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Cumulative Impacts (cumulative + impact)

Distribution by Scientific Domains

Life Sciences	27%
Business, Economics, Finance and Accounting	18%

Selected Abstracts

LANDSCAPE-SCALE ANALYSIS AND MANAGEMENT OF CUMULATIVE IMPACTS TO RIPARIAN ECOSYSTEMS: PAST, PRESENT, AND FUTURE,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2001
Eric D. Stein
ABSTRACT: Analyses of cumulative impacts to riparian systems is an important yet elusive goal. Previous analyses have focused on comparing the number of hectares impacted to the number of hectares restored, without addressing the loss of riparian function or the effect of the spatial distribution of impacts. This paper presents an analysis of the spatial distribution of development-related impacts to riparian ecosystems, that were authorized under Section 404 of the Clean Water Act. Impacts on habitat structure, contiguity, and landscape context were evaluated using functional indices scaled to regional reference sites. Impact sites were mapped using GIS and analyzed for spatial associations. Positive spatial autocorrelation (i.e. clustering of impact sites) resulted from the piecemeal approach to impact assessment, which failed to prevent cumulative impacts. Numerous small projects in close proximity have resulted in adverse impacts to entire stream reaches or have fragmented the aquatic resources to a point where overall functional capacity is impaired. Additionally, the ecological functions of unaffected areas have been diminished due to their proximity to degraded areas. A proactive approach to managing cumulative impacts is currently being used in Orange County, California as part of a Corps of Engineers sponsored Special Area Management Plan (SAMP). The SAMP process is evaluating the ecological conditions and physical processes of the study watersheds and attempting to plan future development in a manner that will guard against cumulative impacts. [source]

MULTISCALE INFLUENCES ON PHYSICAL AND CHEMICAL STREAM CONDITIONS ACROSS BLUE RIDGE LANDSCAPES,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2002
Mark C. Scott
ABSTRACT: Streams integrate biogeochemical processes operating at broad to local spatial scales and long term to short term time scales. Humans have extensively altered those processes in North America, with serious consequences for aquatic ecosystems. We collected data on Upper Tennessee River tributaries in North Carolina to: (1) compare landuse and landscape geomorphology with respect to their ability to explain variation in water quality, sedimentation measures, and large woody debris; (2) determine if landscape change over time contributed significantly to explaining present stream conditions; and (3) assess the importance of spatial scale in examining landuse influences on streams. Stream variables were related to both landuse and landscape geomorphology. Forest cover accounted for the most variation in nearly all models, supporting predictions of nutrient enrichment, thermal pollution, and sedimentation caused by landscape disturbance. Legacy effects from past catchment disturbance were apparent in sedimentation measures. Nitrogen and phosphorus concentrations, as well as stream temperature, were lower where riparian buffers had reforested. Models of stream physicochemistry fit better when predictors were catchment wide rather than more localized (i.e., within 2 km of a site). Cumulative impacts to streams due to changes in landuse must be managed from a watershed perspective with quantitative models that integrate across scales. [source]

THE IMPACT OF PRICES AND CONTROL POLICIES ON CIGARETTE SMOKING AMONG COLLEGE STUDENTS

CONTEMPORARY ECONOMIC POLICY, Issue 2 2001
C Czart
Smoking among youths and young adults rose throughout the 1990s. Numerous policies were enacted to try to reverse this trend. However, little is known about the impact these policies have on the smoking behavior of young adults. This article uses a dichotomous indicator of daily smoking participation in the past 30 days, an ordered measure representing the frequency of cigarette consumption, and a quasi-continuous measure of the number of cigarettes smoked per day on average to examine the impact of cigarette prices, clean indoor air laws, and campus-level smoking policies on the smoking behaviors of a 1997 cross section of college students. The results of the analysis indicate that higher cigarette prices are associated with lower smoking participation and lower levels of use among college student smokers. Local- and state-level clean indoor air restrictions have a cumulative impact on the level of smoking by current smokers. Complete smoking bans on college campuses are associated with lower levels of smoking among current smokers but have no significant impact on smoking participation. Bans on cigarette advertising on campus as well as bans on the sale of cigarettes on campus have no significant effect on the smoking behavior of college students. [source]

