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.
2003
Authors
H. Mäkinen P. Nöjd H.P. Kahle U. Neumann Bjørn Tveite K. Mielikäinen H. Röhle H. SpieckerAbstract
High-frequency variation of Norway spruce radial increment [Picea abies (L.) Karst.] and its dependence on various climatic variables was compared in stands across latitudinal and altitudinal transects in southwestern and eastern Germany, Norway, and Finland. The tested variables included local temperature and precipitation, northern hemisphere temperature anomalies, and the climatic teleconnection patterns (North Atlantic Oscillation, East Atlantic, East Atlantic Jet, East Atlantic/West Russia, and Scandinavian patterns). Climatic impact on radial increment increased towards minimum and maximum values of the long-term temperature and precipitation regimes, i.e. trees growing under average conditions respond less strongly to climatic variation. Increment variation was clearly correlated with temperature. Warm Mays promoted radial increments in all regions. If the long-term average temperature sum at a stand was below 1,200-1,300 degree days, above average summer temperature increased radial increment. In regions with more temperate climate, water availability was also a growth-limiting factor. However, in those cases where absolute precipitation sum was clearly related to radial increment variation, its effect was dependent on temperature-induced water stress. The estimated dates of initiation and cessation of growing season and growing season length were not clearly related to annual radial increment. Significant correlations were found between radial increment and climatic teleconnection indices, especially with the winter, May and August North Atlantic Oscillation indices, but it is not easy to find a physiological interpretation for these findings.
Abstract
During the first half of the 1990-ies, the microlepidopteran Argyresthia retinella Zeller (Lepidoptera: Yponomeutidae) had an outbreak in mountain birch (Betula pubescens Ehrh. ssp. czerepanovii (Orlova) Hamet-Ahti) forests along the coast of northern Norway. In these regions, A. retinella has a univoltine life history and passes the winter as diapausing eggs, contradictory to previous reports from more southern latitudes of Europe, where newly hatched larvae overwinter. Eggs were deposited under lichen, mainly on branches and twigs, and avoided freezing by their ability to supercool. The mean supercooling points (SCPs) from October to March ranged between -35.5 and -36.5 C (lowest in January), and the eggs did not survive exposure below these temperatures. Diapause was terminated in the middle of February, and in April and May the SCP rose to about -30 C. Pre-freeze mortality was evident and had a significant impact on survival when eggs were exposed to temperatures above the SCP.
Abstract
No abstract has been registered
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Authors
Svein Ole Borgen Anne Moxnes JervellAbstract
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Authors
Morten NittebergAbstract
The Norwegian Forest Research Institute (Skogforsk) is conducting a study of mechanised harvesting in cable operations.The activity of cable crane systems is heavily reduced the last years in Norway. There are different reasons for this:Low price on wood High direct logging cost Relative low technical development Hard to recruit workers General scepticism to logging in steep terrain, due to environmental influences The positive environmental effect by use of cable crane systems is not well known, and is overshadowed by the negative publicity. Use of cable crane systems may among other things contribute to reduce technical encroachment in the terrain, road building, and wheeled terrain transport.When the harvesting operation in steep terrain is mechanised the safety will increase and the working load will be easier. We hope this will have a positive effect on recruiting workers to this kind of work.The use of harvester inn logging operation will probably also increase the productivity of the cable crane system, and will hopefully give better economy for steep terrain harvesting. A harvester (Menzi Muck A71) is developed in Switzerland for use in steep and difficult terrain. The harvester is based on a Menzi Muck excavator. The machine is mainly build for operations in steep terrain up to 60 %, but with a safety winch it may operate in steepness up to 100%.The Menzi Muck harvester is now working together with a Owren 400 cable crane system in steep terrain (30 70 % steepness), and Skogforsk will during the project period study the productivity and the operating cost of the cable crane system in cooperation with Menzi Muck harvester, and compare the result with ordinary manual felling. This will be done time study and operational statistics.The project started up 1 July 2002, so at this moment we do not have much data, but within March 2003 we will have data enough to present some results.
