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41.
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In recent years, a significant feature of population change in North American metropolitan areas has been the rapid suburbanization of elderly people. The ability to engage in routine activity may be a necessary condition for the maintenance of independent life styles and psychological well‐being among older suburbanites. Using a conceptual framework based on Parmelee and Lawton's ecological model of aging, this article offers an exploratory investigation of the determinants of the travel of separate samples of elderly male and female suburbanites to each of five destination categories of key service/activity sites in a Canadian city. The results of the tests of ten multiple regression models disclose that the levels of explanation of trip frequency afforded by “autonomy components” (e.g. health‐related characteristics, living arrangements, and income level) vary according to destination category. However, the explanatory power of “security components” (i.e. variables concerning access to destination categories) is generally low. Overall, the findings of the study provide a basis for developing a deeper understanding of the repetitive travel behavior of elderly suburbanites. 相似文献
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Michiala E. Bowen Clive A. McAlpine Alan P.N. House Geoffrey C. Smith 《Biological conservation》2007,140(3-4):273-296
Human land use has modified the structure and function of terrestrial landscapes throughout much of the world, with cropping and livestock grazing the major drivers of landscape change. In many tropical, sub-tropical, temperate and Mediterranean regions, regrowth forests regenerate naturally on abandoned agricultural land if human disturbance declines. With the exception of some tropical forest literature, the broader ecological and conservation literature has largely ignored the potential of regrowth forests to facilitate passive landscape restoration and the recovery of fauna communities in fragmented agricultural landscapes. This paper addresses this deficiency by reviewing the available global evidence of fauna recovery in regrowth forest from 68 papers, identifying the main gaps in current knowledge, and providing directions for further research. The majority of reviewed studies focus on regrowth in tropical regions, which often contain large areas of mature forest. Species’ utilisation of regrowth forest is highly variable and is particularly influenced by land-use history, an important determinant of the structural and compositional characteristics of regrowth forests. While site-scale (<1 ha) forest structure and floristic diversity were frequently studied, only 11 studies considered the spatial configuration and context of habitat patches and just two studies explicitly considered landscape structure. Based on this review, six key research questions are posed to direct future research on this important issue. We conclude that a broader perspective of the role of regrowth forest in the landscape is required if we are to realise the potential benefits of regrowth forest for passive landscape restoration and fauna conservation and recovery. 相似文献
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A range of different biodiversity-based selection methods for nature reserves has been tested for terrestrial environments, including those based on diversity hotspots, endemicity hotspots and complementarity. In this study, we investigate the utility of these approaches for a coral reef embayment. We compare coral and fish species richness in a random accumulation of reserve sites with (a) hotspots analysis, (b) stratified selection of hotspots, and (c) complementarity. Cumulative species-site curves indicated that complementarity maximized the rate of accumulation of species of both corals and fishes in reserves, while the hotspot approach performed moderately well. An equivalent number of reserve sites supported a greater proportion of the coral biodiversity when compared to fishes, reflecting the broader distribution of corals. Our results indicate that when choosing an indicator group as a proxy for representing overall diversity in a reserve network, the group with the greatest heterogeneity will provide the best results. Our findings also show that although a modest number of protected sites (20%) will incorporate much of the local diversity (>75%), species-specific approaches must be incorporated to target rare species. 相似文献
47.
In September 2003 Hurricane Isabel swept through eastern North Carolina and Virginia, destroying most of what formerly ranked among the most extensive remaining stands of Atlantic White-cedar (Chamaecyparis thyoides L., cedar). As Atlantic White-cedar communities are dependent on irregular, large-scale disturbances, the hurricane event can be viewed as an opportunity for perpetuating cedar populations in the Great Dismal Swamp. The success of cedar regeneration in the Dismal Swamp has been influenced by the management strategies employed by Great Dismal Swamp National Wildlife Refuge (active management) and by the adjacent Dismal Swamp State Park (passive management). We investigated the regeneration success of Atlantic White-cedar 5 years following Hurricane Isabel by sampling five stands at the Dismal Swamp State Park withstanding varying impact from the storm and previous windthrow events. We compared our findings to regeneration surveys completed at the adjacent Great Dismal Swamp National Wildlife Refuge. Atlantic White-cedar seedling densities were up to 100 times higher in the actively managed Wildlife Refuge compared to the passively managed State Park. We also determined the seedbank of viable cedar seeds and we described the vegetation at the State Park. The stands at the State Park are now dominated by red maple (Acer rubrum) with a dense shrubby understory. Since viable cedar seeds were still present in the seedbank (>800,000 ha−1), future seedling establishment is possible at the State Park. However, active management is essential for achieving sufficient seedling densities and survival for regenerating a mature cedar stand. 相似文献
48.
Geoffrey?JonesEmail author Rachel?J.?Keedwell Alasdair?D.?L.?Noble Duncan?I.?Hedderley 《Journal of Agricultural, Biological & Environmental Statistics》2005,10(3):306-320
The motivation for this work was to investigate the possibility of accurately determining the age of a tern chick using easily
obtained body measurements. We describe the construction of a nonlinear multivariate hierarchical model for chick growth and
show how it can be estimated using Markov chain Monte Carlo techniques. A simple extension of the analysis allows for estimation
of the ages of unknown chicks. Posterior distributions of the unknown ages are derived, so that the accuracy of age determination
can be examined. We further extend our model and analysis to include the possibility that chicks fall into distinct groups
with different growth characteristics. The technique is illustrated using data on the weight and wing length of black-fronted
terns from the Ohau River, New Zealand. It is found that dating to within one day is possible, but only in some areas of the
data space. The concept of “braiding” of multivariate growth curves is introduced to explain the varying accuracy of age determination. 相似文献
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50.
Theodore E. Howard 《Agriculture and Human Values》1999,16(4):421-430
Modern and historical Japanese societies are and were quite comfortable with a nature defined, designed, and dominated by humans. While contemporary Japanese are concerned about the environment, especially about non-timber (green) forest resources, conservation organizations are generally small and locally focused. Public forests, accounting for 40 percent of all Japan's forests, are intensively managed. At the national level, the timber program is operating below cost and there is increasing emphasis on non-timber management and rural economic development. A professional elite largely determines forest management goals and cultural barriers minimize broad public participation. Increasingly aware of the environmental impacts of their industrial society at home and abroad, the Japanese are becoming more environmentally concerned. Government agencies are especially proactive in enhancing environmental understanding among Japanese citizens and in sharing their resource management expertise with other Pacific Rim nations. 相似文献