Habitat structure and prey aggregation determine the functional response in a soil predator-prey interaction     

Olivera Vucic-Pestic  Björn C. Rall  Ulrich Brose 《Pedobiologia》2010,53(5):307-5

Functional responses describe the per capita consumption rates of predators depending on prey density, which quantifies the energy transfer between trophic levels. We studied a typical interaction of the litter-soil systems between hunting spiders (Pardosa lugubris; Araneae: Lycosidae) and springtails (Heteromurus nitidus; Collembola: Entomobryidae) at varying habitat structure, i.e. with moss vs. without moss. We found a hyperbolic increase in consumption (functional response type II) in the treatment without habitat structure that was converted into a roller-coaster (or dome-shaped in a broad sense) functional response in treatments with habitat structure. Additional experiments suggest that the reduced per capita consumption rates at high prey densities may be explained by aggregative defence behaviour of the springtails. Experimentally, this behaviour was induced by the presence of habitat structure. We analyzed the net-energy gain of this predator-prey interaction by comparing the predator’s metabolic energy loss to its energy gain by consumption. In treatments with habitat structure, the net-energy gain of the predator was limited at intermediate prey densities where prey aggregation reduced the consumption rates. Our results stress the importance of habitat structure and prey behaviour in shaping the functional response in a typical soil-litter predator-prey interaction.  相似文献   

Erstellung eines Moorstandortkataloges als eine grundlage für das moorschutzprogramm in mecklenburg‐vorpommern     

Ulrich Ratzke 《Archives of Agronomy and Soil Science》2013,59(3):187-206

Der Moorstandortkatalog Mecklenburg‐Vorpommern wird als Bestandteil der bodenkundlichen Landesaufnahme seit 1992 durch den Geologischen Dienst erarbeitet. Moore nehmen 12% der Wirtschaftsfläche, entsprechend etwa 300000 ha ein. Fast ausschließlich sind es Niedermoore (nur ca. 5 000 ha Regenmoore) verschiedener Typen unter subkontinentalen Klimabedingungen und größtenteils landwirtschaftlicher Nutzung.

Gegenwärtig sind 30% aller Niedermoorböden, es handelt sich um die größten, mit kartographischen Übersichten, Daten und fachspezifischen Erläuterungen über ihren Aufbau und Zustand katalogisiert. Damit liegt eine wichtige Grundlage für das in Ausarbeitung befindliche Landes‐Moorschutzprogramm vor. Die Daten für jedes Moorgebiet werden im Fachinformationssystem Boden gespeichert. Die auf die Erstellung des Moorstandortkataloges gerichteten Untersuchungen zeigen, daß sich die ursprüngliche Genese der Niedermoore den lithogenetischen und morphologischen Bedingungen ihres Wassereinzugsgebietes anglich. Die Zuordnung der hydrologisch‐genetischen Moortypen folgt weitgehend der geomorphologischen Struktur des Jungmoränengebietes, z.B. Durchströmungsmoore in der ebenen bis welligen Grundmoräne, Küstenüberflutungsmoore am ca. 314km langen Küstenabschnitt der südlichen Ostsee, Kesselmoore in Endmoränengebieten usw.  相似文献   

Biodiversity and direct ecosystem service regulation in the community gardens of Los Angeles,CA     

Lorraine Weller Clarke  G. Darrel Jenerette 《Landscape Ecology》2015,30(4):637-653

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News item     

Hady Farag  Ulrich Hommel 《Euphytica》1991,59(1):97-97

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Efficient analysis of egg yolk proteins and their thermal sensitivity using sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing and nonreducing conditions     

Guilmineau F  Krause I  Kulozik U 《Journal of agricultural and food chemistry》2005,53(24):9329-9336

