Effects of host plant hybridization on resistance to willow leaf rust caused by Melampsora sp.

Patterns of resistance to willow leaf rust caused by Melampsora sp. were measured on Salix eriocephala, Salix sericea, and their interspecific hybrids in natural field populations in 1991–94 and on potted plants in common garden experiments in 1994 and 1995. Testing was carried out to establish if the resistance of hybrids was intermediate between pure parental species (additive), equal to one of the parents (dominant), lower than both parents (susceptible), higher than both parents (resistant), or not different than either parent (null hypothesis). Support was generally found for hybrid susceptibility in the field and common garden experiments, with the null hypothesis of no difference having some support. The results from the common garden study suggest that the susceptibility of hybrids seen in the field is due to genetic differences. Hybridization between these species of willows results in increased susceptibility to this pathogen. The variation among years in the relative susceptibility of hybrid and parental willows may be due to environmental effects on the willows or to shifts in the abundance of Melampsora races.     

Use of near infrared spectroscopy to determine biological and chemical characteristics of organic layers under spruce and beech stands

The chemical composition of organic layers of forest soils shows a high spatial variability and fast methods may be required for its study at a landscape level. The objective was to assess the applicability of near infrared spectroscopy (NIRS) to measure several chemical and biological properties of organic layers in spruce, beech, and mixed spruce‐beech stands. Spectra in the VIS‐NIR region (400—2500 nm) were recorded for 406 samples representing Oi, Oe, and Oa layers of forest soils from Solling (Germany), 195 of them were used for calibration and 211 for validation. The calibration equations for each constituent were developed using the whole spectrum (0^th to 3^rd derivative). Humus samples were analyzed for contents of C and N and contents of P, S, Na, K, Ca, Mg, Mn, Fe, and Al after pressure digestion in HNO₃. Additionally, basal respiration and microbial C (C_mic) were measured. NIRS predicted well the contents of C, N, P, S, Ca, Na, K, Fe, and Al and C/N and C/P ratios: the regression coefficients (a) of a linear regression (measured against predicted values) ranged from 0.9 to 1.1, and the correlation coefficients (r) were greater or equal 0.9. C_mic (a = 0.87, r = 0.83) was predicted satisfactorily, whereas the prediction of the basal respiration (a = 0.74, r = 0.87) was less satisfactory. Due to liming of some of the plots NIRS failed to predict contents of Mg (a = 1.27, r = 0.68). For all chemical and biological characteristics the best prediction performances were achieved using the whole sample population. Splitting the samples into smaller groups according to a dominant tree species or an organic layer did not improve the predictions.<?show $6#>     

Reference points for predators will progress ecosystem‐based management of fisheries

Ecosystem‐based management of fisheries aims to allow sustainable use of fished stocks while keeping impacts upon ecosystems within safe ecological limits. Both the FAO Code of Conduct for Responsible Fisheries and the Aichi Biodiversity Targets promote these aims. We evaluate implementation of ecosystem‐based management in six case‐study fisheries in which potential indirect impacts upon bird or mammal predators of fished stocks are well publicized and well studied. In particular, we consider the components needed to enable management strategies to respond to information from predator monitoring. Although such information is available in all case‐studies, only one has a reference point defining safe ecological limits for predators and none has a method to adjust fishing activities in response to estimates of the state of the predator population. Reference points for predators have been developed outside the fisheries management context, but adoption by fisheries managers is hindered a lack of clarity about management objectives and uncertainty about how fishing affects predator dynamics. This also hinders the development of adjustment methods because these generally require information on the state of ecosystem variables relative to reference points. Nonetheless, most of the case‐studies include precautionary measures to limit impacts on predators. These measures are not used tactically and therefore risk excessive restrictions on sustainable use. Adoption of predator reference points to inform tactical adjustment of precautionary measures would be an appropriate next step towards ecosystem‐based management.     

The Vjosa River corridor: a model of natural hydro-morphodynamics and a hotspot of highly threatened ecosystems of European significance

Landscape Ecology - Large near-natural rivers have become rare in Europe, a fact reflected in the high conservation status of many riverine ecosystems. While the Balkan still harbors several intact...     

