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.
2024
Forfattere
Geir-Harald StrandSammendrag
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Sammendrag
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Sammendrag
Arenosol er en selvdrenert jord med høyt sandinnhold. Jorda har liten evne til å lagre vann og lavt til moderat høyt innhold av organisk materiale. Arealer med Arenosol er tidlig klare for jordarbeiding om våren.
Forfattere
Anne Kari Bergjord OlsenSammendrag
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Forfattere
Jorunn BørveSammendrag
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Forfattere
Fride Høistad Schei Mie Prik Arnberg John-Arvid Grytnes Maren Stien Johansen Jørund Johansen Anna Birgitte Milford Anders Røynstrand Mari Mette TollefsrudSammendrag
Climate change and human activities have accelerated the spread of non-native species, including forest pests and pathogens, significantly contributing to global biodiversity loss. Pathogens pose a significant threat to forest ecosystems due to a lack of coevolution with native hosts, resulting in ineffective defence mechanisms and severe consequences for the affected tree species. Ash dieback, caused by the fungus Hymenoscyphus fraxineus, is a relatively new invasive forest pathogen threatening ash (Fraxinus excelsior) with mortality rates in northern Europe reaching up to 80 %. The loss of ash due to dieback has severe ecological implications, potentially leading to an extinction cascade as ash provides crucial habitats and resources for many organisms. Despite this, the consequences of ash dieback on associated communities are largely unknown. To address this, we analysed changes in species richness, vegetation structure, and composition in 82 permanent vegetation plots across 23 Norwegian woodlands. We compared data collected before and 10–14 years after the emergence of ash dieback. In these woodlands, ash significantly declined in cover, leading to changes in tree species composition and facilitating the establishment of other woody tree species like hazel (Corylus avellana) and the invasive species sycamore (Acer pseudoplatanus). Despite these changes in the tree species composition, no significant alterations were observed in the understory plant community, indicating a degree of ecosystem resilience or a lagging community response. At this point, and with our focus on the vascular plants, we do not find support for cascading effects due to ash dieback. However, our findings demonstrate that one invasive species is facilitating the expansion of another, raising concerns about potential ecological imbalance and cascading effects in the future.
Sammendrag
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Forfattere
Malin Olsen Wedaa Stine Samsonstuen Helge Bonesmo Bente Aspeholen Åby Erland Kjesbu Magne Bergfjord Rune OkstadSammendrag
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Sammendrag
This study examined the economic potential of thinning in pure, even-aged Norway spruce and Scots pine forests in Norway based on simulated stand dynamics using plot data from the Norwegian national forest inventory. Simulated management scenarios included fully mechanized thinning from below of varying intensity including no thinning. The economic evaluation was based on comparing the equivalent annual annuity of the unthinned scenario and the economically best-performing thinning scenario for each studied plot. The findings suggest that only late thinnings in well-stocked stands with sufficiently large trees are economically beneficial. Furthermore, to be economically superior, a thinning intervention itself had to generate enough profit, meaning that the revenue from thinning needed to sufficiently exceed the costs. Profitability of thinning scenarios varied with discount rates and timber prices and depended on whether rotation age was based on maximum net present value or maximum mean annual increment. Thinning was less often profitable in pine compared to spruce stands. This study is among the few that model stand development considering post-thinning stand structures with systematic machine trails while assessing the profitability of such thinning operations.
Sammendrag
1. We propose that the ecological resilience of communities to permanent changes of the environment can be based on how variation in the overall abundance of individuals affects the number of species. Community sensitivity is defined as the ratio between the rate of change in the log expected number of species and the rate of change in the log expected number of individuals in the community. High community sensitivity means that small changes in the total abundance strongly impact the number of species. Community resistance is the proportional reduction in expected number of individuals that the community can sustain before expecting to lose one species. A small value of community resistance means that the community can only endure a small reduction in abundance before it is expected to lose one species. 2. Based on long-term studies of four bird communities in European deciduous forests at different latitudes large differences were found in the resilience to environmental perturbations. Estimating the variance components of the species abundance distribution revealed how different processes contributed to the community sensitivity and resistance. Species heterogeneity in the population dynamics was the largest component, but its proportion varied among communities. Species-specific response to environmental fluctuations was the second major component of the variation in abundance. 3. Estimates of community sensitivity and resistance based on data only from a single year were in general larger than those based on estimates from longer time series. Thus, our approach can provide rapid and conservative assessment of the resilience of communities to environmental changes also including only short-term data. 4. This study shows that a general ecological mechanism, caused by increased strength of density dependence due to reduction in resource availability, can provide an intuitive measure of community resilience to environmental variation. Our analyses also illustrate the importance of including specific assumptions about how different processes affect community dynamics. For example, if stochastic fluctuations in the environment affect all species in a similar way, the sensitivity and resistance of the community to environmental changes will be different from communities in which all species show independent responses.