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71.
An overview of ex situ collections of cultivated flax (Linum usitatissimum L.) and 53 other species of the genus Linum L. is presented. The names of 33 genebanks in 23 countries preserving Linum germplasm and the species preserved at these places are provided. World genebanks engage in ex situ preservation of about 48,000 accessions of cultivated flax (Linum usitatissimum). However, possibly only 10,000 accessions of these are unique. Of the ca. 200 species of the genus Linum, other than L. usitatissimum, 53 are reported to be represented in the world’s ex situ collections with a total of about 900 accessions. Of these, 279 accessions alone refer to the wild progenitor of cultivated flax, Linum bienne Mill. However, L. bienne from the region of origin of cultivated flax is rarely represented in genebank collections. References to publications describing the techniques for ex situ conservation and the infraspecific variation of cultivated flax are made. It is suggested that taxonomic species delimitation within the genus Linum is in need of clarification and that the variation in Linum species for ornamental use or use in breeding is investigated.  相似文献   
72.
73.
Habitat heterogeneity has often been acknowledged as a key factor determining which species occur in a landscape, but we still know little on the nature and relative importance of the processes controlling species distribution and abundance within complex landscape mosaics. We used a framework defined by the compensation, supplementation and complementation models to study the distribution of four species of passerines typical of steppe habitats and identify the degree to which landscape context accounts for their distribution in the steppe-agriculture mosaic of the Crau, southern France. Steppe habitat was the best predictor of species distribution in all cases and that densities were highest in steppe. One of these species, the Calandra lark, is strictly tied to the natural steppe habitats independently of its context. For another species, the Tawny pipit, we document a significant positive effect of the presence, near steppe habitat, of extensive pastoral habitats, such as fallows and grazed crops. Finally, the abundance of the two remaining species, Skylark and Short-toed lark, was negatively affected by the presence of non-herbaceous habitats in the vicinity of steppe habitat. This suggests that the quality of the steppe habitat, as perceived by these species is conditional to the nature of adjacent habitats. Our results suggest that the management of the context in which steppe habitat is imbedded will significantly affect the distribution and abundance of this group of passerines and determine both habitat quality and conservation value at a landscape scale.  相似文献   
74.
Tropical Animal Health and Production - The objective of this article was to investigate the efficiency of GnRH administrations at different time points after induced luteolysis on pregnancy rates...  相似文献   
75.
Municipal wastewater has been applied as a fertilizer to coniferous forest in northern Sweden with the additional aims to purify the wastewater and reduce the treatment costs. This practice has the potential to introduce pathogenic microorganisms from the applied wastewater or sludge to the environment, with a subsequent risk of transmission to exposed humans or animals. Seasonality and climatological conditions, in particular low temperature, humidity and low sun intensity will furthermore affect the persistence of pathogens in the forest in northern Scandinavia and may therefore enhance the survival and thereby the exposure risk. The survival of two pathogens (Salmonella senftenberg and Campylobacter coli) and four fecal indicator organisms; bacteria strains (E. coli and E. fecalis) and bacteriophages (S. typhimurium phage 28 B and ?x174), used here as viral models, was evaluated in microcosms (60 Litre terrariums) with two vegetation regimes (characterized as moss and lichen) at selected temperatures (+3?C to +27?C) and artificial light exposure (light and dark). Salmonella persisted in high numbers after 35 days in the vegetation, indicating a potential risk for further transmission. Neither the vegetation regime nor temperature or light exposure as independent factors governed the reduction of the indicator bacteria and the bacteriophages. The persistence of the indicator organisms was generally best supported in the moss vegetation at low temperature in the dark, where the time for a 90% reduction (T90) was in the range from 8 days (E. coli) to 31 days (Salmonella phage). The die-off characteristics found in this study provide baseline values for further validations in the field and verify that the purification and reuse of municipal wastewater in coniferous forest could potentially be responsible for transmission of fecal pathogens to humans and animals.  相似文献   
76.
Die drastische Reduzierung der Besatzstärke an Rindern auf 0,5–1 GV/ha LF nach der politischen Wende in Ostdeutschland schafft interessante Möglichkeiten der Neugestaltung von Weiden. Um stärker und gleichmäßiger wechselnde Aufenthaltsplätze in der Fläche zu induzieren, könnten Extensivweiden in einer Art aufgelockerter Parklandschaft gestaltet werden. Die Eignung verschiedener Baum‐ und Straucharten für Niedermoore wurde in der Forschungsstation Paulinenaue, nordwestlich von Berlin, analysiert.

