Behavioral repeatability and personality in pit-building antlion larvae under differing environmental contexts

Over the last decades, there has been growing interest among behavioral ecologists in exploring animal personalities. However, while the foraging behavior of active foragers has been extensively studied, only little is known about that of sit-and-wait predators within the personality framework. We investigated the existence of repeatability and personality in pit-building antlion larvae in the context of foraging (pit construction) and habitat selection (relocation distance and direction) over time and under three environmental contexts: thermal conditions, sand depth, and soil type. Over time, repeatability was much stronger for relocation distance than for movement directionality. Additionally, we observed positive correlations across the two levels of sand depth and soil type but not between thermal conditions. Change in substrate type may induce faster decision-making in these sand-dwelling insects or could be perceived by such insects as a more drastic alteration in their habitat. We suggest that different individuals indeed possess distinct personalities. We also suggest that repeatability should be measured at two levels: the amount of energy expenditure (distances and pit construction) and the pattern of energy expenditure (directionality). Finally, our study illustrates how differing environmental conditions can result in differing levels of plasticity, while largely preserving individual personalities.     

Leaching and crop uptake of nitrogen from nitrogen-15-labeled green manures and ammonium nitrate

Green manures can be used as an N source for agricultural crops as a substitute for inorganic N fertilizers. The effects of using green manures on leaching and uptake of N by spring barley (Hordeum vulgare L.) were evaluated in a 2-yr lysimeter study. Ryegrass (Lolium perenne L.) and red clover (Trifolium pratense L.) labeled with (15)N were applied in May of the first year at 160 kg total N ha(-1). Simultaneously, (15)NH(4)(15)NO(3) was applied at 80 kg N ha(-1) to additional lysimeters and others were left without N additions (control). During the second year, all lysimeters, except the control, received 80 kg N ha(-1) as unlabeled NH(4)NO(3). The cumulative, average loads of total N leached during the two years were: 37 (control), 62 (NH(4)NO(3)), 50 (ryegrass manure), and 73 (red clover manure) kg ha(-1). The differences among the treatments were not significant (P > 0.05), but the control had significantly smaller (P < 0.05) leaching loads than the treatments. About 24% of ryegrass- and red clover-derived N and 43% of NH(4)NO(3) were removed through spring barley grain and stover during the two growing seasons. Thus, the N use efficiency in barley was substantially larger when grown with inorganic N fertilizer than when grown with green manure. Viewed in combination with the tendency for larger N leaching loads under red clover manure, claims about water quality benefits of legume-based green manures should be evaluated with regard to the timing of N release and demand for N by the plant.     

Coping with variability and change: Floods and droughts

Floods and droughts are natural phenomena for which the risks of occurrence are likely to continue to grow. Increasing levels of exposure and insufficient adaptive capacity are among the factors responsible for the rising vulnerability. The former is conditioned by anthropopressure (e.g., economic development of flood–prone areas) and adverse effects of climate change; scenarios for future climates indicate the possibility of amplified water–related extremes. This article presents the current situation of coping with extreme hydrological events within the pressure–state–response framework. Among promising response strategies, the role of forecast and warning, and of watershed management are reviewed. Sample success stories and lessons learnt related to hydrological extremes are given and policy implications discussed.     

Sustainable mobility in rural China

Rural areas in China suffer from various problems. The stagnating economic development and a lack of (sufficient) job opportunities and basic services, etc., lead to disadvantages for great parts of China's population. In this context, the transport sector plays a crucial role for the development of rural settlements. Although the degree of undersupply varies between villages, the situation of Chinese villages is often worsened by an insufficient developed transport sector. Regarding mobility in rural China, major constraints and therefore challenges are the difficult access to the transport infrastructure, bad road conditions and the lack of public transport systems. Improvements within the transport sector can be regarded as crucial for the economic and social development of (rural) China and should be carried out in a sustainable and holistic manner using participatory approaches. The aim should be the development of mobility strategies considering the specific needs within the field of transport, which shall have a decisive and positive impact on related sectors. This paper is based on experiences made during the 3 years lasting Sino-European research project SUCCESS (Sustainable Users Concept for China Engaging Scientific Scenario) that analyses the present and the potential future role of transport systems in selected rural areas of China. Referring to the case studies of three villages in rural China, some mobility-related projects that present a favourable impact not only on the transport sector but also on the social system and the economy shall be highlighted. Finally, based on the analysis, instruments and measures for the development of a pathway to a sustainable mobility in rural China will be outlined.     

