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1.
Kyle A. Young 《Environmental management》2000,26(2):131-144
Oncorhynchus sp.), regional governments now restrict timber harvest in riparian forests. I summarize and assess the riparian zone management
guidelines of the states of California, Oregon, and Washington (USA) and the province of British Columbia (Canada). Only Oregon
and British Columbia protect fish-bearing streams with “no-harvest” zones, and only the wider (20–50 m) no-harvest zones for
larger fish-bearing streams in British Columbia are likely to maintain near-natural linkages between riparian and stream ecosystems.
All four jurisdictions protect most streams with “management zones” of variable width, in which timber harvest activities
are restricted. All the management zone guidelines permit the harvest of the largest conifers from riparian forests and will,
if applied over a series of timber harvest rotations (60–80 years), result in the continued removal of potential sources of
large woody debris from the region's watersheds. All four jurisdictions require additional protection for streams and watersheds
that are severely degraded or (in the United States) contain threatened or endangered species. The governments of the PNW
have taken a “manage until degraded, then protect” approach to riparian forest management that is unlikely to maintain or
restore the full suite of riparian-stream linkages necessary for lotic ecosystems to function naturally at the stream, watershed,
basin, or regional scale. 相似文献
2.
Robert L. Beschta Debra L. Donahue Dominick A. DellaSala Jonathan J. Rhodes James R. Karr Mary H. O’Brien Thomas L. Fleischner Cindy Deacon Williams 《Environmental management》2014,53(6):1039-1042
Svejcar et al. (Environ Manage, 2014) offered several perspectives regarding Beschta et al. (Environ Manage 51:474–491, 2013)—a publication that addressed the interacting ecological effects of climate change and domestic, wild, and feral ungulates on public lands in the western United States (US)—by largely focusing on three livestock grazing issues: (1) legacy versus current day impacts; (2) grazing as a fire reduction tool; and (3) the complexity of grazing. Regarding these issues, we indicate that (1) legacy effects to western ecosystems were indeed significant and contemporary livestock use on public lands generally maintains or exacerbates many of those effects; (2) livestock grazing has been a major factor affecting fire frequency, fire severity, and ecosystem trajectories in the western US for over a century; and (3) the removal or reduction of grazing impacts in these altered ecosystems is the most effective means of initiating ecological recovery. Svejcar et al. (Environ Manage, 2014) offer no evidence that livestock use is consistent with the timely recovery of grazing-degraded uplands, riparian areas, or stream systems. We thus conclude that public-land ecosystems can best persist or cope with a changing climate by significantly reducing ungulate grazing and related impacts. 相似文献
3.
The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated
over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau,
Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early
season livestock grazing (June–August), (2) late season livestock grazing (August–September), (3) all season grazing (June–September),
and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation,
and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality
comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but
not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment
was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments.
Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent
control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons)
were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable,
and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO2
− + NO3
− and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal
communities were either nitrogen-limited or not limited by nutrients, depending on stream and season. 相似文献
4.
G. Mathias Kondolf 《Environmental management》1994,18(4):501-509
The North Fork of Cottonwood Creek, in the White Mountains, Inyo National Forest, California, is a critically important refuge
for the Paiute cutthroat trout (Oncorhynchus clarki seleniris), a federally listed threatened species. Habitat for these fish appears to be limited by excessive levels of fine sediment
in the channel, and livestock grazing of riparian meadows has been implicated in delivery of sediment to the channel. However,
the relationships between land use and sediment yield have not been conclusively determined, in large part because there are
no historically ungrazed sites to serve as long-term controls. Accordingly, land-use decisions must be made under scientific
uncertainty. To reduce erosion and sedimentation in the stream, the Forest Service spent approximately US$260,000 from 1981
to 1991 to repair watershed damage from livestock grazing, prevent livestock from traversing steep banks, and limit livestock
access to the channel. Throughout this period, livestock grazing has continued on these lands, yielding less than $12,000
in grazing fees. In revising its Allotment Management Plan for the basin, the Forest Service rejected the “no-grazing” alternative
because it was inconsistent with its Land and Resource Management Plan, which specifies there is to be no net reduction of
grazing.
