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131.
Vaughan H Whitelaw G Craig B Stewart C 《Environmental monitoring and assessment》2003,88(1-3):399-408
The paper describes the Ecological Monitoring and Assessment Network's (EMAN) operational and program response to certain challenges of environmental monitoring in Canada, in particular, efforts to improve the ability of the network to deliver relevant information to decision makers. In addition to its familiar roles, environmental monitoring should deliver feedback to society on environmental changes associated with development patterns, trends, processes and interventions. In order for such feedback to be effective, it must be relevant, timely, useful and accessible: all characteristics that are defined by the user, not the provider. Demand driven environmental monitoring is explored through EMAN's experiences with Canada's Biosphere Reserves, the NatureWatch Program and the Canadian Community Monitoring Network. 相似文献
132.
Connie Stewart Sara Iverson Christopher Field 《Environmental and Ecological Statistics》2014,21(4):775-792
Determining whether the diet of predators has changed is an important ecological problem and appropriate methodology is needed in order to test for differences or changes in diet. It is known that the fatty acid (FA) signature in a predator’s adipose tissue predictably reflects the prey consumed and that, consequently, a change in the FA signatures can be largely attributed to changes in the predator’s diet composition. The use of FA signatures as a means of detecting change in diet presents some statistical challenges however, since the FA signatures are compositional and sample sizes relative to the dimension of a signature are often small due to biological constraints. Furthermore, the FA signatures often contain zeros precluding the direct use of traditional compositional data analysis methods. In this paper, we provide the methodology to carry out valid statistical tests for detecting changes in FA signatures and we illustrate both independent and paired cases using simulation studies and real life seabird and seal data. We conclude that the statistical challenges using FA data are overcome through the use of nonparametric tests applied to the multivariate setting with suitable test statistics capable of handling the zeros that are present in the data. 相似文献
133.
Exploring alternative states in ecological systems with a qualitative analysis of community feedback
Martin P. Marzloff Jeffrey M. Dambacher Stewart D. Frusher 《Ecological modelling》2011,222(15):2651-2662
Demonstrating and predicting the existence of alternative states in natural communities remains a challenge for ecologists and is essential for resource managers. Positive feedback is often presented as central in maintaining alternative ecosystem states, but no formal approach relates this part of theory to real world applications. Through qualitative modelling of community response to long-term perturbations, we define generic mechanistic links between positive feedback and the occurrence of alternative states. Positive feedback diminishes a system's overall resistance to change, and can create and maintain correlations in the relative abundance of variables that coincide with alternative states.Through specific models of the dynamics of Tasmanian rocky-reef communities, which are affected by climate and fishing and persist within alternative states, we demonstrate the ability of our theoretical framework to predict alternative states in ecosystems and inform management intervention. A qualitative knowledge of community structure permits a thorough analysis of system feedback and an assessment of the potential for an ecosystem to exhibit alternative states. We illustrate the usefulness of the approach to inform management priorities, and to focus monitoring and field research on the key drivers of ecosystem dynamics. 相似文献
134.
Nadine A. Amlin Stewart B. Rood 《Journal of the American Water Resources Association》2001,37(6):1709-1720
ABSTRACT: Throughout western North America, willows and cottonwoods are dominant woody plants in riparian zones, streamside areas that are periodically flooded. This study compared tolerances of willows‐Salix discolor, S. exigua, and S. lutea‐and cottonwoods‐Populus angustifolia, P balsamifera, and P deltoides‐to water inundation, one component of stream flooding. Rooted cuttings were grown for 152 days in 10 cm tall pots in water depths from 2.5 to 10 cm (inundated). Shoot and root elongation growth of the inundated cottonwoods were reduced 23 and 45 percent, while S. lutea was relatively unaffected and the inundated sandbar willow, S. exigua, displayed 72 and 43 percent increases in shoot and root elongation. The inundation reduced transpiration in P deltoides and for mature P balsamifera trees that were flooded by a small reservoir on Willow Creek, Alberta. Those flooded trees died in their second year of inundation. The greater inundation tolerance of willows versus cottonwoods is consistent with observations along Midvale Creek, Montana, where beaver dams created a pond in which P trichocarpa died while willows thrived after five years. These patterns of inundation tolerance are consistent with elevational zones of occurrence as willows‐and particularly the sandbar willow—occur at low elevations close to the stream. The understanding of inundation tolerances should assist in the provision of hydrologic patterns that will conserve and restore these shrubs and trees along streams and could permit their establishment along artificial reservoirs. 相似文献
135.
Stacy A. Lischka Tara L. Teel Heather E. Johnson Courtney Larson Stewart Breck Kevin Crooks 《Conservation biology》2020,34(6):1383-1392
Conflicts between people and wild animals are increasing globally, often with serious consequences for both. Local regulations or ordinances are frequently used to promote human behaviors that minimize these conflicts (risk-reducing behaviors), but compliance with ordinances can be highly variable. While efforts to increase compliance could be improved through applications of conservation psychology, little is known about the relative influence of different factors motivating compliance. Using concepts from psychology and risk theory, we conducted a longitudinal study pairing data from mail surveys with direct observations of compliance with a wildlife ordinance requiring residents to secure residential garbage from black bears (Ursus americanus). We assessed the relative influence of beliefs and attitudes toward bears and bear proofing, perceived behavioral control, perceived risks and benefits assigned to bears, norms, trust in management, previous experience with conflicts, and demographics on compliance behavior (i.e., bear proofing). Data on previous experience were obtained through direct observation and survey reports. We found that higher compliance rates were associated with more observed conflicts on a respondent's block. Counter to expectations, however, residents were less compliant when they were more trusting of the management agency and perceived more benefits from bears. We suggest that messages have the potential to increase compliance when they empower residents by linking successful management of conflicts to individual actions and emphasize how reducing conflicts could maintain benefits provided by wildlife. Modifying existing educational materials to account for these psychological considerations and evaluating their impact on compliance behavior over time are important next steps in changing human behaviors relevant to the globally important problem of human-wildlife conflict. 相似文献
136.
