首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
In the last fifty years, many mountain watersheds in temperate countries have known a progressive change from self-standing agro-silvo-pastoral systems to leisure dominated areas characterized by a concentration of tourist accommodations, leading to a drinking water peak during the winter tourist season, when the water level is lowest in rivers and sources. The concentration of water uses increases the pressure on “aquatic habitats” and competition between uses themselves. Consequently, a new concept was developed following the international conferences in Dublin (International Conference on Water and the Environment – ICWE) and Rio de Janeiro (UN Conference on Environment and Development), both in 1992, and was broadly acknowledged through international and European policies. It is the concept of Integrated Water Resource Management (IWRM). It meets the requirements of different uses of water and aquatic zones whilst preserving the natural functions of such areas and ensuring a satisfactory economic and social development. This paper seeks to evaluate a local water resources management system in order to implement it using IWRM in mountain watersheds. The assessment method is based on the systemic approach to take into account all components influencing a water resources management system at the watershed scale. A geographic information system was built to look into interactions between water resources, land uses, and water uses. This paper deals specifically with a spatial comparison between hydrologically sensitive areas and land uses. The method is applied to a French Alps watershed: the Giffre watershed (a tributary of the Arve in Haute-Savoie). The results emphasize both the needs and the gaps in implementing IWRM in vulnerable mountain regions.  相似文献   

2.
Two spatial optimization approaches, developed from the opposing perspectives of ecological economics and landscape planning and aimed at the definition of new distributions of farming systems and of land use elements, are compared and integrated into a general framework. The first approach, applied to a small river catchment in southwestern France, uses SWAT (Soil and Water Assessment Tool) and a weighted goal programming model in combination with a geographical information system (GIS) for the determination of optimal farming system patterns, based on selected objective functions to minimize deviations from the goals of reducing nitrogen and maintaining income. The second approach, demonstrated in a suburban landscape near Leipzig, Germany, defines a GIS-based predictive habitat model for the search of unfragmented regions suitable for hare populations (Lepus europaeus), followed by compromise optimization with the aim of planning a new habitat structure distribution for the hare. The multifunctional problem is solved by the integration of the three landscape functions (“production of cereals,” “resistance to soil erosion by water,” and “landscape water retention”). Through the comparison, we propose a framework for the definition of optimal land use patterns based on optimization techniques. The framework includes the main aspects to solve land use distribution problems with the aim of finding the optimal or best land use decisions. It integrates indicators, goals of spatial developments and stakeholders, including weighting, and model tools for the prediction of objective functions and risk assessments. Methodological limits of the uncertainty of data and model outcomes are stressed. The framework clarifies the use of optimization techniques in spatial planning.  相似文献   

3.
This study assessed coastal erosion vulnerability along a 90-km sector, which included both erosional and accretionary beaches, and different levels of human occupation. Two aerial photogrammetric flights were used to reconstruct coastal evolution between 1977 and 1999. During this period, extensive accretion was recorded updrift of human structures at harbors and ports, e.g., Scoglitti (105.6 m), Donnalucata (52.8 m), and Pozzallo (94.6 m). Conversely, erosion was recorded in downdrift areas, with maximum values at Modica Stream mouth (63.8 m) and Point Castellazzo (35.2 m). Assessments were subsequently divided into four categories ranging from “high erosion” to “accretion.” Several sources were examined to assess human activities and land use. The latter was mapped and divided into four categories, ranging from “very high” to “no capital” land use. Subsequently, coastal erosion vulnerability was assessed by combining land use categories with recorded coastline behavior. Results showed “very high” to “high” vulnerability along 5.8% and 16.6%, respectively, of the littoral, while 20.9% and 56.7%, respectively, was found to exhibit “medium” and “low/very low” vulnerability. A very good agreement between predicted coastal vulnerability and coastal trend had been observed over recent years. Furthermore, several human structures and activities are located within the “imminent collapse zone (ICZ)” which reached maximum values of 17.5 m at Modica Stream and 13.5 m at Point Braccetto.  相似文献   

