摘要:

ABSTRACT:Ecosystem management is an evolving philosophy that many government agencies have adopted in the multiple‐use, sustained‐yield management of federal lands. The primary objective of this philosophy is to sustain the integrity of ecosystems (i.e., their function, composition, and structure) for future generations while providing immediate goods and services to an increasingly diverse public. This objective can be achieved through integrated land evaluation and optimal land use planning that promotes the maintenance or development of landscape patterns and processes that meet societal expectations within the limits of the land's ecological potentials. Landscape ecology and conservation biology principles are critical components of this philosophy. This paper describes how some of these principles can be efficiently used in formulating a framework for ecosystem management on federal lands. The role of landscape ecology in ecosystem characterization and description is stressed, and the appropriateness of integrated ecological assessments to ecosystem management is discus

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03445.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:Protection of ecosystems as entities on the landscape has attracted a wide range of support. Ecosystem‐based public policies are claimed to be more effective, efficient, and scientifically sound than other approaches to environmental and natural resource policy. The ecosystem concept was never intended to serve as a public policy guide or to determine landscape units for land management purposes. This paper critically examines the use of the ecosystem concept in public policy and land use management and analyzes the proposed rule to manage the National Forest System according to ecosystem management principles. The concept is found to be unsuitable as a basis for guiding environmental and natural resource public policies in general while the proposed rule to manage the national forests according to ecosystem management principles is shown to be incoheren

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03446.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:Ecologically effective ecosystem management will require the development of a robust logic, rationale, and framework for addressing the inherent limitations of scientific understanding. It must incorporate a strategy for avoiding irreversible or large‐scale environmental mistakes that arise from social and political forces that tend to promote fragmented, uncritical, short‐sighted, inflexible, and overly optimistic assessments of resource status, management capabilities, and the consequences of decisions and policies. Aquatic resources are vulnerable to the effects of human activities catchment‐wide, and many of the landscape changes humans routinely induce cause irreversible damage (e.g., some species introductions, extinctions of ecotypes and species) or give rise to cumulative, long‐term, large‐scale biological and cultural consequences (e.g., accelerated erosion and sedimentation, deforestation, toxic contamination of sediments). In aquatic ecosystems, biotic impoverishment and environmental disruption caused by past management and natural events profoundly constrain the ability of future management to maintain biodiversity and restore historical ecosystem functions and values. To provide for rational, adaptive progress in ecosystem management and to reduce the risk of irreversible and unanticipated consequences, managers and scientists must identify catchments and aquatic networks where ecological integrity has been least damaged by prior management, and jointly develop means to ensure their protection as reservoirs of natural biodiversity, keystones for regional restoration, management models, monitoring benchmarks, and resources for ecological

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03447.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:We compared the recovery from abusive grazing of aquatic habitat due to different range management on two geomorphically similar rangeland streams in northwest Nevada. Managers excluded livestock from the Mahogany Creek watershed from 1976 to 1990 while allowing rotation of rest grazing on its tributary Summer Camp Creek. Bank stability, defined as the lack of apparent bank erosion or deposition, improved through the study period on both streams, but periodic grazing and flooding decreased stability more on Summer Camp Creek than flooding alone on Mahogany Creek. Pool quantity and quality on each stream decreased because of coarse woody debris removal and sediment deposition during a drought. Fine stream bottom sediments decreased five years after the removal of livestock, but sedimentation increased during low flows in both streams below road crossings. Tree cover increased 35 percent at both streams. Thus, recovery of stability and cover and decreased sedimentation are compatible with rotation of rest grazing on Summer Camp Creek. Width/depth ratio and gravel/cobble percent did not change because they are inherently stable in this stream type. Management activities such as coarse woody debris removal limited pool recover and road crossings increased sedimentation.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03448.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:Detailed studies of long‐term management impacts on rangeland streams are few because of the cost of obtaining detailed data replicated in time. This study uses government agency aquatic habitat, stream morphologic, and ocular stability data to assess land management impacts over four years on three stream reaches of an important rangeland watershed in northwestern Nevada. Aquatic habitat improved as riparian vegetation reestablished itself with decreased and better controlled livestock grazing. However, sediment from livestock disturbances and road crossings and very low stream flows limited the rate of change. Stream type limited the change of pool variables and width/depth ratio, which are linked to gradient and entrenchment. Coarse woody debris removal due to previous management limited pool recovery. Various critical‐element ocular stability estimates represented changes with time and differences among reaches very well. Ocular stability variables tracked the quantitative habitat and morphologic variables well enough to recommend that ocular surveys be used to monitor changes with time between more intensive aquatic surv