The impact of elephants on the marula tree Sclerocarya birrea

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2002
Michelle E. Gadd
Abstract This study determined the abundance, density and population structure of the marula tree, Sclerocarya birrea, in three game reserves in South Africa, and assessed patterns and amounts of new and cumulative impact of elephants. Elephant feeding was very patchy so several attributes of individual trees, sampled transects and communities that might influence elephant herbivory were investigated. The incidence and type of elephant impact (bark, branch or stem breakage) were significantly related to tree diameter, but not to fruiting nor proximity to roads. At the transect level, elephant impact was influenced by density of marula trees, but was not influenced by proximity to roads, nor proportion of marula trees bearing fruits in the vicinity. At the community level, elephant impact was higher on reserves with higher total marula densities. Fourfold differences in elephant densities (0.08,0.30 elephants km,2) did not explain marula consumption: the percentage of trees with branch damage was similar across reserves and bark damage was inversely proportional to elephant density. Variation across reserves may reflect local and landscape-level marula tree abundance, differences in alternative food plants and individual feeding habits. The recorded levels of impact appeared to be sustainable because mortality rates were low, affected trees often recovered, and small trees were not preferentially preyed upon. Résumé Cette étude détermine l'abondance, la densité et la structure de la population de l'arbre à Marula, Sclerocarya birrea, dans trois réserves de faune sud-africaines et évalue le schéma et la totalité des impacts nouveaux et successifs des éléphants. Les éléphants se nourrissaient çà et là, de sorte que l'on a étudié divers attributs des arbres pris individuellement, des transects échantillons et des communautés, qui pouvaient influencer le caractère herbivore des éléphants. L'incidence et le type d'impact (écorces, branches ou jeunes pousses) étaient significativement liés au diamètre de l'arbre, mais non à la fructification, ni à la proximité des routes. Au niveau du transect, l'impact des éléphants était influencé par la densité des arbres à Marula, mais pas par la proximité des routes, ni par la proportion d'arbres à Marula en fruits dans le voisinage. Au niveau de la communauté, l'impact des éléphants était plus élevé dans les réserves qui comptaient la plus forte densité totale d'arbres à Marula. Une différence de 1 à 4 dans la densité des éléphants (0.08-0.30/km2) n'explique pas la consommation de marula : le pourcentage d'arbres présentant des branches endommagées était similaire dans toutes les réserves, et les dommages causés aux écorces étaient inversement proportionnels à la densité des éléphants. La variation observée entre les réserves pourrait refléter l'abondance des arbres à Marula tant locale que liée au paysage, des différences dans l'abondance de nourriture végétale alternative et les habitudes alimentaires individuelles. L'importance de l'impact relevé semblait être soutenable parce que le taux de mortalitéétait faible, que les arbres touchés récupéraient souvent et que les petits arbres n'avaient pas souvent la préférence des éléphants. [source]

Social Environments and Physical Aggression Among 21,107 Students in the United States and Canada

JOURNAL OF SCHOOL HEALTH, Issue 4 2009
William Pickett PhD
ABSTRACT Background:, Physical aggression is an important issue in North American populations. The importance of students' social environments in the occurrence of physical aggression requires focused study. In this study, reports of physical aggression were examined in relation to social environment factors among national samples of students from Canada and the United States. Methods:, Students in grades 6-10 from the United States (n = 14,049) and Canada (n = 7058) who had participated in the Health Behaviour in School-aged Children Survey (HBSC) were studied. Rates of students' physical aggression were compared between the 2 countries. School, family, socioeconomic, and peer-related factors were considered as potential risk factors. A simple social environment risk score was developed using the US data and was subsequently tested in the Canadian sample. Results:, Risks for physical aggression were consistently higher among United States versus Canadian students, but the magnitude of these differences was modest. The relative odds of physical aggression increased with reported environmental risk. To illustrate, US boys in grades 6-8 reporting the highest social environment risk score (5+) experienced a relative odds of physical aggression 4.02 (95% CI 2.7-5.9) times higher than those reporting the lowest score (adjusted OR for risk scores 0 through 5+ was 1.00, 1.19, 2.10, 2.01, 3.71, and 4.02, respectively, ptrend < .001). Conclusions:, Unexpectedly, rates of physical aggression and associations between social environments and students' aggression were remarkably similar in Canada and the United States. Family, peer, and school social environments serve as risk or protective factors, with significant cumulative impact on physical aggression in both countries. Given the observed high rates and the many negative effects of aggression on long-term health, school policies aimed at the reduction of such behavior remain a clear priority. [source]

