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11.
John Loomis Vicki Rameker Andy Seidl 《Journal of Environmental Planning and Management》2004,47(1):83-96
A hedonic price function is estimated that illustrates how the price per acre of open space paid by public buyers such as counties or land trusts, is influenced by local demand and supply factors. The empirical regression model is illustrated using 133 public transactions (73% are purchases and 27% are easements) of open space in the Front Range of Colorado. The mean price per acre was $13 635. If a property provides access to water bodies, this feature increases the price per acre by $937, while adjacency of the parcel to existing park or open space adds $11 039 an acre. A 1% increase in county population results in a 0.27% increase in price per acre. Easements cost $6783 less than purchases, a sizeable cost saving. The prediction capability of the hedonic price equation may be an alternative to traditional real estate appraisal techniques when agencies must determine fair market values of prospective open space parcels that vary in attributes from existing ones. 相似文献
12.
Rachel Vallender Vicki L. Friesen Raleigh J. Robertson 《Behavioral ecology and sociobiology》2007,61(12):1797-1807
We examined two components of reproduction in a population of golden-winged warblers in the initial stages of hybridization
with blue-winged warblers. First, we used genetic analyses of mate choice to determine whether copulations outside the social
pairbond (extra-pair copulations; EPCs) occur in these species and their hybrids. Second, we compared several aspects of reproduction
(pairing success, clutch size, hatching success, fledging success, and loss of paternity) in nests raised by phenotypic golden-winged
warblers to those raised by hybrid individuals. Together, these data provide us with the first quantitative analysis of reproduction
within this hybrid system. Our data suggest several reasons why the level of hybridization between these species is likely
being underestimated. First, many birds in our population showed only subtle phenotypic signs of introgression indicating
that hybrid status can only be determined by close examination. Second, high rates of extra-pair paternity indicate that we
cannot base our estimates of hybridization on pairbond data alone. More than 30% of nestlings were the result of EPCs, occurring
in 55% of all nests. Third, there was no difference in the number of hybrid or “pure” golden-winged warbler males chosen as
social mates, relative to their abundance. Indeed, based on several components of nesting success, it appears as though hybrids
are having as great realized reproductive success as are phenotypic golden-winged warblers in our population. Accordingly,
we argue that hybrid reproductive success and extra-pair fertilizations are likely playing a major role in the ongoing hybridization
between blue-winged and golden-winged warblers. Studies such as this one are important to our understanding of the process
and implications of hybridization, and findings may be applicable to other hybrid zones. 相似文献
13.
Vicki J.Harriott 《Ambio-人类环境杂志》2003,32(2):130-133
引言 随着人们对世界珊瑚礁健康关注程度的日益提高[1],国际珊瑚贸易已被确定为是一件利益悠关的事[2,3].珊瑚和"活岩石"(即:由带有附着生物的死珊瑚构成的岩石或碎石)的商业性贸易被认为有可能造成珊瑚礁局部遭到破坏,包括侵蚀增加和重要生境的丧失[4,5]. 相似文献
14.
Watson A Glaspell B Christensen N Lachapelle P Sahanatien V Gertsch F 《Environmental management》2007,40(6):880-888
Many public land management agencies are committed to understanding and protecting recreation visitor experiences. Parks Canada
is deeply committed to that objective for visitors to Canada’s National Parks. This 2004 study, informed by a 2003 qualitative
study of visitor experiences and influences on those experiences at Auyuittuq National Park in Nunavut, worked to bring 50
potential elements of visitor experiences down to five articulated dimensions of the experience that is currently being received
at this remote eastern arctic park. A hypothesized set of 17 influences on experiences, also reduced to just two factors with
similar response patterns, and with some items that did not flow into the two factors, were used in a regression analysis
to understand the relationship between experiences and factors of influence. A sample of 61.8% (84) of the total recreation
visitor population 16 years of age or older was surveyed during deregistration after the trip. Knowledge about the dimensions
of the experiences currently received and factors of influence on those experiences can be used to guide selection of indicators
for describing objectives and prescribing monitoring protocol. 相似文献
15.
