975 resultados para Forest fires.


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http://digitalcommons.colby.edu/atlasofmaine2006/1006/thumbnail.jpg

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The River Murray, Australia, is a highly regulated river from which almost 80% of mean annual flow is removed for human use, primarily irrigated agriculture. Consequent changes to the pattern and volume of river flow are reflected in floodplain hydrology and, therefore, the wetting/drying patterns of floodplain wetlands. To explore the significance of these changes, macroinvertebrate samples were compared between permanent and temporary wetlands following experimental flooding in a forested floodplain of the River Murray. Weekly samples from two permanent wetlands and four associated temporary sites were used to track changes in macroinvertebrate assemblage composition. Non-metric multidimensional scaling was used to ordinate the macroinvertebrate data, indicating consistent differences between the biota of permanent and temporary wetlands and between the initial and later assemblages in the temporary sites. There were marked changes over time, but little sign that the permanent and temporary assemblages were becoming more alike over the 25-week observation period. The apparent heterogeneity of these systems is of particular importance in developing river management plans which are likely to change flooding patterns. Such plans need to maintain a mosaic of wetland habitats if floodplain biodiversity is to be supported.

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This paper proposes a methodology for measuring community values towards Australian forest policy using chaos theory. The use of chaos theory within social sciences has been restricted due to chaos-based analysis requiring time-continuous data. Using scale-based data, iconographs are suggested as a method of dynamically representing community values for forestry at a higher phase plane. In addition, the method also provides opportunity for control of chaos by policy makers in altering community attitudes.

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The 1990s heralded a new era in forest policy in Australia with the introduction of The National Forest Policy Statement which provided a framework under which native forest resources would be protected whilst also permitting ecologically sustainable timber harvesting. However, the implementation of the statement through the Regional Forest Agreements by state governments appear to contradict the conditions of the policy. Political bias towards development imperatives in implementing RFAs is evident. Community involvement in RFAs has not been satisfactory for sustainable forest use and management, with ongoing dissatisfaction from some stakeholder groups. There is still increased demand for protection of what remains of the various forest reserves. Aboriginal issues have not been settled in line with the expectation of the policy. There are continuing conflicts between the Commonwealth Government and some state governments

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Forest management decisions are often characterised by complexity, irreversibility and uncertainty. Much of the complexity arises from the multiple-use nature of forest goods and services, difficulty in monetary valuation of ecological services and the involvement of numerous stakeholders. Under these circumstances, conventional methods such as cost-benefit analysis are ill-suited to evaluate forest decisions. The Analytic Hierarchy Process (AHP), can be useful in regional forest planing as it can accommodate conflictual, multidimensional, incommensurable and incomparable set of objectives. The objective of this paper is to examine the scope and feasibility of the AHP in incorporating stakeholder preferences into regional forest planning. The Australian Regional Forest Agreement Programme is taken as an illustrative case for the analysis. The results show that the AHP can formalize public participation in decision making and increase the transparency and the credibility of the process.

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The importance of riparian habitats to bird communities is well documented internationally, however the value of these habitats in largely intact landscapes is less well understood, particularly in Australia. Thirty paired riparian and adjacent non-riparian sites were selected within extensive forest mosaics of the Victorian Central Highlands and were surveyed over a two year period. Bird assemblages occurring within riparian habitats supported a significantly greater richness, abundance and diversity of species. These assemblages were also found to have species compositions significantly different from those occurring at adjacent non-riparian sites separated by a distance of approximately 750 m. Differences were attributed to a suite of distinctive species and significant contrasts in the densities of a range of species that occur in both habitat types. At the landscape level, there was a strong patterning of the avifauna centred on riparian habitats. Bird assemblages typically comprised four distinct suites of species: 1. species widespread in forests and woodlands of southeastern Australia; 2. riparian associated species (wet forest intruders); 3. riparian selective species, and; 4. riparian avoiding species. Both physiognomic and floristic differences between riparian and adjacent non-riparian habitats appear to drive responses in the structure of bird communities. There exists a distinctiveness and variability among the range of vegetation types and associated bird assemblages occurring throughout the forest matrix, including in riparian habitats. The occurrence of complimentary bird assemblages throughout the landscape mosaic highlights the importance of whole landscape planning for avifauna conservation.

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Understanding the habitat requirements of a species is critical for effective conservation-based management. In this study, we investigated the influence of forest structure on the distribution of the yellow-footed antechinus (Antechinus flavipes), a small dasyurid marsupial characteristic of dry forests on the inland side of the Great Dividing Range, Australia. Hair-sampling tubes were used to determine the occurrence of A. flavipes at 60 sites stratified across one of the largest remaining tracts of dry box–ironbark forest in south-eastern Australia. We considered the role of six potential explanatory variables: large trees, hollow-bearing trees, coppice hollows, logs, rock cover and litter. Logistic regression models were examined using an information-theoretic approach to determine the variables that best explained the presence or absence of the species. Hierarchical partitioning was employed to further explore relationships between occurrence of A. flavipes and explanatory variables. Forest structure accounted for a substantial proportion of the variation in occurrence of A. flavipes between sites. The strongest influence on the presence of A. flavipes was the cover of litter at survey sites. The density of hollow-bearing trees and rock cover were also positive influences. The conservation of A. flavipes will be enhanced by retention of habitat components that ensure a structurally complex environment in box–ironbark forests. This will also benefit the conservation of several threatened species in this dry forest ecosystem.

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This paper presents a system that employs random forests to formulate a method for subcellular localisation of proteins. A random forest is an ensemble learner that grows classification trees. Each tree produces a classification decision, and an integrated output is calculated. The system classifies the protein-localisation patterns within fluorescent microscope images. 2D images of HeLa cells that include all major classes of subcellular structures, and the associated feature set are used. The performance of the developed system is compared against that of the support vector machine and decision tree approaches. Three experiments are performed to study the influence of the training and test set size on the performance of the examined methods. The calculated classification errors and execution times are presented and discussed. The lowest classification error (2.9%) has been produced by the developed system.

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A method is presented for identification of lung nodules. It includes three stages: image acquisition, background removal, and nodule detection. The first stage improves image quality. The second stage extracts long lobe regions. The third stage detects lung nodules. The method is based on the random forest learner. Training set contains nodule, non-nodule, and false-positive patterns. Test set contains randomly selected images. The developed method is compared against the support vector machine. True-positives of 100% and 85.9%, and false-positives of 1.27 and 1.33 per image were achieved by the developed method and the support vector machine, respectively.