Certain terms and expressions that relate to the environment are problematic in that they vary widely in usage within and between disciplines, and several have been used as synonyms. In an attempt to correct the problem and standardize usage, this paper defines or redefines 10 of the most common environmental terms. Two of these terms, natural environment and environmental change, are defined on the basis of what is meant by natural as reflected by common usage and dictionary entries. The three degradation terms, environmental degradation, land degradation, and soil degradation, are defined as any change or disturbance to the environment, land, or soil perceived to be deleterious or undesirable. A sixth term, soil regeneration, is defined as the reformation of degraded soil through biological, chemical, and/or physical agencies. The remaining four terms, environmental quality, air quality, soil quality, and water quality, are defined as measures of the condition or state of each relative to the requirements of one or more biotic species and/or to any human need or purpose.
Animal disease outbreaks impose significant economic costs that evolve over space and time, but few studies have explicitly modeled their temporal and spatial impacts. Using an integrated epidemiological-economic model, this article demonstrates a methodology that captures the dynamic and spatial effects of animal disease. The model is applied to foot-and-mouth disease in the Southern Cone of South America. The results demonstrate the benefits of spatially sensitive policies in which certain regions within the Southern Cone employ different, coordinated interventions. Further, they highlight policy relevant differences between the dominant short-run and long-run control options. Copyright 2007, Oxford University Press.
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