidroside in spring of the dry rhizomewas 68 % higher than in autumn. While in Norway there were no differences insalidroside content at the different phenological stages (P = 0,097), lowvariation in the content of cinnamic alcohol at both sites was observed, but atendency to a small increase after flowering. The content of total rosavins was significantly higher at drying temperatures at or below 50˚C (P
Authors
J. Limpens G. Granath R Aerts M. M. P. D. Heijmans L. J. Sheppard L. Bragazza B. L. Williams H. Rydin J. Bubier T. Moore L. Rochefort E. A. D. Mitchell A Buttler L. J. L. van den Berg U Gunnarsson AJ Francez R Gerdol M. Thormann P. Grosvernier M. M. Wiedermann M. B. Nilsson M. R. Hoosbeek S. Bayley Jørn-Frode Nordbakken M. P. C. P. Paulissen S. Hotes A. Breeuwer M. Ilomets H. B. M. Tomassen I. Leith B. XuAbstract
Peat bogs have accumulated more atmospheric carbon (C) than any other terrestrial ecosystem today. Most of this C is associated with peat moss (Sphagnum) litter. Atmospheric nitrogen (N) deposition can decrease Sphagnum production, compromising the C sequestration capacity of peat bogs. The mechanisms underlying the reduced production are uncertain, necessitating multifactorial experiments.•We investigated whether glasshouse experiments are reliable proxies for field experiments for assessing interactions between N deposition and environment as controls on Sphagnum N concentration and production. We performed a meta-analysis over 115 glasshouse experiments and 107 field experiments.•We found that glasshouse and field experiments gave similar qualitative and quantitative estimates of changes in Sphagnum N concentration in response to N application. However, glasshouse-based estimates of changes in production – even qualitative assessments – diverged from field experiments owing to a stronger N effect on production response in absence of vascular plants in the glasshouse, and a weaker N effect on production response in presence of vascular plants compared to field experiments.•Thus, although we need glasshouse experiments to study how interacting environmental factors affect the response of Sphagnum to increased N deposition, we need field experiments to properly quantify these effects.
Authors
Stein Michael Tomter Patrizia Gasparini Thomas Gschwantner Petra Hennig Gintaras Kulbokas Andrius Kuliesis Heino Polley Nicolas Robert Jacques Rondeux Giovanni Tabacchi Erkki TomppoAbstract
Estimates of growing stock in European countries vary mainly by using different thresholds for dbh of sample trees, as well as by the inclusion or exclusion of stump and stem top volume. European national forest inventories use dbh thresholds ranging from 0 to 12 cm in estimating the volume of growing stock. COST Action E43 has agreed to a reference definition for growing stock with a dbh threshold of 0 cm. With use of national volume distributions by dbh classes, models for estimating the proportions of growing stock between the national threshold and the 0-cm threshold were constructed. Models for characterizing growing stock distributions were tested, and their predictive abilities were investigated. Similar comparisons were made with respect to the volume of stumps and stem tops. Examples of estimation methods and the resulting percentages of these tree elements of total growing stock are presented.
Abstract
Harvest activity directly impacts timber supply, forest conditions, and carbon stock. Forecasts of the harvest activity have traditionally relied on the assumption that harvest is carried out according to forest management guidelines or to maximize forest value. However, these rules are, in practice, seldom applied systematically, which may result in large discrepancies between predicted and actual harvest in short-term forecasts. We present empirical harvest models that predict final felling and thinning based on forest attributes such as site index, stand age, volume, slope, and distance to road. The logistic regression models were developed and fit to Norwegian national forest inventory data and predict harvest with high discriminating power. The models were consistent with expected landowners behavior, that is, areas with high timber value and low harvest cost were more likely to be harvested. We illustrate how the harvest models can be used, in combination with a growth model, to develop a national business-as-usual scenario for forest carbon. The business-as-usual scenario shows a slight increase in national harvest levels and a decrease in carbon sequestration in living trees over the next decade.
Abstract
Various oils can be used to lower the equilibrium moisture content and increase the service life of Scots pine wood products. The aim of this study was to investigate effects of the lateral wood zone on the brown rot resistance of untreated and linseed oil-impregnated Scots pine wood in a laboratory test (EN 113). Significant differences were found in the mean mass losses of treated and untreated specimens taken from three lateral heartwood zones, but not between specimens taken from sapwood. The treatment had no significant effect on sapwood, although it seems to have some positive effect on the durability of heartwood, apparently due to interactive effects with the high extractives contents of heartwood.
Authors
Jozef Martinka Karol Balog Tomás Chrebet Emília Hroncová Janka DibdiakovaAbstract
The presented article deals with the assessment of combined impact of temperature and flow of oxidising atmosphere, its oxygen concentration and heat flux on the ignition time of isotactic polypropylene (PP). The ignition time was determined in a specially adapted hot air Setchkin furnace at temperatures (450 and 600 °C), density of heat flux (12.4 and 26.4 kW m−2), flows of oxidation mixture (6 and 8 L min−1) and volume oxygen concentrations (3, 9, 15, 21, 27, 33, 39, 45 and 50 %). Obtained data allows us to assume that the temperature influence on PP induction period of ignition increases with decreasing flow rate of oxidising atmosphere. At the flow of oxidising mixture equal to 6 L min−1 and temperature of 600 °C, oxygen concentration had only a negligible impact on the the induction period of ignition in the analysed period. From the presented results, the induction period of ignition depends on the temperature and also on the flow rate of oxidising mixture and oxygen concentration in it. In addition, heat flux has a significant influence on the induction period. However, the quantification of the heat flux influence was not possible with the applied experimental device.