4.
We describe the development of a bird integrity index (BII) that uses bird assemblage information to assess human impacts on 13 stream reaches in the Willamette Valley, Oregon, USA. We used bird survey data to test 62 candidate metrics representing aspects of bird taxonomic richness, tolerance or intolerance to human disturbance, dietary preferences, foraging techniques, and nesting strategies that were affected positively or negatively by human activities. We evaluated the metric responsiveness by plotting each one against a measure of site disturbance that included aspects of land use/land cover, road density, riparian cover, and stream channel and substrate conditions. In addition, we eliminated imprecise and highly correlated (redundant) metrics, leaving 13 metrics for the final index. Individual metric scores ranged continuously from 0 to 10, and index scores were weighted to range from 0 to 100. Scores were calibrated using historical species information to set expectations for the number of species expected under minimally disturbed conditions. Site scores varied from 82 for the least disturbed stream reach to 8.5 for an urban site. We compared the bird integrity index site scores with the performance of other measures of biotic response developed during this study: a fish index of biointegrity (IBI) and two benthic macroinvertebrate metrics. The three assemblages agreed on the general level of disturbance; however, individual sites scored differently depending on specific indicator response to in-stream or riparian conditions. The bird integrity index appears to be a useful management and monitoring tool for assessing riparian integrity and communicating the results to the public. Used together with aquatic indicator response and watershed data, bird assemblage information contributes to a more complete picture of stream condition.  相似文献   

5.
Riparian Zone Management in the Pacific Northwest: Who's Cutting What?   总被引:2,自引:0,他引:2  
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   

6.
Over the last three decades, livestock exclosure research has emerged as a preferred method to evaluate the ecology of riparian ecosystems and their susceptibility to livestock impacts. This research has addressed the effects of livestock exclusion on many characteristics of riparian ecosystems, including vegetation, aquatic and terrestrial animals, and geomorphology. This paper reviews, critiques, and provides recommendations for the improvement of riparian livestock exclosure research. Exclosure-based research has left considerable scientific uncertainty due to popularization of relatively few studies, weak study designs, a poor understanding of the scales and mechanisms of ecosystem recovery, and selective, agenda-laden literature reviews advocating for or against public lands livestock grazing. Exclosures are often too small (<50 ha) and improperly placed to accurately measure the responses of aquatic organisms or geomorphic processes to livestock removal. Depending upon the site conditions when and where livestock exclosures are established, postexclusion dynamics may vary considerably. Systems can recover quickly and predictably with livestock removal (the “rubber band” model), fail to recover due to changes in system structure or function (the “Humpty Dumpty” model), or recover slowly and remain more sensitive to livestock impacts than they were before grazing was initiated (the “broken leg” model). Several initial ideas for strengthening the scientific basis for livestock exclosure research are presented: (1) incorporation of meta-analyses and critical reviews. (2) use of restoration ecology as a unifying conceptual framework; (3) development of long-term research programs; (4) improved exclosure placement/design; and (5) a stronger commitment to collection of pretreatment data.  相似文献   

7.
8.
Many living resources in the Chesapeake Bay estuary have deteriorated over the past 50 years. As a result, many governmental committees, task forces, and management plans have been established. Most of the recommendations for implementing a bay cleanup focus on reducing sediments and nutrient flow into the watershed. We emphasize that habitat requirements other than water quality are necessary for the recovery of much of the bay's avian wildlife, and we use a waterbird example as illustration. Some of these needs are: (1) protection of fast-eroding islands, or creation of new ones by dredge deposition to improve nesting habitat for American black ducks(Anas rubripes), great blue herons(Ardea herodias), and other associated wading birds; (2) conservation of remaining brackish marshes, especially near riparian areas, for feeding black ducks, wading birds, and wood ducks(Aix sponsa); (3) establishment of sanctuaries in open-water, littoral zones to protect feeding and/or roosting areas for diving ducks such as canvasbacks(Aythya valisineria) and redheads(Aythya americana), and for bald eagles(Haliaeetus leucocephalus); and (4) limitation of disturbance by boaters around nesting islands and open-water feeding areas. Land (or water) protection measures for waterbirds need to include units at several different spatial scales, ranging from “points” (e.g., a colony site) to large-area resources (e.g., a marsh or tributary for feeding). Planning to conserve large areas of both land and water can be achieved following a biosphere reserve model. Existing interagency committees in the Chesapeake Bay Program could be more effective in developing such a model for wildlife and fisheries resources.  相似文献   

9.
10.
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   

11.
Comanagement has recently become the most popular approach for reconciling land claims and biodiversity conservation in South Africa and beyond. Following the resolution of land claims on protected areas in South Africa, comanagement arrangements have been created between the relevant conservation authorities and the land claimant communities who are legally awarded tenure rights to the land. However, it is doubtful that these partnerships constitute success for the former land claimants. Using the case of a “resolved” land claim in Mkambati Nature Reserve, Eastern Cape Province, as well as insights from comanagement literature, this paper identifies and discusses three key possible reasons for the unimpressive performance of comanagement in reconciling land restitution and conservation. The first one is the origins of the comanagement idea in the conservation of high value natural resources (e.g., fisheries, forestry), rather than in or including concerns for resource rights. The second reason is the neglect of key conditions for successful comanagement, as discussed in the comanagement literature. The final reason is the ambiguity in settlement agreements, including the use of terminology and concepts that reinforce unequal power relationships, with the state emerging as the powerful partner. This paper concludes that, unless there is a serious reassessment of the comanagement idea as a way of reconciling land reform and conservation, and a possible review of settlement agreements that have relied on comanagement, both the integrity of the “successful land claimant’s rights” and that of conservation remain under threat.  相似文献   

12.
Farm animal welfare is a knowledge domain that can be regarded as a model for new ways of organizing learning and making higher education more responsive to the needs of society. Global concern for animal welfare has resulted in a great demand for knowledge. As a complement to traditional education in farm animal welfare, higher education can be more demand driven and look at a broad range of methods to make knowledge available. The result of an inventory on “farm animal welfare,” “e-learning,” “learning resources,” and “open educational resources” in three different search engines is presented. A huge amount of information on animal welfare is available on the Internet but many of the providers lock in the knowledge in a traditional course context. Only a few universities develop and disseminate open learning resources within the subject. Higher education institutions are encouraged to develop open educational resources in animal welfare for the benefit of teachers, students, society, and, indirectly, animal welfare.  相似文献   

13.
The Hydrogeomorphic (HGM) functional assessment method is predicated on the ability of hydrogeomorphic wetland classification and visual assessment of alteration to provide reference standards against which functions in individual wetlands can be evaluated. The effectiveness of this approach was tested by measuring nitrogen cycling functions in forested wetlands in an urbanized region in New Jersey, USA. Fourteen sites represented three HGM classes and were characterized as “least disturbed reference” or “non-reference” based on initial visual assessment. Water table levels and in situ rates of net nitrogen mineralization, net nitrification, and denitrification were measured over one year in each site. Hydrological alterations, resulting in consistently low or flashy water table levels, were not correlated with a priori designations as reference and non-reference. Although the flat-riverine wetland class had lower net nitrification and higher denitrification rates than riverine or mineral flat wetland classes, this difference was attributable to the lack of hydrologically-altered wetlands in the flat-riverine class, and thus more consistently wet conditions. Within all HGM classes, a classification based on the long-term hydrological record that separated sites with “normal,” saturated hydrology from those with “altered,” drier hydrology, clearly distinguished sites with different nitrogen cycling function. Based on these findings, current practices for designating reference standard sites to judge wetland functions, at least in urbanized regions, are ineffective and potentially misleading. At least one year of hydrological monitoring data is suggested to classify wetlands into groups that have different nutrient cycling functions, particularly in urban landscapes.  相似文献   

14.
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   

15.
Wildfire, like many natural hazards, affects large landscapes with many landowners and the risk individual owners face depends on both individual and collective protective actions. In this study, we develop a spatially explicit game theoretic model to examine the strategic interaction between landowners’ hazard mitigation decisions on a landscape with public and private ownership. We find that in areas where ownership is mixed, the private landowner performs too little fuel treatment as they “free ride”—capture benefits without incurring the costs—on public protection, while areas with public land only are under-protected. Our central result is that this pattern of fuel treatment comes at a cost to society because public resources focus in areas with mixed ownership, where local residents capture the benefits, and are not available for publicly managed land areas that create benefits for society at large. We also find that policies that encourage public expenditures in areas with mixed ownership, such as the Healthy Forest Restoration Act of 2003 and public liability for private values, subsidize the residents who choose to locate in the high-risk areas at the cost of lost natural resource benefits for others.  相似文献   

16.
According to the United States Environmental Protection Agency (US EPA), a significant percentage of residential onsite sewage systems (OSSs) are failing at any given time. The US EPA has therefore issued a set of recommended guidelines for OSS regulatory programs aimed at reducing overall failure rates. We conducted a survey of OSS regulatory program administrators with jurisdictions bordering a Great Lake. Our goal was to determine their programs’ capacities to meet the US EPA’s recommendations. We found that although some local programs meet the US EPA’s recommendations, most do not. In this article, we present our findings and conclusions for one of the US EPA’s models, the baseline “Homeowner Awareness” model. Most areas do not have recommended requirements that systems be inspected when properties transfer between owners. A majority do not track changes in ownership within the computerized databases they use to record information about systems. Although most provide at least “one-time” information to homeowners regarding proper OSS maintenance, most do not contact them periodically with reminders of needed maintenance. We include recommendations for resolving some of the issues that our research identified.  相似文献   