Joint appointment with the University of California White Mountain Research Station, East Line Street, Bishop, California
93518, USA. 相似文献
5.
John Lyons Stanley W. Thimble Laura K Paine 《Journal of the American Water Resources Association》2000,36(4):919-930
ABSTRACT: Forestation of riparian areas has long been promoted to restore stream ecosystems degraded by agriculture in central North America. Although trees and shrubs in the riparian zone can provide many benefits to streams, grassy or herbaceous riparian vegetation can also provide benefits and may be more appropriate in some situations. Here we review some of the positive and negative implications of grassy versus wooded riparian zones and discuss potential management outcomes. Compared to wooded areas, grassy riparian areas result in stream reaches with different patterns of bank stability, erosion, channel morphology, cover for fish, terrestrial runoff, hydrology, water temperature, organic matter inputs, primary production, aquatic macroinvertebrates, and fish. Of particular relevance in agricultural regions, grassy riparian areas may be more effective in reducing bank erosion and trapping suspended sediments than wooded areas. Maintenance of grassy riparian vegetation usually requires active management (e.g., mowing, burning, herbicide treatments, and grazing), as successional processes will tend ultimately to favor woody vegetation. Riparian agricultural practices that promote a dense, healthy, grassy turf, such as certain types of intensively managed livestock grazing, have potential to restore degraded stream ecosystems. 相似文献
6.
The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau, Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early season livestock grazing (June–August), (2) late season livestock grazing (August–September), (3) all season grazing (June–September), and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation, and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments. Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons) were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable, and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO2 ? + NO3 ? and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal communities were either nitrogen-limited or not limited by nutrients, depending on stream and season. 相似文献
7.
Importance of Riparian Forests in Urban Catchments Contingent on Sediment and Hydrologic Regimes 总被引:1,自引:0,他引:1
Roy AH Freeman MC Freeman BJ Wenger SJ Ensign WE Meyer JL 《Environmental management》2006,37(4):523-539
Forested riparian corridors are thought to minimize impacts of landscape disturbance on stream ecosystems; yet, the effectiveness
of streamside forests in mitigating disturbance in urbanizing catchments is unknown. We expected that riparian forests would
provide minimal benefits for fish assemblages in streams that are highly impaired by sediment or hydrologic alteration. We
tested this hypothesis in 30 small streams along a gradient of urban disturbance (1–65% urban land cover). Species expected
to be sensitive to disturbance (i.e., fluvial specialists and “sensitive” species that respond negatively to urbanization)
were best predicted by models including percent forest cover in the riparian corridor and a principal components axis describing
sediment disturbance. Only sites with coarse bed sediment and low bed mobility (vs. sites with high amounts of fine sediment)
had increased richness and abundances of sensitive species with higher percent riparian forests, supporting our hypothesis
that response to riparian forests is contingent on the sediment regime. Abundances of Etheostoma scotti, the federally threatened Cherokee darter, were best predicted by models with single variables representing stormflow (r2 = 0.34) and sediment (r2 = 0.23) conditions. Lentic-tolerant species richness and abundance responded only to a variable representing prolonged duration
of low-flow conditions. For these species, hydrologic alteration overwhelmed any influence of riparian forests on stream biota.
These results suggest that, at a minimum, catchment management strategies must simultaneously address hydrologic, sediment,
and riparian disturbance in order to protect all aspects of fish assemblage integrity. 相似文献
8.
