Effects of chemical modification with glutaraldehyde on the weathering performance of Scots pine sapwood

Scots pine sapwood was treated with glutaraldehyde (GA) in aqueous solution using magnesium chloride as a catalyst in order to evaluate the durability towards weathering. Infrared spectroscopy suggested that GA treatment increased the photo-stability of lignin during artificial weathering of micro-veneers in a QUV over 168?h; photo-protection increased with increasing GA concentration. In comparison with the unmodified controls, GA-modified pine micro-veneer strips exhibited a lower tensile strength loss measured in a zero-span mode in the course of weathering. During 18?months of outdoor exposure, GA-modified pine wood boards exhibited a lower moisture content and water uptake than the unmodified ones. GA treatment also clearly restricted the penetration of blue stain fungi into deeper layers of wood. On the macroscopic scale, the surface of the GA-modified boards was significantly smoother due to less erosion, cracking and minor peeling of tracheids. Scanning electron microscopy further revealed that individual tracheids were detached from the cell compound and then washed away from the unmodified wood surface, whereas tracheids on surfaces of GA-modified wood remained in the tissue compound but displayed many axial and transversal cracks.     

Soil organic carbon stocks,distribution, and composition affected by historic land use changes on adjacent sites

Historic alterations in land use from forest to grassland and cropland to forest were used to determine impacts on carbon (C) stocks and distribution and soil organic matter (SOM) characteristics on adjacent Cambisols in Eastern Germany. We investigated a continuous Norway spruce forest (F-F), a former cropland afforested in 1930 (C-F), and a grassland deforested in 1953 (F-G). For C and N stocks, we sampled the A and B horizons of nine soil pits per site. Additionally, we separated SOM fractions of A and B horizons by physical means from one central soil pit per pedon. To unravel differences of SOM composition, we analyzed SOM fractions by ¹³C-CPMAS NMR spectroscopy and radiocarbon analysis. For the mineral soils, differences in total C stocks between the sites were low (F-F = 8.3 kg m⁻²; C-F = 7.3 kg m⁻²; F-G = 8.2 kg m⁻²). Larger total C stocks (+25%) were found under continuous forest compared with grassland, due to the C stored within the organic horizons. Due to a faster turnover, the contents of free particulate organic matter (POM) were lower under grassland. High alkyl C/O/N-alkyl C ratios of free POM fractions indicated higher decomposition stages under forest (1.16) in relation to former cropland (0.48) and grassland (0.33). Historic management, such as burning of tree residues, was still identifiable in the subsoils by the composition and ¹⁴C activity of occluded POM fractions. The high potential of longer lasting C sequestration within fractions of slower turnover was indicated by the larger amounts of claybound C per square meter found under continuous forest in contrast to grassland.     

Spatial variability of topsoils and vegetation in a grazed steppe ecosystem in Inner Mongolia (PR China)

It is not clear from the literature how the spatial distribution of topsoil and vegetation properties is affected by grazing cessation. Thus, the objective of this study was to elucidate if long‐term grazing exclosure increases spatial heterogeneity of topsoil and vegetation properties in a steppe ecosystem in NE China. Variograms and crossvariograms were calculated for bulk density, organic carbon (OC), total N, and total S concentration, δ¹³C, pH, Ah horizon thickness, vegetation cover, and aboveground biomass. Five sites with different grazing intensities (ungrazed since 1979, ungrazed since 1999, winter grazing, continuously grazed, heavily grazed) were sampled with two different grid sizes, allowing the exploration of scale effects. Small grids (15 m spacing, 5 m nested sampling) exhibited a different spatial structure compared to large grids (50 m spacing, 10 m nested sampling). Spatial distribution in small grids changed with grazing intensity. Generally, heterogeneity of topsoil properties increased with decreasing grazing intensity from a homogeneous to a patchy distribution. We attribute this to vegetation recovery/succession and deposition of windblown material in ungrazed areas. The plot ungrazed since 1999 showed different spatial dependencies than continuously and heavily grazed plots, but has not yet reached the high variability of the plot which was ungrazed since 1979. Large grid sampling did not detect small‐scale variability or grazing impacts, but showed spatial dependencies that were attributed to topography or soil erosion/deposition. Low OC concentration and low Ah thickness were associated with hilltop and shoulder positions, resulting in lower OC stocks at these topographic units.     

