Beyond ‘just’ flood risk management: the potential for—and limits to—alleviating flood disadvantage

Regional Environmental Change - The threat of flooding poses a considerable challenge for justice. Not only are more citizens becoming exposed to risk, but they are expected to play increasingly...     

The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends

In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague.     

Site fidelity and homing behaviour in intertidal fishes

The theory of ecological cognition poses that the brains and behaviour of animals are shaped by the environmental challenges they face in their everyday lives. Site fidelity and homing ability was tested for five species of intertidal rock pool fish by tagging and displacing them to new rock pools at various distances from their ‘home’ rock pools. Three of the species were rock pool specialists whilst the remaining two spend a small proportion of their life in rock pools during early ontogeny. The three specialists showed strong site fidelity with >50 % of individuals found in the same pool 42 days after tagging. In contrast, the non-specialist species showed low fidelity and poor homing abilities. Homing success in the rock pool specialists remained relatively stable as displacement distance increased. The effect of body size on homing ability was species dependent, with only one species showing a significantly greater tendency to home with increasing size.     

Paving the Way for Invasive Species: Road Type and the Spread of Common Ragweed (<Emphasis Type="Italic">Ambrosia artemisiifolia</Emphasis>)

Roads function as prime habitats and corridors for invasive plant species. Yet despite the diversity of road types, there is little research on the influence of these types on the spread of invaders. Common ragweed (Ambrosia artemisiifolia), a plant producing large amounts of allergenic pollen, was selected as a species model for examining the impact of road type on the spread of invasive plants. We examined this relationship in an agricultural region of Quebec, Canada. We mapped plant distribution along different road types, and constructed a model of species presence. Common ragweed was found in almost all sampling sites located along regional (97%) and local paved (81%) roads. However, verges of unpaved local roads were rarely (13%) colonized by the plant. A model (53% of variance explained), constructed with only four variables (paved regional roads, paved local roads, recently mown road verges, forest cover), correctly predicted (success rate: 89%) the spatial distribution of common ragweed. Results support the hypothesis that attributes associated with paved roads strongly favour the spread of an opportunistic invasive plant species. Specifically, larger verges and greater disturbance associated with higher traffic volume create propitious conditions for common ragweed. To date, emphasis has been placed on controlling the plant in agricultural fields, even though roadsides are probably a much larger seed source. Strategies for controlling the weed along roads have only focused on major highways, even though the considerable populations along local roads also contribute to the production of pollen. Management prioritizations developed to control common ragweed are thus questionable.     

A Critique of Estimating Future Costs Using Most Likely Value

ASTM E2137 (Standard Guide for Estimating Monetary Costs and Liability for Environmental Matters, or E2137) is the guidance for developing estimates of future environmental costs. E2137 provides a hierarchy of cost estimation approaches, and expresses an explicit preference for the use of probabilistic cost analysis to develop expected values for environmental costs. Dr. Ram and his colleagues have published an article (Remediation Journal, Autumn 2013) which rejects the use of EV analysis, arguing that while “good in principle” it has little practical value because it is nearly impossible to develop supportable probabilities. The E2137 principles and processes have been used for more than a decade in the context of addressing future environmental costs, yet their view of E2137 renders the standard meaningless. We conclude that the deficiency is not in the ASTM standard, and that when properly constructed, probabilistic analyses can be used to develop expected values with supportable probabilities. ©2015 Wiley Periodicals, Inc.     

