919 resultados para Greater Glider
Resumo:
Accurate habitat mapping is critical to landscape ecological studies such as required for developing and testing Montreal Process indicator 1.1e, fragmentation of forest types. This task poses a major challenge to remote sensing, especially in mixedspecies, variable-age forests such as dry eucalypt forests of subtropical eastern Australia. In this paper, we apply an innovative approach that uses a small section of one-metre resolution airborne data to calibrate a moderate spatial resolution model (30 m resolution; scale 1:50 000) based on Landsat Thematic Mapper data to estimate canopy structural properties in St Marys State Forest, near Maryborough, south-eastern Queensland. The approach applies an image-processing model that assumes each image pixel is significantly larger than individual tree crowns and gaps to estimate crown-cover percentage, stem density and mean crown diameter. These parameters were classified into three discrete habitat classes to match the ecology of four exudivorous arboreal species (yellowbellied glider Petaurus australis, sugar glider P. breviceps, squirrel glider P. norfolcensis , and feathertail glider Acrobates pygmaeus), and one folivorous arboreal marsupial, the greater glider Petauroides volans. These species were targeted due to the known ecological preference for old trees with hollows, and differences in their home range requirements. The overall mapping accuracy, visually assessed against transects (n = 93) interpreted from a digital orthophoto and validated in the field, was 79% (KHAT statistic = 0.72). The KHAT statistic serves as an indicator of the extent that the percentage correct values of the error matrix are due to ‘true’ agreement verses ‘chance’ agreement. This means that we are able to reliably report on the effect of habitat loss on target species, especially those with a large home range size (e.g. yellow-bellied glider). However, the classified habitat map failed to accurately capture the spatial patterning (e.g. patch size and shape) of stands with a trace or sub-dominance of senescent trees. This outcome makes the reporting of the effects of habitat fragmentation more problematic, especially for species with a small home range size (e.g. feathertail glider). With further model refinement and validation, however, this moderateresolution approach offers an important, cost eff e c t i v e advancement in mapping the age of dry eucalypt forests in the region.
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We use a spatially explicit population model to explore the population consequences of different habitat selection mechanisms on landscapes with fractal variation in habitat quality. We consider dispersal strategies ranging from random walks to perfect habitat selectors for two species of arboreal marsupial, the greater glider (Petauroides volans) and the mountain brushtail possum (Trichosurus caninus). In this model increasing habitat selection means individuals obtain higher quality territories, but experience increased mortality during dispersal. The net effect is that population sizes are smaller when individuals actively select habitat. We find positive relationships between habitat quality and population size can occur when individuals do not use information about the entire landscape when habitat quality is spatially autocorrelated. We also find that individual behaviour can mitigate the negative effects of spatial variation on population average survival and fecundity. (C) 1998 Elsevier Science Ltd. All rights reserved.
Resumo:
1. Although population viability analysis (PVA) is widely employed, forecasts from PVA models are rarely tested. This study in a fragmented forest in southern Australia contrasted field data on patch occupancy and abundance for the arboreal marsupial greater glider Petauroides volans with predictions from a generic spatially explicit PVA model. This work represents one of the first landscape-scale tests of its type. 2. Initially we contrasted field data from a set of eucalypt forest patches totalling 437 ha with a naive null model in which forecasts of patch occupancy were made, assuming no fragmentation effects and based simply on remnant area and measured densities derived from nearby unfragmented forest. The naive null model predicted an average total of approximately 170 greater gliders, considerably greater than the true count (n = 81). 3. Congruence was examined between field data and predictions from PVA under several metapopulation modelling scenarios. The metapopulation models performed better than the naive null model. Logistic regression showed highly significant positive relationships between predicted and actual patch occupancy for the four scenarios (P = 0.001-0.006). When the model-derived probability of patch occupancy was high (0.50-0.75, 0.75-1.00), there was greater congruence between actual patch occupancy and the predicted probability of occupancy. 4. For many patches, probability distribution functions indicated that model predictions for animal abundance in a given patch were not outside those expected by chance. However, for some patches the model either substantially over-predicted or under-predicted actual abundance. Some important processes, such as inter-patch dispersal, that influence the distribution and abundance of the greater glider may not have been adequately modelled. 5. Additional landscape-scale tests of PVA models, on a wider range of species, are required to assess further predictions made using these tools. This will help determine those taxa for which predictions are and are not accurate and give insights for improving models for applied conservation management.