River channel migration and cutoff events within large river riparian corridors create heterogeneous and biologically diverse
landscapes. However, channel stabilization (riprap and levees) impede the formation and maintenance of riparian areas. These
impacts can be mitigated by setting channel constraints away from the channel. Using a meander migration model to measure
land affected, we examined the relationship between setback distance and riparian and off-channel aquatic habitat formation
on a 28-km reach of the Sacramento River, California, USA. We simulated 100 years of channel migration and cutoff events
using 11 setback scenarios: 1 with existing riprap and 10 assuming setback constraints from about 0.5 to 4 bankfull channel
widths (bankfull width: 235 m) from the channel. The percentage of land reworked by the river in 100 years relative to current
(riprap) conditions ranged from 172% for the 100-m constraint setback scenario to 790% for the 800-m scenario. Three basic
patterns occur as the setback distance increases due to different migration and cutoff dynamics: complete restriction of cutoffs,
partial restriction of cutoffs, and no restriction of cutoffs. Complete cutoff restriction occurred at distances less than
about one bankfull channel width (235 m), and no cutoff restriction occurred at distances greater than about three bankfull
widths (∼700 m). Managing for point bars alone allows the setbacks to be narrower than managing for cutoffs and aquatic habitat.
Results suggest that site-specific “restriction of cutoff” thresholds can be identified to optimize habitat benefits versus
cost of acquired land along rivers affected by migration processes. 相似文献
9.
Jordan M. West Susan H. Julius Peter Kareiva Carolyn Enquist Joshua J. Lawler Brian Petersen Ayana E. Johnson M. Rebecca Shaw 《Environmental management》2009,44(6):1001-1021
Public lands and waters in the United States traditionally have been managed using frameworks and objectives that were established
under an implicit assumption of stable climatic conditions. However, projected climatic changes render this assumption invalid.
Here, we summarize general principles for management adaptations that have emerged from a major literature review. These general
principles cover many topics including: (1) how to assess climate impacts to ecosystem processes that are key to management
goals; (2) using management practices to support ecosystem resilience; (3) converting barriers that may inhibit management
responses into opportunities for successful implementation; and (4) promoting flexible decision making that takes into account
challenges of scale and thresholds. To date, the literature on management adaptations to climate change has mostly focused
on strategies for bolstering the resilience of ecosystems to persist in their current states. Yet in the longer term, it is
anticipated that climate change will push certain ecosystems and species beyond their capacity to recover. When managing to
support resilience becomes infeasible, adaptation may require more than simply changing management practices—it may require
changing management goals and managing transitions to new ecosystem states. After transitions have occurred, management will
again support resilience—this time for a new ecosystem state. Thus, successful management of natural resources in the context
of climate change will require recognition on the part of managers and decisions makers of the need to cycle between “managing
for resilience” and “managing for change.” 相似文献
10.
Doolittle AA 《Environmental management》2010,45(1):67-81
The study of human-environmental relations is complex and by nature draws on theories and practices from multiple disciplines.
There is no single research strategy or universal set of methods to which researchers must adhere. Particularly for scholars
interested in a political ecology approach to understanding human-environmental relationships, very little has been written
examining the details of “how to” design a project, develop appropriate methods, produce data, and, finally, integrate multiple
forms of data into an analysis. A great deal of attention has been paid, appropriately, to the theoretical foundations of
political ecology, and numerous scholarly articles and books have been published recently. But beyond Andrew Vayda’s “progressive
contextualization” and Piers Blaikie and Harold Brookfield’s “chains of explanation,” remarkably little is written that provides
a research model to follow, modify, and expand. Perhaps one of the reasons for this gap in scholarship is that, as expected
in interdisciplinary research, researchers use a variety of methods that are suitable (and perhaps unique) to the questions
they are asking. To start a conversation on the methods available for researchers interested in adopting a political ecology
perspective to human-environmental interactions, I use my own research project as a case study. This research is by no means
flawless or inclusive of all possible methods, but by using the details of this particular research process as a case study
I hope to provide insights into field research that will be valuable for future scholarship. 相似文献
11.
