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 31 毫秒
1.
ABSTRACT: Integrated watershed ecosystem studies in National Parks or equivalent reserves suggest that effects of external processes on “protected” resources are subtle, chronic, and long-term. Ten years of data from National Park watersheds suggests that temperature and precipitation changes are linked to nitrogen levels in lakes and streams. We envision measurable biotic effects in these remote watersheds, if expected climate trends continue. The condition of natural resources within areas set aside for preservation are difficult to ascertain, but gaining this knowledge is the key to understanding ecosystem change and of processes operating among biotic and abiotic ecosystem components. There is increasing evidence that understanding the magnitude of variation within and between such processes can provide an early indication of environmental change and trends attributable to human-induced stress. The following four papers are case studies of how this concept has been implemented.* These long-term studies have expanded our knowledge of ecosystem response to natural and human-induced stress. The existence of these sites with a commitment to gathering “long-term” ecosystem-level data permits research activities aimed at testing more important hypotheses on ecosystem processes and structure.  相似文献   

2.
An evolving understanding of ecological processes, together with ambiguities in National Park Service policy, have led to multiple interpretations of the role of management in our large natural area National Parks. National Park Service management policies must be dynamic and responsive to changes in scientific knowledge and societal values. We propose that the principal aim of NPS resource management in natural areas is the unimpeded interaction of native ecosystem processes and structural elements. The case of the changing role of natural fire management is used as an example in developing this rationale.  相似文献   

3.
ABSTRACT: Weekly precipitation and stream water samples were collected from small watersheds in Denali National Park, Alaska, the Fraser Experimental Forest, Colorado, Isle Royale National Park, Michigan, and the Calumet watershed on the south shore of Lake Superior, Michigan. The objective was to determine if stream water chemistry at the mouth and upstream stations reflected precipitation chemistry across a range of atmospheric inputs of H+, NH4+, NO3??, and SO42?. Volume-weighted precipitation H+, NH4+, NO3??, and SO42? concentrations varied 4 to 8 fold with concentrations highest at Calumet and lowest in Denali. Stream water chemistry varied among sites, but did not reflect precipitation chemistry. The Denali watershed, Rock Creek, had the lowest precipitation NO3?? and SO42? concentrations, but the highest stream water NO3?and SO42? concentrations. Among sites, the ratio of mean monthly upstream NO3?? concentration to precipitation NO3?- concentration declined (p < 0.001, R2= 0.47) as precipitation NO3?? concentration increased. The ratio of mean monthly upstream to precipitation SO42? concentration showed no significant relationship to change in precipitation SO42? concentration. Watersheds showed strong retention of inorganic N (> 90 percent inputs) across inputs ranging from 0.12 to > 6 kg N ha?1 y?1. Factors possibly accounting for the weak or non-existent signal between stream water and precipitation ion concentrations include rapid modification of meltwater and precipitation chemistry by soil processes, and the presence of unfrozen soils which permits winter mineralization and nitrification to occur.  相似文献   

4.
Cooperation between the United States Department of Agriculture (USDA) Forest Service and the United States Department of Interior (USDI) National Park Service is most often advocated to protect biological diversity on national forests and parks, but the agencies, so far, have done little to implement the biodiversity mandates of such laws as the Endangered Species Act and the National Forest Management Act. The ideological and political history of the Forest Service and Park Service is explored to determine the roots of interagency conflicts. Several recent models of cooperative reform are also critiqued and found to be insufficient to stimulate better working relationships. To protect biodiversity, cooperation must be framed within conservation biology and must place primary emphasis on ecosystem patterns and processes as well as on individual species. Increased education of agency managers, ecosystem-level research, local and regional public participation, scientific oversight committees, new legislation, and enlightened leadership also play important roles. Ultimately, management policies must be reframed within a context of ecocentric values.  相似文献   

5.
Densmore, Roseann V. and Kenneth F. Karle, 2009. Flood Effects on an Alaskan Stream Restoration Project: The Value of Long‐Term Monitoring. Journal of the American Water Resources Association (JAWRA) 45(6):1424‐1433. Abstract: On a nationwide basis, few stream restoration projects have long‐term programs in place to monitor the effects of floods on channel and floodplain configuration and floodplain vegetation, but long‐term and event‐based monitoring is required to measure the effects of these stochastic events and to use the knowledge for adaptive management and the design of future projects. This paper describes a long‐term monitoring effort (15 years) on a stream restoration project in Glen Creek in Denali National Park and Preserve in Alaska. The stream channel and floodplain of Glen Creek had been severely degraded over a period of 80 years by placer mining for gold, which left many reaches with unstable and incised streambeds without functioning vegetated floodplains. The objectives of the original project, initiated in 1991, were to develop and test methods for the hydraulic design of channel and floodplain morphology and for floodplain stabilization and riparian habitat recovery, and to conduct research and monitoring to provide information for future projects in similar degraded watersheds. Monitoring methods included surveyed stream cross‐sections, vegetation plots, and aerial, ground, and satellite photos. In this paper we address the immediate and outlying effects of a 25‐year flood on the stream and floodplain geometry and riparian vegetation. The long‐term monitoring revealed that significant channel widening occurred following the flood, likely caused by excessive upstream sediment loading and the fairly slow development of floodplain vegetation in this climate. Our results illustrated design flaws, particularly in regard to identification and analysis of sediment sources and the dominant processes of channel adjustment.  相似文献   