Resumo:
The habitat requirements of arboreal marsupials were investigated in the dry sclerophyll forests of southeast Queensland, Australia. Species richness and abundance of arboreal marsupials was correlated to the proportion of total stand basal area occupied by lemon-scented gum (Corymbia citriodora), the height of the tallest trees, and density of hollow-bearing trees. The first two factors suggested that the most productive forests were also the most suitable habitats for arboreal marsupials. Importantly, the number of hollow-bearing trees was a significant factor in determining species richness and abundance of arboreal marsupials in this study, with the maximum number of species reached at sites containing greater than or equal to4 hollow-bearing trees/ha, and maximum abundance occurring at sites with :6 hollow-bearingtrees/ha. The proportion of C. citriodora was significant for the presence of the common brushtail possum (Trichosurus vulpecula), greater glider (Petauroides volans), and the yellow-bellied glider (Petaurus australis), while understory Acacia sp. density was important for the presence of the sugar glider (Petaurus breviceps). The yellow-bellied glider was also affected by two other variables: the density of hollow-bearing trees >50 cm diameter at breast height (dbh), and the time since the last logging. Current Codes of Practice regulating the density of hollow-bearing trees and silvicultural practices in state-owned timber production forests appear to provide adequate protection for arboreal marsupials, but the recently introduced increase in timber extraction rates within state forests may be detrimental to the animals. Also, protective prescriptions do not apply to the privately owned and leasehold estates, which contain the majority of the dry sclerophyll forests in southeast Queensland.
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The use of presence/absence data in wildlife management and biological surveys is widespread. There is a growing interest in quantifying the sources of error associated with these data. We show that false-negative errors (failure to record a species when in fact it is present) can have a significant impact on statistical estimation of habitat models using simulated data. Then we introduce an extension of logistic modeling, the zero-inflated binomial (ZIB) model that permits the estimation of the rate of false-negative errors and the correction of estimates of the probability of occurrence for false-negative errors by using repeated. visits to the same site. Our simulations show that even relatively low rates of false negatives bias statistical estimates of habitat effects. The method with three repeated visits eliminates the bias, but estimates are relatively imprecise. Six repeated visits improve precision of estimates to levels comparable to that achieved with conventional statistics in the absence of false-negative errors In general, when error rates are less than or equal to50% greater efficiency is gained by adding more sites, whereas when error rates are >50% it is better to increase the number of repeated visits. We highlight the flexibility of the method with three case studies, clearly demonstrating the effect of false-negative errors for a range of commonly used survey methods.
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This paper reports an example of the application of pharmaceutical technology to wildlife management, specifically the design of an oral delivery system for the common brushtail possum in New Zealand. Designing an oral delivery system requires a knowledge of the time taken for particulates to reach target sites within the gastrointestinal tract (GIT). The transit time for fluid and indigestible particles of two different size ranges was determined in the common brushtail possum (Trichosurus vulpecula). Technetium-labelled (Tc-99m) anion exchange resin particles (75-125 or 500-700 mu m diameter) or solution (Tc-99m-labelled diethylenetriamine pentaacetic acid, Tc-99m-DTPA) was administered orally. At predetermined times after dosing (3, 6, 12, 24 or 32 h), the distribution of radioactivity throughout excised gastrointestinal tracts was determined by gamma scintigraphy. The transit profile was similar for the three formulations investigated. Unlike other closely related hindgut fermenting marsupials, there was no evidence to support the presence of a colonic separating mechanism in the common brushtail possum. Gastrointestinal transit was independent of body mass, gender and time of day that the dose is given. To target the hindgut for oral delivery of protein and peptide biocontrol agents, the formulation Would need to protect the bioactive for approximately 12 h prior to release. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
We examined effects of attentional focus on swimming speed. Participants` task was to swim one length of a pool (16 m) using the front crawl stroke. In Experiment 1, intermediate swimmers were given attentional focus instructions related to the crawl arm stroke or the leg kick, respectively. Participants were instructed to focus on ""pulling your hands back"" or ""pushing the instep down"" (internal focus), or on ""pushing the water back/down"" (external focus), respectively. Swim times were significantly shorter with an external focus. In Experiment 2, a control condition was included. Times were significantly faster in the external focus compared with both the internal focus and control conditions. These findings have implications for enhancing performance in swimming.
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This paper reports the results of an experiment involving a sample of 204 members of the public who were assessed on three occasions about their willingness to pay for the conservation of the mahogany glider. They were asked this question prior to information being provided to them about the glider and other focal wildlife species; after such information was provided, and finally after participants had had an opportunity to see live specimens of this glider. The mean willingness to pay of the relevant samples are compared and found to show significant variations. Theories are considered that help explain the dynamics of these variations. Serious concerns are raised about the capacity of information provision to reveal ‘true’ contingent valuations of public goods.
Resumo:
Reviews the ecological status of the mahogany glider and describes its distribution, habitat and abundance, life history and threats to it. Three serial surveys of Brisbane residents provide data on the knowledge of respondents about the mahogany glider. The results provide information about the attitudes of respondents to the mahogany glider, to its conservation and relevant public policies and about variations in these factors as the knowledge of participants of the mahogany glider alters. Similarly data is provided and analysed about the willingness to pay of respondents to conserve the mahogany glider. Population viability analysis is applied to estimate the required habitat area for a minimum viable population of the mahogany glider to ensure at least a 95% probability of its survival for 100 years. Places are identified in Queensland where the requisite minimum area of critical habitat can be conserved. Using the survey results as a basis, the likely willingness of groups of Australians to pay for the conservation of the mahogany glider is estimated and consequently their willingness to pay for the minimum required area of its habitat. Methods for estimating the cost of protecting this habitat are outlined. Australia-wide benefits seem to exceed the costs. Establishing a national park containing the minimum viable population of the mahogany glider is an appealing management option. This would also be beneficial in conserving other endangered wildlife species. Therefore, additional economic benefits to those estimated on account of the mahogany glider itself can be obtained.
