Patterns and processes of initial terrestrial‐ecosystem development

Ecosystems are characterized as complex systems with abiotic and biotic processes interacting between the various components that have evolved over long‐term periods. Most ecosystem studies so far have been carried out in mature systems. Only limited knowledge exists on the very initial phase of ecosystem development. Concepts on the development of ecosystems are often based on assumptions and extrapolations with respect to structure–process interactions in the initial stage. To characterize the effect of this initial phase on structure and functioning of ecosystems in later stages, it is necessary to disentangle the close interaction of spatial and temporal patterns of ecosystem structural assemblages with processes of ecosystem development. The study of initial, less complex systems could help to better identify and characterize coupled patterns and processes. This paper gives an overview of concepts for the initial development of different ecosystem compartments and identifies open questions and research gaps. The artificial catchment site “Chicken Creek” is introduced as a new research approach to investigate these patterns and processes of initial ecosystem development under defined boundary conditions. This approach allows to integrate the relevant processes with related pattern and structure development over temporal and spatial scales and to derive thresholds and stages in state and functioning of ecosystems at the catchment level.     

Taxonomy and evolution of cultivated plants: Literature review 1987/1988

Summary Important papers on taxonomy and evolution of cultivated plants published in 1987 and 1988 were compiled and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1987/1988

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1987 und 1988 wurden zusammengestellt und kurz kommentiert.

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¶rt; : 1987/1988

, 1987/1988 . .

     

Development of high-performance strand boards: multiscale modeling of anisotropic elasticity

The interrelationships between microstructural characteristics and anisotropic elastic properties of strand-based engineered wood products are highly relevant in order to produce custom-designed strand products with tailored properties. A model providing a link between these characteristics and the resulting elastic behavior of the strand products is a very valuable tool to study these relationships. Here, the development, the experimental validation, and several applications of a multiscale model for strand products are presented. In a first homogenization step, the elastic properties of homogeneous strand boards are estimated by means of continuum micromechanics from strand shape, strand orientation, elastic properties of the used raw material, and mean board density. In a second homogenization step, the effective stiffness of multi-layer strand boards is determined by means of lamination theory, where the vertical density profile and different layer assemblies are taken into account. On the whole, this model enables to predict the macroscopic mechanical performance of strand-based panels from microscopic mechanical and morphological characteristics and, thus, constitutes a valuable tool for product development and optimization.     

Admixing broadleaved to coniferous tree species: a review on yield, ecological stability and economics

For several reasons the conversion of mono-species into mixed-species forests is presently a major concern of forest management and policy in Central Europe. Although it is possible to show a clear trend in favour of mixed-species forests, private forest owners and some forest economists have often not favoured mixed forests, assuming that they are less profitable. The trend towards mixed forests seems mainly for ecological reasons, while sound economic analysis of mixed forests is still rare. Based on this background the objective of the study is to answer the following four questions: (1) Does the yield of mixed-species forests differ from that of pure forests? (2) Does the mixing of tree species influence the ecological stability of forests? (3) Is the economic value of a mixed forest less than that of a monoculture? (4) How do forest economic models integrate the findings on yield and ecological stability of mixed forests? To answer these questions a literature review was conducted on the possible impacts of mixed-species forests. In comparison to pure stands a greater yield is not necessarily given in mixed stands. Yet, mixed-species stands are better able to compensate disturbances than monocultures. Moreover, there is substantial evidence that mixed-species stands are more resistant against biotic and abiotic disturbances. Applying an extended forest economic model, it was possible to demonstrate that mixing large blocks of native broadleaf species into pure conifer forests may lead to a significant reduction of financial risk. From a risk-averse perspective the economic value of a mixed-species forest may thus be greater than that of a mono-species forest. Yet, it became clear that forest economists do not often integrate the research findings on yield and ecological stability of mixed stands in modelling, but rather apply simple bioeconomic modelling. Moreover, in the context of mixed forests economists also largely ignore even classical financial approaches, which consider risk and risk preferences. We concluded that forest economics has to close substantial research gaps. Firstly, the knowledge of how to integrate biophysical properties of mixed forests in bioeconomic modelling is still an open question. Secondly, forest economists have to adopt the modern approaches of financial theory and management science to value mixed forests.     

