Simulation of soil hydrology and establishment of a nitrogen budget of a Mountain Forest

The water fluxes through the mountainous forest ecosystem ‘Mühleggerköpfl’ were simulated by means of the mechanistic soil physical model Hydrus ID. The objective was to set up a nitrogen budget in order to decide if the ecosystem accumulates nitrogen or if nitrogen leaks from the site. The simulated annual loss of N by percolation ranges between 0.4 and 1 g N m⁻² yr⁻ and is smaller than the annual input by bulk and occult deposition, which combines to approx 1.2–1.5 g N m⁻ yr⁻. Obviously the forest soil presently accumulates N. With an N input-rate exceeding the N output, the operationally defined status of N saturation is not yet reached. Comparing the magnitude of the N pool in the soil (several kg N m⁻²) with the rate of the annual increase (a few g N m⁻²yr⁻¹), the process of N saturation is apparently slow.

     

Human–wildlife coexistence in a changing world

Human–wildlife conflict (HWC) is a key topic in conservation and agricultural research. Decision makers need evidence-based information to design sustainable management plans and policy instruments. However, providing objective decision support can be challenging because realities and perceptions of human–wildlife interactions vary widely between and within rural, urban, and peri-urban areas. Land users who incur costs through wildlife argue that wildlife-related losses should be compensated and that prevention should be subsidized. Supporters of human–wildlife coexistence policies, such as urban-dwelling people, may not face threats to their livelihoods from wildlife. Such spatial heterogeneity in the cost and benefits of living with wildlife is germane in most contemporary societies. This Special Section features contributions on wildlife-induced damages that range from human perspectives (land use, psychology, governance, local attitudes and perceptions, costs and benefits, and HWC and coexistence theory) to ecological perspectives (animal behavior). Building on current literature and articles in this section, we developed a conceptual model to help frame HWC and coexistence dimensions. The framework can be used to determine damage prevention implementation levels and approaches to HWC resolution. Our synthesis revealed that inter- and transdisciplinary approaches and multilevel governance approaches can help stakeholders and institutions implement sustainable management strategies that promote human–wildlife coexistence.     

Exposure impacts of Imazapyr formulation on larval development and thyroid histology of Xenopus laevis

Environmental Science and Pollution Research - There are increased concerns about the thyroidal effects of many anthropogenic substances in the environment. These substances include agricultural...     

Dynamic effects of personal initiative on engagement and exhaustion: The role of mood,autonomy, and support

Researchers have neglected dynamic effects of proactive behavior on occupational well‐being. We investigated effects of change in personal initiative over 6 months on changes in emotional engagement and exhaustion over the following 6 months. On the basis of the control‐process theory on affect, we hypothesized that changes in positive and negative moods mediate these effects conditional upon employees' level of perceived organizational support. On the basis of action regulation theory, we assumed that change in job autonomy also acts as a mediator. Data came from 297 employees who responded to 3 surveys separated by 6‐month intervals. Results of latent change score modeling showed that change in personal initiative negatively predicted change in positive mood and, when perceived organizational support was low, positively predicted change in negative mood. In addition, change in personal initiative positively predicted change in job autonomy. Change in personal initiative had negative indirect effects on change in emotional engagement, and positive indirect effects on change in emotional exhaustion through changes in positive and negative moods (but not through change in job autonomy). A reverse causal model did not yield significant indirect effects. Overall, these findings suggest that an increase in proactive behavior can have detrimental effects on occupational well‐being.     

Design of a new monitoring network and first testing of new biological assessment methods according to water framework directive

In most European member states, more or less completely new monitoring networks and assessment methods had to be developed as basic technical tools for the implementation of the EU Water Framework Directive (WFD). In the river basin of the Stever, the largest tributary to the river Lippe (River Rhine, Northrhine-Westphalia, Germany), a WFD-monitoring network was developed, and new German biological methods for rivers, developed for the purposes of the WFD, have been applied. Like most rivers in the German lowland areas, nearly all the river courses of the Stever system are altered by hydro-morphological degradation (straightening, bank fixation, lack of canopy etc.). In 2005 and 2006, the biological quality components of macroinvertebrates, fish and macrophytes were investigated and evaluated for the assessment of the ecological status of about 50 surface water bodies within the whole Stever system. Basic physical and chemical parameters, as well as priority substances, have been analysed in the same period. In this contribution, the design of the new monitoring network, the core principles of the German biological methods, and the most important results of the pilot monitoring will be presented. As main impacts with severe effects on the faunal and floral communities, the many migration barriers and the bad quality of the river morphology could be stated. Organic pollution is no more a severe problem in the Stever. The pilot project was successfully conducted in close collaboration with the water authorities (District Government Münster) and the water association Lippeverband.     

Fluorescence imaging applied to tracer distributions in variably saturated fractured clayey till

The study of mechanisms controlling preferential flow and transport in variably saturated fractured clayey till is often hindered by insufficient spatial resolution or unknown measuring volume. With the objective to study these mechanisms while circumventing the obstacles, tracer experiments with two fluorescent tracers Acid Yellow 7 (AY7) and Sulforhodamine B (SB) were performed at three different rain events for a fall and a summer season. Irrigated areas were excavated down to depths of 2.8 m and the movement of both tracers in the exposed profiles was delineated simultaneously by high spatial resolution apparent concentration maps (pixel approximately 1 mm(2)) obtained with an imaging device. The device consists of a light source and a CCD camera, both equipped with tracer-specific-filters for fluorescent light. The fluorescence images were corrected for nonuniform lighting, changing surface roughness, and varying optical properties of the soil profile. The resulting two-dimensional apparent concentration distribution profiles of the tracers showed that: (i) relative low water content in the upper 10 cm of the irrigated till in summer had a pronounced retardation effect on the AY7-migration and no effect on the SB-migration; (ii) the dead-end biopores were not activated in the fall season; (iii) only 3D fracture-plans connected to hydraulically active 1D-biopores contributed to the leaching; (iv) the tracer migration primary followed macropores during both seasons, though AY7 also followed a topsoil piston transport in summer; (v) the highest tracer pixel apparent concentrations were often found in macropores and most pronounced in the summer season; and (vi) 3D-dilution in fractures seems to play a dominating role in AY7-migration in the fall season.     

A Bayesian approach for incorporating uncertainty and data worth in environmental projects

A data worth model is presented for the analysis of alternative sampling schemes in a special project where decisions have to be made under uncertainty. This model is part of a comprehensive risk analysis algorthm with the acronym BUDA. The statistical framework in BUDA is Bayesian in nature and incorporates both parameter uncertainty and natural variability. In BUDA a project iterates among the analyst, the decision maker, and the field work. As part of the analysis, a data worth model calculates the value of a data campaign before the actual field work, thereby allowing the identification of an optimum data collection scheme. A goal function which depicts the objectives of a project is used to discriminate among different alternatives. A Latin hypercube sampling scheme is used to propagate parameter uncertainties to the goal function. In our example the uncertain parameters are the parameters which describe the geostatistical properties of saturated hydraulic conductivity in a Molasse environment. Our results indicated that failing to account for parameter uncertainty produces unrealistically optimistic results, while ignoring the spatial structure can lead to an inefficient use of the existing data.     

Alternative reproductive tactics and the impact of local competition on sex ratios in the ant Hypoponera opacior

The ant Hypoponera opacior exhibits alternative reproductive morphs of males and females associated with distinct sexual behaviours. Our long-term study reports strong seasonality in sexual production with a mating season in early and one in late summer. Winged (alate) reproductives emerge in June, swarm during the monsoon season and establish new colonies independently. In contrast, wingless worker-like (ergatoid) reproductives that appear in late August mate within their natal or adjacent nests and either do not disperse or establish new nests close by. These divergent dispersal patterns allowed us to analyse the impact of local factors on investment strategies by comparing sex allocation between and within the two reproductive events. The optimal sex ratio for ergatoid reproductives should be influenced both by competition for matings between brothers (local mate competition) and rivalry among young locally dispersing queens for workers, nest sites or food (local resource competition). The greater importance of local resource competition was demonstrated both by a male-biased sex ratio for wingless sexuals and a stronger increase in the number of males with total sexual production than for the number of queens. Microsatellite analysis revealed that inter-nest variation in relatedness asymmetry cannot explain split sex ratios in the August generation. Instead, nests with related ergatoid males raised a male-biased sex ratio contrary to the expectations under local mate competition. In conclusion, male bias in wingless H. opacior indicates that local mate competition is less strong than local resource competition among ergatoid queens over the help of workers during nest foundation.     

Incorporating soil structure and root distribution into plant uptake models for radionuclides: toward a more physically based transfer model

Most biosphere and contamination assessment models are based on uniform soil conditions, since single coefficients are used to describe the transfer of contaminants to the plant. Indeed, physical and chemical characteristics and root distribution are highly variable in the soil profile. These parameters have to be considered in the formulation of a more realistic soil-plant transfer model for naturally structured soils. The impact of monolith soil structure (repacked and structured) on Zn and Mn uptake by wheat was studied in a controlled tracer application (dye and radioactive) experiment. We used Brilliant Blue and Sulforhodamine B to dye flow lines and 65Zn and 54Mn to trace soil distribution and plant uptake of surface-applied particle-reactive contaminants. Spatial variation of the soil water content during irrigation and plant growth informs indirectly about tracer and root location in the soil profile. In the structured monolith, a till pan at a depth of 30 cm limited vertical water flow and root penetration into deeper soil layers and restricted tracers to the upper third of the monolith. In the repacked monolith, roots were observed at all depths and fingering flow allowed for the fast appearance of all tracers in the outflow. These differences between the two monoliths are reflected by significantly higher 54Mn and 65Zn uptake in wheat grown on the structured monolith. The higher uptake of Mn can be modelled on the basis of radionuclide and root distribution as a function of depth and using a combination of preferential flow and rooting. The considerably higher uptake of Zn requires transfer factors which account for variable biochemical uptake as a function of location.