Schlagform und Standortsflora im Jura

Ohne Zusammenfassung     

Long-term sustainability of wood-pasture separation processes—A matter of seed mixtures and management

We studied the performance of different seed mixtures and the influence of liming on the establishment of a montane pasture under acidic site conditions during a wood-pasture separation process from 1998 to 2001 in Styria, Austria. Two treatments (with and without liming) were established, each with four seeding treatments (without seeding, commercial, site-adapted and site-specific mixtures), and all plots were regularly fertilized from 1998 to 2002. Vegetation surveys and forage analyses regarding development of vegetation cover, seeded species persistence, quality and yield parameters were conducted again in 2014 and 2016; soil samples were taken in 2015. After cessation of regular fertilization, the analysed soil parameters declined to levels that were sufficient or low for grasslands. pH decreased again over time, but still was significantly higher (p = .0034) in the liming treatment. The single liming during experimental set-up also caused better long-term performance for nearly all vegetation, quality and yield parameters. The site-specific seed mixture performed best regarding most analysed parameters, under both liming treatments. Concerning seeded species, the habitat-typical species Agrostis capillaris, Festuca rubra agg. and Trifolium repens persisted best with and without liming. All analysed vegetation and yield parameters stayed far behind their results of 2001 and their potential. The use of site-specific seed mixtures supports the establishment of productive grassland on specific locations. The long-term results also illustrated that even low-input management like liming in multi-annual intervals can help to improve acidic site and growing conditions significantly and thereby increases the sustainability of cost-intensive wood-pasture separation processes under similar conditions.     

Are species genetically more sensitive to habitat fragmentation on the periphery of their range compared to the core? A case study on the sand lizard (<Emphasis Type="Italic">Lacerta agilis</Emphasis>)

Context

Species show different sensitivity to habitat loss and fragmentation depending on their specialization. Populations of a species at the range margin are generally assumed to be more stenoecious than populations at the core of the distribution and should therefore be more sensitive to habitat fragmentation.

Objectives

We evaluated the hypothesis that fragmentation effects species more strongly at the range periphery of their range compared to the core, resulting in lower genetic variability in comparable patch sizes and lower gene flow among populations.

Methods

We compared the genetic diversity and structure of five sand lizard (Lacerta agilis) populations at the margin of its range in Bulgaria and of 11 populations at the core of its distribution in Germany. We based the analysis on microsatellites, comprising 15 loci in Bulgaria and 12 in Germany.

Results

All diversity indices declined with patch size. For medium-sized patches all diversity indices were lower at the range periphery compared to the core, with two of them being significant. AIC_c based model selection showed strong support for core/periphery and patch size effects for observed and expected heterozygosity but only a patch size effect for allelic richness. There was no isolation-by-distance and each sampled population was allocated to a separate cluster with high probability for both countries, indicating that all populations are (almost) completely isolated.

Conclusion

Our study indicates an increased sensitivity of a species to fragmentation at the periphery compared to the core of its distribution. This differential sensitivity should be accounted for when prioritizing species based on their fragmentation sensitivity in landscape management.

     

Composition and thermal stability of anthocyanins from chinese purple corn ( Zea mays L.)

Chinese purple corn extracts ( Zea mays L., Zhuozhou, Hebei, China) (EZPC) were selected among five Chinese purple corn hybrids due to their higher anthocyanin content, and their thermal stability was evaluated. The total anthocyanin content and total phenolic content of EZPC were 304.5 +/- 16.32 mg of cyanidin-3-glucoside equiv/100 g of dry seeds and 489.8 +/- 24.90 mg of gallic acid equiv/100 g of dry seeds, respectively. Moreover, the individual anthocyanins of EZPC were determined by HPLC-DAD/ESI-MS analysis. Seven main compounds were determined, including cyanidin-3-(malonylglucoside), cyanidin-3-O-glucoside-2-malonylglucoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, peonidin-3-(malonylglucoside), pelargonidin-3-(6'-malonylglucoside), and peonidin-3-(dimalonylglucoside). The thermal stability of EZPC was studied by differential scanning calorimetry. Thermodynamic analysis showed that the conversion of EZPC followed an Arrhenius relationship, where the delta enthalpy (H) and activation energy (E(a)) were 97.0 J/g and 204 +/- 2.72 kJ/mol, respectively. Furthermore, the relationships between the degree of conversion of EZPC and time or temperature were reported. This study demonstrated that the evaluated Chinese purple corn hybrids are a natural source of anthocyanins and are stable over a wide range of temperatures and times.     

