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.
2014
Forfattere
Mari Mette Tollefsrud Yoshiaki Tsuda Jørn Henrik Sønstebø Małgorzata Latałowa Laura Parducci Thomas Källman Jun Chen Vladimir Semerikov Tore Skrøppa Giovanni Guiseppe Vendramin Christoph Sperisen Martin LascouxSammendrag
During the Last Glacial Maximum, the boreal vegetation was greatly restricted. Climatic variation between regions had different impact on the glacial and postglacial history of tree species, resulting in contrasting distribution of genetic diversity. Norway spruce (Picea abies) and Siberian spruce (P. obovata) are two closely related species which parapatric ranges cover almost the entire boreal region of Eurasia; a vast region that experienced contrasting glacial histories. In the present study we combined extensive paleobotanical and genetic data to reconstruct the joint histories of the two species and to evaluate how their glacial and postglacial histories have affected their genetic structure. Today, Norway spruce and Siberian spruce are clearly genetically differentiated in mitochondrial (mt) and nuclear SSR markers, suggesting that the two species had largely independent glacial histories. Nuclear SSR markers indicate the presence of hybrid individuals on both sides of the Urals and east-west longitudinal genetic structures indicate a wide zone of hybridization. The border for mtDNA is situated along the Ob River in Siberia. Along this river and eastwards, latitudinal genetic structures were weak. In Norway spruce, rather complex population genetic structures are revealed as a result of multiple refugia and contrasting recolonization patterns. The current distribution of Norway spruce is divided into a southern and a northern domain. Coherent with the paleodata, both mtDNA and SSR loci suggest a long lasting separation between these two domains, which however, did not preclude secondary contacts. Within the southern domain, mtDNA and paleodata suggest the presence of several refugia, a pattern that nuclear SSR loci fail to reveal probably reflecting pollen mediated gene flow. In the northern domain, the same data support the recolonization of Scandinavia during the mid Holocene from a large and scattered refugium located on the East European Plain. Recolonization took place along different migration routes, and diversity evolved differentially along these routes. The complex genetic structure at nuclear SSRs in the northern Norway spruce domain may be due to gene flow from the southern domain, gene flow from the hybrid zone along the Ural Mountains and expansion from a separate refugium along the Atlantic coast. The latter is suggested by ancient DNA, the presence of a Scandinavia endemic mitochondrial haplotype and possibly, the current structure at SSR loci, where the origin of a distinct genetic cluster in Central Scandinavia remains to be elucidated. The implications of these findings for the response of the boreal forest to climate, forest management and breeding will be discussed.
Forfattere
Theo RuissenSammendrag
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Konferanseforedrag – Biochar and abiotic NO transformations
Simon Weldon, Peter Dörsch, Daniel Rasse
Sammendrag
Studies examining the effect of biochar on N2O turnover in soil have demonstrated that biochar affects both the rate and product ratio of denitrification. The mechanisms proposed include pH effects on N2O reductase , sorption of N2O and electron shuttling to N2O reductases. Recent studies suggest that pyrolysis alters the redox chemistry of biochar leading to the formation of redox active compounds which are thought to mediate the observed suppression of N2O in biochar amended soil. Redox active components however may not only be of significance to biological processes but also catalyze abiotic reactions of N-species which could confound the estimation of biological effects. Here we report experiments designed to examined abiotic interaction between biochar and NO in anoxic water slurries with biochar of increasing pyrolysis temperature. We determined the fate of NO added to the headspace of closed anoxic bottles using high frequency measurements of NO, N2O and N2. Our initial results show a swift disappearance of added NO which can not entirely be attributed to sorption to the biochar. Small but constant quantities of N2O were generated after NO addition indicating abiotic turnover of NO by biochar. NO is an important signal molecule in the regulation of denitrification and hence it is important to elucidate possible abiotic feedbacks of NO reactions in soil. The results will be discussed relative to the redox properties of the biochars tested.
Sammendrag
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Sammendrag
In an attempt to discern stochastic and deterministic parts of measured signals, we analyze time series from the viewpoint of ordinal pattern statistics. After choosing a suitable embedding dimension $D$, the occurrencies of all $D!$ patterns form a probability distribution $P$. The latter is input to information and complexity functionals describing, e.g., chaotic regimes or stochastic properties due to long-range correlations. Here, we use an information quantifier which is local in pattern probability space, the Fisher information $F$. This is calculable only after fixing a pattern coding scheme, i.e. numbering each and every pattern. It has been demonstrated that $F$ discerns different dynamic regimes for the logistic map to a certain extent; however, this depends on the details of the coding scheme. Here, we seek to find an optimal coding scheme for long-range correlated stochastic processes, mimicking many records e.g. from the geosciences. To increase the contrast between colored noise and deterministic processes, $F$ should be minimal for the former. Structurally similar ordinal patterns should be located adjacent to each other. Similarity is related to the number of inversions in the respective patterns. In practical terms, it is impossible to try all $D!!$ coding schemes whenever$D > 3$; however, we demonstrate a classification of coding schemes into equivalence classes based on the number of "jumps" in the patterns. These are used to improve the Keller and Lehmer coding schemes. The approach has a potential to provide an analytical understanding of the Fisher information for stochastic processes. Results for these optimizations will be shown for both the logistic map and colored ($k$-) noise. As a byproduct, an innovative method to estimate the scaling exponent $k$ emerges. Finally, we comment shortly on the importance of finite size effects, which is always an issue when dealing with observed data.
Forfattere
Marit JørgensenSammendrag
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Forfattere
Marit JørgensenSammendrag
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Forfattere
Sebastian EiterSammendrag
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