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Some of the most frequently chosen approaches to forest population genetics as reflected in the present volume are discussed, and some topics possibly deserving more attention are addressed. Among the first are studies of self-fertilization as a characteristic of forest tree mating systems, gene markers as indicators of adaptive or phylogenetic differentiation, and methodological aspects of the measurement of genetic differentiation. The latter mainly concern generalizable methods of analysis and the involvement of gene markers in the determination of mating systems, detection of mechanisms of frequency dependent selection, and the incorporation of genetic profiles (characteristics of frequency distributions of genetic types) into population genetic analysis. 相似文献
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Two forest soils (Typic Dystrochrept, Entic Haplorthod) with mor and moder were investigated by chemical degradation, IR and CPMAS 13C NMR spectroscopy and pyrolysis (Py) field ionization (FI) mass spectrometry (MS). Chemical analyses show that during litter decomposition, humification, and podzolisation, cellulose and lignin structures decrease considerably, whereas no distinct changes were found for the hemicellulose and protein fractions. These results are consistent with current hypotheses on the conversion of plant residues to stable humic substances, but the sum of chemically identified organic soil components of the litter layers only accounts for 40–50% of total organic carbon. The amounts of different carbon types were estimated by the integration of CPMAS 13C NMR spectra. For the L layers this calculation assigns 56–58% as O-alkyl-C, 20–22% as alkyl-C, 14–16% as aryl-C, and 6–8% as carboxyl-C. With increasing soil depth O-alkyl-C (with polysaccharides as main source) decrease to 31–42%, aliphatic C increases to 36–43%, and aryl- and carboxyl-C show no distinct changes. The hypothesis of an increasing aromaticity during humification in soils therefore is questionable. Data from Py-FIMS confirm and extend the results' of chemical methods as well as IR and 13C NMR spectroscopy. In particular, the Fi mass spectra of the generated pyrolysates show that the increase in polymethylene carbon during the biodegradation and humification of beech and spruce litter is partly due to an increase of saturated fatty acids. This means, Py-FIMS is able to describe the structure of wet-chemically unaccounted, individual humus constituents and thus improves the knowledge about the genesis of humic substances. 相似文献
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Fatty acids as major compounds of soil lipids may affect many soil properties, but the input and turnover rates in soil are largely unknown. The objective of this study was to identify and quantify fatty acids in soils as a result of input from primary sources such as plant residues, farmyard manure and soil organisms, and to evaluate the corresponding turnover- and stabilization processes. The concentrations of n-C10:0 to n-C34:0 fatty acids were determined in the Ap horizon of a Phaeozem with long-term cropping of rye and maize and the treatments ‘Unfertilized’ (‘U’) and fertilized with ‘Farmyard manure’ (‘FYM’). The most important primary sources of fatty acids such as rye and maize stubble and roots, soil micro- and mesofauna, and the applied FYM were also investigated. The quantification of fatty acids by gas chromatography/mass spectrometry (GC/MS) showed that long-term FYM application led to larger concentrations of n-alkyl fatty acids in the plots grown with rye (‘U’: 48.1 μg g−1, ‘FYM’: 57.7 μg g−1, **P≤0.01, n=3) and maize (‘U’: 17.0 μg g−1, ‘FYM’: 23.4 μg g−1, ***P≤0.001, n=3). The observed bimodal fatty acid distribution in soils from n-C10:0 to n-C21:0 and from n-C21:0 to n-C34:0 with a predominance at n-C16:0 and at n-C28:0 was apparently due to input from crop residues, soil organisms and FYM. The short-chain lengths may have originated from the investigated primary sources. The major contributors to the long-chain lengths, with a maximum at n-C28:0, were rye stubble and FYM. A change in mono-culture from rye to maize, 38 years prior to sampling, led to a decrease in fatty acid concentrations by factors of about 2.8 (‘U’) and 2.5 (‘FYM’). Therefore, rye-derived fatty acids and soil tillage had a larger impact on fatty acid pools than the input of primary organic matter. The changes in fatty acid distributions and pools under the consideration of the quantified input of primary organic matter led to the conclusion that the short-chained fatty acids were more rapidly decomposed than the long-chains. 相似文献
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Background
Autochthony in forest tree stands is characterized by a number of criteria, among which the range over which stands act as a population has been suggested to play a central role. Therefore, measures are needed for the delineation of populations or the detection of subpopulation structure. It is argued here that methods of population delineation must be based on the combined consideration of spatial distances and genetic differences between adult individuals. Conventional approaches and a set of newly developed methods are applied to seven isozyme loci in four beech stands which are distinguished by different types of forest management based on natural regeneration. 相似文献6.