Sarah L. M. Stewart David F. Westneat Gary Ritchison 《Behavioral ecology and sociobiology》2010,64(3):463-473
The causes of variation in rates of extra-pair paternity among avian populations remain unclear, but could include environmental
factors such as breeding density and synchrony. By experimentally manipulating nest site availability, we tested the effects
of breeding density on the frequency of extra-pair paternity in eastern bluebirds (Sialia sialis). We also examined the role of breeding synchrony on extra-pair paternity using natural timing of nests. Microsatellite analysis
revealed 34 of 305 nestlings (11.2%) were the result of extra-pair fertilizations; and 21 of 79 broods (26.6%) had at least
one extra-pair nestling. Several measures of breeding density had independent effects on extra-pair paternity. First, experimental
plot type affected extra-pair paternity, with 28 of 34 (82.4%) extra-pair young from nests in high density areas, and only
six (17.6%) from nests in low density areas. Independently of plot type, the number of breeding neighbors within a 320-m radius
was a significant predictor of the likelihood of extra-pair paternity at the nest. Extra-pair paternity was associated with
temporal factors such as absolute timing of breeding and natural levels of local breeding synchrony, but only in bivariate
comparisons. We found a positive interaction between density of neighbors within a 320-m radius and local breeding synchrony;
this term reduced the main effects of synchrony and number of neighbors, but not experimental treatment. Our results demonstrate
the importance of utilizing multiple aspects of proximity in breeding density analyses and testing for interactions between
ecological factors that can influence the behavioral events leading to extra-pair fertilizations. 相似文献
137.
This paper explores the promotion of environmentally sustainable travel and the ways in which individual citizens engage with exhortations to adopt environmentally responsible travel modes. In local contexts, the arguments for promoting modal shifts have focused on issues like congestion, noise reduction and the improvement of local environmental quality. However, in recent years, concerns about global climate change have reframed the promotion of sustainable travel around carbon emissions reductions and more fundamental changes to lifestyle choices as a way of combating climate change. Within this context, this paper considers the ways in which individuals frame sustainable travel through using focus group data collected as part of a wider research project on travel behaviour in the UK. The paper will demonstrate that notions of “sustainable” travel are still largely dominated by localised environmental concerns that have resonances with the everyday experiences and practices of individuals, with many of the factors underlying established discourses of travel behaviour being focused on pragmatic issues like convenience and cost. In contrast, the issue of climate change presents a number of challenges for policy-makers seeking to change behaviour because of the contestations surrounding climate science, political leadership and the perceived role of individual consumers in tackling climate change. 相似文献
138.
139.
Biodegradation half-lives are needed for many applications in chemical screening, but these data are not available for most chemicals. To address this, in phase one of this work we correlated the much more abundant ready and inherent biodegradation test data with measured half-lives for water and soil. In phase two, we explored the utility of the BIOWIN™ models (in EPI Suite™) and molecular fragments for predicting half-lives. BIOWIN™ model output was correlated directly with measured half-lives, and new models were developed by re-regressing the BIOWIN™ fragments against the half-lives. All of these approaches gave the best results when used for binary (fast/slow) classification of half-lives, with accuracy generally in the 70–80% range. In the last phase, we used the collected half-life data to examine the default half-lives assigned by EPI Suite™ and the PBT Profiler™ for use as input to their level III multimedia models. It is concluded that estimated half-lives should not be used for purposes other than binning or prioritizing chemicals unless accuracy improves significantly. 相似文献
140.
Recent federal policy proposals to reduce emissions of sulfur dioxide (SO(2)), nitrogen oxides (NO(x)), and mercury from the US electricity sector promise important improvements in air quality and reductions in acid deposition. The cost of achieving these reductions depends on the form and stringency of the regulation. In this research, we analyze the economic benefits and costs of the US Environmental Protection Agency's (EPA's) Clean Air Interstate Rule (CAIR) as characterized in the supplemental rule proposed in June 2004, and the Clean Air Mercury Rule (CAMR) as proposed in February 2004. The assessment integrates a model of the electricity sector, two models of atmospheric transport of air pollutants, and a model of environmental and public health endpoints affected by pollution. We model explicitly the emissions of SO(2), NO(x), mercury and carbon dioxide (CO(2)) and the effects of changes in emissions of SO(2) and NO(x) on environmental and public health. The manner in which mercury emissions are regulated will have important implications not only for the cost of the regulation, but also for emission levels for SO(2) and NO(x) and where those emissions are located. We find the economic benefits of CAIR and CAMR are far greater than the costs. Recent estimates of benefits of reductions in mercury and acidification indicate that our model captures the lion's share of quantifiable benefits. We also find that the EPA would have been justified on economic grounds in pursuing additional SO(2) emissions reductions beyond the requirements of CAIR. 相似文献