Resumo:
The aim of this study was to investigate the rate of occupational leg swelling depending on the time period of the working day Volumetric variations of the legs of 70 hospital employees, enrolled in three groups, were evaluated. Group I: 35 morning shift workers; Group II: 35 afternoon shift workers; and Group III: 15 individuals randomly selected from Groups I and II, who were evaluated on the day they worked 12 hours consecutively. Volumetry was performed before and after each shift for both legs of the participants in Groups I and II. For Group III volumetry was performed early in the morning, at noon and in the evening, For statistical analysis, the Student`s t-test and Mann-Whitney test were used with an alpha error of 5%. being considered acceptable (P value < 0.05). Significant increases in volume were recorded for the limbs in all three groups (P value < 0.001). On comparing Groups I and II, the accumulation of fluids was significantly higher in the morning than in the afternoon (P value < 0.003). Asymptomatic workers may present with oedema of the legs during their work with the rate of oedema being different for morning and afternoon shifts. The possibility of wearing compression stockings should be considered for this type of work.
Resumo:
This paper describes how watershed protection is being combined with settlement upgrading and land-use management within an area that serves as one of Greater Sao Paulo's main sources of fresh water. This is being undertaken in the municipality of San to Andre. Unlike previous watershed protection measures, which proved ineffective, it recognizes the need to combine the protection of water-sheds with the improvement of conditions in existing settlements and guiding, rather than prohibiting, further settlement. The paper describes how, the community-based watershed management involves the inhabitants of illegal settlements and other stakeholders in an adaptive planning framework that first seeks consensus on what is to be planned before developing the plan, its implementation and its operation, maintenance and monitoring.
Resumo:
Reproduction was studied across a three-year period in two south-east Queensland populations of the squirrel glider, Petaurus norfolcensis, by measuring morphological (body weight, scrotal diameter, cutaneous scent-gland activity, condition index) and physiological (plasma steroid levels) variables. Reproduction showed a seasonal pattern, with peak numbers of pouch young recorded in late autumn and winter. Declines in oestrogen concentrations outside the breeding period indicate that females are anoestrous in the summer months. Most (83%) reproductive females captured during the study were 2-3 years old, but all individuals over one year of age were found to have bred. Average litter size was 1.73 +/- 0.01 (n = 23). Scrotal diameter and testosterone concentrations showed no significant seasonal variation. It is suggested that this is due to the presence of both socially dominant and subordinate males in the data set. Maximum testosterone concentrations did coincide with periods of mating. The condition index showed no relationship with reproductive variables, but it is likely that this results from the manner in which the index was generated.
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Diabetes mellitus is now occurring in epidemic proportions in many countries. Owing to the limited effectiveness of drug prophylaxis of diabetic complications after diabetes has developed, it may be more appropriate to investigate ways to prevent the onset of diabetes. A recent trial published by the Diabetes Prevention Programme Research Group investigated whether lifestyle changes or metformin were effective in delaying the onset of diabetes in subjects with impaired glucose tolerance. The goals of the intensive lifestyle intervention were to achieve and maintain a weight reduction of 7% through a low-calorie, low-fat diet and to engage in physical activity of moderate intensity, such as brisk walking, for at least 150 min/week. The effectiveness of the intensive lifestyle intervention on body weight was initially quite good but decreased over time. Metformin caused some weight loss but to a lesser extent than the intensive lifestyle intervention. Both therapies decreased the fasting plasma glucose levels to a similar extent initially. The intensive lifestyle intervention decreased plasma glycosylated haemoglobin levels to a greater extent than metformin. Both intensive lifestyle intervention and metformin reduced the incidence of diabetes, with the lifestyle intervention having the greater effect.
Resumo:
Glucocorticoids are pivotal for adipose tissue development. Rodent studies suggest that corticosteroid-binding globulin (CBG) modulates glucocorticoid action in adipose tissue. In humans, both genetic CBG deficiency and suppressed CBG concentrations in hyperinsulinemic states are associated with obesity. We hypothesized that CBG deficiency in humans modulates the response of human preadipocytes to glucocorticoids, predisposing them to obesity. We compared normal preadipocytes with subcultured preadipocytes from an individual with the first ever described complete deficiency of CBG due to a homozygous null mutation. CBG-negative preadipocytes proliferated more rapidly and showed greater peroxisome proliferator-activated receptor-gamma-mediated differentiation than normal preadipocytes. CBG was not expressed in normal human preadipocytes. Glucocorticoid receptor number and binding characteristics and 11beta-hydroxysteroid dehydrogenase activity were similar for CBG-negative and normal preadipocytes. We propose that the increased proliferation and enhanced differentiation of CBG-negative preadipocytes may promote adipose tissue deposition and explain the obesity seen in individuals with genetic CBG deficiency. Furthermore, these observations may be relevant to obesity occurring with suppressed CBG concentrations associated with hyperinsulinemia.