6.
ABSTRACT: Land use and surface water data for nitrogen and pesticides (1995 to 1997) are reported for the Walnut Creek Watershed Monitoring Project, Jasper County Iowa. The Walnut Creek project was established in 1995 as a nonpoint source monitoring program in relation to watershed habitat restoration and agricultural management changes implemented at the Neal Smith National Wildlife Refuge by the U.S. Fish and Wildlife Service. The monitoring project utilizes a paired‐watershed approach (Walnut and Squaw creeks) as well as upstream/downstream comparisons on Walnut for analysis and tracking of trends. From 1992 to 1997, 13.4 percent of the watershed was converted from row crop to native prairie in the Walnut Creek watershed. Including another 6 percent of watershed farmed on a cash‐rent basis, land use changes have been implemented on 19.4 percent of the watershed by the USFWS. Nitrogen and pesticide applications were reduced an estimated 18 percent and 28 percent in the watershed from land use changes. Atrazine was detected most often in surface water with frequencies of detection ranging from 76–86 percent. No significant differences were noted in atrazine concentrations between Walnut and Squaw Creek. Nitrate‐N concentrations measured in both watersheds were similar; both basins showed a similar pattern of detection and an overall reduction in nitrate‐N concentrations from upstream to downstream monitoring sites. Water quality improvements are suggested by nitrate‐N and chloride ratios less than one in the Walnut Creek watershed and low nitrate‐N concentrations measured in the subbasin of Walnut Creek containing the greatest amount of land use changes. Atrazine and nitrate‐N concentrations from the lower portion of the Walnut Creek watershed (including the prairie restoration area) may be decreasing in relation to the upstream untreated component of the watershed. The frequencies of pesticide detections and mean nitrate‐N concentrations appear related to the percentage of row crop in the basins and subbasins. Although some results are encouraging, definitive water quality improvements have not been observed during the first three years of monitoring. Possible reasons include: (1) more time is needed to adequately detect changes; (2) the size of the watershed is too large to detect improvements; (3) land use changes are not located in the area of the watershed where they would have greatest effect; or (4) water quality improvements have occurred but have been missed by the project monitoring design. Longer‐term monitoring will allow better evaluation of the impact of restoration activities on water quality.  相似文献   

7.
8.
The United States Congress established Grand Canyon National Park in 1919 to preserve for posterity the outstanding natural attributes of the canyon cut by the Colorado River. In some cases National Park Service attempts to maintain Grand Canyon's natural environment have been thwarted by activities outside the park. One of the most obvious external threats is Glen Canyon Dam, only 26 km upstream from the park boundary. Constructed in 1963, this gigantic dam has greatly altered the physicochemical and biological characteristics of 446 km of the Colorado River in Grand Canyon National Park. The river's aquatic ecosystem has been greatly modified through the loss of indigenous species and the addition of numerous exotics. We consider this anexotic ecosystem. The riparian ecosystem has been less modified, with addition of a few exotics and no loss of natives—this we consider anaturalized ecosystem.The great dilemma now faced by park managers is that, after 20 years of managing resources along a river controlled by Glen Canyon Dam, the Bureau of Reclamation has proposed major changes in operational procedures for the dam. Scientists and managers from the National Park Service, Bureau of Reclamation, and cooperating federal and state resource management agencies are using a systems analysis approach to examine the impacts of various Colorado River flow regimes on aquatic, riparian, and recreational parameters in the park. This approach will help in the development of management alternatives designed to permit the most efficient use of that river's natural resources without their destruction.  相似文献   

