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
Audun Korsæth Anne Zimmer Jacobsen Anne-Grete Roer Hjelkrem Trond Henriksen U. Sonesson Arne Oddvar Skjelvåg Helge Bonesmo Anders Hammer StrømmanAbstract
This is an Accepted Manuscript of an article published by Taylor & Francis in Acta Agriculturae Scandinavica, Section A - Animal Science on 30 Apr 2013, available online: http://www.tandfonline.com/doi/abs/10.1080/09064702.2013.783619
Abstract
No abstract has been registered
Abstract
The use of forest biomass for bioenergy purposes, directly or through refinement processes, has increased in the last decade. One example of such use is the utilization of logging residues. Branch biomass constitutes typically a considerable part of the logging residues, and should be quantified and included in future forest inventories. Airborne laser scanning (ALS) is widely used when collecting data for forest inventories, and even methods to derive information at the single-tree level has been described. Procedures for estimation of single-tree branch biomass of Norway spruce using features derived from ALS data are proposed in the present study. As field reference data the dry weight branch biomass of 50 trees were obtained through destructive sampling. Variables were further derived from the ALS echoes from each tree, including crown volume calculated from an interpolated crown surface constructed with a radial basis function. Spatial information derived from the pulse vectors were also incorporated when calculating the crown volume. Regression models with branch biomass as response variable were fit to the data, and the prediction accuracy assessed through a cross-validation procedure. Random forest regression models were compared to stepwise and simple linear least squares models. In the present study branch biomass was estimated with a higher accuracy by the best ALS-based models than by existing allometric biomass equations based on field measurements. An improved prediction accuracy was observed when incorporating information from the laser pulse vectors into the calculation of the crown volume variable, and a linear model with the crown volume as a single predictor gave the best overall results with a root mean square error of 35% in the validation.
Abstract
1. Neodiprion sertifer nucleopolyhedrovirus (NeseNPV) is widely used as a viral bio-insecticide against larvae of the European pine sawfly N. sertifer (Geoff.) (Hymenoptera: Diprionidae), which is one of the most harmful defoliators of pines in Northern Europe. A major obstacle to studying this pathogenic virus in nature is the difficulty of confirming and quantifying the presence of NeseNPV. 2. In the present study, we developed real-time polymerase chain reaction (PCR) primers, based on the caspid gene 39 sequence, for the specific and quantitative detection of NeseNPV. The quantitative real-time PCR (qPCR) assay can detect virus from any substrate tested, including different insect life stages (egg, larval, adult), pine foliage, and litter or ground vegetation. The reproducible detection limit for the real-time assay is 0.013 pg of viral DNA (0.013 × 10−12 g), corresponding to 136 viral genomes or approximately one to seven virus occlusion bodies per sample. 3. qPCR is a specific, quantitative, sensitive, reliable and flexible procedure, and is a good supplement to conventional microscopy- or bioassay-based methods for detection of the virus. We have used qPCR to quantify the level of NeseNPV in samples collected in the field after aerial application of the virus, and demonstrated significantly higher virus levels in sawfly larvae from sprayed areas compared with unsprayed control areas 4 weeks after spraying. 4. This qPCR assay can be used to determine important aspects of the biology of NeseNPV (e.g. virus levels in different insect life stages and in their microhabitats on pine foliage and in forest litter).
Authors
Toril Drabløs Eldhuset Nina Elisabeth Nagy Daniel Volařík Isabella Børja Roman Gebauer Igor A. Yakovlev Paal KrokeneAbstract
Purpose: Drought-induced tree susceptibility is a major risk associated with climate change. Here we report how an 11-week drought affected tracheid structure, gene expression, and above- and belowground growth in 5-year-old Norway spruce trees (Picea abies) under controlled conditions. Results: The canopy of trees subjected to severe drought had significantly less current-year needle biomass, and fewer tracheids and tracheid rows in current-year shoots compared to fully watered control trees. Belowground tissues were more strongly affected by drought than aboveground tissues. In fine roots (<2 mm diameter) severe drought significantly reduced root biomass, root diameter, root length density and root surface area per soil volume compared to the control. Tracheid diameter and hydraulic conductivity in fine roots were significantly lower and tracheid flatness higher in trees subjected to severe drought than in control trees, both for long and short roots. Transcripts of the drought-related dehydrins PaDhn1 and PaDhn6 were strongly upregulated in stem bark and current-year needles in response to drought, whereas PaDhn4.5 was down-regulated. Conclusions: This study demonstrates that drought reduces biomass and hydraulic conductivity in fine roots and needles. We suggest that the ratio between PaDhn6 and PaDhn4.5 may be a sensitive marker of drought stress in Norway spruce.