Growth dynamics and biomass accumulation of 8-year-old hybrid poplar clones in a short-rotation plantation on a clayey-sandy mining substrate with respect to plant nutrition and water budget

In 1995 a short-rotation plantation (2.5 ha) was established in the mining region Welzow-Süd in Brandenburg, Germany, on a clayey-sandy, lignite- and pyrite-free substrate in order to study the biomass potentials of fast-growing tree species (hybrid poplar clones). In this study, special emphasis was placed on yield aspects as well as on the interaction between soil and plants, especially with regard to the plant nutrition and soil–water relationships. So far, the results indicate that the cultivation of hybrid poplar clones in a short-rotation plantation is an adequate tool for establishing alternative land-use systems in the post-mining landscape as a potential source of biomass energy. Aboveground biomass production ranged from 24–49 t dry matter (DM) per hectare at age 8. In particular during this period of investigation, nitrogen nutrition of the clones decreased to below a threshold of 20 mg g^–1 DM in the year 2002. Investigations of the water budget of low- and high-yielding clones indicated that differences in the biomass accumulation seemed to be accompanied by different water-use efficiencies.     

Greenhouse gas emissions after application of digestate: short-term effects of nitrification inhibitor and application technique effects

Nitrogen-use efficiency in arable agriculture after organic fertilization can be improved by the incorporation of digestate into soil and through the use of nitrification inhibitors. To test the efficiency and the interaction of these measures, a laboratory microcosm study was conducted with undisturbed samples from two arable soils – a Gleysol and a Plaggic Anthrosol. Treatments were digestate application by injection to 15 or 20 cm depths or by trailing hose with subsequent incorporation. Half of the replicates of each application treatment were treated with the nitrification inhibitor 3,4-dimethyl pyrazole phosphate (DMPP). Emissions of the greenhouse gases (GHGs) CO₂, N₂O and CH₄ were monitored during 51 days of incubation. Deeper injection (20 cm) did not lead to different GHG emissions compared with a shallow injection (15 cm). Application of DMPP decreased cumulative N₂O emissions significantly by 17–70%. DMPP inhibited N₂O fluxes and NO₃- production, suggesting a positive effect of DMPP on the mitigation of direct GHG emission and nitrate leaching at least during several weeks after digestate fertilization. The effect of DMPP is independent of the application technique.     

Development,growth, and nitrogen use of autumn- and spring-sown facultative wheat

Spring-sown crops are expected to have a higher risk of drought during summer in the next decades in Central Europe due to expected climate change. Therefore, a two-year experiment was conducted under Pannonian growing conditions in Eastern Austria to investigate the effect of autumn- and spring-sowing of facultative wheat. Autumn-sowing of facultative wheat enhanced crop development, soil coverage, crop stand height, crop growth rate, and nitrogen (N) utilization efficiency during the vegetation period compared to spring-sowing; duration of growth stages was prolonged and crops were earlier ripe. In contrast, spring-sowing resulted in higher relative growth rates, higher N concentrations of aboveground dry matter, higher relative N uptake rates, and more mineral N in the soil. At harvest, grain yield and yield components ears m^?2 and thousand kernel weight (TKW) were higher in autumn-sown than in spring-sown wheat, resulting thereby in an increased seed yield. Spring-sown wheat had higher N concentrations in grain and in straw. Anyhow, N yield was slightly higher with autumn-sowing due to the higher grain and straw yields. Grain and straw yield, plant stand height, ears m^?2, and TKW were impaired in the second experimental year by a severe drought for both sowing dates as well as N concentrations and N yields of grain and straw, partial factor N use efficiency and N utilization efficiency. But the yield components harvest index, grains m^?2, and grains ear^?1 were strongly impaired with spring-sowing under drought conditions. Thus, autumn-sowing of wheat resulted in higher yield stability across both years, based on these yield components highlighting possible benefits of autumn-sowing with expected summer drought under climate change.     