Transport of [14C]benazolin and bromide in large zero-tension outdoor lysimeters and the undisturbed field in a sandy soil

In order to investigate the transferability of lysimeter results to the actual field situation, a leaching study with [¹⁴C]benazolin and bromide was carried out in a sandy soil. A suction base system, where soil water and solute fluxes through a lateral cross-sectional sampling area could be measured in an undisturbed field environment, was developed as reference system. Using that measuring instrument, possible artefacts of the lysimeter system could be excluded. The outflow of soil water and leaching of benazolin and bromide showed no system-related differences between the lysimeters and the undisturbed field represented by the suction base station. Higher outflow of leachate and bromide in the lysimeters could be attributable to different meteorological conditions at the lysimeter and the field station. © 1999 Society of Chemical Industry     

Photochemistry of vinclozolin in water and methanol–water solution

The photolysis of the fungicide vinclozolin in aqueous and methanol–water (50 + 50 by volume) solution has been examined. Irradiation at λ = 254 nm for 10 minutes resulted in <90% and ≤95% substrate transformation respectively. The dissipation of vinclozolin both in water and methanol + water was linear and the calculated half-lives were 1.01 and 2.0 min respectively. Irradiation (8 h) with UV light (λ ≥ 290 nm) resulted in 10% degradation of the chemical, which is of the same magnitude as that of the control (not irradiated). Irradiation (8 h) under artificial sunlight (Suntest) in the presence of commercially available humic acid (K-salt) resulted in 55% degradation of the chemical. Photolysis leads to the opening of the 2,4-oxazolidine-dione ring, forming 3,5-dichlorophenyl isocyanate and 3,5-dichloroaniline. In addition, dechlorination and elimination of the  CHCH₂ moiety takes place, and one or both the chlorine atoms are replaced by a methoxy group. © 1999 Society of Chemical Industry     

Sediment Properties for Assessing the Erosion Risk of Contaminated Riverine Sites. An approach to evaluate sediment properties and their covariance patterns over depth in relation to erosion resistance. First investigations in natural sediments (11 pp)

Background, Aim and Scope   Riverine sediments store large quantities of hazardous contaminants, remaining a 'legacy of the past' world-wide. Natural events such as floods may cause the resuspension of polluted sediments and accordingly, the former immobilized contaminants might become bioavailable and toxic again. Hence, a comprehensive erosion risk assessment of contaminated sites is of crucial importance. The present study aimed to implement 'master-variables' for a reliable, easy-to-manage and economically more viable determination of stability in cohesive sediments. Materials and Methods: A wide range of physico-chemical (bulk density, water content, particle size, mineral composition, cation exchange capacity / CEC, total organic matter / TOC, liquid and plastic limits of a soil) and biological (macrofauna abundances, microalgal biomass and species composition, bacterial cell numbers, EPS fractions such as carbohydrates and proteins) properties were determined simultaneously over depth spanning the zone between 0-35 cm. The data were related to sediment stability, determined as the 'critical shear stress for mass erosion' in the SETEG (Stroemungskanal zur Ermittlung der tiefenabhaengigen Erosionsstabilitaet von Gewaessersedimenten) - flume. The investigations were done on natural sediments, thereby covering vertical (over depth), spatial (different study sites) and temporal (different seasons) aspects to ensure the transferability of the data. Here, first data originating from three contaminated reservoirs in the lock-regulated River Neckar / Germany are presented. Results: Comparison of the rather low critical shear stress values (resisting force of sediment, determined in SETEG) with the possibly occurring natural bottom shear stresses (attacking force, calculated for different hydraulic scenarios) at the three reservoirs indicated a severe risk of sediment erosion even under moderate hydraulic conditions and was not restricted to the surface. Critical shear stress was characterised by the following sediment properties of depth, grain size, CEC (Cation Exchange Capacity) and concentrations of TOC (Total Organic Carbon), proteins as well as carbohydrates (water- and resin-extractable). Firstly, biological stabilisation by extracellular polymeric substances (EPS) could be shown for riverine sediments, even over depth. Secondly, erosion resistance was determined by the inter-particles forces, an interplay of the biologically produced compounds constituting active surfaces and the binding capacity as well as charge densities of the sediments. The combined influence of sedimentological and biological properties on sediment stability over depth was assessed by PCA (Principal Component Analysis). Discussion: Hence, a better correlation coefficient between sediment stability and the master variables could be achieved (Main component II: Polymeric substances, R = 0.7, Main component III: Grain size, TOC, CEC, R = 0.9) compared to single correlations. Conclusions: The present paper revealed the combined influence of physico-chemical and biological properties on sediment stability over depth by simultaneous investigation and statistical evaluation. It can be shown, that inter-particle forces, determined by particles size classes, CEC, TOC and polymeric substances such as proteins and carbohydrates, affected sediment stability most. Thereby, the impact of biogenic sediment mediation on riverine sediment stabilisation became evident, even over depth, where mostly sedimentological parameters were considered as important before. Recommendations and Perspectives: The importance of a comprehensive risk assessment of contaminated riverine sites was again highlighted in the present study by the comparison of natural occurring bottom shear stresses with the determined sediment erosion resistance. If a realistic risk assessment is to be derived, the stabilizing potential of micro-organisms needs to be taken into account and the covariance patterns of biological and physico-chemical sediment properties have to be addressed.