Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2021
Forfattere
Ruth Jaén-Molina Águedo Marrero-Rodríguez Juli Caujapé-Castells Dario Isidro Ojeda AlayonSammendrag
With a wide distribution range including Europe and Asia, Lotus (Leguminosae) represents the largest genus within Loteae. It is particularly diverse in the Mediterreanean region and in the five archipelagos of Macaronesia (Atlantic Ocean). However, little is known about the relationships among the 14 sections currently recognized within Lotus and about the timing and patterns of its colonization in the Macaronesian region. In this investigation, we use four DNA regions (nuclear ribosomal ITS plus three plastid regions) in the most comprehensive sampling of Lotus species to date (some endemic species within the Canary Islands were poorly represented in previous phylogenetic analyses) to infer relationships within this genus and to establish patterns of colonization in Macaronesia. Divergence time estimates and habitat reconstruction analyses indicate that Lotus likely diverged about 7.86 Ma from its sister group, but all colonization events to Macaronesia occurred more recently (ranging from the last 0.23 to 2.70 Ma). The diversification of Lotus in Macaronesia involved between four and six independent colonization events from four sections currently distributed in Africa and Europe. A major aspect shaping the current distribution of taxa involved intra-island colonization of mainly new habitats and inter-island colonization of mostly similar habitats, with Gran Canaria and Tenerife as the major sources of diversification and of further colonization events. Section Pedrosia is the most diverse in terms of colonization events, number of species, and habitat heterogeneity, including a back-colonization event to the continent. Subsections within Pedrosia radiated into diverse habitat types recently (late Pleistocene, ca 0.23–0.29 Ma) and additional molecular markers and sampling would be necessary to understand the most recent dispersal events of this group within the Canary Islands and Cape Verde.
Sammendrag
Field-based monitoring of deer food availability and browsing on recruiting forest trees is a necessary but labour-intensive task. We explored how such estimates from a low-resolution multipurpose national forest inventory (NFI) (plot density 0.3 km−2) corresponded with estimates from local inventories that specifically and in greater detail monitor the availability of deer food and browsing intensity (LFI) (plot density 2–3 km−2). We used NFI and LFI data from 16 moose Alces alces ranges (mean area 276 ± SE 69 km2) in southern Norway. Only the height segment 30–130 cm of browsable trees could be obtained from the NFI data, while moose can browse trees from 30 to 300 cm in height. According to the LFI, the browse species did not have similar proportions of their browsable stems below 130 cm. Using only the stems from heights of 30–130 cm overestimated the availability of RAS (rowan, aspen and sallow) relative to birch (silver birch and downy birch) and Scots pine. The browsable biomass per stem of each species also varied between ranges, which introduces uncertainty to the food availability estimates that are based on stems only. Nevertheless, the NFI density of stems at 30–130 cm heights can be a useful index for species-specific comparisons of browse availability across ranges, because the variations between ranges in stem densities outweighed the biomass variations per stem. The NFI and LFI estimates of the species-specific densities of stems at 30–130 cm heights were significantly related and close to isometric (1:1), especially for RAS and pine. We did not find strong relationships between NFI and LFI in the browsing intensity (i.e. proportion of shoots that were browsed during the winter). The explained variation was only 11% (R2) for RAS (p = 0.281) and 32% for pine (p = 0.028). This was likely due to the small sample sizes of browsed trees in the NFI and methodological differences between the NFI and LFI in how browsing intensity is estimated. Conclusions Using data from national forest inventories can be an efficient but low-resolution way to monitor browse availability for deer, provided that the monitoring includes the full range of tree heights reachable for the deer (e.g., 30–300 cm for moose). It is also a prerequisite that the number of NFI plots is sufficient to cover the spatial variability of the area. Regarding browsing intensities, adjustments in both the NFI and LFI approaches are needed to make the two monitoring schemes more comparable.