9.
The Swift Creek catchment, the first catchment to be affected should any impact occur as a result of mining of the Jabiluka uranium ore deposit, is located partly within the World Heritage Kakadu National Park (KNP), and partly within the Jabiluka Mineral Lease (JML) that has been excised from KNP. Preliminary linking of a landform evolution model with a Geographic Information System (GIS) has been completed and tested on a catchment-wide basis for long-term total catchment management. This project represents the first attempt to apply the model on a catchment-wide basis in the region. Linking the model with a GIS enhances the modelling process, as the GIS assists in the derivation, storage, manipulation, processing and visualisation of geo-referenced data on a catchment-wide scale. This preliminary assessment of landform evolution in the Swift Creek catchment demonstrates the complex process associated with the parameterisation of the SIBERIA model, and illustrates the benefits of integrating GIS with landform evolution modelling techniques. Additional research is required to develop a more integrated GIS and landform evolution modelling approach to assessing the possible impacts of mining on catchment sedimentary and hydrological processes.  相似文献   

10.
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 research.  相似文献   

11.
Management of many African game reserves is today often still an art based on experience and intuition, rather than a science. Decision-making is based on an informal integration of accumulated individual knowledge and keen field observations. Data are generally poorly captured and curated. Until fairly recently, denominators of biological parameters (such as the unit of land or unit of plant production used as measurement) have generally been treated as being homogenous. The patchiness of landscapes and the issue of ecological scaling were ignored, often because of a lack of appropriate technical tools. The ecological data available on the 49,000-ha Songimvelo Game Reserve (SGR) result from a number of discrete survey and monitoring projects undertaken by different researchers, with different objectives, at different spatial and temporal scales. A landscape ecological approach towards research and monitoring is appropriate for an area of the size and diversity of the SGR. A combination of a database approach and spatial representation was used to consolidate and integrate data across temporal and spatial scales. Herbivore spatial and temporal distribution patterns were explored across three spatial scales. An understanding was achieved of the importance of landscape patchiness in controlling resource availability for herbivores. This insight is important in guiding management and monitoring of the SGR by placing perceived patch overutilization in its proper landscape context. The landscape ecological approach bridges the traditional scale-independent view to a more contemporary scale-related understanding of ecosystem diversity and functioning.  相似文献   

12.
ABSTRACT: It is increasingly recognized that natural resources research should in many cases be broadened in scope and oriented toward more general “environmental” problems. Locales with a history of “watershed” research can be eminently suited for development of comprehensive, environmental research programs. This is recognized in many research efforts of the International Biological Program (IBP), where watershed research sites have been successfully utilized for intensive investigations of process and function of selected ecosystems or ecosystem components. In the North American Subarctic there is almost no history of “watershed” studies. Basic data on hydrometeorologic parameters such as precipitation amounts and areal and seasonal distribution of runoff are scarce; the data framework within which environmental understanding can be structured is exceedingly sketchy. Opportunity exists in the discontinuous-permafrost settings of central Alaska to begin rectifying this situation. A basic program of multi-agency, multi-discipline research and data acquisition for the most significant hydrologic subregions is being developed, based around several existing environmental research areas (chiefly the Bonanza Creek Experimental Forest, the Caribou-Poker Creeks Research Watershed, the Wickersham Dome Fire Study Area, and a series of outlying sites).  相似文献   

13.
14.
Activities beyond national park boundaries are now the principal source of threats to park natural resource integrity. Assessing the full impact of major threats as air and water pollution requires a long-term ecosystem-level approach in research design and execution, and park management. Failure to take such an approach renders most existing park data bases useless in the documentation of external threats. While the concept of managing national parks as ecosystems is not new, Park Service research and its organization have not provided the information necessary for such a basis of management. Quantifying the impacts on park resources due to external hydrologic regulation and air pollution is a good example of the need to employ an ecosystem approach in research. However, implementing such a program will require a fundamental change in research administration, priority setting, and conceptual approach.The first four of the articles in this special section arise from an AAAS symposium onExternal Threats to Ecosystems of the National Parks in the USA, which was convened in 1982. The articles have been revised to reflect subsequent developments in this field. The first article, by Dr. Stottlemyer, the symposium organizer, serves as an introduction to the topic. The fifth article in this special section was submitted separately, but included because it also is related to this particular topic.  相似文献   

15.
Parks and protected areas are a global ecological, social and health resource visited by over 8 billion people annually. Their use can yield substantial benefits, but only if a balance between ecological integrity and sustainable visitation is struck. This research explores the potential influence of climate-driven environmental change on visitation to North America's most popular glacier, the Athabasca Glacier in Jasper National Park, Canada. Photorealistic environmental visualizations were used to gauge visitors’ perceptions of environmental change and potential impacts on consumer behaviour. Results suggest that impacts could substantially diminish the site's pull as a tourism destination. Rather than improving visitation prospects, expert-proposed adaptations underestimated the importance of perceived naturalness and contributed to further potential decline. Findings are relevant to protected areas planning and management. They suggest that a natural path to climate change adaptation is the best way to support both ecological integrity and the long-term tourism pull of protected areas.  相似文献   

