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.
2016
Forfattere
Ingrid Agathe Bay-Larsen Ingebjørg Vestrum Vibeke Lind Camilla Risvoll Margarita Novoa Garrido Michael RoledaSammendrag
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Forfattere
Igor A. Yakovlev Elena Carneros YeonKyeong Lee Jorunn Elisabeth Olsen Carl Gunnar FossdalSammendrag
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Sammendrag
The purpose of this study is to increase the basic understanding of outbreak dynamics in order to improve the management of bark beetle outbreaks. The spruce bark beetle Ips typographus is a major disturbance agent of European forests and is the continent’s most economically and environmentally damaging bark beetle. Outbreaks of the spruce bark beetle are often triggered by large windfall episodes, and we have utilized a unique opportunity to study a Slovakian outbreak where little salvage logging was performed in some areas after a 2.5 million m3 storm-felling in 2004. Our analyses focused on the first five years after the windfall, and we used a combination of empirical data and simulation models to understand the spatial patterns of beetle-killed forest patches developing during the outbreak. The univoltine beetle population used an increasing proportion of the windfelled trees during the two first seasons after the storm, but from the third season onwards our comparisons of inter-patch distance distributions indicated a transition from beetle production largely in windfall areas to a self-sustaining outbreak with infestation patches developing independently of the windthrows. The size of new infestation patches formed after this transition was modeled as a function of beetle pressure, estimated by the proportion of a circle area surrounding new patches that was covered by infestation patches the previous year. Our model results of patch size distribution did not correspond well with the empirical data if patch formation was modeled as a pure dispersal–diffusion process. However, beetle aggregation on individual trees appears to be important for patch development, since good correspondence with empirical data was found when beetle aggregation was incorporated in the modeled dispersal process. The strength of correspondence between the beetle aggregation model and the empirical data varied with the density of aggregation trees in the modeled landscape, and reached a maximum of 83% for a density of three aggregation trees per infestation patch. Our results suggest that efficient removal of windfelled trees up until the start of the second summer after a major windfall is important to avoid a transition into a patch-driven bark beetle outbreak that is very difficult to manage. Our results also indicate that the outcome of a patch-driven outbreak is difficult to predict, since the development of new infestation patches is not a simple function of beetle pressure but is also affected by beetle behavior and local forest conditions.
Sammendrag
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Sammendrag
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Forfattere
Kjell AndreassenSammendrag
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Forfattere
Marta Camino-Serrano Elisabeth Graf Pannatier Sara Vicca Sebastiaan Luyssaert Mathieu Jonard Philippe Ciais Bertrand Guenet Bert Gielen Josep Peñuelas Jordi Sardans Peter Waldner Sophia Etzold Guia Cecchini Nicholas Clarke Zoran Galic Laure Gandois Karin Hansen Jim Johnson Uwe Klinck Zora Lachmanová Antti-Jussi Lindroos Henning Meesenburg Tiina M. Nieminen Tanja G. M. Sanders Kasia Sawicka Walter Seidling Anne Thimonier Elena Vanguelova Arne Verstraeten Lars Vesterdal Ivan A. JanssensSammendrag
Dissolved organic carbon (DOC) in surface waters is connected to DOC in soil solution through hydrological pathways. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site studies have failed so far to establish consistent trends in soil solution DOC, whereas increasing concentrations in European surface waters over the past decades appear to be the norm, possibly as a result of recovery from acidification. The objectives of this study were therefore to understand the long-term trends of soil solution DOC from a large number of European forests (ICP Forests Level II plots) and determine their main physico-chemical and biological controls. We applied trend analysis at two levels: (1) to the entire European dataset and (2) to the individual time series and related trends with plot characteristics, i.e., soil and vegetation properties, soil solution chemistry and atmospheric deposition loads. Analyses of the entire dataset showed an overall increasing trend in DOC concentrations in the organic layers, but, at individual plots and depths, there was no clear overall trend in soil solution DOC. The rate change in soil solution DOC ranged between −16.8 and +23 % yr−1 (median = +0.4 % yr−1) across Europe. The non-significant trends (40 %) outnumbered the increasing (35 %) and decreasing trends (25 %) across the 97 ICP Forests Level II sites. By means of multivariate statistics, we found increasing trends in DOC concentrations with increasing mean nitrate (NO3−) deposition and increasing trends in DOC concentrations with decreasing mean sulfate (SO42−) deposition, with the magnitude of these relationships depending on plot deposition history. While the attribution of increasing trends in DOC to the reduction of SO42− deposition could be confirmed in low to medium N deposition areas, in agreement with observations in surface waters, this was not the case in high N deposition areas. In conclusion, long-term trends of soil solution DOC reflected the interactions between controls acting at local (soil and vegetation properties) and regional (atmospheric deposition of SO42− and inorganic N) scales.
Forfattere
Marta Camino-Serrano Elisabeth Graf Pannatier Sara Vicca Sebastiaan Luyssaert Mathieu Jonard Philippe Ciais Bertrand Guenet Bert Gielen Josep Peñuelas Jordi Sardans Peter Waldner Sophia Etzold Guia Cecchini Nicholas Clarke Galić Galic Laure Gandois Karin Hansen Jim Johnson Uwe Klinck Zora Lachmanová Antti-Jussi Lindroos Henning Meesenburg Tiina M. Nieminen Tanja G.M. Sanders Kasia Sawicka Walter Seidling Anne Thimonier Elena Vanguelova Arne Verstraeten Lars Vesterdal Ivan A. JanssensSammendrag
Det er ikke registrert sammendrag