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251.
Julia Ohl Alexander Wezel Glenn H. Shepard Jr. Douglas W. Yu 《Environment, Development and Sustainability》2008,10(6):827-843
In this study, we investigate whether traditional swidden agriculture on nutrient-poor tropical soils can sustainably support
a growing indigenous population within Manu National Park, Peru. Based on interviews with 50 Matsigenka farmers, as well as
GPS mapping and field visits, we established the location and size of all 124 swidden gardens cultivated in 2000 and 2001.
Using a GIS-based soil map of Manu Park, we identify the total extent of potential arable land (1) throughout the park zones
currently available for Matsigenka habitation, and (2) within the vicinity of the two study communities. Taking into account
current per capita garden size, cultivation and fallow practices, we calculate the maximum human carrying capacity of swidden
agriculture for (1) all available park zones and (2) the immediate vicinity of the two current communities. Even given the
second, highly limited scenario, the sustainable human carrying capacity is estimated to be 2,138 individuals, which is far
higher than the current population of about 420 people. Thus, arable land does not appear to be a limiting factor for the
growth of the indigenous population in Manu Park at the current time. Other possible limiting factors for population growth
are identified and discussed. We conclude that a conservation policy of population stabilization around the current settlements
is viable in that it will not result in reduced resource availability over the next few decades, and that the challenge is
to identify and mitigate the forces causing population fissioning and spread.
Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
252.
Lorin A. Neuman-Lee Gareth R. Hopkins Edmund D. Brodie Jr. Susannah S. French 《Journal of environmental science and health. Part. B》2013,48(6):442-448
This study examined the effects of sub-lethal exposure of the ubiquitous pesticide malathion on the behavior of the model orthopteran species, the house cricket (Acheta domesticus). Increasing concentrations of malathion caused male crickets to increase periods of non-directional movement, such as twitching and grooming, directional movement, and to seek out shelter less. These are all behavioral alterations that may increase the cricket's chances of being preyed upon, and thus have the potential for serious ecological consequences through trophic transfer. This study also revealed that female crickets appeared to be less affected by malathion than their male conspecifics, indicating a potential sex-bias in both susceptibility and possible predator attack. 相似文献
253.
George R. Holdren Jr. Timothy C. Strickland Bernard J. Cosby David Marmorek David Bernard Robert Santore Charles T. Driscoll Linda Pardo Carolyn Hunsaker Robert S. Turner John Aber 《Environmental management》1993,17(3):355-363
The critical loads approach is emerging as an attractive means for evaluating the effects of atmospheric deposition on sensitive
terrestrial and aquatic ecosystems. Various approaches are available for modeling ecosystem responses to deposition and for
estimating critical load values. These approaches include empirical and statistical relationships, steady-state and simple
process models, and integrated-effects models. For any given ecosystem, the most technically sophisticated approach will not
necessarily be the most appropriate for all applications; identification of the most useful approach depends upon the degree
of accuracy needed and upon data and computational requirements, biogeochemical processes being modeled, approaches used for
representing model results on regional bases, and desired degree of spatial and temporal resolution. Different approaches
are characterized by different levels of uncertainty. If the limitations of individual approaches are known, the user can
determine whether an approach provides a reasonable basis for decision making. Several options, including point maps, grid
maps, and ecoregional maps, are available for presenting model results in a regional context. These are discussed using hypothetical
examples for choosing populations and damage limits.
The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared
at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental
Technology, Inc., and Interagency Agreement #1824-B014-A7 with the U.S. Department of Energy and at Oak Ridge National Laboratory
managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental
Sciences Division Publication No. 3904. It has been subjected to the agency’s peer and administrative review and approved
for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献
254.
Carolyn Hunsaker Robin Graham Robert S. Turner Paul L. Ringold George R. Holdren Jr. Timothy C. Strickland 《Environmental management》1993,17(3):335-341
The United States Environmental Protection Agency, with support from the US Department of Energy and the National Oceanographic
and Atmospheric Administration, has been evaluating the feasibility of an effects-based (critical loads) approach to atmospheric
pollutant regulation and abatement. The rationale used to develop three of the six steps in a flexible assessment framework
(Strickland and others, 1992) is presented along with a discussion of a variety of implementation approaches and their ramifications.
