Analyzing the effect of stepping stones on target patch colonisation in structured landscapes for Eurasian lynx

With habitat loss and fragmentation having become two of the major threats to the viability of species, the question of how to manage landscapes for species conservation has attracted much attention. In this context, the planning of stepping stones has been proposed to increase connectivity in fragmented landscapes. We present a simulation study with a neutral landscape approach to assess the effects of stepping stones on colonization success. To that end, we used a spatially explicit, calibrated population model of the European lynx (Lynx lynx) coupled with structured landscapes, in which we could control the landscape parameters of dispersal habitat coverage and contagion, as well as the number and size of stepping stones available for breeding. In general, we found that colonization success increased with increasing habitat coverage but decreased with increasing habitat contagion, while the introduction of stepping stones had significant effects in critical situations. Especially at low to medium dispersal habitat coverage and high disperser mortality, stepping stones had a positive effect on colonization success when they were large enough to produce new dispersers, but negative effects when they were small and located in a way that dispersers would be distracted from more suitable breeding habitat patches. The latter clearly constituted a shading effect and argues for a thorough consideration of the trade-offs related to stepping stone size and location when implementing stepping stones as a conservation measure, especially when the number of individuals of conservation concern is low.     

Signal recognition particle receptor exposes the ribosomal translocon binding site

Signal sequences of secretory and membrane proteins are recognized by the signal recognition particle (SRP) as they emerge from the ribosome. This results in their targeting to the membrane by docking with the SRP receptor, which facilitates transfer of the ribosome to the translocon. Here, we present the 8 angstrom cryo-electron microscopy structure of a "docking complex" consisting of a SRP-bound 80S ribosome and the SRP receptor. Interaction of the SRP receptor with both SRP and the ribosome rearranged the S domain of SRP such that a ribosomal binding site for the translocon, the L23e/L35 site, became exposed, whereas Alu domain-mediated elongation arrest persisted.     

Greenhouse gas emissions from Silphium perfoliatum and silage maize cropping on Stagnosols

Background

The sustainability of bioenergy is strongly affected by direct field-derived greenhouse gas (GHG) emissions and indirect emissions form land-use change. Marginal land in low mountain ranges is suitable for feedstock production due to small impact on indirect land-use change. However, these sites are vulnerable to high N₂O emissions because of their fine soil texture and hydrology.

Aims

The perennial cup plant (Silphium perfoliatum L.) might outperform silage maize (Zea mays L.) on cold, wet low mountain ranges sites regarding yield and ecosystem services. The aim of this study was to assess whether the cultivation of cup plant also provides GHG mitigation potential compared to the cultivation of maize.

Methods

A t-year field experiment was conducted in a low mountain range region in western Germany to compare area and yield-scaled GHG emissions from cup plant and maize fields. GHG emissions were quantified using the closed chamber method.

Results

Cup plant fields emitted an average of 3.6 ± 4.3 kg N₂O-N ha^–1 year^–1 (–85%) less than maize fields. This corresponded to 74.0 ± 94.1 g CO_2-eq kWh^–1 (–78%) less emissions per produced electrical power. However, cup plant had a significantly lower productivity per hectare (–34%) and per unit of applied nitrogen (–32%) than maize.

Conclusion

Cup plant as a feedstock reduces direct field-derived GHG emissions compared to maize but, due to lower yields cup plant, likely increases emissions associated with land-use changes. Therefore, the increased sustainability of bioenergy from biogas by replacing maize with cup plant is heavily dependent on the performance of maize at these sites and on the ecosystem services of cup plant in addition to GHG savings.     

Evaluation of calibrated passive sampling for quantifying ammonia emissions in multi-plot field trials with slurry application

Background

There is a great need for simple and inexpensive methods to quantify ammonia emissions in multi-plot field trials. However, methods that meet these criteria have to be thoroughly validated. In the calibrated passive sampling approach, acid traps placed in the center of quadratic plots absorb ammonia, enabling relative comparisons between plots. To quantify ammonia emissions, these acid trap samplings are scaled by means of a transfer coefficient (TC) obtained from simultaneous measurements with the dynamic tube method (DTM). However, dynamic tube measurements are also comparatively costly and time-consuming.

Aims

Our objective was to assess the best practice for using calibrated passive sampling in multi-plot field trials. One particular challenge in such experiments is to evaluate the influence of ammonia drift between plots.

Methods

In a series of eight multi-plot field trials, acid traps and DTM were used simultaneously on all plots to measure ammonia emissions caused by different slurry application techniques. Data obtained by both methods were correlated, and the influence of the ubiquitous ammonia background on both methods was evaluated by comparing net values, including the subtraction of the background with gross values (no background subtraction). Finally, we provide recommendations for calculating a TC for calibrating relative differences between plots, based on simultaneous acid trap and dynamic tube measurements on selected plots.