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03449.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:The need to monitor and forecast water resources accurately, particularly in the western United States, is becoming increasingly critical as the demand for water continues to escalate. Consequently, the National Weather Service (NWS) has developed a geostatistical model that is used to obtain areal estimates of snow water equivalent (the thtal water content in all phases of the snowpack), a major source of water in the West. The areal snow water equivalent estimates are used to update the hydrologic simulation models maintained by the NWS and designed to produce extended streamflow forecasts for river systems throughout the United States. An alternative geostatistical technique has been proposed to estimate snow water equivalent. In this research, we describe the two methodologies and compare the accuracy of the estimates produced by each technique. We illustrate their application and compare their estimation accuracy using snow data collected in the North Fork Clearwater River basin in Idaho.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03450.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:The full range of environmental and economic services of ground water need to be accounted for in policy decisions. Non‐recognition of these services imputes a lower value for the ground water resource in establishing policies. We describe a conceptual framework for identifying and measuring the economic value of groundwater. The valuation framework links changes in physical characteristics of ground water to services provided by ground water and the economic effects of changes in ground water services. In addition to the framework, we develop a general protocol to follow for assessing the benefits of ground water policies. Application of the protocol will aid in establishing structure and consistency across policy assessments and improve the accuracy and completeness of benefit estimates, avoid double‐counting problems, and eliminate duplication of ground water valuation effo

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03451.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:This paper uses the fundamental values of decision makers to guide a long‐term wastewater planning process at Seattle Metro, a major utility district. Multiattribute value assessment is used to elicit the objectives of several elected officials and other key decision makers. The results are structured into a fundamental objectives hierarchy and a means‐ends objectives network. A set of measures to indicate the performance of planning alternatives in terms of the fundamental objectives is developed. Preliminary value tradeoffs between objectives are elicited from several elected officials. The results of these steps are useful for many aspects of long‐term planning: facilitating communication about values and priorities; designing attractive alternatives that are more likely to serve stakeholder interests; identifying information needed to evaluate alternatives; clarifying the relative importance of information about different impacts; providing a basis for quantitative evaluation of the alternatives with multiple objective analysis; and focusing attention on key tradeoffs that will affect the choice of alterna

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03452.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:We compared two interpolation schemes for calculation of hourly accumulation of radar‐rainfall. The schemes are: (1) the Advection Method, and (2) the Space‐Time Kriging Method. The performance of the methods is investigated using numerical simulation experiments. Space‐time evolution of rainfall fields is generated from a stochastic model. The generated fields are sampled following typical radar scanning strategies, and the investigated schemes are applied to obtain accumulated rainfall patterns. The statistical results and a visual analysis of the graphical images suggest that it is advisable to use an interpolation scheme for radar observations even when storm velocity is not high. The Space‐Time Kriging Method provides the best results for low wind velocity. The Advection Method has the smallest standard deviation and mean absolute error, and preserves well the true rainfall pattern for high wind v

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03453.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ABSTRACT:Agricultural and urban activities in the West Wellfield Interim Protection Area (WWIPA), located in West Dade County in South Florida, have the potential to impact both the environmentally sensitive Everglades and the Biscayne Aquifer. The Hydrological Simulation Program‐FORTRAN (HSPF) is used to simulate surface runoff, ground water recharge, and transport of sediments, nutrients, and pesticides in the WWIPA, as a basis to quantify impacts and evaluate alternatives. Presented are four model test runs that consider current conditions, the effect of future urbanization of the agricultural land, as well as two preventive actions to minimize pollution levels. Preventive actions include application of minimum required rates of fertilizers and replacement of fertilizers by sewage sludge. Model results show that under current practices, sediments, nutrients, and pesticides are present in surface runoff and nutrients enter the ground water, and that both urbanization and preventive actions result in pollutant reduction

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1996.tb03454.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY