Nitrous oxide emissions after incorporation of winter oilseed rape (Brassica napus L.) residues under two different tillage treatments

The aim of this study was to investigate the effect of crop residues from winter oilseed rape on N₂O emissions from a loamy soil and to determine the effect of different tillage practices on N₂O fluxes. We therefore conducted a field experiment in which crop residues of winter oilseed rape (Brassica napus L., OSR) were replaced with ¹⁵N labelled OSR residues. Nitrous oxide (N₂O) emissions and ¹⁵N abundance in the N₂O were determined for a period of 11 months after harvest of OSR and in the succeeding crop winter wheat (Triticum aestivum L.) cultivated on a Haplic Luvisol in South Germany. Measurements were carried out with the closed chamber method in a treatment with conventional tillage (CT) and in a treatment with reduced soil tillage (RT). In both tillage treatments we also determined N₂O fluxes in control plots where we completely removed the crop residues. High N₂O fluxes occurred in a short period just after OSR residue replacement in fall and after N‐fertilization to winter wheat in the following spring. Although N₂O emissions differed for distinct treatments and sub‐periods, cumulative N₂O emissions over the whole investigation period (299 days) ranged between 1.7 kg and 2.4 kg N₂O‐N ha^?1 with no significant treatment effects. More than half of the cumulative emissions occurred during the first eight weeks after OSR replacement, highlighting the importance of this post‐harvest period for annual N₂O budgets of OSR. The contribution of residue N to the N₂O emission was low and explained by the high C/N‐ratio fostering immobilization of mineral N. In total only 0.03% of the N₂O‐N emitted in the conventional tillage treatment and 0.06% in the reduced tillage treatment stemmed directly from the crop residues. The ¹⁵N recovery in the treatments with crop residues was 62.8% (CT) and 75.1% (RT) with more than 97% of the recovered ¹⁵N in the top soil. Despite our measurements did not cover an entire year, the low contribution of the OSR residues to the direct N₂O emissions shows, that the current IPCC tier 1 approach, which assumes an EF of 1%, strongly overestimated direct emissions from OSR crop residues. Furthermore, we could not observe any relationship between tillage and crop residues on N₂O emission, only during the winter period were N₂O emissions from reduced tillage significantly higher compared to conventional tillage. Annual N₂O emission from RT and CT did not differ.     

Strategic planning for new woodlands in the urban periphery: through the lens of social inclusiveness

Current strategies for creating new woodlands in the urban periphery aim to provide as many people as possible with a recreational green space close to where they live. When taking a socially inclusive approach, however, this also involves a number of ‘distributional’ questions. These refer to the kind of people likely to benefit the most from such a plan: urban or suburban residents, low or high-income groups, and so forth. This article presents a GIS-based working method aimed at exploring different options for urban woodland proposals with regard to their positioning in relation to residential areas, as well as the socio-spatial characteristics of those areas. The example of seven possible locations for a new ‘peri-urban forest’ in Antwerp, Belgium was used to demonstrate the method's potential to address relevant questions in socially inclusive planning and hence, to improve strategic planning for new urban woodlands.     

Necrotizing encephalitis of unknown cause in Fennoscandian Arctic foxes (Alopex lagopus).

A neurologic disease affected a colony of endangered Fennoscandian arctic foxes (Alopex lagopus) kept in captivity for breeding purposes. Several outbreaks of disease occurred between 1994 and 2004. The clinical signs included ataxia, indications of anosmia, blindness, and abnormal behavior. The disease was characterized by severe necrotizing encephalitis affecting mostly the cranial cerebrum, basal ganglia, and olfactory bulbs. Investigations to identify the etiology of the disease included testing for several infectious agents known to cause encephalitis in carnivores. Tests for Toxoplasma gondii, Encephalitozoon cuniculi, Neospora caninum, canine distemper virus, rabies, adenovirus type 1, Borna disease virus, and Listeria monocytogenes were negative. The colony was closed, and the cause of the disease remains undetermined.     

Forecasting development of understory American beech after partial cutting in uneven-aged northern hardwood stands

American beech (Fagus grandifolia Ehrh.) in the understory of northern hardwood stands can interfere with the development of more desirable species such as sugar maple (Acer saccharum Marsh.). Yet, managers have had only limited methods for identifying stands where beech might dominate a new cohort. We examined five uneven-aged stands in New York State to determine the degree of influence that understory beech has on species development after a cutting treatment. No significant differences between stands were found, allowing us to develop a single model for evaluation. Understory beech was assessed using a species index value (SIV), which measures the proportion of stems, weighted by height, for a species on a milacre plot. We used a 5×5 transition matrix to compare pre- and post-cut beech importance levels. Stand-level trends showed an overall increase in the proportion of sample plots with higher levels of understory beech after cutting, with the likelihood of change on individual plots dependent on their pre-cut status. Plots with either no beech or very high levels of beech changed little after cutting, while beech was more likely to reach critical levels of dominance when pre-cut SIV was medium or higher. The transition matrix gives forest managers a means to forecast the probable level of future beech importance following cutting, based upon precursor conditions.     