Possibilities for reducing nitrate leaching from agricultural land

Agricultural soil is a contributor of nitrate to natural waters. High nitrate levels in water leached from soils are related to high nitrate concentrations in drinking water, and excess levels change the ecological balance of rivers and lakes. In this paper, sound solutions to the major environmental issue of limiting nitrate leaching by modifying agricultural practices are discussed. The causes of nitrate leaching from agricultural land are briefly explained and existing measures for the reduction of nitrate losses are described, analyzed and evaluated. Reduction of nutrient leaching is not a question of organic or conventional farming, but rather of the introduction and use of appropriate countermeasures. We propose the following guiding principles to minimize leaching from agricultural soils. To some extent these principles require a new way of thinking: i) environmental indexing of fields and consideration of spatial variability within fields in relation to their contribution to leaching losses within a catchment; ii) reduction of nitrogen inputs to soil to levels slightly below those expected to give the optimum yield by applying less nitrogen fertilizer and by a further reduction in animal density; and iii) use of a range of counter-measures (catch crops, minimum tillage, control of biological processes, etc.) depending on how sensitive the farming system, soil and climate are to the risk of nitrate leaching.     

Toward chemical-free reclamation of biologically pretreated greywater: solar photocatalytic oxidation with powdered activated carbon

Heterogeneous photocatalytic oxidation is a water reclamation technology which avoids chemical consumption and can be powered by solar radiation. Because this generally sustainable process is of limited efficiency for the treatment of biologically pretreated greywater, it was combined with activated carbon adsorption. The effluent of a constructed wetland for treatment of separately collected greywater was subjected to photocatalytic oxidation using the photocatalyst titanium dioxide (TiO₂) “P25” in both the absence and the presence of powdered activated carbon (PAC). Photocatalytic oxidation alone with UV fluences of about 10 Wh L^?1 was not capable of reducing total organic carbon (TOC) from an initial concentration of 5.5 mg L^?1 safely below 2 mg L^?1 as a prerequisite for high-quality water reuse purposes. However, when PAC was added, TOC concentrations subsequent to photocatalytic oxidation were less than 2 mg L^?1 even after reusing the TiO₂/PAC mixture 10 times. PAC addition is estimated to reduce the insolation area necessary to achieve this target by solar photocatalytic oxidation of biologically treated greywater by a factor 7. This combination process represents an innovative chemical-free technology within wastewater reuse schemes.     

Solidification with water as a treatment method for air pollution control residues

The process of solidification with water was studied on air pollution control (APC) residues from incineration of refuse-derived fuel (RDF) regarding mechanical strength and leaching behaviour of solidified material. Factorial design in two levels was applied to investigate the impact of water addition, time, and temperature to mechanical strength of solidified material. Factors time and temperature, as well as the interaction between the addition of water and time significantly (alpha=0.05) influenced the mechanical strength of solidified material. The diffusion-leaching test NEN 7345 was performed to investigate if the leaching behaviour of elements from solidified material was determined by diffusion. Since it was found that leaching is not diffusion controlled, the long-term leaching behaviour was not assessed. However, the investigation showed that some of the studied components (Al, Hg, Mn, Pb, Si, and Zn) could be considerably demobilised by solidification with water. Concentrations of As, Cd, Co, Cu, Fe, and Ni were either below or not quite above the detection limits to be included in the analysis of leaching behaviour. The elements least demobilised by solidification were Cl, Cr, K, and Na.