E‐environment: Hype and promise

The Internet and electron‐based technologies offer the promise of abundant environmental improvements. But how will the “information revolution” play out in the real world? © 2000 John Wiley & Sons, Inc.     

Susceptibility of Eucalyptus globulus to Mnesampela privata defoliation in relation to a specific foliar wax compound

Summary. Increased abundance of several aliphatic benzyl and phenylethyl alkanoates were previously associated with reduced defoliation of Eucalyptus globulus Labill. by the autumn gum moth (Mnesampela privata Guenée) in two clonally replicated F₂ families. We examine the robustness of this association by comparing the abundance of the implicated foliar wax compounds with defoliation levels in three plantation sites and a genetics trial in northern Tasmania. At all locations, the aliphatic alkanoate, benzyl n-tetracosanoate (C₂₄), was found in significantly higher abundance in the foliar wax of E. globulus trees that had displayed low M. privata damage (designated resistant) compared to trees that had displayed high damage (designated susceptible). Further, when sites were combined, benzyl n-tetracosanoate (C₂₄) accounted for 16 % of variation in field defoliation. Field defoliation was also positively correlated to M. privata oviposition both in the field and on foliage sprigs in a cage. In the cage bioassay, oviposition accounted for 20 % of variation in field defoliation making it a better predictor of tree defoliation in the field than either field oviposition, which accounted for 9 % of variation, or screening foliage for the abundance of benzyl n-tetracosanoate (C₂₄). Despite both benzyl n-tetracosanoate (C₂₄) and oviposition being related to field defoliation, there was no statistically significant relationship between the abundance of benzyl n-tetracosanoate (C₂₄) and oviposition in the field or cage bioassay. Further work is therefore required to determine if increased levels of this compound in the foliar wax operates as a direct deterrent to M. privataoviposition.     

Incorporating behaviour into simple models of dispersal using the biological control agent Dicyphus hesperus

We explored the utility of incorporating easily measured, biologically realistic movement rules into simple models of dispersal. We depart from traditional random walk models by designing an individual-based simulation model where we decompose animal movement into three separate processes: emigration, between-patch movement, and immigration behaviour. These processes were quantified using experiments on the omnivorous insect Dicyphus hesperus moving through a tomato greenhouse. We compare the predictions of the individual-based model, along with a series of biased random walk models, against an independent experimental release of D. hesperus. We find that in this system, the short-term dispersal of these insects is described well by our individual-based model, but can also be described by a 2D grid-based biased random walk model when mortality is accounted for.     

Establishing and using study criteria to ensure the rigor and robustness of survival compliance testing at hydroelectric dams

An elaborate set of criteria have been developed by fish managers and regulators to assure the accuracy, precision, representativeness, and robustness of survival compliance studies coordinated within the Federal Columbia River Power System in the northwestern USA. Dam passage survival, defined as survival from the dam face to the tailrace mixing zone, must be ≥96 % for spring out migrating juvenile salmonids [i.e., yearling Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss)] and ≥93 % for summer outmigrants (i.e., subyearling Chinook salmon). Survival must be estimated with a standard error ≤1.5 %. However, these quantitative benchmarks are only part of a multifaceted set of criteria, including representative dam operations, river discharge levels, and fish selection, along with tests of model validity that must be satisfied. These criteria are illustrated using acoustic-tag survival compliance studies conducted at The Dalles Dam on the Columbia River, 2010–2012. The results suggest evaluation criteria for survival compliance tests must balance the needs for rigor and robustness with the ability to reasonably perform the tests in naturally varying riverine systems.     

Direct and indirect land-use change as prospective climate change indicators for peri-urban development transitions

With urban areas responsible for a significant share of total anthropogenic emissions, greenhouse gas (GHG) emissions due to land-use change (LUC) induced by peri-urban (PU) development have the potential to be considerable. Despite this, there is little research into the transition from PU cropland to housing in terms of contribution to global warming. This paper presents a cross-sectoral integrative method for prospective climate change evaluation of PU LUC. Specifically, direct LUC (dLUC) GHG emissions from converting PU cropland to greenfield housing were examined. Additionally, GHG emissions due to displaced crop production inducing indirect LUC (iLUC) elsewhere were assessed. GHG impacts of dLUC and iLUC were each determined to be approximately 8 per cent of total GHG emissions due to a greenfield housing development displacing PU cropland. This magnitude of dLUC and iLUC emissions suggests that both have importance in future land-use decision making with respect to PU environments.     

The development of alum rates to enhance the remediation of phosphorus in fluvial systems following manure spills

Following the remediation of animal manure spills that reach surface waters, contaminated streambed sediments are often left in place and become a source for internal phosphorus (P) loading within the stream in subsequent flow. The objective of this study was to develop treatment rates and combinations of alum and CaCO(3) to mitigate P from contaminated sediments of different particle size distributions following a manure spill. Sediment specific alum and CaCO(3) treatment rates were developed based upon the resultant alum treatment ranges established for each sediment type. Clay loam sediments required 54% more alum to mitigate P desorption relative to sediments that contain at least 60% sand. Amending sediments with the highest rates of alum/alum + CaCO(3), resulted in a 98-100% reduction in P desorption and a similar water column pH for all sediments types. Observations from this study demonstrated the effectiveness of alum/alum + CaCO(3) to increase P retention in sediments following a manure spill.