Growth performance and management of a mixed rainforest tree plantation

Monoculture plantations of Pinus, Eucalyptus and Acacia have been established oil rainforest lands throughout the world. However, this type of reforestation generally supplies low quality timber and contributes to landscape simplification. Alternatives to exotic monoculture plantations are now beginning to gain momentum with farmers and landholders attempting to establish a variety of rainforest trees in small plantations. When compared to the well studied commercial species, knowledge concerning the growth and management of many of these rainforest species is in its infancy. To help expand this limited knowledge base an experimental plantation of 16 rainforest tree species in a randomised design was established near Mt. Mee, in south-eastern Queensland, Australia. Changes in growth, form (based on stem straightness, branch size and branchiness), crown diameters and leaf area of each species were examined over 5 years. Patterns of height growth were also measured monthly for 31 months. Species in this trial could be separated into three groups based on their overall growth after 5 years and their growth patterns. Early successional status, low timber density, high maximum photosynthetic rates and large total leaf areas were generally correlated to rapid height growth. Several species (including Araucaria cunninghamii, Elaeocarpus grandis, Flindersia brayleyana, Grevillea robusta and Khaya nyasica) had above average form and growth, while all species in the trial had considerable potential to have increased productivity through tree selection. As canopy closure occurred at the site between years four and five, growth increments declined. To reduce stand competition a number of different thinning techniques could be employed. However, simple geometric or productivity based thinnings appear to be inappropriate management techniques for this mixed species stand as they would either remove many of the best performing trees or nearly half the species in the trial. Alternatively, a form based thinning would maintain the site's diversity, increase the average form of the plantation and provide some productivity benefits.

Transport safety for older people: A study of their experiences, perceptions and management needs

With evidence of increasing accident risk due to age-related declines in health and cognition affecting driver performance, there is a need for research promoting safe mobility of older people. The present study aimed to identify transport options and licensing issues for a group of older people in an Australian community. Ninety-five participants aged 75 and over were interviewed about their driving status and accident record and tested for cognitive ability. After stratification on cognitive level and driver status (current, ex-driver or non-driver), 30 were selected for further in-depth interviews concerning demographics, licence status and impact of change, travel options available and used, and travel characteristics. Considerable reliance on the motor vehicle as the mode of transport and the decision to cease driving were major quality-of-life issues. There was little evidence of planning and support in making the decision to stop driving. Some differences in transport decisions on the basis of cognitive level were evident; however, people with severely compromised cognitive ability (and, therefore, unable to give informed consent) had been excluded. The study suggested the need for resources to assist older people/carers/health professionals to plan for the transition from driver to non-driver and to manage alternative transport options more effectively

Uncertainty during organizational change: Types, consequences, and management strategies

This research tested a model that classifies change uncertainty into three interrelated types: strategic, structural, and job-related. We predicted that control would mediate the effects of job-related uncertainty upon psychological strain, and that management communication and participation in decision-making (PDM) would reduce uncertainty and increase feelings of control. The model was tested in a public sector organization and the results supported it. Control was found to mediate the effects of job-related uncertainty upon psychological strain. Management communication was negatively related to strategic uncertainty, whereas PDM was negatively related to structural and job-related uncertainty, suggesting different mechanisms to deal with the types of uncertainty during change. Finally, PDM was positively associated with feelings of control and negatively associated with psychological strain. These results suggest that PDM can short-circuit the damaging effects of uncertainty by allowing employees to have a say in change related organizational affairs, thereby instilling a sense of control over their circumstances.

Process, performance, and pollution potential: A review of septic tank-soil absorption systems

On-site wastewater treatment and dispersal systems (OWTS) are used in non-sewered populated areas in Australia to treat and dispose of household wastewater. The most common OWTS in Australia is the septic tank-soil absorption system (SAS) - which relies on the soil to treat and disperse effluent. The mechanisms governing purification and hydraulic performance of a SAS are complex and have been shown to be highly influenced by the biological zone (biomat) which develops on the soil surface within the trench or bed. Studies suggest that removal mechanisms in the biomat zone, primarily adsorption and filtering, are important processes in the overall purification abilities of a SAS. There is growing concern that poorly functioning OWTS are impacting upon the environment, although to date, only a few investigations have been able to demonstrate pollution of waterways by on-site systems. In this paper we review some key hydrological and biogeochemical mechanisms in SAS, and the processes leading to hydraulic failure. The nutrient and pathogen removal efficiencies in soil absorption systems are also reviewed, and a critical discussion of the evidence of failure and environmental and public health impacts arising from SAS operation is presented. Future research areas identified from the review include the interactions between hydraulic and treatment mechanisms, and the biomat and sub-biomat zone gas composition and its role in effluent treatment.

Relationship between work performance and personality traits in Hong Kong organizational settings

Four hundred and thirty-seven employees from four Hong Kong organizations completed the Traditional Chinese versions of the Fifteen Factor Personality Questionnaire Plus (15FQ+) and the Cross-Cultural Personality Assessment Inventory (CPAI-2) (indigenous scales) and provided objective and memory-based recent performance appraisal scores. A number of significant bivariate correlations were found between personality and performance scores. Hierarchical multiple regression analyses revealed that a number of the scales from the 15FQ+ contributed to significantly predicting four of the performance competency dimensions, but that the CPAI-2 indigenous scales contributed no incremental validity in performance prediction over and above the 15FQ+. Results are discussed in the light of previous research and a call made for continued research to further develop and increase the reliability of the Chinese instruments used in the study and to enable generalization of the findings with confidence.

Species performance and site relationships for rainforest timber species in plantations in the humid tropics of Queensland

The performance of 32 tropical rainforest and eucalypt tree species grown in private, mixed species plantations was examined. There were two objectives: 1) to summarise the growth of species by soil and rainfall classes, 2) to investigate the degree of variability in growth rates with respect to environmental variables. Data were collected from 112 plots established in the Community Rainforest Reforestation Program (CRRP) plantations across sites in the humid tropics of central and north Queensland. Sites ranged from sea level to 1160 m above sea level, with annual rainfall from 800 mm to 4300 mm, on soils derived from basalt, metamorphic and granite parent material. Species performance was significantly related to climatic and edaphic variables but the strength of these relationships differed among taxa.

Effects of memory load and distraction on performance and event-related slow potentials in a visuospatial working memory task

Brain electrical activity related to working memory was recorded at 15 scalp electrodes during a visuospatial delayed response task. Participants (N = 18) touched the remembered position of a target on a computer screen after either a 1 or 8 sec delay. These memory trials were compared to sensory trials in which the target remained present throughout the delay and response periods. Distracter stimuli identical to the target were briefly presented during the delay on 30% of trials. Responses were less accurate in memory than sensory trials, especially after the long delay. During the delay slow potentials developed that were significantly more negative in memory than sensory trials. The difference between memory and sensory trials was greater at anterior than posterior electrodes. On trials with distracters, the slow potentials generated by memory trials showed further enhancement of negativity whereas there were minimal effects on accuracy of performance. The results provide evidence that engagement of visuospatial working memory generates slow wave negativity with a timing and distribution consistent with frontal activation. Enhanced brain activity associated with working memory is required to maintain performance in the presence of distraction. © 1997 by the Massachusetts Institute of Technology

Environmental poisoning: Presentation and management

Environmental poisoning is most commonly associated with chronic longterm exposure to toxins rather than to acute exposure. Such repeated exposure to sublethal doses of compounds and elements presents problems in risk assessment. This is primarily because the data are unavailable to describe relationships between dose and effect at lower levels of exposure to toxins. Bioavailability of toxins also presents a problem because the data on bioavailability are sparse and seldom as high as the default of 100% bioavailability commonly used in risk assessment. Examples are presented of two toxins: arsenic as an elemental anthropogenic and geologic poison and ciguatoxin, a polyether ladder compound, as a toxin produced naturally by dinoflagellates. Bioavailability drives the toxicity of arsenic from contaminated sites, whereas tissue accumulation drives the toxicity of ciguatoxin. Considerable benefit is derived from the harmonization of regulatory processes where there is linkage of health and environmental factors in the derivation of credible risk assessment.