Removing Chinese Privet (Ligustrum sinense Lour.) and Establishing Native Plants in a Flooded Riparian Corridor in North‐Central Texas,USA

The objectives of this study were to evaluate the allelopathic effects of Chinese privet (Ligustrum sinense Lour.) extract on native seeds and cuttings and to assess the survivability of native plants in a flooded riparian corridor. Field sites occupied the Trinity River floodplain in southeast Dallas County, Texas. Eight native species were evaluated. They were soapberry, red mulberry, persimmon, elderberry, beautyberry, coralberry, mustang grape, and heartleaf peppervine. From this study, we concluded that:

• Truncating privet at ground level and applying equal parts of glyphosate and water to the stump effectively kills the plant;
• Once removed, privet does not curtail establishment of native plants;
• A 60‐day (d) flood killed most plants, with red mulberry being the most resilient;
• A 1% leaf and berry extract from privet significantly reduced soapberry seed germination; and
• A 1% extract from various parts of privet did not significantly affect root growth from cuttings.

     

Pollinators,pests, and predators: Recognizing ecological trade-offs in agroecosystems

Ecological interactions between crops and wild animals frequently result in increases or declines in crop yield. Yet, positive and negative interactions have mostly been treated independently, owing partly to disciplinary silos in ecological and agricultural sciences. We advocate a new integrated research paradigm that explicitly recognizes cost-benefit trade-offs among animal activities and acknowledges that these activities occur within social-ecological contexts. Support for this paradigm is presented in an evidence-based conceptual model structured around five evidence statements highlighting emerging trends applicable to sustainable agriculture. The full range of benefits and costs associated with animal activities in agroecosystems cannot be quantified by focusing on single species groups, crops, or systems. Management of productive agroecosystems should sustain cycles of ecological interactions between crops and wild animals, not isolate these cycles from the system. Advancing this paradigm will therefore require integrated studies that determine net returns of animal activity in agroecosystems.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0696-y) contains supplementary material, which is available to authorized users.     

Traffic noise and executive functioning in urban primary school children: The moderating role of gender

The objective of this study was to examine the relationships between noise and school children's executive functioning (EF). The study included 311 children (146 boys and 165 girls) aged 7–11 years, who lived in the center of Belgrade. Teachers rated children's EF on a standard scale evaluating their ability to work independently in a focused manner to achieve an end goal as well as children's ability to follow directions carefully. Residential noise exposure was estimated in three daytime intervals, one evening interval and two nighttime intervals in the middle of the streets where children lived. School noise exposure was measured on three different school days in front of children's schools. Socioeconomic status (mother's highest level of education and family income) was used as a statistical control. There were no significant main effects of ambient noise levels on EF, however, a significant interaction indicated adverse noise impacts on boy's EF. We discuss possible reasons for male EF vulnerability to noise.     

Positive vs. false detection: A comparison of analytical methods and performance for analysis of cyclic volatile methylsiloxanes (cVMS) in environmental samples from remote regions

Contamination and analytical variation can significantly hinder trace analysis of cyclic methyl volatile siloxanes (cVMS); potentially resulting in the report of false positives at concentrations approaching detection limits. To assess detection and variation associated with trace cVMS analysis in environmental matrices, a co-operative laboratory comparison for the analysis of octametylcyclotetrasiloxane (D4), decamethylcylcopentasiloxane (D5), and dodecametylcyclohexasiloxane (D6) in sediment and biota from the Svalbard Archipelago was conducted. Two definitions of detection limits were evaluated in this study; method detection limits (MDL, matrix defined) and limits of detection (LOD, solvent defined). D5 was the only cVMS detected above both LOD (0.08–0.81 ng g⁻¹ ww) and MDL (0.47–2.36 ng g⁻¹ ww) within sediment by all laboratories where concentrations ranged from 0.55 to 3.91 ng g⁻¹ ww. The percentage of positive detects for D5 decreased by 80% when MDL was defined as the detection limit. D5 was also detected at the highest frequency among all laboratories in fish liver with concentrations ranging from 0.72 to 345 ng g⁻¹ ww. Similar to sediment, percentage of positive detects for D5 decreased by 60% across all laboratories for fish livers when using MDL (0.68–3.49 ng g⁻¹ ww). Similar observations were seen with both D4 and D6, indicating that sample matrix significantly contributes to analytical response variation. Despite differences in analytical methods used between laboratories, good agreement was obtained when using MDL to define detection limits. This study shows the importance of incorporating variation introduced by sample matrices into detection limit calculations to insure data accuracy of cVMS at low concentrations.     

A Plume Rise Model Compared with Observations

Dimensional arguments are used to predict plume rise for buoyant plumes in both stable and neutral air, for both calm and windy conditions. Dominant terms are assumed to be windpseed ū, “buoyancy flux” F (proportional to heat efflux), and a stability parameter s (proportional to potential temperature gradient). Observations presented support the dimensional analysis predictions, except that for final rise in a neutral atmosphere they are adeauate only for a conservative estimate of rise. The method is extended to predict maximum ground concentration of effluent gases in the worst situations {windy neutral and fumigation) for open country, valleys, and “canyons.” These predictions are compared ivith limited observations.     

Roadside Coniferous Windbreaks as Sinks For Vehicular Lead Emissions

The role of a roadside windbreak of white pine trees in modifying the dispersion of vehicular lead emissions was evaluated. The lead content of foliage and twigs of various ages adjacent to and far from the road was analyzed by atomic absorption spectrophotometry. The lead burden of older needles and twigs was consistently greater than that of younger organs, and was greater in samples taken adjacent to than far from the road. The pattern of lead accumulation on mature needles, but not twigs, varied with precipitation prior to sampling. Twigs retained particles more effectively than needles throughout the season; twigs retained about 115% more lead as µg g^-1 and about 2050% more lead as µg cm^-2 than similarly located needles. The lead content of soil beneath the windbreak was compared with that of an adjacent, undisturbed field to assess whether the presence Of the windbreak resulted in lead enrichment of the underlying soil. The soil between the curb and the windbreak contained about 50% more lead than that of the field at a similar distance from the road. Within the windbreak, the soil contained about twice the lead content of the soil in the open field at a similar distance from the curb. Windbreaks function as sinks for vehicular lead emissions and thus decrease their dispersion from roads.     

Progress Toward a Uniform Air Pollution Index

Recently, various authors^1–4 have indicated that a need exists to establish a uniform air pollution index for communities throughout the nation.Although the literature reveals several attempts to develop air pollution indices,^5–7 none of these indices has received widespread acceptance by state and local air pollution control agencies, probably because none has received the active support or endorsement of the federal government. We now wish to report that significant progress has been made at the federal level toward the goal of a recommended national air pollution index.