Crifasi RR 《Environmental management》2005,36(5):625-639
“A skyscraper is as natural as a bird’s nest” –Alan Watts
For millennia, people have altered freshwater ecosystems directly through water development and indirectly by global change
and surrounding land-use activities. In these altered ecosystems, human impacts can be subtle and are sometimes overlooked
by the people who manage them. This article provides two case studies near Boulder, Colorado that demonstrate how perceptions
regarding these ecosystems affect their management. These examples are typical of lakes and streams along the Front Range
of Colorado that are simultaneously natural and social in origin. Although natural, many of the region’s freshwater ecosystems
are affected by ongoing ecologic, hydrologic, chemical, and geomorphic modifications produced by human activity. People and
nature are both active participants in the production of these freshwater ecosystems. The concept of “hybridity,” borrowed
from geographers and social scientists, is useful for describing landscapes of natural and social origin. Hybrid freshwater
ecosystems are features of the humanized landscape and are derived from deliberate cultural activities, nonhuman physical
and biological processes, and incidental anthropogenic disturbance. Our perceptions of “natural” freshwater ecosystems and
what definitions we use to describe them influences our view of hybrid systems and, in turn, affects management decisions
regarding them. This work stresses the importance of understanding the underlying societal forces and cultural values responsible
for the creation of hybrid freshwater ecosystems as a central step in their conservation and management. 相似文献
12.
Eucalyptus albens (White Box) woodlands are among the most poorly conserved and threatened communities in Australia. Remnants are under further
threat from stock grazing, deteriorating soil conditions, weed invasion, and salinity. There is an urgent need to restore
degraded White Box and other woodland ecosystems to improve landscape function. However, there is still a poor understanding
of the ecology of degraded woodland ecosystems in fragmented agricultural landscapes, and consequently a lack of precise scientific
guidelines to manage these ecosystems in a conservation context. State and Transition Models (STMs) have received a great
deal of attention, mainly in rangeland applications, as a suitable framework for understanding the ecology of complex ecosystems
and to guide management. We have developed a STM for endangered White Box woodlands and discuss the merits of using this approach
for land managers of other endangered ecosystems. An STM approach provides a greater understanding of the range of states,
transitions, and thresholds possible in an ecosystem, and provides a summary of processes driving the system. Importantly,
our proposed STM could be used to clarify the level of “intactness” of degraded White Box woodland sites, and provide the
impetus to manage different states in complementary ways, rather than attempting to restore ecosystems to one pristine stable
state. We suggest that this approach has considerable potential to integrate researcher and land manager knowledge, focus
future experimental studies, and ultimately serve as a decision support tool in setting realistic and achievable conservation
and restoration goals. 相似文献
13.
Kathleen A. Dwire Sandra E. Ryan Laura J. Shirley Danna Lytjen Nick Otting Mark K. Dixon 《Journal of the American Water Resources Association》2006,42(1):201-212
Streamside vegetation frequently regenerates faster than upland vegetation following wildland fire and contributes to the recovery of riparian and stream ecosystems. Limited data are available, however, on the post‐fire growth of riparian species and the influence of herbivory on regeneration. To determine post‐fire regrowth of riparian vegetation, height, crown area, crown volume, and browse levels were measured for key riparian shrub species in streamside burned and unburned plots along second‐order streams in western Wyoming. Shrubs in the burned plots were subject to high levels of browse ‐ up to 84 percent of the leaders were browsed ‐ by native ungulates in 2002, the second post‐fire year (September 2001 to September 2002). In summer 2003, the burned watershed was also grazed by livestock, resulting in increased browse levels and decreased shrub heights for several species. In the third post‐fire year, September 2002 to September 2003, four of the six most common species showed no increase in crown area or crown volume, indicating that the combination of native ungulate and cattle browsing suppressed their growth. Potential impacts of grazing on post‐fire recovery of stream and riparian ecosystems are discussed. 相似文献
14.