Authors
J.W. Hudgins Erik Christiansen Vincent R. FranceschiAbstract
Conifers have defenses such as the production of phenolic compounds and resins that can be induced by bark beetles and other invading organisms, but the signaling agents involved are unknown. The anatomical effects of methyl jasmonate (MJ), a potent inducer of certain plant defenses, were compared with wounding of the bark of 1215-year-old trees of five conifer species.Wounding in all species resulted in tissue necrosis and wound periderm development immediately around the wound site. One cm from the wound, swelling of phloem polyphenolic parenchyma cells and phenolic accumulation were observed in Pseudotsuga menziesii (Mirb.) Franco, Picea pungens Engelman, Larix occidentalis Nutt. and Pinus monticola Douglas ex D. Don, but not in Taxus brevifolia Nutt.Traumatic resin ducts were formed in response to wounding in three species of Pinaceae, but not in P. monticola, which formed irregular clusters of cells rather than ducts. Taxus brevifolia did not form resin ducts in response to either wounding or MJ treatment.In the Pinaceae species studied, surface application of 100 mM MJ caused similar anatomical changes to those observed in response to wounding, including phenolic accumulation, cell swelling and traumatic resin duct formation, but it did not induce a wound periderm.Traumatic resin ducts differed in size among the study species, ranging from small in L. occidentalis to very large in P. menziesii. In P. menziesii, P. pungens and L. occidentalis, traumatic resin ducts were more abundant after MJ treatment than after wounding. We conclude that the octadecanoid pathway is likely involved in defense responses in stems of the Pinaceae, but not necessarily in other taxa.
Authors
Trond Knapp Haraldsen Per Anker PedersenAbstract
No abstract has been registered
Authors
B. Michalzik Edward Tipping Jan Mulder J.F. Gallardo Lancho Egbert Matzner C.L. Bryant Nicholas Clarke S. Lofts J.F. Vicente EstebanAbstract
DyDOC describes soil carbon dynamics, with a focus on dissolved organic carbon (DOC). The model treats the soil as a three-horizon profile, and simulates metabolic carbon transformations, sorption reactions and water transport. Humic substances are partitioned into three fractions, one of which is immobile, while the other two (hydrophilic and hydrophobic) can pass into solution as DOC. DyDOC requires site-specific soil characteristics, and is driven by inputs of litter and water, and air and soil temperatures. The model operates on hourly and daily time steps, and can simulate carbon cycling over both long (hundreds-tothousands of years) and short (daily) time scales. An important feature of DyDOC is the tracking of 14C, from its entry in litter to its loss as D014C in drainage water, enabling information about C dynamics to be obtained from both long-term radioactive decay, and the characteristic 14C pulse caused by thermonuclear weapon testing during the 1960s ("bomb carbon"). Parameterisationis performed by assuming a current steady state. Values of a range of variables, including C pools, annual DOC fluxes, and 14C signals, are combined into objective functions for least-squares minimisation. DyDOC has been applied successfully to spruce forest sites at Birkenes (Norway) and Waldstein ( Germany), and most of the parameters have similar values at the two sites. The results indicate that the supply of DOC from the surface soil horizon to percolating water depends upon the continual metabolic production of easily leached humic material. In contrast, concentrations and fluxes of DOC in the deeper soil horizons are controlled by sorption processes, involving comparatively large pools of leachable organic matter. Times to reach steady stateare calculated to be several hundred years in the organic layer, and hundreds-to-thousands of years in the deeper mineral layers. It is estimated that DOC supplies 89 % of the mineral soil carbon at Birkenes, and 73 % at Waldstein. The model, parameterised with "steady state" data, simulates short-term variations in DOC concentrations and fluxes, and in DO 14C, which are in approximate agreement with observations
Abstract
No abstract has been registered