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
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Knowledge of soil microtopography and its changes in space and over time is important to the understanding of how tillage influences infiltration, runoff generation and erosion. In this study, the use of a terrestrial laser scanner (TLS) is assessed for its ability to quantify small changes in the soil surface at high spatial resolutions for a relatively large surface area (100 m2). Changes in soil surface morphology during snow cover and melt are driven by frost heave, slaking, pressure exertion by the snowpack and overland flow (erosion and deposition). An attempt is undertaken to link these processes to observed changes at the soil surface. A new algorithm for soil surface roughness is introduced to make optimal use of the raw point cloud. This algorithm is less scale dependent than several commonly used roughness calculations. The results of this study show that TLSs can be used for multitemporal scanning of large surfaces and that small changes in surface elevation and roughness can be detected. Statistical analysis of the observed changes against terrain indices did not yield significant evidence for process differentiation.
Abstract
Aims Bacterial decays of onion bulbs have serious economic consequences for growers, but the aetiologies of these diseases are often unclear. We aimed to determine the role of Rahnella, which we commonly isolated from bulbs in the United States and Norway, in onion disease. Methods and Results Isolated bacteria were identified by sequencing of housekeeping genes and/or fatty acid methyl ester analysis. A subset of Rahnella spp. strains was also assessed by multilocus sequence analysis (MLSA); most onion strains belonged to two clades that appear closely related to R. aquatilis. All tested strains from both countries caused mild symptoms in onion bulbs but not leaves. Polymerase chain reaction primers were designed and tested against strains from known species of Rahnella. Amplicons were produced from strains of R. aquatilis, R. victoriana, R. variigena, R. inusitata and R. bruchi, and from one of the two strains of R. woolbedingensis. Conclusions Based on binational testing, strains of Rahnella are commonly associated with onions, and they are capable of causing mild symptoms in bulbs. Significance and Impact of the Study While Rahnella strains are commonly found within field‐grown onions and they are able to cause mild symptoms, the economic impact of Rahnella‐associated symptoms remains unclear.
Authors
Bjørn Økland Daniel Flø Martin Schroeder Peter Zach Dragos Cocos Petri Martikainen Juha Siitonen Michail Y. Mandelshtam Dmitry L. Musolin Seppo Neuvonen Jozef Vakula Christo Nikolov Åke Lindelöw Kaljo VoolmaAbstract
1 Ips amitinus arrived in Northern Europe at the beginning of 1900s, although its recent expansions to the northernmost conifers have been rapid. 2 Analyses of recent records, MaxEnt models and regional population size estimates are used to discuss its peculiar range shifts and potential as a forest pest in Northern Europe. 3 Ips amitinus was probably absent in northern glacial refugia for Norway spruce in the Russian plain and northward expansions from its glacial refugia in the Central European mountains may have been slowed down by: (i) ecological barriers of post-glacial dry plains and bogs in Central Europe; (ii) heavy utilization of conifers; and (iii) Allee effects as a result of fragmented forests and an unfavourable climate for a cold-adapted species in the continental lowlands. 4 MaxEnt models predict that I. amitinus may become widespread in the Northern European forests, whereas its populations in the southernmost mountain ranges of Europe may decline in the future. 5 The population levels of I. amitinus in recently invaded northern areas are still lower than those in core areas of Central Europe, although the population development in Central Europe indicates that future bark beetle outbreak periods may boost the I. amitinus populations in Northern Europe as well.
Authors
Inger-Lise Steffensen Christiane Kruse Fæste Trine Husøy Helle Katrine Knutsen Gro Haarklou Mathisen Robin Ørnsrud Angelika Agdestein Johanna Eva Bodin Edel O. Elvevoll Dag Olav Hessen Merete Hofshagen Åshild Krogdahl Asbjørn Magne Nilsen Trond Rafoss Olaug Taran Skjerdal Gaute Velle Yngvild Wasteson Gro Ingunn Hemre Vigdis Vandvik Jan AlexanderAbstract
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Authors
Manuel de la Estrella Jan J. Wieringa Frans J. Breteler Dario Isidro Ojeda AlayonAbstract
On the basis of a new phylogeny of the Detarioideae, with a particular focus on Englerodendron Harms, Anthonotha P.Beauv. and related genera, the possible options for delimiting monophyletic genera are discussed. As a result, Isomacrolobium Aubrév. & Pellegr. and Pseudomacrolobium Hauman are synonymised under Englerodendron. The following 12 new combinations are formed within the expanded Englerodendron: E. brachyrhachis (Breteler) Estrella & Ojeda, E. explicans (Baill.) Estrella & Ojeda, E. graciliflorum (Harms) Estrella & Ojeda, E. hallei (Aubrév.) Estrella & Ojeda, E. isopetalum (Harms) Breteler & Wieringa, E. lebrunii (J.Léonard) Estrella & Ojeda, E. leptorrhachis (Harms) Estrella & Ojeda, E. mengei (De Wild.) Estrella & Ojeda, E. nigericum (Baker f.) Estrella & Ojeda, E. obanense (Baker f.) Estrella & Ojeda, E. triplisomere (Pellegr.) Estrella & Ojeda and E. vignei (Hoyle) Estrella & Ojeda. A key to identification of the 17 species now recognised within Englerodendron is presented.
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Authors
Mekjell MelandAbstract
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