Urbanized landscapes favored by fig-eating birds increase invasive but not native juvenile strangler fig abundance

Propagule pressure can determine the success or failure of invasive plant range expansion. Range expansion takes place at large spatial scales, often encompassing many types of land cover, yet the effect of landscape context on propagule pressure remains largely unknown. Many studies have reported a positive correlation between invasive plant abundance and human land use; increased propagule pressure in these landscapes may be responsible for this correlation. We tested the hypothesis that increased rates of seed dispersal by fig-eating birds, which are more common in urban habitats, result in an increase in invasive strangler fig abundance in landscapes dominated by human land use. We quantified abundance of an invasive species (Ficus microcarpa) and a native species (F. aurea) of strangler fig in plots spanning the entire range of human land use in South Florida, USA, from urban parking lots to native forest. We then compared models that predicted juvenile fig abundance based on distance to adult fig seed sources and fig-eating bird habitat quality with models that lacked one or both of these terms. The best model for juvenile invasive fig abundance included both distance to adult and fig-eating bird habitat terms, suggesting that landscape effects on invasive fig abundance are mediated by seed-dispersing birds. In contrast, the best model for juvenile native fig abundance included only presence/absence of adults, suggesting that distance from individual adult trees may have less effect on seed limitation for a native species compared to an invasive species undergoing range expansion. However, models for both species included significant effects of adult seed sources, implying that juvenile abundance is limited by seed arrival. This result was corroborated by a seed addition experiment that indicated that both native and invasive strangler figs were strongly seed limited. Understanding how landscape context affects the mechanisms of plant invasion may lead to better management techniques. Our results suggest that prioritizing removal of adult trees in sites with high fig-eating bird habitat may be the most effective method to control F. microcarpa abundance.     

Passing the Panda Standard: A TAD Off the Mark?

Tilapia, a tropical freshwater fish native to Africa, is an increasingly important global food commodity. The World Wide Fund for Nature (WWF), a major environmental nongovernmental organization, has established stakeholder dialogues to formulate farm certification standards that promote “responsible” culture practices. As a preface to its “tilapia aquaculture dialogue,” the WWF for Nature commissioned a review of potential certification issues, later published as a peer-reviewed article. This article contends that both the review and the draft certification standards subsequently developed fail to adequately integrate critical factors governing the relative sustainability of tilapia production and thereby miss more significant issues related to resource-use efficiency and the appropriation of ecosystem space and services. This raises a distinct possibility that subsequent certification will promote intensive systems of tilapia production that are far less ecologically benign than existing widely practiced semi-intensive alternatives. Given the likely future significance of this emergent standard, it is contended that a more holistic approach to certification is essential.     

Effect of four alcohols on adsorption, desorption, and movement of cadmium, nickel, and zinc through soils

Miscible-displacement experiments were conducted to compare the effects of aqueous soil solutions with ethyl alcohol, ethylene glycol, diethylene glycol, and triethylene glycol on the movement of metals through soils. Aqueous or alcohol solutions containing 1 mM each Cd, Ni, and Zn and 5 mM Ca were perfused through columns containing River Sand, Canelo loam (Canelo 1) or Mohave sandy clay loam (Mohave scl) until effluent metal concentrations (C) equaled influent concentrations (C₀) or CC₀⁻¹ = 1. In general, the order of sorption was Zn > Ni > Cd in aqueous-perfused columns, while in alcohol-perfused columns sorption of Ni Cd ≥ Zn. In comparison to aqueous solutions, alcohols reduced total metal sorption by at least 25%. Metal sorption was best correlated to cation exchange capacity of the soil, sorption of metals being greatest in the Mohave scl and least in the River Sand. After CC₀⁻¹ = 1 was reached, columns were leached with deionized water. While leaching did not affect the sorption of metals in columns which had been perfused with aqueous solvents, sorption behavior of metals changed significantly in columns which had been perfused with alcohol solvents. Leaching caused desorption of 5 to 30% of the sorbed Ni. In general, Cd was desorbed (up to 45%) from the soils tested. The exceptions were River Sand columns perfused with diethylene and triethylene glycol in which additional Cd was sorbed to the soil from the soil solution. Additional Zn was sorbed in all columns tested with the exception of the Canelo 1 column perfused with ethyl alcohol.     