Southern Portugal is experiencing a rapid change in land use due to the spread of intensive farming systems, namely olive production systems, which can cause strong negative environmental impacts and affect the ecological integrity of aquatic ecosystems. This study aimed to identify the main environmental disturbances related with olive grove intensification on Mediterranean-climate streams in southern Portugal, and to evaluate their effects on fish assemblage structure and integrity. Twenty-six stream sites within the direct influence of traditional, intensive, and hyper-intensive olive groves were sampled. Human-induced disturbances were analyzed along the olive grove intensity gradient. The integrity of fish assemblages was evaluated by comparison with an independent set of least disturbed reference sites, considering metrics and guilds, based on multivariate analyses. Along the gradient of olive grove intensification, the study observed overall increases in human disturbance variables and physicochemical parameters, especially organic/nutrient enrichment, sediment load, and riparian degradation. Animal load measured the impact of livestock production. This variable showed an opposite pattern, since traditional olive groves are often combined with high livestock production and are used as grazing pasture by the cattle, unlike more intensive olive groves. Stream sites influenced by olive groves were dominated by non-native and tolerant fish species, while reference sites presented higher fish richness, density and were mainly occupied by native and intolerant species. Fish assemblage structure in olive grove sites was significantly different from the reference set, although significant differences between olive grove types were not observed. Bray–Curtis similarities between olive grove sites and references showed a decreasing trend in fish assemblage integrity along the olive grove intensification gradient. Olive production, even in traditional groves, led to multiple in-stream disturbances, whose cumulative effects promoted the loss of biota integrity. The impacts of low intensity traditional olive groves on aquatic ecosystems can be much greater when they are coupled with livestock production. This paper recommends best practices to reduce negative impacts of olive production on streams, contributing to guide policy decision-makers in agricultural and water management. 相似文献
15.
Thomas J. Myers Sherman Swanson 《Journal of the American Water Resources Association》1996,32(2):253-265
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 surveys. 相似文献
16.
ABSTRACT: The hydrologic impacts of livestock grazing schemes on selected plant communities and soils at Fort Stanton, New Mexico, were evaluated. Simulated rainfall was applied to 1 m2plots. On a mesa-top, infiltration rates for a grassland livestock exclosure and a pinyon pine-juniper community closely approximated each other and were significantly greater (P = 0.10) than either a moderate continuous or a heavy continuous treatment in a grassland community. Sediment concentration from the heavy continuous treatment was more than twice that of the other treatments. Infiltration rates on the hillside site were highest in a pinyon pine-juniper community receiving short duration grazing. Infiltration for this treatment was found to be significantly higher (P = 0.10) than that of a short duration grazing treatment, but not from a rest rotation grazing treatment on grassland. The short duration grazing treatment on a grassland had the highest sediment concentration, while the rest rotation grazing on a grassland and the short duration pinyon pine-juniper treatments were found to be similar. In the bottomland site, a fertilized and unfertilized treatment showed no significant difference in infiltration or sediment concentration, although twice as many animals were present on the fertilized treatment. 相似文献
17.
The regional-scale importance of an aquatic stressor depends both on its regional extent (i.e., how widespread it is) and
on the severity of its effects in ecosystems where it is found. Sample surveys, such as those developed by the U.S. Environmental
Protection Agency’s Environmental Monitoring and Assessment Program (EMAP), are designed to estimate and compare the extents,
throughout a large region, of elevated conditions for various aquatic stressors. In this article, we propose relative risk
as a complementary measure of the severity of each stressor’s effect on a response variable that characterizes aquatic ecological
condition. Specifically, relative risk measures the strength of association between stressor and response variables that can
be classified as either “good” (i.e., reference) or “poor” (i.e., different from reference). We present formulae for estimating
relative risk and its confidence interval, adapted for the unequal sample inclusion probabilities employed in EMAP surveys.
For a recent EMAP survey of streams in five Mid-Atlantic states, we estimated the relative extents of eight stressors as well
as their relative risks to aquatic macroinvertebrate assemblages, with assemblage condition measured by an index of biotic
integrity (IBI). For example, a measure of excess sedimentation had a relative risk of 1.60 for macroinvertebrate IBI, with
the meaning that poor IBI conditions were 1.6 times more likely to be found in streams having poor conditions of sedimentation
than in streams having good sedimentation conditions. We show how stressor extent and relative risk estimates, viewed together,
offer a compact and comprehensive assessment of the relative importances of multiple stressors. 相似文献
18.
