Ecosystem Health最新文献

ABSTRACT

Ethics guidelines for professionals in the risk sciences are relatively recent. The need for accountability is recognized by many professionals, and has led to the development of ethics guidelines, anchored in organization-specific mission statements or sets of core values. Almost none of the professions’ existing codes reflect on broader social consequences such as concern for ecological integrity. The importance of this consideration was recently noted in The Toronto Resolution where ensuring ecological integrity was directly linked to professional conduct. Guidelines are useful and necessary for professional development and day-to-day functioning, but alone they are insufficient to ensure that professionals learn about ethics and how to apply the guidelines while simultaneously recognizing the broader social consequences of their professional pursuits. In the interests both of professional accountability, as well as concern for the seamless web upon which all life-support systems depend, each profession needs an ethics infrastructure. This paper provides a comprehensive organizational infrastructure, comprising a seven-step program—focusing more on process than on content—for the integration of ethics into professional life. A framework for action is developed, integrating several operationalizable process steps. Difficulties in raising professional awareness and introducing an ethics infrastructure are discussed in the context of epidemiology. Professional organization and consensus on core values are seen as laying the foundation for an ethics program. To implement a program, codifying professional conduct in the form of ethics guidelines, establishing consistent procedures and review processes, and establishing ethics education and training, are essential. Furthermore, introducing incentives to encourage ethical conduct, an ethics consultation service, and ongoing oversight and commitment, are critical components for success. Its process goals would include ongoing review, education, dissemination, and adherence to the professions’ core values, into which concern for issues beyond the narrow confines of professional pursuits would be integrated.

ABSTRACT

Landscape ecology is a field that has grown from realizing that maintenance of ecological resources requires management at several spatial and temporal scales, including landscape-level ecosystems as whole units of study and management. The subsequent need for characterizing landscape structure has led to a variety of measurements for assessing different aspects of spatial patterns; however, most of these measurements are known to depend on both the spatial extent of a specified landscape and the measurement grain. Therefore, measurements that incorporate a range of scales would be most informative. In response, this article introduces a new method for obtaining a multiresolution characterization of land cover fragmentation patterns within a fixed geographic extent. Our particular interest is in watershed-delineated extents. The method applies the concept of conditional entropy as one moves from larger “parent” land cover pixels to smaller “child” pixels that are heirarchically nested within the parent pixels. When applied over a range of resolutions, one obtains a “conditional entropy profile.” The conceptual and methodological development of conditional entropy profiles is presented, followed by current and future directions for evaluating and applying this methodology.

ABSTRACT

The incessant quest for economic growth has dominated human energies for centuries. However, the costs in terms of social and ecological disruption have seldom been taken into account. In consequence, the Earth’s ecosystems have been increasingly disabled. The root problem lies in archaic economic thinking that is completely divorced from natural process. This thinking entrains the notions of unlimited substitution for scarce resources, growth without limits, and the myth that nature’s services are in never-ending supply. If there is to be a viable future for humankind, this thinking must give way to the realization that the economic process has steadily undermined one of the most critical societal goals, namely, that of preserving the health and integrity of the earth’s ecosystems. If we are to find our way, economic development must be tempered by ecological and social realities.

ABSTRACT

Most ecosystems require periodic disturbances to maintain their integrity, and human modification of natural disturbance regimes (e.g. fire frequency) often leads to deleterious changes. Ponderosa pine (Pinus ponderosa P. & C. Lawson) forests in the western United States are selected as examples. They were maintained in an open, park-like condition because of frequent low-intensity disturbances: fires and/or pest outbreaks. Fires enhanced grass cover, helped to reduce the buildup of organic matter, eliminated weak trees, and controlled pests. Euro-American settlement changed this balance by allowing heavy livestock grazing, which caused damage to the grass cover and contributed to soil erosion and depletion of the nutrient pool. Later, the policy of fire suppression promoted the establishment of a greater density of ponderosa pine and understory thickets at the expense of the grasses and caused excessive accumulation of coarse organic matter. Productivity of the forest subsequently declined and the thickets stagnated. Today, even unlogged ponderosa pine forests exhibit profound signs of stress: slow production and growth, decreased rate of nutrient cycling, simplified vertical and horizontal structure, and increased extent of disease. Some ecosystem services, such as the provision of soil and water quality, high biodiversity, and aesthetic value, are impaired.

ABSTRACT

Ecosystem health is evaluated as an integrated assessment based on ecosystem stability, resilience, and vulnerability concepts. Special emphasis is focused on two dimensions in the ecosystem health concept: a geocentric approach (i.e., considering any impacts or interactions in terms of their effects on natural geosystems or ecosystems) which deals with assessment of natural ecosystems and their disturbance; and an anthropocentric approach, which concerns effects on human beings and human environment. Analysis of the relevant terminology leads to the development of a conceptual framework for ecosystem health. A suggested method of environmental risk assessment is based on ranking and merging into one criterion a series of individual estimates: bioresources abundance, biodiversity, ecosystem stability and resilience, and feedback effects of a disturbed environment on human beings and their activities.

Subsistence hunting for Cree of the western James Bay region of northern Ontario, Canada, is a way of life. In this study, it is shown that ∼15% of the radiographic charts examined had evidence of pellets contained in the gastrointestinal system, intraluminally, and/or in the appendix. It is assumed that the consumption of wildgame with lead shot embedded in the tissue was the source of the pellets. Because the presence of lead shot in the human gastrointestinal tract appears to increase the body burden of lead and considerable evidence is available on the occurrence of lead poisoning in waterfowl due to the ingestion of lead pellets,it is suggested that the use of lead shot should be discontinued nationwide in Canada. Although bismuth/tin shot has been growing in appeal because of several recent waterfowl studies demonstrating its nontoxic nature, caution is advised because of the uncertainty about the toxicity of bismuth in humans, especially when consumed as whole pellets or fragments in wildmeats. We maintain that the nontoxic alternative of choice at this time is steel shot.

ABSTRACT

Anthropogenic emissions of greenhouse gases are enhancing the natural greenhouse effect. It is almost universally accepted that this will lead to a warming of the earth’s surface. It is also accepted that this warming will lead to a spread of the insects that transmit several infections, currently restricted to the tropics, such as malaria, leishmaniasis, yellow fever, and dengue fever, among others. We calculated the expected increase in the density of female adult forms of anopheline mosquitoes by assuming temperature-dependent functions on the rates of the mosquitoes life cycles. Other mosquito characteristics, such as the feeding interval, were also calculated as functions of environmental temperature. The resultant increase in the density of adult females as a function of the increase in temperature was related to an increase in malaria risk by the calculations of the basic reproductive ratio and the vectorial capacity, which permitted the application of the mathematical model for malarial transmission.