Limited salvage logging effects on forest regeneration after moderate-severity windthrow.

Recent conceptual advances address forest response to multiple disturbances within a brief time period, providing an ideal framework for examining the consequences of natural disturbances followed by anthropogenic management activities. The combination of two or more disturbances in a short period may produce "ecological surprises," and models predict a threshold of cumulative disturbance severity above which forest composition will be drastically altered and regeneration may be impaired. Salvage logging (the harvesting of timber after natural disturbances; also called "salvaging" or "sanitary logging") is common, but there have been no tests of the manner in which salvaging after natural wind disturbance affects woody plant regeneration. Here we present findings from three years after a moderate-severity wind disturbance in west-central Tennessee, USA. We compare two unsalvaged sites and two sites that had intermediate-intensity salvaging. Our approach demonstrates the calculation of cumulative severity measures, which combine natural windthrow severity and anthropogenic tree cutting and removal, on a plot-by-plot basis. Seedling/sapling density and species richness were not influenced by cumulative disturbance severity, but species diversity showed a marginal increase with increasing cumulative severity. The amount of compositional change (from predisturbance trees to post-disturbance seedlings/saplings) increased significantly with cumulative severity of disturbance but showed no evidence of thresholds within the severity range examined. Overall, few deleterious changes were evident in these sites. Moderate-severity natural disturbances followed by moderate-intensity salvaging may have little detrimental effect on forest regeneration and diversity in these systems; the ecological surprises and threshold compositional change are more likely after combinations of natural and anthropogenic disturbances that have a much greater cumulative severity.     

Slow-stir water solubility measurements of selected alcohols and diesters

The surface chemical characteristics of activated carbon treated by ozone and alkaline are determined in terms of surface functional groups and surface acidity. Surface functional groups are analyzed by the IR spectroscopic method and Boehm's titration technique. The surface acidity of activated carbon is determined by electrophoretic mobility measurements. The oxygen concentration of activated carbon increases upon ozone and NaOH treatment. Surface functional groups increase mostly in the hydroxyl and carboxyl categories rather than the carbonyl category upon ozone and NaOH treatment.     

Evaluation of a fluorometric screening method for predicting total PAH concentrations in contaminated sediments

A fluorometric screening method was used to estimate total polycyclic aromatic hydrocarbon (t-PAH) concentrations in sediments collected from the St. Louis River Area of Concern (AOC) in northeastern Minnesota. Sediments were collected as part of a Regional Environmental Monitoring and Assessment Program (R-EMAP) study to assess sediment quality in the AOC. The screening method was calibrated using a PAH surrogate standard consisting of eight PAHs commonly found in the St. LouisRiver system, at their approximate proportions. Estimated PAHconcentrations were compared to GC/MS measured `true' PAH concentrations to evaluate the overall predictive power of thescreening method. Regression analysis of log transformed estimated versus true PAH concentration yielded an r² of 0.72 (n = 86). In addition, the rates of false positive and false negative predictions associated with the screening methodwere determined relative to different sediment effects concentrations (SECs) for total PAHs. In general, the rate of false positive predictions was shown to increase as the SEC criteria value decreased, while false negative rates remainedconsistently low (below 7%). Methodological recommendations which led to a three-fold reduction in false negatives, and theimproved prediction of both high and low PAH samples, are presented.     

Behavior of beaver in lakes with varying water levels in Northern Minnesota

We studied the effects of winter water drawdowns (2.3 m) on beavers in Voyageurs National Park, Minnesota, USA. Our study was designed to sample areas within the park that differed in water drawdown regime. Lodges were counted and beavers were livetrapped and radio-implanted to study behavior, movements, and mortality. Active beaver lodge density, determined by aerial survey in 1984 and 1986, was greatest along the shoreline of the drawdown reservoir. In winter beavers living on the drawdown reservoir spent less time inside their lodges than did beavers from stable water environments, foraged more above ice, and they were unable to fully use stored food. Only one case of starvation in the drawdown reservoir was documented, but beavers in reservoirs that were drawn down survived winter in poorer condition than did beavers living in areas in which water levels remained high. In spite of an increasing population and lack of widespread mortality, winter water drawdowns did alter beaver behavior. To reduce these impacts, total annual water fluctuation should not exceed 1.5 m, and winter drawdown should not exceed 0.7 m. Possible management alternatives and costs are discussed.     

