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.
2012
Authors
Ivano Brunner Mark R. Bakker Robert G. Björk Yasuhiro Hirano Martin Lukac Xavier Aranda Isabella Børja Toril Eldhuset Heljä-Sisko Helmisaari Christophe Jourdan Bohdan Konôpka Bernat Claramunt López Carolina Miguel Pérez Hans Persson Ivika OstonenAbstract
Background and Aims: Forest trees directly contribute to carbon cycling in forest soils through the turnover of their fine roots. In this study we aimed to calculate root turnover rates of common European forest tree species and to compare them with most frequently published values. Methods: We compiled available European data and applied various turnover rate calculation methods to the resulting database. We used Decision Matrix and Maximum-Minimum formula as suggested in the literature. Results: Mean turnover rates obtained by the combination of sequential coring and Decision Matrix were 0.86 yr−1 for Fagus sylvatica and 0.88 yr−1 for Picea abies when maximum biomass data were used for the calculation, and 1.11 yr−1 for both species when mean biomass data were used. Using mean biomass rather than maximum resulted in about 30 % higher values of root turnover. Using the Decision Matrix to calculate turnover rate doubled the rates when compared to the Maximum-Minimum formula. The Decision Matrix, however, makes use of more input information than the Maximum-Minimum formula. Conclusions: We propose that calculations using the Decision Matrix with mean biomass give the most reliable estimates of root turnover rates in European forests and should preferentially be used in models and C reporting.
Authors
Guro BrodalAbstract
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Authors
Guro BrodalAbstract
Sydowia polyspora was found to be seed borne on true fir (Abies spp.) where it is associated with two serious diseases; current season needle necrosis (CSNN) and Sclerophoma shoot dieback [1]. To our knowledge, S. polyspora was previously only reported to be seed borne on Scots pine (Pinus sylvestris) [3]. In 2009, we discovered S. polyspora on Norway spruce (Picea abies) seedlings from germination tests at the Norwegian Forest Seed Center. This indicated that S. polyspora also was seed borne on spruce. Based on this, we wanted to investigate how widespread S. polyspora was on conifer seeds. In 2010, we tested 44 seed lots from 8 genera. S. polyspora was isolates from seeds from the following genera; Abies, Larix, Picea, Pinus, Pseudotsuga, Thuja, and Tsuga. Interestingly, they are the exact same genera that Funk [2] reported S. polyspora from on diseased foliage and shoots. We found S. polyspora on Norway spruce harvested in 1970, thus, the fungus may survive for decades in seed lots. In Norway, Sclerophoma shoot dieback has been found on Norway spruce in Christmas tree fields. Fungal species from a number of other genera were also detected in the seed test, but here we only report S. polyspora.
Abstract
The outcome of a compatible mycorrhizal interaction is different from that in a compatible plant–pathogen interaction; however, it is not clear what mechanisms are used to evade or suppress the host defence. The aim of this work is to reveal differences between the interaction of Norway spruce roots to the pathogen Ceratocystis polonica and the ectomycorrhizal Laccaria bicolor, examine if L. bicolor is able to evade inducing host defence responses typically induced by pathogens, and test if prior inoculation with the ectomycorrhizal fungus affects the outcome of a later challenge with the pathogen. The pathogen was able to invade the roots and caused extensive necrosis, leading to seedling death, with or without prior inoculation with L. bicolor. The ectomycorrhizal L. bicolor colonised primary roots of the Norway spruce seedlings by partly covering, displacing and convoluting the cells of the outer root cortex, leaving the seedlings healthy. We detected increased total peroxidase activity, and staining indicating increased lignification in roots as a response to C. polonica. In L. bicolor inoculated roots there was no increase in total peroxidase activity, but an additional highly acidic peroxidase isoform appeared that was not present in healthy roots, or in roots invaded by the pathogen. Increased protease activity was detected in roots colonised by C. polonica, but little protease activity was detected in L. bicolor inoculated roots. These results suggest that the pathogen efficiently invades the roots despite the induced host defence responses, while L. bicolor suppresses or evades inducing such host responses in this experimental system.
Authors
Sheng-Hong Li Nina Elisabeth Nagy Almuth Hammerbacher Paal Krokene Xue-Mei Niu Jonathan Gershenzon Bernd SchneiderAbstract
Norway spruce (Picea abies) bark contains specialized phloem parenchyma cells that swell and change their contents upon attack by the bark beetle Ips typographus and its microbial associate, the blue stain fungus Ceratocystis polonica. These cells exhibit bright autofluorescence after treatment with standard aldehyde fixatives, and so have been postulated to contain phenolic compounds. Laser microdissection of spruce bark sections combined with cryogenic NMR spectroscopy demonstrated significantly higher concentrations of the stilbene glucoside astringin in phloem parenchyma cells than in adjacent sieve cells. After infection by C. polonica, the flavonoid (+)-catechin also appeared in phloem parenchyma cells and there was a decrease in astringin content compared to cells from uninfected trees. Analysis of whole-bark extracts confirmed the results obtained from the cell extracts and revealed a significant increase in dimeric stilbene glucosides, both astringin and isorhapontin derivatives (piceasides A to H), in fungus-infected versus uninfected bark that might explain the reduction in stilbene monomers. Phloem parenchyma cells thus appear to be a principal site of phenolic accumulation in spruce bark.
Abstract
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Authors
Venche TalgøAbstract
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Authors
Venche TalgøAbstract
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Authors
Venche TalgøAbstract
No abstract has been registered