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.
2009
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Authors
Jorunn Elisabeth Olsen Anna Holefors Lars Morten Opseth Daniel Asante Olavi Junttila Jørgen Aleksander Mølmann Igor A. Yakovlev Carl Fossdal Øystein JohnsenAbstract
No abstract has been registered
Abstract
Stream flow observations from a geographical region are known to often exhibit strong common behavior. In order to assess the temporal evolution of the complexity of stream flow time series from all over Europe, we employ the recently developed Linear Variance Decay dimension density (δLV D). It is estimated as the parameter of an exponential decay function fitted to the remaining variances of the eigenvalues of a covariance matrix. Scaling between zero and one, δLV D can be interpreted as a measure of the proportion of linear independent components in a multivariate record.....
Authors
Nadeem Yaqoob Igor A. Yakovlev Paal Krokene Harald Kvaalen Halvor Solheim Carl Gunnar FossdalAbstract
Clonal variation towards resistance has been observed in Norway spruce Heterobasidion annosum s.l. (H.a). H.a. is the main cause of root rot and has a severe economic impact on an economically important conifer tree species. Annual financial losses are in the hundreds of millions of Euros annually. Less susceptible clones appear to have an efficient system of recognizing the pathogen and initiating early defense signalling events. Active defense responses can be started locally and transmitted systemically. This work focus on the expression both spatially (systemically) and temporally in this pathosystem. Two-year-old, somatic saplings of the Norway spruce clone were challenged with H.a., wounded, methyl jasmonate painted and compared to untreated controls and ninety plants were used for the experiment. Stem samples were collected at 1, 3, 6 and 13 days post inoculation (d.p.i). The stem of the saplings were divided into sections along its length and the bark and wood separated from each other at time of collection. In order to see local response an area of 1cm including the site of inoculation was collected, while the spatial (systemic) response was assessed in sections collected at distances of 3 and 6cm away from the site of inoculation. The separated bark and wood were analysed for differential gene expression by qRT-PCR, and the results from peroxidases (PaPX3 and PaPX2) and a chitinase (PaChi4) are presented. Both local and systemic up- and down-regulation were observed at the transcriptional level in both bark and wood, up to 2000 fold local increase in expression was observed for PaChi4.
Abstract
In this study, we surveyed the long term effects of liming and fertilizing in old Scots pine stands on the ectomycorrhiza (ECM) colonization, tree growth and needle nutrient concentration 35 years later. Four mature stands of Scots pine on low productive mineral soil were limed in 1959 and 1964 with total doses of limestone ranging from 3 to 15 Mg ha1 and fertilized with nitrogen (N) in 1970. Thirty-five years after the first liming treatment, all stands were analysed for tree growth and needle nutrient concentrations and two of the stands were also analysed for ECM colonization. ECM colonization increased significantly with liming from 61.5% in the control plots to 88% in the plot with the highest limestone dose...
Authors
Anita Sønsteby Ola M. HeideAbstract
Octoploid strawberry (Fragaria × ananassa Duch.) cultivars can be classified into mono-flowering (single-cropping or June-bearing) and perpetual-flowering (everbearing) types according to their horticultural performance. Whereas floral induction in mono-flowering cultivars is well-documented, the literature on the control of flowering of perpetual-flowering cultivars is rather inconsistent. Photoperiod and temperature control of flowering in several perpetual-flowering strawberry cultivars of widely varying pedigree were therefore studied in controlled environments. Flower bud initiation in all cultivars was significantly advanced by long day (LD) conditions at temperatures of 15°C and 21°C; while, at 27°C, flowering took place under LD conditions only. When vegetative plants growing in short day (SD) at 27°C were transferred to LD conditions at the same temperature, they consistently initiated flower buds and started flowering after about 4 weeks. At such a high temperature, flowering could thus be turned on and off by switching between SD and LD conditions. At 9°C, flowering was substantially delayed, and, at this temperature, flowering was unaffected by photoperiod. Runner formation was generally promoted by high temperature and SD conditions, but the photoperiodic effect varied between experiments. We conclude that everbearing strawberry cultivars, in general, whether of the older European type or the modern Californian type, are qualitative (obligatory) LD plants at high temperature (27°C), and quantitative LD plants at intermediate temperatures. Only at temperatures below 10°C these cultivars are day-neutral.
Authors
Arve Heistad Razak Seidu Andreas Svarstad Flø Adam Paruch Jon Fredrik Hanssen Thor-Axel StenströmAbstract
Tie long-term use of a filter-based, on-site wastewater treatment system increases nutrient discharge to receiving waters and may reduce its hygienic barrier efficiency. The main purpose of this research was to assess the hygienic barrier efficiency and the associated health risks of an on-site system that had exceeded its 5-yr design capacity with respect to phosphorus (P) removal. The system was investigated for bacteria and virus removal and assessed with respect to potential health risks in relation to reuse of effluent for irrigation. The system consists of a septic tank, a pressure-dosed vertical flow biofilter, and an up-flow filter unit with lightweight clay aggregates. The total P concentration in the effluent had increased gradually from initially <0.1 mg P L-1 during the first 2 yr of operation to 1.8 mg P L-1 after 5.3 yr. Escherichia coli was used as an indicator organism for fecal bacteria removal, whereas bacteriophages phi X174 and Salmonella typhimurium phage 28B (S.t. 28B) were used to model enteric virus removal. An overall decrease in E. coli removal occurred from a complete (approximately 5.6 log(10)) reduction during the first 3 yr of operation to 2.6 log(10) reduction. The removal amounts of the bacteriophages phi X174 and S.t. 28B were 3.9 and 3.7 log(10), respectively. Based on removal of S.t. 28B, the risks of rotavirus infection and disease for the investigated scenarios were above the acceptable level of 10(-4) and 10(-3), respectively, as defined by the World Health Organization.
Abstract
No abstract has been registered
Authors
Svein Solberg Andreas Brunner Kjersti Holt Hanssen Holger Lange Erik Næsset Miina Rautiainen Pauline StenbergAbstract
In this study we demonstrate how airborne laser scanning (ALS) can be applied to map effective leaf area index (LAI(e)) in a spruce forest, after being calibrated with ground based measurements. In 2003 and 2005, ALS data and field estimates of LAI(e) were acquired in a Norway spruce forest in SE Norway. We used LI-COR's LAI-2000 (R) Plant canopy analyzer ("LAI-2000") and hemispherical images ("HI") for field based estimates of LAI(e). ALS penetration rate calculated from first echoes and from first and last echoes was strongly related to field estimates of LAI(e). We fitted regression models of LAI(e) against the log-transformed inverse of the ALS penetration rate, and in accordance with the Beer-Lambert law this produced a linear, no-intercept relationship. This was particularly the case for the LAI-2000, having R-2 values > 0.9. The strongest relationship was obtained by selecting ALS data from within a circle around each plot with a radius of 0.75 times the tree height. We found a slight difference in the relationship for the two years, which can be attributed to the differences in the ALS acquisition settings. The relationship was valid across four age classes of trees representing different stages of stand development, except in one case with newly regenerated stands which most likely was an artifact. Using LAI(e) based on HI data produced weaker relationships with the ALS data. This was the case even when we simulated LAI-2000 measurements based on the HI data. (C) 2009 Elsevier Inc. All rights reserved.