Taxonomy and evolution of cultivated plants: Literature review 1984/1985

Summary Important papers on taxonomy and evolution of cultivated plants published in 1984 and 1985 were compiled and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1984/1985

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1984 und 1985 wurden zusammengestellt und kurz kommentiert.

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: 1984–1985

, 1984 1985 . .

     

Collection of indigenous taxa of cultivated plants in the Georgian SSR 1985

Summary In continuation of joint activities since 1981 in Western Georgia a further mission for studying and collecting indigenous forms of cultivated plants and their wild relatives has been carried out by staff members of the Institute of Botany, Tbilisi, and the Zentralinstitut für Genetik und Kulturpflanzenforschung, Gatersleben, in September/October 1985. 445 accessions, mainly of legumes, vegetables, spice plants and maize could be collected in South-western Georgia (Adaria, area around Boromi). Gene-erosion is highly advanced for field crops (especially cereals), may be as a result of the specialization to subtropical cultures near the coast and to tobacco, respectively cattle-breeding in higher mountainous regions. But many local races of garden crops are still cultivated now. A large amount of indigenous taxa of cultivated plants, of potential value for plant breeding and botanically interesting, could be obtained. The collection work in the Georgian SSR should be continued.

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Sammlung indigener Kulturpflanzensippen in der Georgischen SSR 1985

Zusammenfassung In Fortführung der 1981 begonnenen gemeinsamen Unternehmungen im westlichen Georgien führten Mitarbeiter des Instituts für Botanik Tbilisi und des Zentralinstituts für Genetik und Kulturpflanzenforschung Gatersleben im September/Oktober 1985 eine weitere Reise zum Studium und zur Sammlung indigener Kulturpflanzenformen und verwandter Wildsippen durch. Im südwestlichen Georgien (Adarien, Gebiet um Boromi) konnten 445 Proben, hauptsächlich von Leguminosen, Gemüse- und Gewürzpflanzen sowie Mais, gesammelt werden. Infolge der Spezialisierung auf subtropische Kulturen in Künstennähe und auf den Anbau von Tabak bzw. auf die Viehzucht in den höheren Gebirgsregionen ist die Generosion bei Feldkulturen, insbesondere bei den Getreiden, weit fortgeschritten. Dagegen sind noch viele Landsorten gärtnerischer Kulturen im Anbau. Eine große Menge für die Pflanzenzüchtung potentiell wertvoller und botanisch interessanter indigener Kulturpflanzensippen wurde erfaßt. Die Sammeltätigkeit in der Georgischen SSR sollte fortgesetzt werden.

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1985

1981 , — 1985 () () . - ( ) 445 , , , . , , . , . , , . .

     

Binding of the human Prp31 Nop domain to a composite RNA-protein platform in U4 snRNP

Although highly homologous, the spliceosomal hPrp31 and the nucleolar Nop56 and Nop58 (Nop56/58) proteins recognize different ribonucleoprotein (RNP) particles. hPrp31 interacts with complexes containing the 15.5K protein and U4 or U4atac small nuclear RNA (snRNA), whereas Nop56/58 associate with 15.5K-box C/D small nucleolar RNA complexes. We present structural and biochemical analyses of hPrp31-15.5K-U4 snRNA complexes that show how the conserved Nop domain in hPrp31 maintains high RNP binding selectivity despite relaxed RNA sequence requirements. The Nop domain is a genuine RNP binding module, exhibiting RNA and protein binding surfaces. Yeast two-hybrid analyses suggest a link between retinitis pigmentosa and an aberrant hPrp31-hPrp6 interaction that blocks U4/U6-U5 tri-snRNP formation.