Authors
Håvard Kauserud Einar Heegaard Ulf Büntgen Rune Halvorsen Simon Egli Beatrice Senn-Irlet Irmgard Krisai-Greilhuber Wolfgang Dämon Tim Sparks Jenni Nordén Klaus Høiland Paul Kirk Mikhail A. Semenov Lynne Boddy Nils Christian StensethAbstract
In terrestrial ecosystems, fungi are the major agents of decomposition processes and nutrient cycling and of plant nutrient uptake. Hence, they have a vital impact on ecosystem processes and the terrestrial carbon cycle. Changes in productivity and phenology of fungal fruit bodies can give clues to changes in fungal activity, but understanding these changes in relation to a changing climate is a pending challenge among ecologists. Here we report on phenological changes in fungal fruiting in Europe over the past four decades. Analyses of 746,297 dated and geo-referenced mushroom records of 486 autumnal fruiting species from Austria, Norway, Switzerland, and the United Kingdom revealed a widening of the annual fruiting season in all countries during the period 1970–2007. The mean annual day of fruiting has become later in all countries. However, the interspecific variation in phenological responses was high. Most species moved toward a later ending of their annual fruiting period, a trend that was particularly strong in the United Kingdom, which may reflect regional variation in climate change and its effects. Fruiting of both saprotrophic and mycorrhizal fungi now continues later in the year, but mycorrhizal fungi generally have a more compressed season than saprotrophs. This difference is probably due to the fruiting of mycorrhizal fungi partly depending on cues from the host plant. Extension of the European fungal fruiting season parallels an extended vegetation season in Europe. Changes in fruiting phenology imply changes in mycelia activity, with implications for ecosystem function.
Abstract
Stand and disturbance dynamics are key processes that need to be assessed along with climate-species interactions if we are to better understand the impacts of climate change on species. In this study we investigated the biotic interactions (competition) between species, the influence of disturbance type, and changes in resource availability (moisture and light) on the response of six tree species to climate change in the northwest region of central British Columbia, Canada. Two ecological models were parameterized, linked together and coupled to climate change scenarios to explore the interactions between: (1) the response of species in the regeneration phase and (2) the role of disturbance, resource availability and competition on determining stand composition and productivity. Climate change was found to reduce soil moisture availability which resulted in a decline in regeneration potential for all species on dry sites and negative to neutral responses on sites with higher water availability. Following fire, stand dynamics and composition were modeled to undergo significant changes under the 2080s climate compared to current climate conditions on dry and mesic sites. Changes in stand dynamics under climate change were marginal following bark beetle disturbances. While significant changes to stand dynamics were found on dry sites, the presented results suggest that the sites with the highest moisture availability maintain the same general stand dynamics and composition following disturbances under climate change. This study highlights the need to consider species response to climate change in interaction with existing stand conditions, disturbance type, competition, resource availability, not just temperature and precipitation.
Authors
Peder GjerdrumAbstract
Scaling accuracy is of utmost importance to obtain optimal sawn timber yield in primary breakdown. In this article, sawmill observations, review of available publications and supplementary tests are combined to analyse the accuracy of conifer roundwood scaling. The influence of important log parameters are considered for various scaling technology: one- and twodirectional (1Dir and 2Dir) shadow scanners and three-dimensional (3Dim) reflected beam scanners. Standard error for each of the terms, ovality, bark and scanner technology, is discussed. The overall accuracy for diameter under bark can be calculated by adding the variances for each independent term. Results show that for unbarked logs, 2Dir shadow scanner remains the most accurate technology. For barked logs, 3Dim reflected laser beam scanner combines the highest accuracy and the ability of providing a wide range of important log parameters. For a case study sawmill, annual roundwood consumption are reduced by 2.0% by transferring from scaling unbarked logs in a two-dimensional shadow scanner to 3Dim scanning of barked logs, while keeping the volume yield of the sawn timber.
Authors
Bernt-Håvard Øyen Petter Nilsen Fredrik Bøhler Kjell AndreassenAbstract
Models for predicting diameter increment in multi-storey spruce stands following mountain forest selective cutting (MFS) were developed. They were based on increment cores, tree ring analyses and stump registrations. The presented models rely upon time series data from 1600 trees in thirty-one Norway spruce stands in south-eastern and central parts of Norway. The selective cuttings were heavy; on average two thirds of the standing volume were cut. The increment following the interventions was highly variable, resulting in large random variability in the models with R2 varying between 0.18–0.31 for individual tree diameter growth and 0.40–0.50 for mean tree stand diameter growth. Dummy variables referring to three first 5-year periods after cutting were found to increase the precision and significantly reduce the random error. Selected models were validated using a test material from central Norway and also compared with the mostly applied Norwegian diameter increment models. Despite a large random variation in all models, the model performances appeared logical and the general fit to the data was acceptable. Based on tests, two diameter increment models are recommended for future yield prognoses in MFS. The models should also be of interest for wider use in other parts of the Nordic and Baltic boreal zone.