The multiple functional properties of egg yolk are mostly influenced by its complex protein composition. The high lipid content of egg yolk as well as the low solubility of delipidated egg yolk lipoproteins make analysis by conventional chromatographic or electrophoretic techniques a difficult task. This work describes a method to profile egg yolk proteins after delipidation with acetone using sodium dodecyl sulfate polyacrylamide gel electrophoresis on precast 8-18% T polyacrylamide gradient gels. Twenty bands were obtained for the whole egg yolk profile with molecular weights ranging between 5 and 221 kDa. The bands were identified based on their molecular weight and by comparison with isolated egg yolk subfractions. The dissociation behavior under reducing and nonreducing conditions provided additionally helpful information for identification and characterization of the yolk proteins. The method presented is very well suited for assaying the thermal sensitivity of whole yolk and its components and thus for the characterization of heat treatment processes.  相似文献   

Distortion of genetically modified organism quantification in processed foods: influence of particle size compositions and heat-induced DNA degradation     

Moreano F  Busch U  Engel KH 《Journal of agricultural and food chemistry》2005,53(26):9971-9979

Milling fractions from conventional and transgenic corn were prepared at laboratory scale and used to study the influence of sample composition and heat-induced DNA degradation on the relative quantification of genetically modified organisms (GMO) in food products. Particle size distributions of the obtained fractions (coarse grits, regular grits, meal, and flour) were characterized using a laser diffraction system. The application of two DNA isolation protocols revealed a strong correlation between the degree of comminution of the milling fractions and the DNA yield in the extracts. Mixtures of milling fractions from conventional and transgenic material (1%) were prepared and analyzed via real-time polymerase chain reaction. Accurate quantification of the adjusted GMO content was only possible in mixtures containing conventional and transgenic material in the form of analogous milling fractions, whereas mixtures of fractions exhibiting different particle size distributions delivered significantly over- and underestimated GMO contents depending on their compositions. The process of heat-induced nucleic acid degradation was followed by applying two established quantitative assays showing differences between the lengths of the recombinant and reference target sequences (A, deltal(A) = -25 bp; B, deltal(B) = +16 bp; values related to the amplicon length of the reference gene). Data obtained by the application of method A resulted in underestimated recoveries of GMO contents in the samples of heat-treated products, reflecting the favored degradation of the longer target sequence used for the detection of the transgene. In contrast, data yielded by the application of method B resulted in increasingly overestimated recoveries of GMO contents. The results show how commonly used food technological processes may lead to distortions in the results of quantitative GMO analyses.  相似文献   

Computerized apparatus for measuring dynamic flavor release from liquid food matrices     

Rabe S  Krings U  Banavara DS  Berger RG 《Journal of agricultural and food chemistry》2002,50(22):6440-6447

A fully computer-controlled apparatus was designed. It combines a glass reactor with a temperature-controlled hood, in which headspace volatiles are captured. Flavored liquids can be introduced into the reactor and exposed to conditions of temperature, air flow, shear rate, and saliva flow as they occur in the mouth. As the reactor is completely filled before measurements are started, creation of headspace just before sampling start prevents untimely flavor release resulting in real time data. In the first 30 s of flavor release the concentrations of the volatiles can be measured up to four times by on-line sampling of the dynamic headspace, followed by off-line trapping of the samples on corresponding Tenax traps and analysis using GC-TDS-FID. Flavor compounds from different chemical classes were dissolved in water to achieve concentrations typically present in food (micrograms to milligrams per liter). Most of the compounds showed constant release rates, and the summed quantities of each volatile of three 10 s time intervals correlated linearly with time. The entire method of measurement including sample preparation, release, sampling, trapping, thermodesorption, and GC analysis showed good sensitivity [nanograms (10 s)(-1)] and reproducibility (mean coefficient of variation = 7.2%).  相似文献   

Historical Contaminated Sediments and Soils at the River Basin Scale     

Ulrich?F?rstnerEmail author  Susanne?Heise  René?Schwartz  Bernhard?Westrich  Wolfgang?Ahlf 《Journal of Soils and Sediments》2004,4(4):247-260