Gregorius J. Sips Mariëlle J. G. Dirven Joke T. Donkervoort Francien M. van Kolfschoten Claudia M. E. Schapendonk My V. T. Phan Annemieke Bloem Anna F. van Leeuwen Mariechristine E. Trompenaars Marion P. G. Koopmans Annemiek A. van der Eijk Miranda de Graaf Ewout B. Fanoy 《Zoonoses and public health》2020,67(4):453-459
Norovirus constitutes the most frequently identified infectious cause of disease outbreaks associated with untreated recreational water. When investigating outbreaks related to surface water, a One Health approach is insightful. Historically, there has been a focus on potential contamination of recreational water by bird droppings and a recent publication demonstrating human noroviruses in bird faeces suggested this should be investigated in future water‐related norovirus outbreaks. Here, we describe a One Health approach investigating a norovirus outbreak in a natural playground. On social media, a large amount of waterfowl were reported to defecate near these playground premises leading to speculations about their potential involvement. Surface water, as well as human and bird faecal specimens, was tested for human noroviruses. Norovirus was found to be the most likely cause of the outbreak but there was no evidence for transmission via waterfowl. Cases had become known on social media prior to notification to the public health service underscoring the potential of online media as an early warning system. In view of known risk factors, advice was given for future outbreak investigations and natural playground design. 相似文献
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Anna-Lena Berg Dolores Gavier-Widén Kristina Nilsson Frederik Widén Mikael Berg Sune Gregorius Erik Agren Maria Erlandsson Torsten M?rner 《Journal of veterinary diagnostic investigation》2007,19(1):113-117
A neurologic disease affected a colony of endangered Fennoscandian arctic foxes (Alopex lagopus) kept in captivity for breeding purposes. Several outbreaks of disease occurred between 1994 and 2004. The clinical signs included ataxia, indications of anosmia, blindness, and abnormal behavior. The disease was characterized by severe necrotizing encephalitis affecting mostly the cranial cerebrum, basal ganglia, and olfactory bulbs. Investigations to identify the etiology of the disease included testing for several infectious agents known to cause encephalitis in carnivores. Tests for Toxoplasma gondii, Encephalitozoon cuniculi, Neospora caninum, canine distemper virus, rabies, adenovirus type 1, Borna disease virus, and Listeria monocytogenes were negative. The colony was closed, and the cause of the disease remains undetermined. 相似文献
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Curie-point pyrolysis-gas chromatography/mass spectrometry and temperature-programmed in-source pyrolysis-field ionization mass spectrometry have been used for the chemical characterization of the organic material in agricultural soils with organic carbon contents between 1 and 1.5%. The results obtained from whole-soil samples, extractable humic substances and nonextractable humin by both techniques indicate for the Ap of a Gleysol thermal degradation products of carbohydrates, intact and/or biodegraded lignin, flavonoids, tannins and/or polyphenols, lipids, aliphatic polymers, and nitrogen-containing compounds. On a qualitative basis similar results have been obtained for the Ap of a Luvisol. The alkylbenzenes, alkylnaphthalenes, (di)alkylphenols, and alkyltoluenes identified are of special interest because these aryl-alkyl compounds demonstrate covalent linkages between aliphatic chains and aromatic subunits in soil organic matter. This type of linkage between individual subunits of the complex and polydisperse organic material enables the flexibility of rigid aromatic systems. 相似文献
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Backround
P. avium, a pioneer tree species that colonizes early forest successional stages, is assumed to require an effective strategy allowing stably repeatable rounds of local establishment, dispersal and local extinction. Consequently, the early replacement of cherry by climax tree species makes the establishment of several local generations very unlikely, especially in central European continuous cover forests. This has to be seen in connection with the mixed reproduction system involving asexual reproduction as a complementary adaptational strategy. Tests of the local establishment of wild cherry must therefore consider the possibility of first generation establishment via seedling recruitment potentially followed by an asexual generation (root suckering). Successful establishment can therefore be determined only among adult individuals with the option of detecting vegetative reproduction at these stages. To test the implied suggestion about local establishment strategies of wild cherry, nuclear microsatellites were used to analyse patterns of asexual propagation among adult stages that have been subjected to one of two major types of forest management. These management types, the historical "coppice with standards system" (CWS) and the "high forest system" (HFS), can be reasonably assumed to have affected the reproduction system of P. avium. 相似文献10.
Influence of organic matter quality on consistency of agricultural soils The soil organic matter of two samples similar in the texture and approximately in the organic C contents, but very differently in the consistency properties, were investigated by pyrolysis-field ionization mass spectrometry (Py-FIMS). The shifts of the values of the liquid and plastic limits towards higher moisture contents are explained by a different quality of soil organic matter, in particular by higher amounts of longchained lipids (C8-32 alkanes, alkenes, fatty acids), N-compounds and lignin dimers. 相似文献