Costs and Risks of Segregating GM Wheat in Canada

CANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2006
William W. Wilson
An analytical model was developed to explore prospective costs and risks of alternative testing strategies for a marketing system in Canada which markets both genetically modified (GM) and Non-GM wheats. The problem is solved using stochastic optimization, base case results are defined, and sensitivities conducted to evaluate impacts of selected variables. Added costs include: testing, rejection, and a risk premium which is required for handlers to be indifferent between the current and the proposed dual system. Protocols would require testing at the point of loading at the primary elevator, and export elevator, and supplementing this information with some form of grower variety declaration. There are several sources of inherent risks in such a system. For buyers, the cumulative impact of these is the risk of receiving GM content in a Non-GM shipment. For sellers, it is the risk of having a Non-GM shipment rejected. For sellers, the risk of rejection was typically less than 2%, and for buyers, the risk was typically less than 0.02%. Nous avons élaboré un modèle analytique pour explorer les coûts et les risques potentiels de la mise en place de nouvelles stratégies pour analyser le grain si le Canada décidait de commercialiser du blé génétiquement modifié (GM) et du blé non génétiquement modifié (NGM). Le problème est résolu à l'aide d'une optimisation stochastique; des scénarios de référence sont définis et des tests de sensitivité sont effectués pour évaluer l'impact de variables sélectionnées. Les coûts supplémentaires comprennent les coûts d'analyses, les coûts liés au rejet ainsi qu'une prime de risque exigée pour que les manutentionnaires demeurent indifférents entre le système actuel et le système double proposé. Les protocoles obligeraient la tenue d'analyses au point de chargement du silo primaire ainsi qu'au silo terminal, auxquelles s'ajouterait une certaine forme de déclaration du céréaliculteur sur la variété. Ce genre de système comporte plusieurs sources de risques inhérents. Pour les acheteurs, l'impact cumulatif est le risque de recevoir un chargement de blé NGM contenant du blé GM. Pour les vendeurs, c'est le risque qu'un chargement de blé NGM soit rejeté. Pour les vendeurs, le risque de rejet était généralement inférieur à 2%, et pour les acheteurs, le risque était généralement inférieur à 0.02%. [source]

Evaluating the physiological and physical consequences of capture on post-release survivorship in large pelagic fishes

FISHERIES MANAGEMENT & ECOLOGY, Issue 2 2007
G. B. SKOMAL
Abstract, Sharks, tunas and billfishes are fished extensively throughout the world. Domestic and international management measures (quotas, minimum sizes, bag limits) mandate release of a large, yet poorly quantified, number of these fishes annually. Post-release survivorship is difficult to evaluate, because standard methods are not applicable to large oceanic fishes. This paper presents information on the current approaches to characterising capture stress and survivorship in sharks, tunas and marlins. To assess mortality associated with capture stress, researchers must examine the cumulative impacts of physical trauma and physiological stress. Physical trauma, manifested as external and internal tissue and organ damage, is caused by fishing gear and handling. Gross examination and histopathological sampling have been used to assess physical trauma and to infer post-release survivorship. Exhaustive anaerobic muscular activity and time out of water cause physiological stress, which has been quantified in these fishes through the analyses of blood chemistry. Conventional, acoustic and archival tagging have been used to assess post-release survivorship in these species. Future studies relating capture stress and post-release survivorship could yield information that helps fishermen increase survivorship when practicing catch and release. [source]