Background, Aims, and Scope  

Data from the Elbe River and its tributaries indicate, despite extensive improvement in water quality during the last 15 years, that the respective sediment situation of many priority pollutants has not reached an acceptable level. For the coming decades, risks for downstream sites and stakeholders will persist, mainly due to secondary sources originating from historical pollution of soils and sediments in the catchment area. In practice, a catchment-wide assessment of historical contaminated soil and sediment should apply a three-step approach: (i) Identification of substances of concern (s.o.c.) and their classification into ’hazard classes of compounds’; (ii) identification of areas of concern (a.o.c.) and their classification into ‘hazard classes of sites’; (iii) identification of areas of risk (a.o.r.) and their assessment relative to each other with regard to the probability of polluting the sediments in the downstream reaches. The conversion of this concept has to consider the underlying philosophy of the EU Water Framework Directive, particularly with respect to the analysis and monitoring of priority substances in solid matrices. However, major deficiencies are still in the assessment and prognosis of resuspension processes, and potential approaches to fill this gap are described both in theory and from examples of the Elbe River.  相似文献   

Temporal variation in precipitation chemistry on the shore of the Chesapeake Bay     

Thomas E. Jordan  David L. Correll  Donald E. Weller  Nancy M. Goff 《Water, air, and soil pollution》1995,83(3-4):263-284

We studied precipitation chemistry at the Rhode River on the western shore of the Chesapeake Bay. We sampled on an event basis, beginning in 1973 for some constituents in bulk precipitation. Beginning in 1981, we also sampled wet precipitation separately from bulk precipitation. In this report, we examine temporal variability of precipitation chemistry at different time scales. Several constituents showed long-term trends. In bulk precipitation, hydronium concentration increased by 27% of its mean concentration per decade, calcium by 67%, ammonium by 28%, and nitrate by 25%, while organic nitrogen decreased by 41%, organic phosphorus by 31%, and organic carbon by 16%. In wet precipitation, ammonium increased by 33% and calcium by 100%, while magnesium decreased by 78% per decade. Concentrations differed greatly among precipitation events, increasing as the volume of precipitation decreased and as the interval since the previous event increased. Most constituents also showed marked seasonal variation. We used a regression model to predict concentrations for each event from month, precipitation volume, and the time since the previous event. We evaluated how much of the interannual variability could be explained by these factors. The event-scale model accounted for almost half of the variability among annual means for ammonium, sodium, and magnesium in bulk precipitation, and for potassium in wet precipitation. This suggests that much of the interannual variability of concentrations may result from interannual variation in the temporal distribution of precipitation.  相似文献   

Ökologische Gruppierung von Böden nach ihrem chemischen Bodenzustand     

B. Ulrich 《植物养料与土壤学杂志》1981,144(3):289-305

Ecological grouping of soils according to their chemical soil state On the base of the solubility of carbonic acid, calcium carbonate, as well as the oxidic compounds of Al and Fe existing in soils, the following buffer ranges are defined and separated from each other by pH values in the soil solution: Carbonic acid/Carbonate buffer range (pH 6.2 to 8.6), Carbonic acid/Silicate buffer range (pH 5.0 to 6.2), Exchanger buffer range (pH 4.2 to 5.0), Aluminium buffer range (pH 2.8 to 4.2), Iron buffer range (pH 2.4 to 3.8). The buffer capacities are calculated and literature indications regarding buffer rates are compiled. The characteristical chemical soil state is demonstrated for the various buffer ranges with aid of a soil collection. With increasing soil acidification the Ca/Al mole ratio in fine roots decreases from values > 1 to values around 0.3; this is taken as evidence for increasing disposition for Al-toxicity. It is suggested to attach soil horizons to buffer ranges on the base of pH(H₂O) measurements made on field fresh samples. The measurement of pH in salt solution is taken as measure for the amplitude of the chemical soil state in case of H-ion or salt stress.  相似文献