Results

Treatment mean values obtained by both methods correlated well. For most field trials, R² values between 0.6 and 0.8 were obtained. Ammonia background concentrations affected both methods. Drift between plots contributed to the background for the acid traps, whereas the contamination of the chamber system might have caused the background for the DTM. Treatments with low emissions were comparatively more affected by that background.

Conclusion

For a robust application of calibrated passive sampling, we recommend calculating the TC based on a treatment with high ammonia emissions, reducing the relative influence of the ubiquitous ammonia background.     

Contrast‐enhanced ultrasonography characteristics of intrathoracic mass lesions in 36 dogs and 24 cats

Contrast‐enhanced ultrasonography (CEUS) is increasingly available for veterinary patients, however limited studies describe the use of this method for characterizing intrathoracic mass lesions. The aim of this prospective, observational study was to describe CEUS enhancement patterns for intrathoracic mass lesions in a sample of cats and dogs. Sixty patients (36 dogs, 24 cats) were included. Standardized CEUS examinations were performed for 41 pulmonary masses (68%) and 19 mediastinal masses (32%). Final diagnosis was based on cytology and/or histopathology. Absolute time to enhancement (TTE) values were recorded for the intrathoracic mass lesions and spleen. The spleen was used as a reference parenchymal organ to calculate relative TTE (rTTE) values. Absolute TTE of the spleen and intrathoracic mass lesions differed for dogs and cats (P = 0.001). The rTTE values significantly differed between lesions of neoplastic versus non‐neoplastic origin (P = 0.004). The majority of neoplastic pulmonary masses were supplied by bronchial arteries (63%), while most nonneoplastic pulmonary masses were supplied by pulmonary arteries (78%). The sensitivity and specificity for detecting pulmonary neoplastic masses with rTTE were 63% and 78%, respectively. Enhancement patterns for mediastinal thymomas and lymphomas significantly differed (P = 0.002). Thymomas enhanced heterogeneously in a centripetal pattern (86%), whereas lymphomas typically enhanced uniformly in a centrifugal pattern (75%). Findings indicated that CEUS is a feasible method for characterizing intrathoracic mass lesions in dogs and cats, however, the diagnostic sensitivity for detecting neoplastic pulmonary masses was low.     

A method to generate soilscapes from soil maps

Digital soil mapping for large areas is challenging if mapping resolution should be as high as possible and sampling should be as sparse as possible. Generally, the more complex the soil associations in a landscape, the more samples are required to systematically cover the entire feature space. Moreover, regions should be modeled separately if the patterns of spatial variation vary on subregion level. A systematic segmentation of a landscape into soilscapes is additionally important for a feasible application of soil‐sensing approaches. In this paper, we introduce a semiautomated approach to segment nominal spatial datasets based on the local spatial frequency distribution of the mapping units. The aim is to provide homogeneous and nonfragmented segments with smoothed boundaries. The methodological framework for the segmentation comprises different spatial and nonspatial techniques and focuses mainly on a moving‐window analysis of the local frequency distribution and a k‐means cluster analysis. Based on an existing soil map (1:50,000), we derived six segments for the Nidda catchment (Central Hesse, Germany), comprising 1600 km². As segmentation is based on a soil map, soilscapes are derived. In terms of the feature space, these soilscapes show a higher homogeneity compared to the entire landscape. Advantages compared to an existing map of landscape units are discussed. Segmenting a landscape as introduced in this study might also be of importance for other disciplines and can be used as a first step in biodiversity analysis or setting up environmental‐monitoring sites.     

Applicability of ground‐penetrating radar as a tool for nondestructive soil‐depth mapping on Pleistocene periglacial slope deposits

Soil depth plays a decisive role in determining soil properties in mountainous regions for ecological site assessment. To evaluate the use of ground‐penetrating radar (GPR) for fast and high‐resolution mapping within mountainous regions, we examined the possibilities and limitations of GPR to determine soil depth over bedrock and to delineate individual substrate layers formed during the Pleistocene in a periglacial environment (Pleistocene periglacial slope deposits, PPSD). Selected catenae in representative subregions of the study area (Dill catchment, SE Rhenish Massif, Germany) have been successfully mapped using GPR. A practicable method was developed using a 400 MHz antenna to reach a mean penetration depth of 1.5 m and to map different substrates and layers of PPSD based on calibrations of the GPR at soil pits along 12 catenae. Colluvium, the three types of PPSD layers, as well as the in situ bedrock could be distinguished in most sections of the GPR surveys. Characteristic GPR facies caused by intrinsic material properties of the different substrates, such as stone content and soil moisture content, could be distinguished in different geomorphologic and lithological settings. A layer‐based velocity distribution was determined for characteristic substrate layers at soil pits enabling us to considerably enhance the accuracy of soil‐depth prediction. Compared to traditionally surveyed soil profiles, our results demonstrate an accuracy of layer thickness surveying within a standard deviation of approx. 0.1 m. It is demonstrated that the combination of GPR with conventional soil‐pit mapping is an efficient and valid method to produce high‐resolution data of substrate distribution.     

Natural diversity of inflorescence architecture traces cryptic domestication genes in barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.)

Many-grained mutants occurring spontaneously among their less well-endowed field mates may have appeared to early farmers as fortunate twists of fate foreboding wealth and abundance. In domesticated barley, the number of kernel rows in spike can be tripled by recessive mutant alleles at the Six-rowed spike 1 (vrs1) locus that abolish the suppression of lateral spikelet fertility. In another barley row-type, so called intermedium-spike (int), lateral floret size is often intermediate between six-and two-rowed types. Phenotypic and sequence analyses of our intermedium-spike collection revealed that other genes can increase the size of florets and even stimulate occasional grain setting in lateral spikelets. Here, we show that a complete six-rowed phenotype occurs in a diverse panel of intermedium-spike barley carrying wildtype Vrs1 in the presence of the Int-c.a allele of the intermedium spike-c (int-c) gene, previously considered only as a modifier of lateral spikelet fertility. Int-c.a-type alleles had arisen before domestication and are associated with the enlargement of lateral florets in wild barley, suggesting that natural selection/evolution acts towards reduced lateral floret size. Since Int-c.a cannot overcome the suppression of lateral florets in the genomic background of wild barleys, we infer the existence of other gene loci, at which novel alleles or allelic combinations were selected for after domestication, to increase grain number of barley independently of Vrs1.     

Analysis on pedodiversity and spatial subset representativity—the German soil map 1:1,000,000

Knowledge about spatial soil variation in terms of measured pedodiversity, as well as the spatial distribution of soils in terms of spatial subset representativity, offers the possibility to estimate the quality and variance within a soil map. Additionally, it can help to identify representative sample locations. Demonstrated at the German soil map at a scale of 1:1,000,000, this study describes a methodology to analyze the distribution of taxonomical pedodiversity using the Simpson index and a new approach to derive representative spatial subsets based on a modified χ²‐test (χ_m²), which can be used as monitoring areas. To analyze the spatial composition of the soil map and to detect differences in the underlying mapping schemes of the German soil map 1:1,000,000, three different spatial data structures were studied: (1) the entire soil map, (2) the soil map segmented into geomorphological regions, and (3) the soil map segmented into the Federal States of Germany. Representative patches of varying sizes were statistically derived for all spatial subsets as well as the entire soil map ranging from 20 km × 20 km up to 70 km × 70 km. The results show that the measured pedodiversity is linked to both the geomorphology as well as the political borders of the Federal States. On the one hand, this reveals the uncertainty of measuring pedodiversity on the basis of soil‐class maps as the spatial representation of pedodiversity is influenced by the different mapping traditions and methods applied in the 16 Federal States of Germany. On the other hand, it allows the analysis of the aggregation schemes of different landscapes. The presented approach helps to understand large soilscapes and to compare different soil maps of different states and countries as well as to enhance the soil map with additional information. Furthermore, the representative patches can be used to select soil‐monitoring areas.     

Effect of grassland harvesting frequency and N-fertilization on stocks and dynamics of soil organic matter in the temperate climate

ABSTRACT

Management of grassland may affect the dynamics of soil organic carbon (SOC). Objectives were to analyze the effect of different harvesting frequencies and nitrogen fertilization regimes on SOC and total N stocks in a field trial on a sandy loam to loamy sand soil of a grassland site near Kiel (Germany). Additionally, effects on microbial biomass C (C_mic) and ergosterol (as proxy for fungi) contents, water-stable aggregate size-classes and density fractions were studied. In the surface soil (0–10 cm), SOC and total N stocks, amounts of large water-stable macroaggregates (> 2000 µm) and contents of C_mic and ergosterol were significantly higher under a five cut regime. C_mic (r_Spearman = 0.61) and ergosterol contents (r_Spearman = 0.67) were correlated with amounts of large water-stable macroaggregates suggesting that fungi and microbial biomass play an important role in binding of small macroaggregates into large macroaggregates. The free light fraction of SOM showed significantly higher C concentrations under three cut compared to five cut at 30–60 cm, presumably related to the C/N ratio and the decomposability of root litter. This study indicates the importance of cutting frequency on SOC and total N stocks, amounts of large macroaggregates and contents of C_mic and ergosterol.