|
|
|
| Registros recuperados: 6.820 | |
|
| |
|
|
| Lee, Kai N; Williams College; Kai.N.Lee@williams.edu. |
| Adaptive management is appraised as a policy implementation approach by examining its conceptual, technical, equity, and practical strengths and limitations. Three conclusions are drawn: (1) Adaptive management has been more influential, so far, as an idea than as a practical means of gaining insight into the behavior of ecosystems utilized and inhabited by humans. (2) Adaptive management should be used only after disputing parties have agreed to an agenda of questions to be answered using the adaptive approach; this is not how the approach has been used. (3) Efficient, effective social learning, of the kind facilitated by adaptive management, is likely to be of strategic importance in governing ecosystems as humanity searches for a sustainable economy. |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adaptive management; Conservation biology; Ecosystem management; Sustainability transition; Sustainable development. |
| Ano: 1999 |
|
| |
|
|
| Johnson, Fred; U.S. Fish and Wildlife Service; fred_a_johnson@fws.gov; Williams, Ken; ; byron_ken_williams@nbs.gov. |
| Waterfowl harvest management in North America, for all its success, historically has had several shortcomings, including a lack of well-defined objectives, a failure to account for uncertain management outcomes, and inefficient use of harvest regulations to understand the effects of management. To address these and other concerns, the U.S. Fish and Wildlife Service began implementation of adaptive harvest management in 1995. Harvest policies are now developed using a Markov decision process in which there is an explicit accounting for uncontrolled environmental variation, partial controllability of harvest, and structural uncertainty in waterfowl population dynamics. Current policies are passively adaptive, in the sense that any reduction in structural... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adaptive management; Harvest; Hunting regulations; Markov decision process; Migratory birds; Optimization; Uncertainty; Waterfowl.. |
| Ano: 1999 |
|
| |
|
| |
|
| |
|
|
| The diversity, expressed as species richness in equal-sized samples, of wood-living beetles in successional stages of deciduous forest after forest fires approximately 100 years ago did not differ between patch sizes in this study. Thus, the crucial question for conservation is whether the lack of reduction in diversity in small patches means that a number of small patches can elevate the regional diversity as efficiently as can one larger area. In the present study, the smaller patches did not differ from larger patches in substrate availability, quality, or heterogeneity. The frequency of a group of species was measured as the number of occurrences, viz. the number of trees on which a species was found, summed over all species in the group. The number of... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Alpha (local) diversity; Beta (between-habitats) diversity; Deciduous forest; Disturbance; Diversity; Fire; Gamma (regional) diversity; Invasion; Matrix habitat; Patch size; Species-richness.. |
| Ano: 1999 |
|
| |
|
|
| Carpenter, Stephen R; University of Wisconsin-Madison; srcarpen@wisc.edu; Brock, William; University of Wisconsin; brock@macc.wisc.edu; Hanson, Paul; University of Wisconsin; pchanson@facstaff.wisc.edu. |
| Simulation models were developed to explore and illustrate dynamics of socioecological systems. The ecosystem is a lake subject to phosphorus pollution. Phosphorus flows from agriculture to upland soils, to surface waters, where it cycles between water and sediments. The ecosystem is multistable, and moves among domains of attraction depending on the history of pollutant inputs. The alternative states yield different economic benefits. Agents form expectations about ecosystem dynamics, markets, and/or the actions of managers, and choose levels of pollutant inputs accordingly. Agents have heterogeneous beliefs and/or access to information. Their aggregate behavior determines the total rate of pollutant input. As the ecosystem changes, agents update their... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adaptive agent models; Adaptive management; Bounded rationality; Ecological economics; Ecosystem oscillations; Integrated models; Lake eutrophication; Nonpoint pollution; Phosphorus cycles; Simulation models; Social-natural systems.. |
| Ano: 1999 |
|
| |
|
| |
|
| |
|
|
| Gordon, Line; Stockholm University; line@system.ecology.su.se; Folke, Carl; Stockholm University; calle@system.ecology.su.se; Falkenmark, Malin; Swedish Natural Science Research Council;; Engwall, Maria; ;. |