17.
The protection of wetlands and riparian areas has emerged as an important environmental planning issue. In the United States, several federal and state laws have been enacted to protect wetlands and riparian areas. Specifically, the federal Clean Water Act includes protection requirements in Sections 301 and 303 for state water quality standards, Section 401 for state certification of federal actions (projects, permits, and licenses), and Section 404 for dredge and fill permits. The Section 401 water quality state certification element has been called the “sleeping giant” of wetlands protection because it empowers state officials to veto or condition federally permitted or licensed activities that do not comply with state water quality standards. State officials have used this power infrequently. The purpose of this research was to analyze the effectiveness of state wetland and riparian programs. Contacts were established with officials in each state and in the national and regional offices of key federal agencies. Based on interviews and on a review of federal and state laws, state program effectiveness was analyzed. From this analysis, several problems and opportunities facing state wetland protection efforts are presented.  相似文献   

18.
Brownfields are abandoned, idled, or underused sites whose reuse necessitates some sort of intervention. These sites are largely urban and are frequently contaminated. Brownfield management options can be associated with three types of environmental consequences: those resulting from changes in the site’s environmental quality (primary impacts); those resulting from the actual intervention stage (secondary impacts); and, if the vocation of the site changes, those resulting from effects on regional land use (tertiary impacts). Different stakeholders and decision-making contexts will place a different importance on each of these types of impacts. This article proposes a framework for comparing brownfield management options in regard to these three types of environmental impacts and for interpreting these results from different perspectives. The assessment framework is based on consequential life cycle assessment (LCA), which is shown to provide environmental information on the three types of impacts. The results for a case study are presented, where a “rehabilitation” option allowing residential redevelopment is compared to an “exposure minimization” option not resulting in the site being reused. Calculated primary and tertiary impacts are favorable to the rehabilitation option, whereas secondary impacts are favorable to the exposure minimization option. A ternary diagram presents the favorable option for different stereotypical perspectives. Tertiary impacts are much greater than secondary impacts, and consequently all perspectives that consider tertiary impacts favor rehabilitation. The perspective that considers primary and secondary impacts receives conflicting information. The ternary diagram, showing results for all perspectives, could possibly be useful for consensus-building among stakeholders.  相似文献   

19.
Landscape planning and restoration in mine closure areas is not only an inevitable choice to sustain mining areas but also an important path to maximize landscape resources and to improve ecological function in mine closure areas. The analysis of the present mine development shows that many mines are unavoidably facing closures in China. This paper analyzes the periodic impact of mining activities on landscapes and then proposes planning concepts and principles. According to the landscape characteristics in mine closure areas, this paper classifies available landscape resources in mine closure areas into the landscape for restoration, for limited restoration and for protection, and then summarizes directions for their uses. This paper establishes the framework of spatial control planning and design of landscape elements from “macro control, medium allocation and micro optimization” for the purpose of managing and using this kind of special landscape resources. Finally, this paper applies the theories and methods to a case study in Wu’an from two aspects: the construction of a sustainable land-use pattern on a large scale and the optimized allocation of typical mine landscape resources on a small scale.  相似文献   

20.
ABSTRACT: Riparian zones perform a variety of biophysical functions that can be managed to reduce the effects of land use on instream habitat and water quality. However, the functions and human uses of riparian zones vary with biophysical factors such as landform, vegetation, and position along the stream continuum. These variations mean that “one size fits all” approaches to riparian management can be ineffective for reducing land use impacts. Thus riparian management planning at the watershed scale requires a framework that can consider spatial differences in riparian functions and human uses We describe a pilot riparian zone classification developed to provide such a framework for riparian management in two diverse river systems in the Waikato region of New Zealand. Ten classes of riparian zones were identified that differed sufficiently in their biophysical features to require different management. Generic “first steps” and “best practical” riparian management recommendations and associated costs were developed for each riparian class. The classification aims to not only improve our understanding of the effectiveness of riparian zone management as a watershed management tool among water managers and land owners, but to also provide a basis for deciding on management actions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号