Variegated neoliberalization: geographies, modalities, pathways

GLOBAL NETWORKS, Issue 2 2010
NEIL BRENNER
Abstract Across the broad field of heterodox political economy, ,neoliberalism' appears to have become a rascal concept , promiscuously pervasive, yet inconsistently defined, empirically imprecise and frequently contested. Controversies regarding its precise meaning are more than merely semantic. They generally flow from underlying disagreements regarding the sources, expressions and implications of contemporary regulatory transformations. In this article, we consider the handling of ,neoliberalism' within three influential strands of heterodox political economy , the varieties of capitalism approach; historical materialist international political economy; and governmentality approaches. While each of these research traditions sheds light on contemporary processes of market-oriented regulatory restructuring, we argue that each also underplays and/or misreads the systemically uneven, or ,variegated', character of these processes. Enabled by a critical interrogation of how each approach interprets the geographies, modalities and pathways of neoliberalization processes, we argue that the problematic of variegation must be central to any adequate account of marketized forms of regulatory restructuring and their alternatives under post-1970s capitalism. Our approach emphasizes the cumulative impacts of successive ,waves' of neoliberalization upon uneven institutional landscapes, in particular: (a) their establishment of interconnected, mutually recursive policy relays within an increasingly transnational field of market-oriented regulatory transfer; and (b) their infiltration and reworking of the geoinstitutional frameworks, or ,rule regimes', within which regulatory experimentation unfolds. This mode of analysis has significant implications for interpreting the current global economic crisis. [source]

Information needs to support environmental impact assessment of the effects of European marine offshore wind farms on birds

IBIS, Issue 2006
A.D. FOX
European legislation requires Strategic Environmental Assessments (SEAs) of national offshore wind farm (OWF) programmes and Environmental Impact Assessments (EIAs) for individual projects likely to affect birds. SEAs require extensive mapping of waterbird densities to define breeding and feeding areas of importance and sensitivity. Use of extensive large scale weather, military, and air traffic control surveillance radar is recommended, to define areas, routes and behaviour of migrating birds, and to determine avian migration corridors in three dimensions. EIAs for individual OWFs should define the key avian species present; as well as assess the hazards presented to birds in terms of avoidance behaviour, habitat change and collision risk. Such measures, however, are less helpful in assessing cumulative impacts. Using aerial survey, physical habitat loss, modification, or gain and effective habitat loss through avoidance behaviour can be measured using bird densities as a proxy measure of habitat availability. The energetic consequences of avoidance responses and habitat change should be modelled to estimate fitness costs and predict impacts at the population level. Our present ability to model collision risk remains poor due to lack of data on species-specific avoidance responses. There is therefore an urgent need to gather data on avoidance responses; energetic consequences of habitat modification and avoidance flights and demographic sensitivity of key species, most affected by OWFs. This analysis stresses the importance of common data collection protocols, sharing of information and experience, and accessibility of results at the international level to better improve our predictive abilities. [source]

LANDSCAPE-SCALE ANALYSIS AND MANAGEMENT OF CUMULATIVE IMPACTS TO RIPARIAN ECOSYSTEMS: PAST, PRESENT, AND FUTURE,

Composite estimates of physiological stress, age, and diabetes in American Samoans

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2007
Douglas E. Crews
Abstract Composite estimates of physiological stress such as allostatic load (AL) were developed to help assess cumulative impacts of psychosocial and physical stressors on the body. Physiological responses to stress generally accelerate somatic wear-and-tear and chronic degenerative conditions (CDCs). Following McEwen (Neuropsychopharmacology 22 (1999) 108,124) and others, primary physiological mediators of somatic stress responses include glucocorticoids (cortisol), catecholamines (adrenaline and noradrenaline), and serum dihydroepiandosterone-sulfate (DHEA-S). Conversely, blood pressure (BP), serum HDL and total cholesterol, glycated hemoglobin (HbA1c), and waist/hip (w/h) ratio are modulated by such hormones, thereby acting as secondary mediators of stress response. When these risk factors are aggregated into a composite score, higher stress loads are associated with increased risks for days of school/work missed, functional losses, morbidity, and mortality in US samples. To examine stress loads in American Samoans, data on all 6 secondary mediators along with estimates of body habitus (i.e. height, weight, circumferences, skinfolds) and physiology (i.e. fasting insulin, LDLc, triglycerides, fasting glucose) were measured on 273 individuals residing on Tutuila Island in 1992. Four combinations of these physiological factors were used to determine composite estimates of stress. These were then assessed by sex for associations with age and the presence of diabetes. Composite estimates of stress load were higher in Samoan women than men. Associations with age tended to be low and negative in men, but positive in women, appearing to reflect cultural circumstances and population history. Stress load scores also were higher among those with diabetes than those without among both men and women. These results suggest that composite estimates of stress may be useful for assessing future risks of CDC's and the senescent processes that may underlie them in cross-cultural research. Am J Phys Anthropol, 2007. © 2007 Wiley-Liss, Inc. [source]