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.
2013
Authors
Peder Gjerdrum Birger EikenesAbstract
Strength properties are central for most wood applications. This paper describes variation of and co-variation between various strength parameters observed in clear wood. More than a dozen strength and density parameters were measured, each on ten samples from five different height levels from each of 21 planted, mature spruce trees. In general, strength and coefficient of variation comply with standard listed values. Between strength parameters usually modest, but always positive, correlation was found. Only 53% of the overall strength variation could be extracted in the first principal component, related to density. MOE and MOR are the two most closely correlated traits, and cleavage the one to show weakest connection to all other traits. Compression, MOR and hardness are closest correlated to density; however, the significance of density being partially masked by a considerable variation between samples from similar locations in the stem supposed to demonstrate parallel quality. All traits are stronger correlated to density than to ring width. In addition to density a substantial part, 5 to 30%, of strength variation could be attributed to tree effect, indication a potential for strength improvement by genetic selection. The finding confirms strength parameters to be far from collinear, i.e. strength is truly multidimensional.
Abstract
No abstract has been registered
Abstract
Fine roots contribute to net primary production in forests, but knowledge of fine root longevity and turnover is still incomplete and limited to few tree species. In this study, we used minirhizotrons to compare fine root biomass, longevity and turnover of Pinus sylvestris L., Betula pendula Roth and Picea abies (L) Karst. in southern Sweden. Minirhizotron tubes were installed in 2006 and root images were taken in 2007–2010. Soil cores were used to estimate fine root biomass. Soil samples were taken from the humus layer and from 0 to 10 cm, 10 to 20 cm and 20 to 30 cm depth in the mineral soil. Only images from the humus layer and the upper 10 cm of mineral soil were included in root analysis. Spruce has a higher aboveground production than pine and birch in southern Sweden and this was reflected in larger fine root biomass as well as higher fine root biomass production. The annual tree fine root biomass production (humus and 0–30 cm in mineral soil) was 73, 78 and 284 g m−2 in pine, birch and spruce stands, respectively. Thicker fine roots tended to live longer. The majority of the fine roots were thinner than 0.5 mm in diameter, with a turnover rate (KM) of 0.4 year−1. When comparing all fine roots, i.e. all roots 0–2 mm, pine had the highest longevity, 1120 days, compared with 900 days for spruce and 922 days for birch (KM).
Abstract
No abstract has been registered
Authors
Felix Herzog Philippe Jeanneret Youssef Ammari Siyka Angelova Michaela Arndorfer Debra Bailey Katalin Balázs András Báldi Marion Bogers Robert Bunce Jean-Philippe Choisis David Cuming Peter Dennis Tetyana Dyman Sebastian Eiter Zoltán Elek Eszter Falusi Wendy Fjellstad Thomas Frank Jürgen Friedel Salah Garchi Ilse Geijzendorffer Tiziano Gomiero Gergely Jerkovich Rob Jongman Max Kainz Esezah Kakudidi Eszter Kelemen Roland Kölliker Norman Kwikiriza Anikó Kovács-Hostyánszki Luisa Last Gisela Lüscher Gerardo Moreno Charles Nkwiine John Opio Marie-Louise Oschatz Maurizio Guido Paoletti Károly Penksza Philippe Pointereau Susanne Riedel Jean-Pierre Sarthou Manuel Schneider Norman Siebrecht Daniele Sommaggio Siyka Stoyanova Erich Szerencsits O. Szalkovski Stella Targetti Davide Viaggi Jerylee Wilkes-Allemann Sebastian Wolfrum Sergiy Yashchenko Tommaso ZanettiAbstract
No abstract has been registered
Abstract
To better understand the historic range of variability in the fire regime of Fennoscandian boreal forests we cross-dated 736 fire scars of remnant Scots pine (Pinus sylvestris L.) wood samples in a 3.6 km2 section of the Trillemarka-Rollagsfjell Reserve of south-central Norway. Using a kernel range application in GIS we spatially delineated 57 individual forest fires between 1350 and the present. We found a strong anthropogenic signal in the fire regime from 1600 and onwards: (i) infrequent variably sized fires prior to 1600 shifted to frequent fires gradually decreasing in size during the 1600s and 1700s, with only a few small fires after 1800; (ii) time intervals between fires and the hazard of burning showed substantial differences pre- and post-1600; (iii) fire seasonality changed from late- to early-season fires from the 1626 fire and onwards; and (iv) fire severity decreased gradually over time. Written sources corroborated our results, narrating a history where anthropogenic forest fires and slash-and-burn cultivation expanded with the increasing population from the late 1500s. Concurrently, timber resources increased in value, gradually forcing slash-and-burn cultivators to abandon fires on forest land. Our results strengthen and expand previous Fennoscandian findings on the anthropogenic influence of historic fire regimes.
Authors
Joachim Paul Spindelbøck Zöe Cook Matthew I. Daws Einar Heegaard Inger Elisabeth Måren Vigdis VandvikAbstract
Background and Aims: Across their range, widely distributed species are exposed to a variety of climatic and other environmental conditions, and accordingly may display variation in life history strategies. For seed germination in cold climates, two contrasting responses to variation in winter temperature have been documented: first, an increased ability to germinate at low temperatures (cold tolerance) as winter temperatures decrease, and secondly a reduced ability to germinate at low temperatures (cold avoidance) that concentrates germination towards the warmer parts of the season. Methods: Germination responses were tested for Calluna vulgaris, the dominant species of European heathlands, from ten populations collected along broad-scale bioclimatic gradients (latitude, altitude) in Norway, covering a substantial fraction of the species' climatic range. Incubation treatments varied from 10 to 25 °C, and germination performance across populations was analysed in relation to temperature conditions at the seed collection locations. Key Results: Seeds from all populations germinated rapidly and to high final percentages under the warmer incubation temperatures. Under low incubation temperatures, cold-climate populations had significantly lower germination rates and percentages than warm-climate populations. While germination rates and percentages also increased with seed mass, seed mass did not vary along the climatic gradients, and therefore did not explain the variation in germination responses. Conclusions: Variation in germination responses among Calluna populations was consistent with increased temperature requirements for germination towards colder climates, indicating a cold-avoidance germination strategy conditional on the temperature at the seeds' origin. Along a gradient of increasing temperatures this suggests a shift in selection pressures on germination from climatic adversity (i.e. low temperatures and potential frost risk in early or late season) to competitive performance and better exploitation of the entire growing season.
Abstract
No abstract has been registered
Authors
Stefanos Xenarios Paul PavelicAbstract
No abstract has been registered