From Bathymetry to Bioshields: A Review of Post-Tsunami Ecological Research in India and its Implications for Policy 总被引:1,自引:0,他引:1
Nibedita Mukherjee Farid Dahdouh-Guebas Vena Kapoor Rohan Arthur Nico Koedam Aarthi Sridhar Kartik Shanker 《Environmental management》2010,46(3):329-339
More than half a decade has passed since the December 26th 2004 tsunami hit the Indian coast leaving a trail of ecological,
economic and human destruction in its wake. We reviewed the coastal ecological research carried out in India in the light
of the tsunami. In addition, we also briefly reviewed the ecological research in other tsunami affected countries in Asia
namely Sri Lanka, Indonesia, Thailand and Maldives in order to provide a broader perspective of ecological research after
tsunami. A basic search in ISI Web of Knowledge using keywords “tsunami” and “India” resulted in 127 peer reviewed journal
articles, of which 39 articles were pertaining to ecological sciences. In comparison, Sri Lanka, Indonesia, Thailand and Maldives
had, respectively, eight, four, 21 and two articles pertaining to ecology. In India, bioshields received the major share of
scientific interest (14 out of 39) while only one study (each) was dedicated to corals, seagrasses, seaweeds and meiofauna,
pointing to the paucity of research attention dedicated to these critical ecosystems. We noted that very few interdisciplinary
studies looked at linkages between pure/applied sciences and the social sciences in India. In addition, there appears to be
little correlation between the limited research that was done and its influence on policy in India. This review points to
gap areas in ecological research in India and highlights the lessons learnt from research in other tsunami-affected countries.
It also provides guidance on the links between science and policy that are required for effective coastal zone management. 相似文献
19.
The Precautionary Principle is a legal mechanism for managing the environmental risk arising from incomplete scientific knowledge
of a proposal's impacts. The Precautionary Principle is applied to actions that carry with them the potential for serious
or irreversible environmental change. The model proposed in this paper draws on methods used in a range of disciplines for
modeling (potentially highly nonlinear) interactions between multiple parts of a complex system. These methods have been drawn
together under the common mathematical umbrella of Fitness Landscape Theory. It is argued that the model, called “Environmental
Impact Fitness Landscapes,” allows statements about the sensitivity of the gross effect from a set of impacts to be made when the number of impacts in the set, and/or their degree of interaction, is varied.
It is argued that this can be achieved through identification of “meta” or “emergent” properties of the set itself, without
reference to the specific causal chains determining behavior in specific instances. While such properties are very general,
they may at least allow for the parameterization of the effects of sets of impacts where interactions are highly uncertain
and empirical data severely limited, i.e., situations that would typically invoke the Precautionary Principle. 相似文献
20.
Thomas Hruby 《Environmental management》2009,43(6):1219-1243
Regulators protecting riparian areas need to understand the integrity, health, beneficial uses, functions, and values of this
resource. Up to now most methods providing information about riparian areas are based on analyzing condition or integrity.
These methods, however, provide little information about functions and values. Different methods are needed that specifically
address this aspect of riparian areas. In addition to information on functions and values, regulators have very specific needs
that include: an analysis at the site scale, low cost, usability, and inclusion of policy interpretations. To meet these needs
a rapid method has been developed that uses a multi-criteria decision matrix to categorize riparian areas in Washington State,
USA. Indicators are used to identify the potential of the site to provide a function, the potential of the landscape to support
the function, and the value the function provides to society. To meet legal needs fixed boundaries for assessment units are
established based on geomorphology, the distance from “Ordinary High Water Mark” and different categories of land uses. Assessment
units are first classified based on ecoregions, geomorphic characteristics, and land uses. This simplifies the data that need
to be collected at a site, but it requires developing and calibrating a separate model for each “class.” The approach to developing
methods is adaptable to other locations as its basic structure is not dependent on local conditions. 相似文献