Consistent set of additive biomass functions for eight tree species in Germany fit by nonlinear seemingly unrelated regression

Key message

Biomass functions are relevant for an easy and quick estimation of tree biomass. Nevertheless, additive biomass functions for different species and different components have not been published for the area of Germany, yet. Now, we present a set of additive biomass functions for estimating component and total mass for eight species and up to nine components.

Context

Biomass functions are relevant for an easy and quick estimation of tree biomass, e.g. for carbon budget calculation. Component-specific functions offer even more detail and can be used to answer questions about, e.g., biomass allocation to different components, (nutrient) element stock and flows or the amount and re-distribution of harvested biomass and its consequences.

Aims

Since there exists no published additive biomass functions in the context of Germany, we aimed at providing such equations for different species and different components using a comprehensive data set from different sources.

Methods

We collected several data sets for eight relevant tree species (Norway spruce, n =?1150 trees; Silver fir, n =?31; Douglas fir, n =?161; Scots pine, n =?460; European beech, n =?918; Oak, n =?313; Sycamore, n =?28 and European ash, n =?37) in Germany and adjacent countries, homogenised the component information, imputed missing values and applied nonlinear seemingly unrelated regression to eight (for deciduous trees species) respectively nine (for conifereous species) components simultaneously.

Results

The collected data set contains trees from 7 cm diameter in breast height to around 80 cm. From this broad data basis, we established two sets of additive biomass functions: a simple model using the predictors diameter in breast height and tree height as well as a more elaborate model using up to six predictors.

Conclusion

Finally, we can present additive models for the eight relevant tree species in Germany. Models for Silver fir, European ash and Sycamore are rather limited in their model range due to their input data; the other models are based on a broad range of predictors and are considered to be broadly applicable.

     

Effect of grazing on wind driven carbon and nitrogen ratios in the grasslands of Inner Mongolia

Wind erosion and dust storms are common phenomena in the semi-arid Xilingele grassland (Inner Mongolia) and contribute considerably to matter balances. Dust emission and dust deposition affect particles of the silt and clay fraction and the organic matter predominantly, the carriers for nutrients in soils. Based on wind erosion measurements in spring 2005 and 2006 the organic carbon and total nitrogen contents of dust were analyzed to determine the contribution of wind erosion processes on C- and N-ratios to the grasslands.     

Formation of alpha-dicarbonyl compounds in beer during storage of Pilsner

With the aim of determining the formation of alpha-dicarbonyl intermediates during beer aging on the shelf, alpha-dicarbonyls were identified and quantified after derivatization with 1,2-diaminobenze to generate quinoxalines. The sensory effects of alpha-dicarbonyls were evaluated by the quantification of key Strecker aldehydes and by GC-olfactometry (GCO)analysis of beer headspace using solid phase microextraction. Four alpha-dicarbonyls, reported here for the first time, were detected in fresh and aged beers, three were derived from the 2,3-enolization pathway of mono- and disaccharides, and the fourth was derived from the epimerization of 3-deoxy-2-hexosulose. Ten alpha-dicarbonyls were quantified during beer processing and during different periods of beer aging at 28 degrees C. The aging periods were from 15 to 105 days. During beer aging, 1-deoxydiuloses were produced and degraded, while 1,4-dideoxydiuloses were produced at the highest rates. The GCO analysis indicated that forced beer aging increased the amounts of furaneol, trans-2-nonenal, and phenylacetaldehyde. The blockage of alpha-dicarbonyls inhibited the accumulation of sensory-active aldehydes in the beer headspace.     

The Mycobacterium avium subsp. paratuberculosis ELISA response by parity and stage of lactation

Two cross-sectional studies were carried out to determine the enzyme-linked immunosorbent assay (ELISA) response to Mycobacterium avium subsp. paratuberculosis (Map) by cow characteristics and stage of lactation. One of the studies (referred to as "milk-group") used milk samples from all lactating cows (n=7994) in 108 Danish dairy herds. The other study (referred to as "serum-group") used serum samples collected from all cows (n=5323) in a subset of 72 herds from the 108 herds. These samples were analysed using a similar ELISA for detection of antibodies.The results from the ELISAs were interpreted with two cut-off values as the optimal cut-off value is not known, and as several levels are recommended to be used in practice. The results showed that the probability of being ELISA-positive was two to three times lower for cows in parity 1 relative to cows in other parities using both milk and serum ELISA. At the beginning of the lactation the probability of being positive was highest in the milk ELISA. In the serum ELISA the odds of being positive was highest at the end of lactation. The findings are important in the interpretation of ELISA results at cow level with a subsequent tentative diagnosis and correction for parity and stage of lactation should be considered when providing a diagnosis of paratuberculosis. Some issues related to the pathogenesis are also discussed.     