Abstract
Fire is the most important ecological factor governing boreal forest stand dynamics. In low- to moderate-severity fires, the post-fire growth of the surviving trees varies according to fire frequency, intensity and site factors. Little is known about the growth responses of Scots pine (Pinus sylvestris L.) following fires in boreal forests. We quantified changes in tree growth in the years following 61 historical forest fires (between 1210 and 1866) in tree-ring series collected from fire-scarred Scots pine trees, snags and stumps in Trillemarka nature reserve in south-central Norway. Basal area increment 10 years pre-, 5 years post-, and 11-20 years post-fire were calculated for 439 fire scars in 225 wood samples. We found a slight temporary growth reduction 5 years post-fire followed by a marked growth increase 11-20 years post-fire. Beyond 20 years post-fire, the long-term tree growth declined steadily up to approximately 120 years. Our results indicate that recurring fires maintained high tree growth in remnant Scots pines, most probably due to a reduction in tree density and thus decreased competition.
Authors
Erlend Nybakk Anders Lunnan Jan Inge Jenssen Pablo CrespellAbstract
Accepted version of an article from journal of Biomass and Bioenergy
Abstract
No abstract has been registered
Abstract
In Norway, water quality of small streams draining agricultural catchments has been monitored since 1993 by the Agricultural and Environmental Monitoring Program. This article attempted to examine the concentration levels, temporal dynamics and long-term trends (1993–2009 and 1996–2009) of Al, Fe, Cu, Mn and Zn in streams draining the catchment areas of Skuterud (4.5 km2) and Mørdre (6.8 km2), located in south-east Norway. In the Mørdre stream, Al, Fe, Cu, Mn and Zn all showed statistically significant downward trends (p<0.05), whilst in the Skuterud stream only Al and Fe showed statistically downward significance (p<0.05). The general declining trends of metal concentrations are most likely associated with reduction of acid rain deposition in southern Norway. In spite of this declining trends, over the 14–17 years of monitoring mean monthly concentrations of total Al (2.0–3.2 mg L−1), Fe (1.3–2.5 mg L−1) and Cu (8.9–26.1 µg L−1) in Skuterud and Mørdre streams, respectively exceeded the limits of the Norwegian Water Framework Directives, whereas the concentrations of Mn (22.3–40.8 µg L−1) and Zn (13.1–99.4 µg L−1) fell within the range of desired limits. Of the total water samples analysed from Skuterud (n=370) and Mørdre streams (n=255), nearly 80–84%, 70–87% and 79–96% were above the desired limits for Al (0.2 mg L−1), Fe (0.3 mg L−1) and Cu (3 µg L−1), respectively. In 2011, water analysis from drainage of forest soils (in Skuterud catchment) measured total Al: 0.42–0.79 mg L−1 and total Fe: 0.84–1.0 mg L−1 which were two to three folds greater than the desired limits. In general, weak correlations between runoff and concentrations of the metals in the streams were noted. Future research should focus on identifying the sources of Al, Fe and Cu and management interventions of elevated metal inputs to Skuterud and Mørdre streams.
Authors
Karl Henrik Haugholt Matthieu Jean P Lacolle Marion O'Farrell Atle Honne Kari Anne Hestnes Bakke Aina Lundon RussenesAbstract
A low-cost Fourier transform infrared (FTIR) instrument was developed where the traditional He–Ne reference laser was replaced by a low-cost linear encoder. An RMS sampling error of less than 20 nm was achieved by oversampling both the interferogram and the encoder signal and then resampling the interferogram using a correction table for the encoder. A gas calibration model was developed for the system, which was chosen to have a stroke length of 21 mm and, thereby, a resolution of 0.4 cm −1 after apodization. The instrument was mounted on a vehicle and employed in an agricultural field test for measuring soil emissions, in particular nitrous oxide (N 2 O ). The concentration of N 2 O was measured with a root mean squared error of 6 ppb. The results compared well with lab-based gas chromatography measurements.