A cognitive‐affective stress propensity model was examined using field study data. Structural equation models analyses tested hypothesized and alternate models to determine their goodness‐of‐fit with the data. The results supported a direct relationship between stress propensity and strain, and an indirect, mediated relationship between stress propensity and strain through a subjective stress construct. In addition, stress propensity was found to moderate the relationships of experienced negative affect with somatic and with psychological strain, and with one of three measures of subjective stress. Implications of the results for research and practice are discussed. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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Christopher J. DeHeer Vicki L. Backus Joan M. Herbers 《Behavioral ecology and sociobiology》2001,49(5):375-386
Models of social evolution predict a strong relationship between ecological factors and sociogenetic organization in social insects (e.g. queen number, nestmate relatedness and population structure). Despite a large body of coherent theory, empirical support for these predictions is weak. Here we report the results of an experiment that manipulated two ecological parameters, food and nestsite availability, thought to be important for a population of the forest ant Myrmica punctiventris. Earlier work had shown that the sociogenetic structure varies between two populations of this species, and an ecological experiment in one of the populations (in Vermont) revealed that food supplementation had the strongest effects on nestmate relatedness. We repeated the experiment in the second population (in New York) and obtained strikingly different results. We show that nestsite supplementation had the strongest effect in the New York population, and that adding both food and nestsites affected nestmate relatedness in a direction opposite to that reported from the Vermont study. These results show that the ecological context is critically important for understanding the determinants of colony structure in ants. Furthermore, comparison of our data with that of a previous study shows that social organization in New York is temporally unstable. Thus, not only do ecological factors strongly influence social organization, but their influence can vary over time. Our study underscores the need for detailed information on the natural history and ecology of social species. 相似文献
18.
Problem
Falls from heights in residential construction are common, especially among inexperienced workers.Methods
We conducted a comprehensive needs assessment to determine gaps in the school-based apprentice carpenters' fall prevention training. A team of carpenter instructors and researchers revised the fall prevention training to fill these gaps. Apprentice evaluation and feedback guided ongoing curricular improvements.Results
Most apprentice carpenters performed work tasks at heights prior to training and fall protection techniques were not commonly used at residential construction sites. Priorities of the revised school-based training included safe ladder habits, truss setting, scaffold use, guarding floor openings, and using personal fall arrest systems. New apprentices were targeted to ensure training prior to exposure at the workplace. We used adult learning principles to emphasize hands-on experiences. A framed portion of a residential construction site was fabricated to practice fall protection behaviors in a realistic setting. The revised curriculum has been delivered consistently and apprentice feedback has been very favorable.Conclusions
Integration of needs assessment results was invaluable in revising the school-based carpenters apprentice fall prevention curriculum. Working closely with the instructors to tailor learning experiences has provided preliminary positive results.Impact on Industry
The fall safety of the residential construction industry continues to lag behind commercial construction and industrial settings. The National Occupational Research Agenda includes a Strategic Goal to strengthen and extend the reach of quality training and education in the construction industry via mechanisms such as construction safety and health training needs assessments. This study demonstrates how a structured process can be used to identify and remedy gaps and improve training effectiveness. We encourage others to take steps to assess and increase the impact of training efforts directed at all residential construction professionals; including both union and non-union workers. The implications are even greater in the non-union sector where most U.S. residential work is done. 相似文献19.
Michael W. Suplee Vicki Watson Walter K. Dodds Chris Shirley 《Journal of the American Water Resources Association》2012,48(5):1008-1021
Suplee, Michael W., Vicki Watson, Walter K. Dodds, and Chris Shirley, 2012. Response of Algal Biomass to Large‐Scale Nutrient Controls in the Clark Fork River, Montana, United States. Journal of the American Water Resources Association (JAWRA) 48(5): 1008‐1021. DOI: 10.1111/j.1752‐1688.2012.00666.x Abstract: Nutrient pollution is an ongoing concern in rivers. Although nutrient targets have been proposed for rivers, little is known about long‐term success of programs to decrease river nutrients and algal biomass. Twelve years of summer data (1998‐2009) collected along 383 km of the Clark Fork River were analyzed to ascertain whether a basin‐wide nutrient reduction program lowered ambient total nitrogen (TN) and total phosphorus (TP) concentrations, and bottom‐attached algal biomass. Target nutrient and algal biomass levels were established for the program in 1998. Significant declines were observed in TP but not TN along the entire river. Downstream of the city of Missoula, TP declined below a literature‐derived TP saturation breakpoint and met program targets after 2005; TN was below targets since 2007. Algal biomass also declined significantly below Missoula. Trends there likely relate to the city’s wastewater facility upgrades, despite its 20% population increase. Upstream of Missoula, nutrient reductions were less substantial; still, TP and TN declined toward saturation breakpoints, but no significant reductions in algal biomass occurred, and program targets were not met. The largest P‐load reduction to the river was from a basin‐wide phosphate laundry detergent ban set 10 years before, in 1989. We document that nutrient reductions in rivers can be successful in controlling algal biomass, but require achievement of concentrations below saturation and likely close to natural background. 相似文献
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