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Census Period (census + period)
Selected AbstractsChanging Skill Intensity in Australian IndustryTHE AUSTRALIAN ECONOMIC REVIEW, Issue 1 2007Ross Kelly This article examines changes in industry skill scores for Australia for the period 1991 to 2001 using indices of cognitive skill for industry based on Census employment data. Changes in mean industry cognitive skill levels are analysed, as are the relative contributions of changes to the occupational structure within industry and changes to the industry structure of employment. The main findings are that the drivers of skill change differed substantially between the two Census periods. Prior to 1996 the majority of the change was due to shifts towards industries with a more highly skilled workforce. After 1996 changes in the economy-wide skill level were dominated by within-industry changes in occupational composition. This coincided with a sharp pickup in the rate of capital expenditure on information and communication technologies. The increasing use of part-time employment overall had a deskilling effect. [source] Large-scale dynamics in colonization and extinction for breeding birds in BritainJOURNAL OF ANIMAL ECOLOGY, Issue 3 2002Kevin J. Gaston Summary 1A number of generalizations have been made as to the effects of the area of occupancy, population size, dispersal ability and body size of species on their relative rates of local colonization and extinction. 2Here, data on the breeding bird assemblage of Britain are used to test these generalizations. The complete geographical ranges of British birds have been censused twice, in the periods 1968,72 and 1988,91, allowing rates of colonization and extinction between these periods to be estimated. 3The local colonization dynamics of species are influenced independently by their range sizes and the dispersal abilities of adult birds: species with smaller range sizes and larger dispersal distances were more likely to have colonized new areas between the two census periods. 4The local extinction dynamics of species are influenced independently by their population sizes and body masses: species with smaller population sizes and body sizes were more likely to have gone extinct from areas inhabited in the first census period. 5These results remain when controlling for the effects of phylogenetic relatedness. 6These analyses uphold many commonly held generalizations about the correlates of local colonization and extinction, and suggest that the long-term evolutionary history of these bird species has influenced their potential to respond to current ecological conditions. [source] Population dynamics of an endangered heathland shrub, Epacris stuartii (Epacridaceae): Recruitment, establishment and survivalAUSTRAL ECOLOGY, Issue 1 2002David A. Keith Abstract The only known population of the endangered shrub Epacris stuartii Stapf was studied from 1994 to 2001 using demographic census techniques. The effects of substrate, a fire and a storm on the emergence and survival of seedlings and the survival of established plants of different sizes were examined using failure-time analyses and logit-linear models. Ninety-five per cent of seedling emergence was delayed until the second post-fire spring, an unusual response among species with persistent soil seed banks. Mortality of seedlings was extreme compared with larger-seeded species, but diminished significantly with age. Seedling mortality varied significantly between substrates: 40% of seedlings persisted for more than 5 years in mineral soil, whereas less than 10% lived more than a year on rock and intermediate substrates. However, seedling numbers and local densities were lower on soils than other substrates. Background mortality of established plants was lower on soil and intermediate substrates (0.5% per year) than on rock (3% per year). Small plants may be more susceptible than large plants on rock, but not on soil. Both the fire and the storm resulted in elevated mortality of established plants. The population exhibited a variable response to fire, with plants on rock and intermediate substrates behaving as obligate seeders, whereas plants in soil resprouted. This appears to be the first report of microhabitat variation in fire response at sympatric scales. The effects of the storm were apparently independent of substrate and plant size. The essentially independent disturbance regimes comprising recurring fires and storms are likely to have a profound effect on the long-term population dynamics of E. stuartii. Over the 7-year census period, recruitment has failed to compensate for mortality, resulting in a 30% net decline in the population. The demographic census has proved to be crucial in the detection and diagnosis of this decline. [source] Large-scale dynamics in colonization and extinction for breeding birds in BritainJOURNAL OF ANIMAL ECOLOGY, Issue 3 2002Kevin J. Gaston Summary 1A number of generalizations have been made as to the effects of the area of occupancy, population size, dispersal ability and body size of species on their relative rates of local colonization and extinction. 2Here, data on the breeding bird assemblage of Britain are used to test these generalizations. The complete geographical ranges of British birds have been censused twice, in the periods 1968,72 and 1988,91, allowing rates of colonization and extinction between these periods to be estimated. 3The local colonization dynamics of species are influenced independently by their range sizes and the dispersal abilities of adult birds: species with smaller range sizes and larger dispersal distances were more likely to have colonized new areas between the two census periods. 4The local extinction dynamics of species are influenced independently by their population sizes and body masses: species with smaller population sizes and body sizes were more likely to have gone extinct from areas inhabited in the first census period. 5These results remain when controlling for the effects of phylogenetic relatedness. 6These analyses uphold many commonly held generalizations about the correlates of local colonization and extinction, and suggest that the long-term evolutionary history of these bird species has influenced their potential to respond to current ecological conditions. 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