Quantitative methods in cross-national management research: Trends and equivalence issues

Cross-national management articles published in 24 major management-related journals from 1981 to 1987 are reviewed. The methods used in the quantitative articles are categorized according to the characteristics of the research sites, data, and analytical methods. The review indicates increasing methodological sensitivity, complexity, and sophistication as compared to that found in earlier reviews. Improvement in the field could occur through improved understanding of the inherent limitations in cross-cultural equivalence and through increased attention to qualitative analysis as a means to handle the ‘etic-emic’ dilemma.     

Silver concentrations in Welsh soils and their dispersal from derelict mine sites

In west and north Wales silver was mined extensively between 1750 and 1900, where it was frequently present as its sulphide form, argentite, whilst also occurring as a guest element in galena and sphalerite. Determination of the silver content of a range of soil types from areas devoid of mines by flameless atomic absorption spectrometry established normal background levels. Soils derived from black shales, or rich in organic matter were inherently richer in silver than the sandstone or limestone derived soils examined. Soils once exposed to contamination from the mining activities of the 19th Century can still be identified as they show elevated levels of silver. Fluvially derived contamination is confined to valley floodplains, but aerial transportation of mine spoil wastes enhance metal levels around derelict mine sites. Spoil analysed from areas of different geology contained a range of silver values reflecting variations in ore type, grain size and technique of ore extraction.     

Modeling postfire conifer mortality for long-range planning

A model is presented for predicting mortality of conifers after wildfire. The model requires stand data inputs and is linked with a mathematical fire behavior model that calculates fireline intensity. Fraction of crown volume killed is calculated for each species in a stand based on mensurational data. Duration of lethal heat at the base of trees is calculated from fuel consumption and burning time values. Fraction of crown volume killed and the ratio of critical time for cambial kill to duration of lethal heat are independent variables in a function that calculates probability of mortality. The model produces reasonable estimates of stand mortality for fire and site characteristics found in the northern Rocky Mountains, USA. It has a broad resolution appropriate for use in fire management planning and has potential applications for coniferous forests throughout the United States.     

Character strengths in organizations

Character refers to qualities within individuals that lead them to desire and to pursue the good. We propose that strengths of character are a neglected but critically important resource for organizations. Character matters because it leads people to do the right thing, and the right thing can be productive and profitable. Copyright © 2006 John Wiley & Sons, Ltd.     

A Procedure for Performing Population-Level Ecological Risk Assessments

/ In 1997, Oregon enacted amendments to its state hazardous waste site cleanup law which emphasize risk-based remedial action decisions. In a departure from US EPA practice, the amended statute and associated rules require that protection of ecological receptors occur at the population level for all plants and animals not listed as threatened or endangered. By rule, the acceptable risklevel for populations of ecological receptors is a 10% or less chance that 20% or more of the total local population would receive an exposure greater than the toxicity reference value for a hazardous substance. This paper describes a practical procedure for performing population-level ecological risk assessments using a combination of relatively simple techniques. The procedure involves: (1) establishing a distribution of exposures and a contaminant-specific toxicity reference value, either as a point value or a distribution, for an individual receptor, (2) estimating the abundance of these receptors within their local populations, (3) estimating the probability of an individual receptor experiencing an exposure in excess of the toxicity reference value, (4) estimating the number of individual receptors in the local population likely to experience an exposure above the toxicity reference value greater than 10% of the time, and (5) determining whether this number is greater than 20% of the total local population.