The rationale proposes that it is necessary to provide an explicit statement of the condition of the resource that is considered
valuable (assessment end point) because: (1) individual ecosystem components may be more or less sensitive to deposition,
(2) it is necessary to select indicators of ecosystem condition that can be objectively measured and that reflect changes
in the quality of the assessment end point, and (3) acceptable status (i.e., value of indicator and quality of assessment
end point at critical load) must be defined. The rationale also stresses the importance of defining the assessment regions
and subregions to improve the analysis and understanding of the indicator response to deposition. Subregional definition can
be based on a variety of criteria, including informed judgment or quantitative procedures. It also depends on the geographic
scale at which exposure and effects models are accurate and on data availability, resolution, and quality.
The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared
at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental
Technology, Inc., and Interagency Agreement #1824-B014-A7 with the US Department of Energy and at Oak Ridge National Laboratory
managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental
Sciences Division Publication No. 3903. It has been subjected to the agency’s peer and administrative review and approved
for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献
255.
Susan Power Bratton Raymond C. Mathews Jr. Peter S. White 《Environmental management》1980,4(5):433-448
Agricultural management in Cades Cove, an historic district in Great Smoky Mountains National Park, has affected natural resources both within the district and in the adjoining natural areas. Aquatic impacts of haying and cattle grazing included increases in water temperatures, turbidity, nutrient loading, and bacterial counts and decreases in benthic macroinvertebrate density and fish biomass. Wildlife populations, including groundhogs, wild turkeys, and white-tailed deer, have increased in the open fields and around the periphery of the historic district. Intensive deer foraging has removed deciduous seedlings and saplings from woodlots, lowering species diversity and favoring coniferous reproduction. Cades Cove has limestone habitats unique in the park, and both deer browse and cattle grazing may have disturbed populations of rare plant species. Effects on water quality are detectable at a campground 15 stream km from the agricultural area, and the effects of deer foraging extend about 1 km beyond the open fields.Since historic landscape preservation is presently a goal of the park, managing for open vistas in Cades Cove will require some sort of continuing disturbance. Conversion of cattle pastures to hayfields would reduce aquatic impacts but the deer herd might increase as a result of reduced competition for forage. Retarding old field succession would increase populations of native plant species dependent on sunlight, but would require government-funded mowing. Other options are discussed. Completely eliminating the effects of the historic district on adjoining areas may be impossible, at least under present economic constraints. 相似文献
256.
257.
A Delphi survey, the Dade Toxics Community Assessment, was used to develop a consensus between citizen and professional members of the Dade TOXICS Task Force, as a part of a public participation project in Dade County, Florida. The results showed an agreement between the two groups on the ranking of the five major problems to be studied by the task force. 相似文献
258.
Lawrence R. Klar Jr. Aldo Ghirin 《Journal of the American Water Resources Association》1983,19(3):477-481
The purpose of this study was to identify attitudes toward the recreational use of drinking water reservoirs in Massachusetts among municipal water supply managers in the state. Compared to the findings of recent studies assessing the attitudes of the general public, water officials were found to advocate highly restrictive views. No officials said that recreation was an insignificant source of water supply pollution; however, opinions were not found to be related to respondents' exposure to the literature on the topic. The majority were not, in fact, familiar with the literature assessing the impact of recreation on water supply reservoirs. 相似文献
259.
There is abundant evidence that many factors can influence the toxicity of a particular pollutant including environmental fluctuations, season of the year, stage in life cycle, size, and sex. All of these factors should be assessed before making a judgment of the effect on natural populations. Such an assessment can be conceptualized using a simple population model through whichcontrol gates operate as functions of 1). the direct self-maintainance feedback from existing adult population biomass and 2). the recruitment of new individuals due to the maturation of larvae. By extracting general principles of organismic response to pollutants it is possible to incorporate the information into large-scale ecosystem models which would serve as working tools for answering environmental decision-making problems. 相似文献
260.
ABSTRACT: A graphical procedure for classifying aquifer management strategy is proposed for use as a visual aid. The increasing demand for water, changes in the type of water uses and water sources, and economic consideration indicate that optimal strategies can shift over time. The procedure is described and, as an example, applied to the Tucson Basin. This procedure provides a simple visual tool for nonhydrologists, demonstrates the importance of water use and source interplay, and allows consideration of the time element in managing ground-water resources. 相似文献