Occurrence pattern of Pararge aegeria (Lepidoptera: Nymphalidae) with respect to local habitat suitability, climate and landscape structure

Distribution patterns of wild species are affected by environmental variables, such as climate, anthropogenic land use or habitat quality, which act simultaneously at different scales. To examine the relative importance of particular factors and scales on population response we investigated the speckled wood butterfly Pararge aegeria (L.) as a model organism occupying semi-natural habitats. Its distribution was recorded in 23 study sites (5×5 km) over a 2 year study period. The sites were located in agricultural landscapes within seven Temperate European countries. Environmental predictors were mapped at a local and a regional scale. Logistic regression models were then developed to represent humid (beneficial) and dry (adverse) weather conditions during larval development. The humid year model predicted that P. aegeria is equally but generally not very dependent on local and regional factors, resulting in generally high occurrence probabilities. In contrast, the dry year model predicted severe restrictions of P. aegeria to both high quality patches and landscapes with beneficial structural and climatic preconditions. As both models resulted in entirely different predictions, our study showed that the sensitivity of P. aegeria to local and landscape features might change, and that factors of less importance could easily become limiting factors. The results stress that high quality landscape is important at both the local and regional scale even for species that are considered relatively robust. They also sound a note of caution when predictions about population response for management purposes are based on just a single or a few year(s) of observation.     

Conduction velocities and myelinated fiber diameter spectra of the infraorbital and palpebral nerves of the dog

Maximum conduction velocities of compound-action potentials of the infraorbital (ION) and palpebral (PN) nerves were determined by averaging potentials evoked and recorded through subcutaneous needle electrodes. The specificity of the stimulating and recording sites was verified by recording before and after cutting the nerves. Conduction times for orthodromically and antidromically conducted potentials of the ION were essentially the same. The unipolarly recorded antidromic compound-action potentials of the ION were of higher peak-to-peak amplitude and were more reliably recorded than were the bipolarly recorded orthodromic action potentials. Areas of cutaneous innervation were not found for the PN. Neuromuscular blockade eliminated the volume-conducted muscle action potentials that were recorded after PN stimulation, allowing triphasic nerve action potentials to be recorded unobscured. Mean conduction velocities were: ION = 83.9 +/- 3.5 m/s; PN = 56.4 +/- 2.8 m/s. Distributions of the external diameters of myelinated fibers within the ION and the PN were determined.     

Involvement of hepatic xenobiotic related genes in bromadiolone resistance in wild Norway rats, Rattus norvegicus (Berk.)

To examine the role of xenobiotic relevant genes in bromadiolone resistance in wild Norway rats (Rattus norvegicus) we compared the constitutive liver gene expression and expression upon bromadiolone administration in bromadiolone resistant and anticoagulant susceptible female rats using a LNA microarray and quantitative PCR. Resistant rats showed significantly higher constitutive expression of the cytochrome P450 genes Cyp2c13 and Cyp3a2 and lower expression of Cyp2e1 and Gpox1 compared to the susceptible rats. The Cyp1a2, Cyp2c13, Cyp2e1, Cyp3a2 and Cyp3a3 genes were significantly higher expressed in resistant than susceptible rats upon bromadiolone exposure. To establish how bromadiolone affected xenobiotic gene expression in the two strains we compared bromadiolone expression profiles to saline profiles of both strains. Bromadiolone mediated significant up-regulation of Cyp2e1 and Cyp3a3 expression in the resistant rats whereas the rodenticide conferred down-regulation of Cyp2e1, Cyp3a3 and Gpox1 and induction of Cyp2c12 expression in susceptible rats. Cyp2c13 and Cyp3a2 expression were markedly suppressed in both strains upon treatment. This suggests that xenobiotic relevant enzymes play a role in bromadiolone resistance in the Norway rat. A high constitutive expression of Cyp2c13 and Cyp3a2 and induction of Cyp1a2, Cyp2e1 and Cyp3a3 expression during bromadiolone exposure may increase the resistance to bromadiolone presumably by facilitating increased detoxification and decreased liver injury.