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.
2022
Forfattere
Vilde Lytskjold Haukenes Lisa Åsgård Johan Asplund Line Nybakken Jørund Rolstad Ken Olaf Storaunet Mikael OhlsonSammendrag
Knowledge about the spatial variation of boreal forest soil carbon (C) stocks is limited, but crucial for establishing management practices that prevent losses of soil C. Here, we quantified the surface soil C stocks across small spatial scales, and aim to contribute to an improved understanding of the drivers involved in boreal forest soil C accumulation. Our study is based on C analyses of 192 soil cores, positioned and recorded systematically within a forest area of 11 ha. The study area is a south-central Norwegian boreal forest landscape, where the fire history for the past 650 years has been reconstructed. Soil C stocks ranged from 1.3 to 96.7 kg m−2 and were related to fire frequency, ecosystem productivity, vegetation attributes, and hydro-topography. Soil C stocks increased with soil nitrogen concentration, soil water content, Sphagnum- and litter-dominated forest floor vegetation, and proportion of silt in the mineral soil, and decreased with fire frequency in site 1, feathermoss- and lichen-dominated forest floor vegetation and increasing slope. Our results emphasize that boreal forest surface soil C stocks are highly variable in size across fine spatial scales, shaped by an interplay between historical forest fires, ecosystem productivity, forest floor vegetation, and hydro-topography.
Sammendrag
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Forfattere
Rune Halvorsen Odd Arne Brenn Erik Framstad Geir Gaarder Ivar Gjerde Fride Høistad Schei Olav Skarpaas Ken Olaf Storaunet Anne Sverdrup-ThygesonSammendrag
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Forfattere
Ken Olaf StoraunetSammendrag
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Populærvitenskapelig – Naturskogsdynamikk, skogstruktur og død ved
Ken Olaf Storaunet, Olav Skarpaas
Sammendrag
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Sammendrag
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Sammendrag
Knowledge of the temporal variation in reproductive success and its key driving factors is crucial in predicting animal population persistence. Few studies have examined the effects of a range of explanatory factors operating simultaneously on the same population over a long period. Based on 41 years of monitoring (1979–2019), we tested prevailing hypotheses about drivers of annual variation in breeding success in two sympatric species of boreal forest grouse—the capercaillie (Tetrao urogallus) and the black grouse (T. tetrix)—in a 45 km2 boreal forest landscape. From counts in early August, we measured breeding success (chicks/hen) along with potential determining factors. We formulated five main hypotheses on causes of variation (hen condition, chick weather, chick food, predation, demographic characteristics) and derived 13 associated explanatory variables for analysis. We first tested the five hypotheses separately and then used model selection (AICc) to rank the best predictive models irrespective of hypotheses. Lastly, we used path analysis to illuminate potential causal relationships. Barring demographic characteristics, all hypotheses were supported, most strongly for chick food and predation. Among predictor variables, chick food (insect larvae and bilberry fruit crops), vole and fox abundances, the winter-NAO index, and temperature after hatching, had the strongest effect sizes in both species. Precipitation after hatching had no detectable effect. Model selection indicated bottom-up factors to be more important than predation, but confounding complicated interpretation. Path analysis suggested that the high explanatory power of bilberry fruiting was due not only to its direct positive effect on chick food quality but also to an indirect positive effect on vole abundance, which buffers predation. The two components of breeding success—proportion of hens with broods and number of chicks per brood—were uncorrelated, the former having the strongest effect. The two components had different ecological correlates that often varied asynchronously, resulting in overall breeding success fluctuating around low to moderate levels. Our study highlights the complexity of key explanatory drivers and the importance of considering multiple hypotheses of breeding success. Although chick food appeared to equal or surpass predation in explaining the annual variation in breeding success, predation may still be the overall limiting factor. Comparative and experimental studies of confounded variables (bilberry fruiting, voles, and larvae) are needed to disentangle causes of variation in breeding success of boreal forest grouse.
Forfattere
Roberto Guidetti Łukasz Kaczmarek Milena Roszkowska Terje Meier Tommy Prestø K. Ingemar Jönsson James David Mervyn Speed Elisabeth Stur Ivar Gjerde Lasse Topstad Kristian Hassel Torbjørn EkremSammendrag
Background: Tardigrades are common in most habitats, however few studies have focusedon large faunistic survey, specifically on tardigrade diversity in forests. Up to now, only 61 species have been recorded in different types of forest in Norway with an additional 25 found in limnic environments in forests. Although little is known about the ecological preferences of many species, previous studies have found that tardigrade diversity and community composition are significantly affected by ecological variables. In this study we associate georeferenced tardigrade species records with forest type, substrate type and substrate composition in order to see if tardigrade diversity and species communities can be associated with ecological characteristics of Norwegian forests. Methods: In total 390 moss, lichen and litter samples were collected from 12 forests in central and southern Norway in the summers of 2017 and 2018 and later stored in paper envelopes. For the identification modern literature and keys for specific genera and groups of species were used. For statistical analyses, moss and lichen substrate of each sample was classified according to the main species, life form, growth forms and habitat of substrate and associated with each tardigrade identification and sample metadata. Results: A total of 17 407 specimens were identified, encompassing in total 132 species (including some new species). Species richness increases with precipitation, but does not change with temperature or precipitation seasonality. The distribution of species richness between life forms and forest types showed considerable variation within and among the variables. Disregarding variables with low sample numbers, among life forms only acrocarpous moss samples appeared to deviate with respect to species richness, containing less species than substrates with other life forms. Conclusions: Tardigrades in Norwegian forest are extremely abundant, frequent and diverse. Moreover, it appears that that certain species and/or entire communities prefer specific microhabitats.