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291.
There is a lack of research on the effects of logging on Canadian amphibians. We compared the abundance of terrestrial salamanders in old-growth forests with that in young and mature post-harvest stands. We also measured habitat features of amphibians and contrasted these with old-growth and harvested stands to assess the effects of forest harvest. Quadrat searches demonstrated that clearcut harvesting reduces terrestrial amphibian populations by up to 70% in coastal old-growth forests. We suggest that this reduction results from a decrease in availability of moist microhabitats. Salamander densities within 10 meters of streams in managed stands were similar to those near and away from streams in old growth. We recommend that forest managers recognize the needs of terrestrial amphibians and help maintain amphibian populations by preserving cool, moist habitats. This can be accomplished within cutblocks by (1) maintaining an even distribution of logs and snags as stable, moist microhabitats; (2) retaining some understory as sources of shade, and (3) preserving streamside buffers. Managers must also ensure some level of landscape connectivity to enable climate-sensitive amphibians to disperse and recolonize marginal habitats. 相似文献
292.
Emmanuelle Cam Lynn Lougheed† Russell Bradley‡ Fred Cooke§ 《Conservation biology》2003,17(4):1118-1126
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Biotic and abiotic factors involved in surface coal mine reclamation were evaluated on 81 mine sites in Mercer County, Pennsylvania, USA. Soil moisture and organic content were the two most important factors in determining the establishment and growth of vegetation on mined lands. Soil bacteria and fungi populations were also related to these soil conditions, and soil micro-organisms were important in the decomposition of organic materials as well as factors in the rate and type of natural succession occurring on these lands. The succession of native plant species increases the density and stability of plant communities on mined lands. The importance of natural succession in mined-land reclamation and the use of these lands by wildlife is discussed.Supported by Grant-In-Aid, Natural Geographic Society. 相似文献
295.
A laboratory experiment (N = 149) tested two hypotheses: that choice of reward will have a positive impact on task performance and that choice would lead to arousal, as measured by reaction speed. The role that feedback information concerning whether subjects were being rewarded for performance on a prior task was also examined. The results revealed that choice and choice interacting with feedback were related to performance, but the choice had no impact on arousal. Self-determination theory may be used to help interpret these findings. The choice and feedback are non-controlling and informational to recipients which may increase perceptions of competence and self-initiative with an accompanying increase in intrinsic motivation to perform well on the task. These theoretical implications and some questions for future research and practical applications are discussed. 相似文献
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Fred Granek 《Journal of Cleaner Production》2011,19(5):559-560
As part of Ontario's Toxics Reduction Strategy, the Ontario Ministry of the Environment provided funding for two years to a partnership of the Ontario Centre for Environmental Technology Advancement (OCETA) and the Canadian Manufacturers & Exporters (CME) to deliver a Cleaner and Greener Manufacturing Program, which will include the development and delivery of training and technical assistance programs on toxics reduction and pollution prevention (P2). Over the next two years, OCETA and CME will be working with small-to-medium sized manufacturers to demonstrate the business value of toxics reduction and pollution prevention planning to help motivate businesses to move into a greener economy. 相似文献
298.
The take of Nearctic songbirds for the caged-bird trade is an important cultural and economic activity in Mexico, but its sustainability has been questioned. We relied on the theta-logistic population model to explore options for setting allowable levels of take for 11 species of passerines that were subject to legal take in Mexico in 2010. Because estimates of population size necessary for making-periodic adjustments to levels of take are not routinely available, we examined the conditions under which a constant level of take might contribute to population depletion (i.e., a population below its level of maximum net productivity). The chance of depleting a population is highest when levels of take are based on population sizes that happen to be much lower or higher than the level of maximum net productivity, when environmental variation is relatively high and serially correlated, and when the interval between estimation of population size is relatively long (> or = 5 years). To estimate demographic rates of songbirds involved in the Mexican trade we relied on published information and allometric relationships to develop probability distributions for key rates, and then sampled from those distributions to characterize the uncertainty in potential levels of take. Estimates of the intrinsic rate of growth (r) were highly variable, but median estimates were consistent with those expected for relatively short-lived, highly fecund species. Allowing for the possibility of nonlinear density dependence generally resulted in allowable levels of take that were lower than would have been the case under an assumption of linearity. Levels of take authorized by the Mexican government in 2010 for the 11 species we examined were small in comparison to relatively conservative allowable levels of take (i.e., those intended to achieve 50% of maximum sustainable yield). However, the actual levels of take in Mexico are unknown and almost certainly exceed the authorized take. Also, the take of Nearctic songbirds in other Latin American and Caribbean countries ultimately must be considered in assessing population-level impacts. 相似文献
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Prioritizing Pacific Salmon Stocks for Conservation 总被引:3,自引:1,他引:2
Fred W. Allendorf David Bayles Daniel L. Bottom Kenneth P. Currens Christopher A. Frissell David Hankin James A. Lichatowich Willa Nehlsen Patrick C. Trotter & Thomas H. Williams 《Conservation biology》1997,11(1):140-152
Over 300 native stocks of Pacific salmon, steelhead, and coastal cutthroat trout (Oncorhynchus spp.) are at risk of extinction in the Pacific Northwest. With only limited resources available for conservation and recovery, prioritization of these stocks may become necessary if meaningful measures are to be implemented. We propose criteria by which prioritization may be guided. First, we rank stocks for risk of extinction, either by population viability analysis or by a set of surrogate measures. Then we rank stocks for biological consequences of extinction, using sets of questions designed to establish the genetic and evolutionary consequences and the ecological consequences if a stock were to become extinct. Together, these rankings allow stocks to be prioritized for a range of possible actions, with those stocks at highest risk and bearing the greatest biological consequences of extinction receiving attention first. Application of the prioritization process to 20 Pacific anadromous salmonid stocks worked as intended, although data limitations are considerable. The process is most likely to work successfully when applied to many stocks on which data exist, when several experts carry out the prioritization, and when the results are peer reviewed. 相似文献