Forfattere
Erling MeisingsetSammendrag
Det er ikke registrert sammendrag
Sammendrag
The objective of this study was to determine morphological and anatomical leaf characteristics and stomatal traits of three European (Pyrus communis L.) cultivars, three Asian [Pyrus pyrifolia (Burm. f.) Nakai] pear cultivars together with one interspecies hybrid (P. pyrifolia × P. communis ‘Bartlett’) and link them with the resistance to pathogens. Pear trees were grown under the standard practice without irrigation. Fully developed leaves were picked from the middle part of the extension shoots at the beginning of the July. Leaf traits were measured on leaves picked the same day. Anatomy of leaves was determined under light microscopy (LM) while scanning electron microscopy (SEM) was used for the examination of the stomata cells. Asian pear cultivars (‘Kousui’, ‘Nijisseiki’ and ‘Niitaka’) had much higher leaf parameters (width, length, stem length and leaf area) than the European cultivars (‘Conference’, ‘Williams Bartlett’, ‘Abbate Fetel’) and interspecies hybrid (‘Kieffer Seedling’). Midrib parameters (length and width) were the highest in ‘Kosui’ and ‘Nijisseiki’. Leaves of ‘Kieffer Seedling’ and ‘Abbate Fetel’ were the thickest, mainly due to increased palisade and spongy parenchyma thickness. The leaf stomata density significantly varied among the pear cultivars, ranging from 89.53 stomata mm‑2 (‘Nijisseiki’) up to 134.07 stomata mm‑2 (‘Housui’). SEM proved that Asian pear cultivars and ‘Kieffer Seedling’ shared ‘paracytic’ stomata type, while European pear cultivars had ‘anomocytic’ stomata type. Cluster analysis distinguished pear cultivars into two distinct groups, where European cultivars formed first sub-cluster and Asian together with ‘Kieffer Seedling’ second sub-cluster. Midrib traits and stomata type made a clear separation between the clusters. These results might suggest that thickness of midrib could be a huge barrier for Psylla sp. probing in Asian pears, thus representing one of the key factors in the resistance of these cultivars.
Sammendrag
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.
Forfattere
Paul Eric AspholmSammendrag
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Forfattere
Bjørn Egil FløSammendrag
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Forfattere
Bjørn Egil FløSammendrag
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Forfattere
Ryan C. Burner Vidar Selås Sverre Kobro Rannveig Margrete Jacobsen Anne Sverdrup-ThygesonSammendrag
Introduction Insects are reported to be in decline around the globe, but long-term datasets are rare. The causes of these trends are elusive, with changes in land use and climate among the top candidates. Yet if species traits can predict rates of population change, this can help identify underlying mechanisms. If climate change is important, for example, high-latitude species may decline as temperate species expand. Land use changes, however, may impact species that rely on certain habitats. Aims and methods We present 30 years of moth captures (comprising 97,032 individuals of 808 species) from a site in southeast Norway to test for population trends that are correlated with species traits. We use time series analyses and joint species distribution models combined with local climate and habitat data. Results and discussion Species richness declined by 8.2% per decade and total abundance appeared to decline as well (−9.4%, p = 0.14) but inter-annual variability was high. One-fifth of species declined, although 6% increased. Winter and summer weather were correlated with annual rates of abundance change for many species. Opposite to general expectation, many species responded negatively to higher summer and winter temperatures. Surprisingly, species’ northern range limits and the habitat in which their food plants grew were not strong predictors of their time trends or their responses to climatic variation. Complex and indirect effects of both land use and climate change may play a role in these declines. Implications for insect conservation Our results provide additional evidence for long-term declines in insect abundance. The multifaceted causes of population changes may limit the ability of species traits to reveal which species are most at risk.
Forfattere
Hans Martin Hanslin Trygve S. Aamlid Ellen Johanne Svalheim Geir Kjølberg Knudsen Harald Bratli Karin NormannSammendrag
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