| Global freshwater assessments have not addressed the linkages among water vapor flows, agricultural food production, and terrestrial ecosystem services. We perform the first bottom-up estimate of continental water vapor flows, subdivided into the major terrestrial biomes, and arrive at a total continental water vapor flow of 70,000 km3/yr (ranging from 56,000 to 84,000 km3/yr). Of this flow, 90% is attributed to forests, including woodlands (40,000 km3/yr), wetlands (1400 km3/yr), grasslands (15,100 km3/yr), and croplands (6800 km3/yr). These terrestrial biomes sustain society with essential welfare-supporting ecosystem services, including food production. By analyzing the freshwater requirements of an increasing demand for food in the year 2025, we... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Catchment management; Ecohydrological landscape; Evapotranspiration; Food production; Freshwater management; Global freshwater assessment; Resilience; Terrestrial ecosystem services; Trade-offs; Water use efficiency; Water vapor flows.. |
| Ano: 1999 |
|
| |
|
|
| Dunham, Jason; University of Nevada-Reno; jdunham@proaxis.com; Peacock, Mary; University of Nevada-Reno; mpeacock@scs.unr.edu; Tracy, C. Richard; University of Nevada-Reno; dtracy@unr.edu; Nielsen, Jennifer; Stanford University; jnielsen@leland.stanford.edu; Vinyard, Gary; University of Nevada-Reno; gvinyard@med.unr.edu. |
| Risks of population extinction have been estimated using a variety of methods incorporating information from different spatial and temporal scales. We briefly consider how several broad classes of extinction risk assessments, including population viability analysis, incidence functions, and ranking methods integrate information on different temporal and spatial scales. In many circumstances, data from surveys of neutral genetic variability within, and among, populations can provide information useful for assessing extinction risk. Patterns of genetic variability resulting from past and present ecological and demographic events, can indicate risks of extinction that are otherwise difficult to infer from ecological and demographic analyses alone. We provide... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Extinction risk; Genetic variation; Incidence function analysis; Population viability analysis; Ranking methods; Risk assessment; Spatial scale; Temporal scale.. |
| Ano: 1999 |
|
| |
|
| |
|
|
| Johnson, Barry L; USGS, Upper Midwest Enviromental Sciences Center; barry_johnson@usgs.gov. |
| In making resource management decisions, agencies use a variety of approaches that involve different levels of political concern, historical precedence, data analyses, and evaluation. Traditional decision-making approaches have often failed to achieve objectives for complex problems in large systems, such as the Everglades or the Colorado River. I contend that adaptive management is the best approach available to agencies for addressing this type of complex problem, although its success has been limited thus far. Traditional decision-making approaches have been fairly successful at addressing relatively straightforward problems in small, replicated systems, such as management of trout in small streams or pulp production in forests. However, this success... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adaptive management; Decision making; Ecological resilience; Ecosystem management; Flexibility; Replicated systems; Resource management agencies; Stakeholders.. |
| Ano: 1999 |
|
| |
|
| |
|
| |
|
|
| Robinson, George; University at Albany, State University of New York; grobins@csc.albany.edu; Zappieri, Jeffrey; NYS Department of State, Division of Coastal Resources; jjamzip@superior.net. |
| A 50-yr precedent was reversed in 1995 when, following a powerful windstorm, salvage logging was disallowed in the protected Adirondack Park State Forest Preserve of New York, United States. Damage from a similar windstorm in 1950 had provoked massive salvage operations, approved by the New York State legislature on the grounds of fire prevention and resource conservation. Following the 1995 storm, state conservation officers and consulting ecologists were prepared with up-to-date assessment tools and a theoretical framework that treated large disturbances as normal ecosystem processes; the executive branch acted in accord with their recommendations to forgo salvage. Prior to these events in New York State, federal forest preserves in western states had... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adirondack Park; Forest disturbance; Forest health legislation; Public land use; Salvage logging; Science and public policy; Wildfire; Windstorm.. |
| Ano: 1999 |
|
| |
|
| |
|
| |
| Registros recuperados: 6.820 | |
|
|
|