Developments to a landfill processes model following its application to two landfill modelling challenges

The landfill model LDAT simulates the transport and bio-chemical behaviour of the solid, liquid and gas phases of waste contained in a landfill. LDAT was applied to the LMC1 and LMC2 landfill modelling challenges held in 2009 and 2011. These were blind modelling challenges with the model acting in a predictive mode based on limited early time sections of full datasets. The LMC1 challenge dataset was from a 0.34 m deep 0.48 m diameter laboratory test cell, and the LMC2 dataset was from a 55 m × 80 m 8 m deep landfill test cell which formed part of the Dutch sustainable landfill research programme at Landgraaf in the Netherlands. The paper describes developments in LDAT arising directly from the experience of responding to the two challenges, and discusses the model input and output data obtained from a calibration using the full datasets.The developments include the modularisation of the model into a set of linked sub-models, the strategy for converting conventional waste characteristics into model input parameters, the identification of flexible degradation pathways to control the CO₂:CH₄ ratio, and the application of a chemical equilibrium model that includes a stage in which the solid waste components dissolve into the leachate.     

Settlement decisions in blue tits: difference in the use of social information according to age and individual success

Dispersers are expected to assess breeding habitat quality before settlement. Although cues reflecting habitat quality are well studied, social cues have not been as well evaluated. In this paper, we studied breeding habitat selection during 3 years in a natural population of blue tits, Cyanistes caeruleus, breeding in nest-boxes. Our aim was to investigate if this species used conspecific density and/or reproductive success of con- and heterospecifics (i.e., social cues) in settlement decisions. The patterns observed were consistent with the idea that juveniles, when dispersing from their natal patches, did not react to any of the cues that we tested. In contrast, breeders that dispersed seemed to respond to both conspecific mean patch reproductive success (PRS) and breeding density of the settlement patch in the year of dispersal, their response differing according to their own reproductive success. Indeed, failed breeders moved to areas with high PRS and low density relative to source patches, while successful breeders behaved the opposite. The comparison between juveniles and adults might be modulated by the limited time available to juveniles to gather information on PRS and density at the end of the dispersing year. Adults lacking these time constraints, however, seemed to rely on these conspecific cues although limited by their own quality. Additionally, breeders were more likely to be immigrants in patches with relatively low breeding success and density the previous year, suggesting that settlement is influenced by multiple cues, which may reveal information on different aspects of habitat and be available at different moments. Collectively, our results support the importance of social cues for blue tits’ settlement.     

Using single- and multi-target regression trees and ensembles to model a compound index of vegetation condition

An important consideration in conservation and biodiversity planning is an appreciation of the condition or integrity of ecosystems. In this study, we have applied various machine learning methods to the problem of predicting the condition or quality of the remnant indigenous vegetation across an extensive area of south-eastern Australia—the state of Victoria. The field data were obtained using the ‘habitat hectares’ approach. This rapid assessment technique produces multiple scores that describe the condition of various attributes of the vegetation at a given site. Multiple sites were assessed and subsequently circumscribed with GIS and remote-sensed data.     

Evaluating Conservation Program Success with Landsat and SWAT

In the United States, many state and federally funded conservation programs are required to quantify the water quality benefits resulting from their efforts. The objective of this research was to evaluate the impact of conservation practices subsidized by the Oklahoma Conservation Commission on phosphorus and sediment loads to Lake Wister. Conservation practices designed to increase vegetative cover in grazed pastures were evaluated using Landsat imagery and the Soil and Water Assessment Tool (SWAT). Several vegetative indices were derived from Landsat imagery captured before and after the implementation of conservation practices. Collectively, these indicators provided an estimate of the change in vegetative soil cover attributable to conservation practices in treated fields. Field characteristics, management, and changes in vegetative cover were used in the SWAT model to simulate sediment and phosphorus losses before and after practice implementation. Overall, these conservation practices yielded a 1.9% improvement in vegetative cover and a predicted sediment load reduction of 3.5%. Changes in phosphorus load ranged from a 1.0% improvement to a 3.5% increase, depending upon initial vegetative conditions. The use of fertilizers containing phosphorus as a conservation practice in low-productivity pastures was predicted by SWAT to increase net phosphorus losses despite any improvement in vegetative cover. This combination of vegetative cover analysis and hydrologic simulation was a useful tool for evaluating the effects of conservation practices at the basin scale and may provide guidance for the selection of conservation measures subsidized in future conservation programs.