Winterobstbaumspritzung 1949/50 im Stadtgebiet Ludwigshafen

Ohne Zusammenfassung     

Iron oxidation in different types of groundwater of Western Siberia

Background, aim, and scope  The groundwaters of Western Siberia contain high concentrations of iron, manganese, silicon, ammonium, and, in several cases, hydrogen sulfide, carbonic acids, and dissolved organic substances. Generally, the groundwaters of Western Siberia can be divided into two major types: one type with a relatively low concentration of humic substances and high hardness (water of A type) and a second type with a relatively low hardness and high concentration of humic substances (water of B type). For drinking water production, the waters of A type are mostly treated in the classical way by aeration followed by sand bed filtration. The waters of B type often show problems when treated for iron removal. A part of iron practically does not form the flocs or particles suitable for filtration or sedimentation. The aim of this work was to determine the oxidizability of Fe(II), to characterize the iron colloids, and to investigate the complexation of the iron ions with humic substances and the coagulation of the iron colloids in the presence of dissolved organic matter. Materials and methods  Water samples of the A and B types were taken from bore holes in Western Siberia (A type: in Tomsk and Tomsk region, B type: in Beliy Yar and Kargasok). Depth of sampling was about 200 m below surface. The oxidation of the groundwater samples by air oxygen and ozone was done in a bubble reactor consisting of a glass cylinder with a gas-inlet tube. To produce ozone, a compact ozone generator developed by Tomsk Polytechnic University was used. For the characterization of the colloids in the water of B type, the particle size distribution and the zeta potential were measured. To investigate the formation of complexes between iron and humic substances in the water of B type, size exclusion chromatography was used. The coagulation behavior of iron in the presence of dissolved organic substances was investigated at different pH values. The agglomerates were detected by measuring the optical density using a UV-Vis spectrometer. Results  Ozone showed, as expected, a faster oxidation of Fe(II) than air oxygen. The rate constants for Fe(II) oxidation were not much different for the waters of A and B types when the same oxidation process was used. However, the removal of iron after oxidation and filtration was higher in the water of A type than in the water of B type. No evidence for the formation of soluble complexes between iron and humic substances were found. In the water of A type, the coagulation process started at pH = 4.5 and accelerated with increasing pH value. In the water of B type, the coagulation of colloids occurred only at pH = 11 and higher. Discussion  The oxidation experiments indicated no major effect of dissolved organic carbon concentration on the kinetics of Fe(II) oxidation. In contrast to this, the humic substances showed a significant influence on the aggregation behavior of the iron hydroxide colloids. Due to the sorption of humic substances on the iron hydroxide colloids, they were highly stable in the pH range between 4.5 and 10. The particle size measurements confirmed the presence of small colloids in the water of B type. In contrast to this, the iron hydroxide colloids aggregated rapidly at pH = 11. Conclusions  The results showed a great influence of humic substances on the iron removal from groundwaters of Western Siberia with high organic content. The sorption of humic substances on the iron colloids does not obviously allow their coagulation and formation of flocs suitable for filtration or sedimentation. Recommendations and perspectives  By treatment of groundwaters containing high amounts of humic substances, some problems with the removal of iron are likely to occur. To increase the effectiveness of iron removal, the surface coating and pH-dependent charge effects should be taken into account by the selection and optimization of water treatment processes. The iron colloids coated by humic substances should be separated from the water phase by membrane filtration or by flocculation followed by filtration through different solid materials.     

Investigation of the lactosylation of whey proteins by liquid chromatography-mass spectrometry

Heat treatment of milk induces a reaction between the milk proteins and lactose, resulting in lactosylated protein species. The lactosylation of the two major whey proteins alpha-lactalbumin and beta-lactoglobulin was investigated by reversed phase liquid chromatography-mass spectrometry (LC-MS). Three sample series, consisting of aqueous model solutions of each whey protein separately and in mixture and whole milk, were heated for different time periods, and the progression of the lactosylation reaction was monitored. The observed degrees of lactosylation and the reaction kinetics showed that the lactosylation of beta-lactoglobulin was not influenced by the presence of other components, whereas the lactosylation of alpha-lactalbumin was enhanced in whole milk compared to the aqueous model systems. An in-depth evaluation of the LC-MS data yielded information regarding changes of physicochemical properties of the whey proteins upon lactosylation. Whereas retention time shifts indicated changes in hydrophobicity for both alpha-lactalbumin and beta-lactoglobulin, changes in the charge state distribution denoting conformational alterations were observed only for beta-lactoglobulin. The analysis of different liquid and solid milk products showed that the lactosylation patterns of the whey proteins can be used as indicators for the extent of heat treatment.     

The enhanced mineralization of simazine and bentazon in soil after plant uptake

[triazine-ring-¹⁴C] simazine and [benzene-ring-¹⁴C] bentazon were added to the epipedon of a Luvisol from loess with and without maize shoots or roots (2 g/100 g soil) and mineralization proceeded in accordance with the standardized BBA degradation method at 50% of the maximum water holding capacity of the soil and at 22°C. The same degradation study was conducted using maize shoots (simazine) and maize roots (bentazon) which had taken up either ¹⁴C-simazine or ¹⁴C-bentazon from soil application. After 93 days of incubation 6.6% (simazine) or 7.2% (bentazon) of this plant incorporated ¹⁴C was mineralized to ¹⁴CO₂. This was 4–10 times greater than the mineralization of active ingredients applied to the soil and 4–6 times higher when compared to variants which in addition received maize shoots (simazine) or roots (bentazon) as an additional energy source for microbial development. Apparently as a consequence of the more intensified degradation processes, the bound residue fractions were higher by a factor of 2 when the residual radiocarbon reached the soil already incorporated into plant material.     

Stratigraphic diatom and chemical evidence for acid strip-mine lake recovery

Stratigraphic analyses of diatoms and chemical compounds in a sediment core were utilized to investigate the recovery of an acid strip-mine lake in southern Ohio. The chemical stratigraphy suggests that chemical recovery of the lake, defined as the rise and maintenance of water pH at values above 4.5, is a discrete process marked in the core by a sharp rise in the sediment concentrations of metals. The diatom data suggest that biological recovery may occur in stages, beginning at the sediment-water interface. As the lake ages, there is a transition from a community dominated by a single acidophilous species characteristic ofbbenthic habitats to a community composed of many planktonic, epiphytic, and benthic species of primarily alkaliphilous preference. Biological development is not directly correlated with the chemical recovery.