Habitat factors for land snails in European beech forests with a special focus on coarse woody debris

Analyses of land snails and habitat factors in acid beech forests were conducted in southern Germany (northern Bavaria). The objectives were to study the effects of habitat characteristics on snail density and species richness. Habitat structures were determined for 37 plots in one big forest. We found a significant relationship between the number of snail species and individuals and the following set of habitat factors coverage of herbaceous layer, growing stock, mean diameter at breast height of the three largest trees (DBHmax), stand age, total dead wood volume per ha, and advanced decomposed dead wood volume per ha. We use maximally selected rank statistics to estimate cutpoints separating stands with low densities, from stands with high snail densities. Here, we define cutpoints for a significant higher snail density at a stand age of 187 years, 57 m³/ha dead wood, 40 m³/ha advanced decomposed dead wood, 63 cm DBHmax and more than 1% herbaceous layer. For species richness, cutpoints are estimated at 338 m³/ha stand volume, 170 years stand age, 50 m³/ha total dead wood amount, 15 m³/ha advanced decomposed dead wood and 56 cm DBHmax. The microhabitat analysis shows a higher pH value and a higher Calcium content at the bottom of large snags and under large lying dead wood pieces in comparison to litter, upper mineral soil and at the bottom of vital living trees. Snail species and individual density are significantly linked to these patterns of chemical parameters. The identified cutpoints are a good base for ecological management decisions in forest management.     

An improved low-input method for establishing calliandra hedgerows on small-scale farms in western Kenya

Direct seeding methods for nitrogen (N)-fixing tree-legumes by small-scale farmers were developed and studied in humid and sub-humid areas of western Kenya. We focused on the first six months of establishment of calliandra (Calliandra calothyrsus Meissner) multipurpose hedgerows. Direct seeding became effective, reliable, and significantly better than for zero-control treatments when improving A) water uptake by scratching the hard seeds with a sandal against a hard, rough surface, B) phosphorus (P) nutrition by mixing 150 g/m of kitchen wood-ash (1.3% P) into a 10 cm deep, 20 wide cm soil band 5 cm below the seeds, and C) root nodulation by transferring 100 g/m Rhizobium-colonised soil, or 0.5 crushed, incubated nodule, from a calliandra hedge. The field germination was 90% after two weeks, and the hedges were green and about 2 m tall in the dry season six months later. This revised version was published online in June 2006 with corrections to the Cover Date.     

A combinational approach of multilocus sequence typing and other molecular typing methods in unravelling the epidemiology of Erysipelothrix rhusiopathiae strains from poultry and mammals

Erysipelothrix rhusiopathiae infections re-emerged as a matter of great concern particularly in the poultry industry. In contrast to porcine isolates, molecular epidemiological traits of avian E. rhusiopathiae isolates are less well known. Thus, we aimed to (i) develop a multilocus sequence typing (MLST) scheme for E. rhusiopathiae, (ii) study the congruence of strain grouping based on pulsed-field gel electrophoresis (PFGE) and MLST, (iii) determine the diversity of the dominant immunogenic protein SpaA, and (iv) examine the distribution of genes putatively linked with virulence among field isolates from poultry (120), swine (24) and other hosts (21), including humans (3). Using seven housekeeping genes for MLST analysis we determined 72 sequence types (STs) among 165 isolates. This indicated an overall high diversity, though 34.5% of all isolates belonged to a single predominant ST-complex, STC9, which grouped strains from birds and mammals, including humans, together. PFGE revealed 58 different clusters and congruence with the sequence-based MLST-method was not common. Based on polymorphisms in the N-terminal hyper-variable region of SpaA the isolates were classified into five groups, which followed the phylogenetic background of the strains. More than 90% of the isolates harboured all 16 putative virulence genes tested and only intI, encoding an internalin-like protein, showed infrequent distribution. MLST data determined E. rhusiopathiae as weakly clonal species with limited host specificity. A common evolutionary origin of isolates as well as shared SpaA variants and virulence genotypes obtained from avian and mammalian hosts indicates common reservoirs, pathogenic pathways and immunogenic properties of the pathogen.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0216-x) contains supplementary material, which is available to authorized users.     

Anti-Muellerian hormone levels in plasma of Holstein-Friesian heifers as a predictive parameter for ovum pick-up and embryo production outcomes

The aim of this study was to investigate whether plasma anti-Muellerian hormone (AMH) levels of Holstein-Friesian heifers could be used to predict ovum pick-up (OPU) and embryo production outcomes. Plasma samples and data were collected from 64 heifers, which underwent repeated OPU with subsequent in vitro embryo production followed by embryo flushing after superovulation. AMH levels were significantly positively correlated with the number of follicles aspirated per OPU session (r = 0.45), recovered oocytes per OPU (r =0.43) and in vitro produced embryos per OPU (r = 0.28). No significant correlations between AMH and in vivo produced embryos were ascertained. Our results suggest that correlations between AMH and outcomes of an OPU-IVF program are too low to use AMH as a precise predictive parameter for the success of a particular OPU procedure in Holstein-Friesian heifers. However, AMH can help to identify groups of very good or very poor oocyte donors.     

Nutrient cycling and soil leaching in eighteen pure and mixed stands of beech (Fagus sylvatica) and spruce (Picea abies)

Studies on the combined effects of beech–spruce mixtures are very rare. Hence, forest nutrition (soil, foliage) and nutrient fluxes via throughfall and soil solution were measured in adjacent stands of pure spruce, mixed spruce–beech and pure beech on three nutrient rich sites (Flysch) and three nutrient poor sites (Molasse) over a 2-year period. At low deposition rates (highest throughfall fluxes: 17 kg N ha⁻¹ year⁻¹ and 5 kg S ha⁻¹ year⁻¹) there was hardly any linkage between nutrient inputs and outputs. Element outputs were rather driven by internal N (mineralization, nitrification) and S (net mineralization of organic S compounds, desorption of historically deposited S) sources. Nitrate and sulfate seepage losses of spruce–beech mixtures were higher than expected from the corresponding single-species stands due to an unfavorable combination of spruce-similar soil solution concentrations coupled with beech-similar water fluxes on Flysch, while most processes on Molasse showed linear responses. Our data show that nutrient leaching through the soil is not simply a “wash through” but is mediated by a complex set of reactions within the plant–soil system.