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.
2019
Authors
Karin Westlund Petrus Jönsson Dag Fjeld Peter Rauch Christoph KoglerAbstract
Seasonal variations in wood supply are linked to the regional operating environment. This study constitutes the Norwegian contribution to Era-Net MultiStrat (Multimodal strategies for more resilient wood supply) covering oceanic, sub-arctic and continental climate zones. The oceanic zone is characterized by considerable seasonal variation in both temperature and precipitation. The goal of the study was to seek solutions for more resilient wood supply under these conditions. The study started with a general mapping of wood supply management processes including common demand and supply risks (WP1). The work continued with analysis of three years of production and transport reports (2014-2016) with tracking of roadside stocks and transport lead times (WP2). Daily temperature, precipitation, and snowpack were tracked with data from 65 surrounding weather stations. A simple multimodal transport problem with a rolling selection of planning horizons was then used to find the efficient multimodal solutions for the core, adjacent and peripheral supply regions through 12 balance periods per year (WP3). The transport analysis covers 65 supply districts feeding 6 assortment groups to 10 mills via 11 shipping terminals. The transport analysis varied both vessel cargo capacity and cargo collection practices. The results demonstrated a wide range of solutions to ensure roundwood availability with limited increases in system costs. While the transport analysis demonstrated the contribution of the multimodal solutions to structural flexibility, it also revealed a bottleneck for resilience of the wood supply system; seasonal variation in truck transport output (m3km/week). The geographical distribution of seasonality showed the main source to be one particular supply region. A subsequent wood supply planning workshop with production managers indicated that a bottleneck for improved production planning was short wood purchase and planning horizons. A simple optimization experiment was therefore set up to quantify the feasibility of more specific site-type selection according to actual soil and seasonal weather conditions for the selected region. On-line grid-based groundwater modeling was used to monitor weekly geographical variations in bearing capacity and the experiment provided a plausible re-scheduling of flows to reduce variation in delivery volumes and transport output.
Abstract
No abstract has been registered
Authors
Kamila S. Zając Bjørn Arild Hatteland Barbara Feldmeyer Markus Pfenninger Anna Filipiak Leslie Robert Noble Dorota Lachowska-CierlikAbstract
Arion vulgaris Moquin-Tandon, 1855 is regarded as one of the 100 most invasive species in Europe. The native distribution range of this species is uncertain, but for many years, the Iberian Peninsula has been considered as the area of origin. However, recent studies indicate that A. vulgaris probably originated from France. We have investigated the genetic structure of 33 European populations (Poland, Norway, Germany, France, Denmark, Switzerland) of this slug, based on two molecular markers, mitochondrial cytochrome c oxidase subunit I (COI, mtDNA) and nuclear zinc finger (ZF, nDNA). Our investigation included published data from two previous studies, giving a total of 95 populations of A. vulgaris from 26 countries. This comprehensive dataset shows comparable haplotype diversity in Central, North and Western Europe, and significantly lower haplotype diversity in the East. All haplotypes observed in the East can be found in the other regions, and haplotype diversity is highest in the Central and Western region. Moreover, there is strong isolation by distance in Central and Western Europe, and only very little in the East. Furthermore, the number of unique haplotypes was highest in France. This pattern strongly suggests that A. vulgaris has originated from a region spanning from France to Western Germany; hence, the slug is probably alien/invasive in other parts of Europe, where it occurs. Our results indicate the necessity to cover as much of the distribution range of a species as possible before making conclusive assumptions about its origin and alien status.
