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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.

2021

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Abstract

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses /by/4.0/).

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Abstract

A new stubby-root nematode belonging to the Trichodorus sparsus complex was found in association with serious damage to Hill’s Yew hedges (Taxus x media ´Hillii´) in Oslo in 2017, characterised by chlorosis, wilting and loss of needles. T. hellalae n. sp. is about 800 μm long with medium-sized onchiostyle (55 μm, average), characterized in male by two ventromedian cervical papillae located beyond the onchiostyle region and with the secretory excretory pore (SE-pore) in between, in most type specimens, three ventromedian precloacal supplements with the posteriormost one opposite the anterior end of spicule manubrium and spicules 40 μm long (average) with widened manubrium, gradually tapered to a narrower blade without ornamentation of striae or bristles, but showing a minor indentation at level of posterior border of capsule of suspensor muscles. Gubernaculum with thickened keel-like posterior end and a thickened refractive anterior border. Females are characterised by a short pear-shaped vagina, less than 1/3rd of corresponding body width and very small rounded triangular vaginal sclerotized pieces in longitudinal optical section and vulva pore-like in ventral view; on each body side one sublateral body pore at about 3.5 body width anterior to vulva and one postadvulvar body pore. According to D2-D3 analyses, the Trichodorus hellalae n. sp. sequences are embedded in a maximally supported clade with several T. variabilis lineages. However, morphological and molecular species delimitation both support Trichodorus hellalae n. sp. as being a new species. Therefore, T. variabilis now appears to in fact consists of several cryptic species.

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Abstract

Aim Many thematic land cover maps, such as maps of vegetation types, are based on field inventories. Studies show inconsistencies among field workers in such maps, explained by inter-observer variation in classification and/or spatial delineation of polygons. In this study, we have tested a new method to assess the accuracy of these two components independently. Location Four study sites dominated by different ecosystems in southeast Norway. Methods We have used a vegetation-based land cover classification system adapted to a map scale of 1:5,000. First, a consensus map, a map that can be considered an approximation of a flawless map, was established. Secondly, the consensus map was adapted to test the accuracy of classification and polygon delineation independently. We used 10 field workers to generate a consensus map, and 14 new field workers (in pairs) to test the accuracy (n = 7). Results The results show that the accuracy of polygon delineation is lower than that of land cover classification. This is in contrast with previous studies, but previous research designs have not enabled a separation of the two accuracy components. Conclusion We recommend strengthening the training and harmonization of field workers in general, and increasing the emphasis on polygon delineation.