16.
ABSTRACT: Dam removal has been proposed as an effective method of river restoration, but few integrative studies have examined ecological responses to the removal of dams. In 1999, we initiated an interdisciplinary study to determine ecological responses to the removal of a 2 m high dam on lower Manatawny Creek in southeastern Pennsylvania. We used an integrative monitoring program to assess the physical, chemical, and biological responses to dam removal. Following removal in 2000, increased sediment transport has led to major changes in channel form in the former impoundment and downstream reaches. Water quality did not change markedly following removal, probably because of the impoundment's short hydraulic residence time (less than two hours at base flow) and infrequent temperature stratification. When the impoundment was converted to a free flowing reach, the composition of the benthic macroinvertebrate and fish assemblages in this portion of Manatawny Creek shifted dramatically from lentic to lotic taxa. Some fish species inhabiting the free flowing reach downstream from the dam were negatively affected by large scale sediment transport and habitat alteration following dam removal, but this appears to be a short term response. Based on our observations and experiences in this study, we provide a list of issues to evaluate when considering future dam removals.  相似文献   

17.
Populations of introduced European wild boar, feral pigs, and combinations of both types (all Susscrola L.) inhabit thirteen areas in the National Park Service system. All parks have relatively stable populations, with the exception of Great Smoky Mountains National Park, which reported a rapidly expanding wild boar population. Suspected and documented impacts were apparently related to pig densities and sensitivity of the ecosystem; the three largest units with dense wild pig populations reported the most damage. Overall, wild pigs are a relatively minor problem for the Park Service; however, problems are severe in at least three parks, and there is potential for invasion of wild boars into several additional parks in the Appalachian Mountains. More specific information is needed on numbers of wild pigs and their impacts in the various parks.  相似文献   

18.
ABSTRACT: We have developed an approach which examines ecosystem function and the potential effects of climatic shifts. The Lake McDonald watershed of Glacier National Park was the focus for two linked research activities: acquisition of baseline data on hydrologic, chemical and aquatic organism attributes that characterize this pristine northern rocky mountain watershed, and further developing the Regional Hydro-Ecosystem Simulation System (RHESSys), a collection of integrated models which collectively provide spatially explicit, mechanistically-derived outputs of ecosystem processes, including hydrologic outflow, soil moisture, and snow-pack water equivalence. In this unique setting field validation of RHESSys, outputs demonstrated that reasonable estimates of SWE and streamflow are being produced. RHESSys was used to predict annual stream discharge and temperature. The predictions, in conjunction with the field data, indicated that aquatic resources of the park may be significantly affected. Utilizing RHESSys to predict potential climate scenarios and response of other key ecosystem components can provide scientific insights as well as proactive guidelines for national park management.  相似文献   

19.
Ecosystems, though impacted by global environmental change, can also contribute to the adaptation and mitigation of such large scale changes. Therefore, sustainable ecosystem management is crucial in reaching a sustainable future for the biosphere. Based on the published literature and publicly accessible data, this paper discussed the status and trends of forest, grassland, and wetland ecosystems in China that play important roles in the ecological integrity and human welfare of the nation. Ecological degradation has been observed in these ecosystems at various levels and geographic locations. Biophysical (e.g., climate change) and socioeconomic factors (e.g., intensive human use) are the main reasons for ecosystem degradation with the latter factors serving as the dominant driving forces. The three broad categories of ecosystems in China have partially recovered from degradation thanks to large scale ecological restoration projects implemented in the last few decades. China, as the largest and most populated developing nation, still faces huge challenges regarding ecosystem management in a changing and globalizing world. To further improve ecosystem management in China, four recommendations were proposed, including: (1) advance ecosystem management towards an application-oriented, multidisciplinary science; (2) establish a well-functioning national ecological monitoring and data sharing mechanism; (3) develop impact and effectiveness assessment approaches for policies, plans, and ecological restoration projects; and (4) promote legal and institutional innovations to balance the intrinsic needs of ecological and socioeconomic systems. Any change in China’s ecosystem management approach towards a more sustainable one will benefit the whole world. Therefore, international collaborations on ecological and environmental issues need to be expanded.  相似文献   

20.
Following a global trend, the new policy goals emphasize the need to protect rather than to use the ability of ecosystems to recover from disturbances. This necessitates the adoption of response measurements to quantify ecological condition and monitor ecological change. Response monitoring focuses on properties that are essential to the sustainability of the ecosystem. These monitoring tools can be used to establish natural ranges of ecological change within ecosystems, as well as to quantify conceptually acceptable and unacceptable ranges of change. Through a framework of biological criteria and biological impairment standards, the results of response monitoring can become an integral part of future water resource management strategies in South Africa.  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