Don't just pass the parcel: Accidents that would not have occurred if those involved had talked together

In many design organisations responsibility for a project is passed on from one group of people to another. The research chemists develop a process and then pass it on to the process design group who blame the chemists for their ignorance of what is practicable. The project is then passed to the mechanical engineering group who develop the detailed design while the electrical, instrument and other specialized groups add their contributions. The project then passes to the construction team and finally to the team who will start up and operate the plant. These different groups may be in different buildings or places and may rarely or never speak to each other.Many accidents and operating problems have arisen as a result of such “pass the parcel” organisation. Some are described. To avoid these problems representatives of all the various groups should meet regularly as the project progresses. Each group is then able to suggest changes that will make the design easier for them and can comment on features which will increase their costs. Everyone will gain some knowledge of other groups' problems.     

Assessment of football grounds for player safety

Professional football clubs have a duty under UK health and safety legislation to carry out risk assessments of their activities; one requirement under this duty is to assess the impact of ground layout on player safety. To assist clubs in meeting this requirement, a Ground Player-safety Score (GPS) has been developed that is defined by a base-factor, determined from the position of perimeter fencing in relation to the pitch, but which is degraded when other hazards, e.g. advertising hoardings, photographers and TV equipment, are present in the areas contiguous with the playing area. This approach has been used to assess the layouts of forty seven English and Scottish professional football clubs. The assessment showed that only 42% of the English and 71% of the Scottish clubs achieved an acceptable score. However, in all but a few cases the clubs could modify their ground layout to improve the GPS and reduce risks to players without capital expenditure. With these changes, acceptable GPS figures could be achieved by 92% of the English and by 100% of the Scottish clubs.     

The history of process safety

It is my pleasure to present these thoughts on the history of process safety and my involvement in the development of that history.     

Putting the 'E' into LSPs: Representing the Environment within Local Strategic Partnerships (LSPs) in the UK

This article reports the findings of a qualitative study with residents living in six deprived neighbourhoods in the UK and the front-line workers and local policymakers responsible for the renewal of these areas. The study was an attempt to raise awareness of local environmental concerns in the context of a national and local policy agenda, which has, until recently, largely overlooked the impacts of degraded environments on the lives and activities of the people who live in them. A key aim for the study was to raise people's concerns with local decision-makers and examine how far these might be addressed through the existing financial, administrative and legislative arrangements for neighbourhood renewal in the UK, namely Local Strategic Partnerships. The research was designed to provide practical lessons and policy recommendations for others wishing to raise the profile of environmental justice in the context of neighbourhood level regeneration projects, in both the UK and elsewhere in the 'developed' world.     

REGIONAL WATER SUPPLY PLANNING BY INTERACTIVE SYSTEMS ANALYSIS1

Abstract: This paper describes an interactive data and model generator that is intended to bridge the gap between the water resource enginner and planner and the mathematical progrmming systems approach to regional water supply planning. The optimization objective is to minimize total annual cost with respect to capital investment and operation and maintenance costs. The matrix generator formulates the necessary hydrologic, demographic and programming problem for system optimization. The interactive program guides the user through the input and optimization segments, totally eliminates the chore of manually structuring the model matrix aides in eliminating errors, and allows use by planners without skill in mathematical programming.     

HYDRAULIC FRICTION LOSS IN SMALL DIAMETER PLASTIC PIPELINES1

ABSTRACT: Although estimation of hydraulic friction loss in pipelines is one of the most frequent routine computations made by water supply engineers, almost no post-construction analysis of the accuracy of these calculations exists in the literature. This paper reports the field measured friction losses in three one-mile sections of small diameter pvc pipe which had been in service for 10 years. Hazen-Williams and Darcy-Weisbach equations are examined to provide a framework for comparing Hazen-Williams coefficients recommended by pipe manufacturers to those obtained by the field measurements. The conclusion is that the C_HW factor of 150 recommended by most pvc pipe manufacturers is too high for the diameter-velocity combinations encountered in rural dead-end small diameter lines. The measured coefficients averaged 133 which is close to that predicted by superimposing Hazen Williams coefficients on the Moody diagram from which the friction factor for the Darcy-Weisbach equation is obtained.