Untersuchungen zeigten, daß zukünftig insbesondere ausländische Rinderrassen vor zu starker UV‐Belastung geschützt werden sollten. Die heutigen ausgeräumten Weidelandschaften bieten nicht genügend Schatten und auch nicht ausreichend Windund Wetterschutz während des Winters. Die Entwicklung von vielfältig strukturierten Weiden verbessert das Wohlbefinden der Tiere als auch die Biodiversität des gesamten Ökosystems. Die Landschaft gewinnt durch die Variation von Landschaftselementen, der Stoffkreislauf wird geregelter und die Akzeptanz für den ländlichen Raum in der Bevölkerung steigt.  相似文献   
77.
Abstract

The aim of the study was to analyse aspects of fen soil quality for grassland use with regard to the different topsoil structure and their status of earthification/moorshification (degradation). Fifty fens of different origin, structural status and land use intensity were sampled, analysed and scored by different methods: Visual Soil Assessment, Peerlkamp test and Muencheberg Soil Quality Rating. Suitable soil structure scores were found at different land use intensities with the exception of stock tracks on pastures. These had lower water and air permeability and lower soil strength. Highest visual scores of macrostructure were found where the water table was deeper; while highest overall soil quality scores occurred where the water table was optimum. The accelerated status of moorshification had no effect on the soil quality scores and on the crop yield. At lower levels of soil development (earthification) the crop yield was slightly lower due to higher proportions of inedible plants. It may be concluded that degraded peat soils will have no loss of soil quality and have relatively high soil quality for grassland use if the water table can be managed in a suitable range and the sward quality is maintained.  相似文献   
78.
This study derives grassland communities from site, climate and land use characteristics, allowing yield estimation within the framework of model scenarios. Based on the dominant species, about 450 relevés, primarily of extensively used grassland from four regions of the North-East German lowlands, were classified into vegetation types using a cluster analysis. These types were then reclassified to known phytosociological communities. The relationship between the vegetational composition and the abiotic explanatory variables were verified by a discriminant analysis. The water supply level proved to be the most important factor influencing grassland vegetation. The impact of historical land use (especially the persistence of formerly sown species) reduced prognostic quality.  相似文献   
79.
The diversity of pale flax (Linum bienne Mill.) as the progenitor of cultivated flax (L. usitatissimum L.) has not been well documented and the domestication syndromes in cultivated flax are poorly understood. An attempt was made to characterize 34 pale flax accessions and six cultivated flax accessions collected during 2007 summer in Turkey. A total of 12 quantitative and 7 qualitative characters covering vegetative and generative plant parts, including phenological traits, were assessed. The occurrence of yellow anthers well known in cultivated flax is reported for the first time in pale flax. Pale flax displayed larger variation in vegetative plant parts and growth habit than the cultivated flax and more heterogeneity within accessions. Within pale flax, a higher degree of variation was observed in many generative parts such as the flower characters than in the capsule and seed characters. Based on the assayed characters, the pale flax from Turkey was grouped into three clusters and these clusters were associated with site elevation and longitude, further confirming local genetic differentiation in pale flax from Turkey. These findings are significant for further studies of flax domestication history and useful for further exploitation of wild flax in genetic improvement of cultivated flax.  相似文献   
80.
The Southern Pre-Pyrenees experienced a substantial land-use change over the second half of the 20th century owing to the reduction of agricultural activities towards the formation of a more natural forest landscape. The land-use change over the last 50 years with subsequent effects on water and sediment export was modelled with the process-based, spatially semi-distributed WASA-SED model for the meso-scale Canalda catchment in Catalonia, Spain. It was forwarded that the model yielded plausible results for runoff and sediment yield dynamics without the need of calibration, although the model failed to reproduce the shape of the hydrograph and the total discharge of several individual rainstorm events, hence the simulation capabilities are not yet considered sufficient for decision-making purposes for land management. As there are only a very limited amount of measured data available on sediment budgets with altered land-use and climate change settings, the WASA-SED model was used to obtain qualitative estimates on the effects of past and future change scenarios to derive a baseline for hypothesis building and future discussion on the evolution of sediment budgets in such a dryland setting. Simulating the effects of the past land-use change, the model scenarios resulted in a decrease of up to 75% of the annual sediment yield, whereas modelled runoff remained almost constant over the last 50 years. The relative importance of environmental change was evaluated by comparing the impact on sediment export of land-use change, that are driven by socio-economic factors, with climate change projections for changes in the rainfall regime. The modelling results suggest that a 20% decrease in annual rainfall results in a decrease in runoff and sediment yield, thus an ecosystem stabilisation in regard to sediment export, which can only be achieved by a substantial land-use change equivalent to a complete afforestation. At the same time, a 20% increase in rainfall causes a large export of water and sediment resources out of the catchment, equivalent to an intensive agricultural use of 100% of the catchment area. For wet years, the effects of agricultural intensification are more pronounced, so that in this case the intensive land-use change has a significantly larger impact on sediment generation than climate change. The WASA-SED model proved capable in quantifying the impacts of actual and potential environmental change, but the reliability of the simulation results is still circumscribed by considerable parameterisation and model uncertainties.  相似文献   
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