Abstract
No abstract has been registered
Authors
Endre Hansen Fønhus Mikael Bruce TalbotAbstract
No abstract has been registered
Abstract
Preferential flow may become significant in partially frozen soils because infiltration can occur through large, initially air-filled pores surrounded by a soil matrix with limited infiltration capacity. The objectives of this study were to develop and evaluate a dual-permeability approach for simulating water flow and heat transport in macroporous soils undergoing freezing and thawing. This was achieved by introducing physically based equations for soil freezing and thawing into the dual-permeability model MACRO. Richards’ equation and the heat flow equation were loosely coupled using the generalized Clapeyron equation for the soil micropore domain. Freezing and thawing of macropore water is governed by a first-order equation for energy transfer between the micropore and macropore domains. We assumed that macropore water was unaffected by capillary forces, so that water in macropores freezes at 0°C. The performance of the model was evaluated for four test cases: (i) redistribution of water in the micropore domain during freezing, (ii) a comparison between the first-order energy transfer approach and the heat conduction equation, (iii) infiltration and water flow in frozen soil with an initially air-filled macropore domain, and (iv) thawing from the soil surface during constant-rate rainfall. Results show that the model behaves in accordance with the current understanding of water flow and heat transport in frozen macroporous soil. To improve modeling of water and heat flow in frozen soils, attention should now be focused on providing experimental data suitable for evaluating models that account for macropore flow.
Authors
Jihong Liu ClarkeAbstract
No abstract has been registered
Authors
Masoud Mahdianpari Mahdi Motagh Vahid Akbari Fariba Mohammadimanesh Bahram SalehiAbstract
Synthetic Aperture Radar (SAR) data have gained interest for a variety of remote sensing applications, given the capability of SAR sensors to operate independent of solar radiation and day/night conditions. However, the radiometric quality of SAR images is hindered by speckle noise, which affects further image processing and interpretation. As such, speckle reduction is a crucial pre-processing step in many remote sensing studies based on SAR imagery. This study proposes a new adaptive de-speckling method based on a Gaussian Markov Random Field (GMRF) model. The proposed method integrates both pixel-wised and contextual information using a weighted summation technique. As a by-product of the proposed method, a de-speckled pseudo-span image, which is obtained from the least-squares analysis of the de-speckled multi-polarization channels, is also produced. Experimental results from the medium resolution, fully polarimetric L-band ALOS PALSAR data demonstrate the effectiveness of the proposed algorithm compared to other well-known de-speckling approaches. The de-speckled images produced by the proposed method maintainthe mean value of the original image in homogenous areas, while preserving the edges of features in heterogeneous regions. In particular, the equivalent number of look (ENL) achieved using the proposed method improves by about 15% and 47% compared to the NL-SAR and SARBM3D de-speckling approaches, respectively. Other evaluation indices, such as the mean and variance of the ratio image also reveal the superiority of the proposed method relative to other de-speckling approaches examined in this study.
Authors
Patrick J. Drohan Marianne Bechmann Anthony Buda Faruk Djodjic Donnacha Doody Jonathon M. Duncan Antti Iho Phil Jordan Peter J. Kleinman Richard McDowell Per-Erik Mellander Ian A. Thomas Paul J. A. WithersAbstract
The evolution of phosphorus (P) management decision support tools (DSTs) and systems (DSS), in support of food and environmental security has been most strongly affected in developed regions by national strategies (i) to optimize levels of plant available P in agricultural soils, and (ii) to mitigate P runoff to water bodies. In the United States, Western Europe, and New Zealand, combinations of regulatory and voluntary strategies, sometimes backed by economic incentives, have often been driven by reactive legislation to protect water bodies. Farmer‐specific DSSs, either based on modeling of P transfer source and transport mechanisms, or when coupled with farm‐specific information or local knowledge, have typically guided best practices, education, and implementation, yet applying DSSs in data poor catchments and/or where user adoption is poor hampers the effectiveness of these systems. Recent developments focused on integrated digital mapping of hydrologically sensitive areas and critical source areas, sometimes using real‐time data and weather forecasting, have rapidly advanced runoff modeling and education. Advances in technology related to monitoring, imaging, sensors, remote sensing, and analytical instrumentation will facilitate the development of DSSs that can predict heterogeneity over wider geographical areas. However, significant challenges remain in developing DSSs that incorporate “big data” in a format that is acceptable to users, and that adequately accounts for catchment variability, farming systems, and farmer behavior. Future efforts will undoubtedly focus on improving efficiency and conserving phosphate rock reserves in the face of future scarcity or prohibitive cost. Most importantly, the principles reviewed here are critical for sustainable agriculture.
Authors
Stig A. BorgvangAbstract
No abstract has been registered