The wilderness use simulation model applied to Colorado River boating in Grand Canyon National Park,USA

A modification of the Shechter-Lucas Wilderness Use Simulation Model (WUSM) for peak season boating on the Colorado River through Grand Canyon National Park, USA, is evaluated as a tool for making management decisions. A new microcomputer program to select trip itineraries for inclusion in the WUSM that was developed as part of this study is presented. This program simplifies user input and expands the WUSM's usefulness as a tool for management decisions by randomizing itinerary schedules based on probabilities developed from actual use of sites by canyon visitors. Model usefulness is demonstrated by simulating various management changes and comparing use levels of attraction sites and campgrounds as well as numbers of encounters between parties. The WUSM is being used as part of an ongoing study, to reflect the impact of fluctuating flow regimes through the turbines at Glen Canyon Dam on river trips.     

Vegetation and soil recovery in wilderness campsites closed to visitor use

Recreational use of wilderness results in impacts to vegetation and soil in trails and campsites. Traditionally, campsite impact studies have compared campsites receiving various levels of use with unused control areas. Field studies in Sequoia National Park, California, indicate that the degree of impact to vegetation and soils also varies within campsites. The central areas of campsites, where trampling is concentrated, show lower plant species diversity, differences in relative species cover, more highly compacted soils, and lower soil nutrient concentrations than do peripheral, moderately trampled, and untrampled areas within the same campsite. Three years after closure to visitor use, the central areas show less increase in mean foliar plant cover, and soils remain more highly compacted than in previously moderately trampled areas of the same sites. Changes in relative species cover over time are used to assess both resiliency to trampling and species composition recovery within campsites closed to visitor use.     

Evaluation of anthropogenic atmospheric inputs on US national park ecosystems

It is estimated that more than half the threats to national park resources originate outside park boundaries, and most threats are attributable to degradation of air and water quality. Atmospheric contaminants are the principal source of external threats to national park ecosystems. This article examines the potential impact to national park resources by anthropic atmospheric inputs and summarizes present research methods and results regarding impacts. Air quality monitoring currently receives much more emphasis and support than effects research. Present research on effects focuses on vegetation impact, biomonitoring, and acid rain. This research and that of other investigators suggest that the most likely impacts will not be direct cause-effect situations, but indirect, incremental, and possibly synergistic effects on the interactions of ecosystem components. Conceptually, such alteration of interactions can be measured through long-term observation of biogeochemical cycles, energy transfer, and community structure and function. But traditional Park Service research has not emphasized the ecosystem and especially ecosystem processes and component interactions. Most research on effects, then, must begin with baseline data acquisition. A research program to mitigate present national data base deficiencies would require a fundamental change in present research priorities, administration, and funding.     

Are bison exotic in the Wrangell-St. Elias National Park and Preserve?

The effect of past distributions of animal populations now extinct in an area from unknown causes is considered relative to their status as exotic or native in national parks. The example is the bison (Bisonbison) on the Copper and Chitina river drainages in Alaska in the USA which was introduced prior to establishment of Wrangell-St. Elias National Park and Preserve. The fossil record suggests that bison were present as recently as 500 years ago in Alaska. The policy of the US National Park Service to maintain natural ecosystems and restrict or eliminate exotic species raises the issue of whether this species should be treated as exotic or native.     

MODERNIZATION OF NATIONAL WEATHER SERVICE RIVER FORECASTING TECHNIQUES1

The National Weather Service is nearing the conclusion of a five year period of transition from index type catchment modelling to the use of conceptual hydrologic models. The decision to make this technological change was based on an extensive research project in which various catchment models were tested in a wide variety of basins and their strong and weak points ascertained. This project is described. Some of the problems involved in the changeover, which are discussed, are practical parameter optimization methods, computer requirements for the more complex technology, data requirements, fitting of the catchment model to major river systems, training of personnel and staffing problems.     

Implementation of two new resource management information systems in Australia

This paper describes the development and implementation ofPREPLAN, A Pristine Environment Planning Language and Simulator, for two conservation areas in Australia, Kosciusko National Park (New South Wales) and Tutanning Nature Reserve (Western Australia).PREPLAN was derived from the North American gradient modeling systems and theForest Planning Language and Simulator (FORPLAN), but includes unique characteristics not previously available.PREPLAN includes an integrated resource management data base, modules for predicting site-specific vegetation, fuels, animals, fire behavior, and fire effects, and an English language instruction set.PREPLAN was developed specifically to provide available information and understanding of ecosystems to managers in a readily accessible and usable form, and to provide the motivation to conduct additional required research projects. An evaluation of the system's advantages and limitations is presented, and the way the utilization of such systems is improving natural area decision making throughout Australia is discussed.     

The development and applications of a Drought Early Warning System in Botswana*

This article describes the indicators and data sources used by the Botswana Drought Early Warning System formally established in early 1984, the main uses of the indicators in the assessment of drought conditions and the design of relief programmes are outlined. Limitations of the sources of data available are discussed, as is the feasibility of adding some possible further indicators. In conclusion, the importance of a functioning Early Warning System in a country highly susceptible to repeated droughts is stressed, in the context of die current effort to elaborate a comprehensive National Food Strategy and to establish a Regional Early Warning System for Southern Africa.     

Including past and present impacts in cumulative impact assessments

Environmental concerns such as loss of biological diversity and stratospheric ozone depletion have heightened awareness of the need to assess cumulative impacts in environmental documents. More than 20 years of experience with the National Environmental Policy Act (NEPA) have provided analysts in the United States with opportunities for developing successful techniques to assess site-specific impacts of proposed actions. Methods for analyzing a proposed action's incremental contribution to cumulative impacts are generally less advanced than those for project-specific impacts.The President's Council on Environmental Quality (CEQ) defines cumulative impact to include the impacts of past, present and reasonably foreseeable future actions regardless of who undertakes the action. Court decisions have helped clarify the distinction between reasonably foreseeable future actions and other possible future actions. This paper seeks to clarify how past and present impacts should be included in cumulative impact analyses.The definition of cumulative impacts implies that cumulative impact analyses should include the effects of all past and present actions on a particular resource. Including past and present impacts in cumulative impact assessments increases the likelihood of identifying significant impacts. NEPA requires agencies to give more consideration to alternatives and mitigation and to provide more opportunities for public involvement for actions that would have significant impacts than for actions that would not cause or contribute to significant impacts. For an action that would contribute to significant cumulative impacts, the additional cost and effort involved in increased consideration of alternatives and mitigation and in additional public involvement may be avoided if the action can be modified so that its contributions to significant cumulative impacts are eliminated.Managed by Lockheed Martin Energy Research Corporation under contract DE-AC05-84OR21400 with the US Department of Energy.     

Mercury photoreduction and photooxidation in lakes: Effects of filtration and dissolved organic carbon concentration

Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon(DOC) concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kejimkujik National Park, Nova Scotia(DOC: 2.6–15.4 mg/L). Filtered(0.2 μm) and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations(p = 0.04) of photoreducible divalent mercury(Hg(II)RED)(mean of 754 ± 253 pg/L) than filtered samples(mean of 482 ± 206 pg/L);however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DOC was not significantly related to gross photoreduction rate constants in filtered(R~2= 0.43; p = 0.08) and unfiltered(R~2= 0.02; p = 0.71) samples; DOC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DOC was significantly negatively related with Hg(Ⅱ)_(RED) in unfiltered(R2= 0.53; p = 0.04), but not in filtered samples(R~2= 0.04;p = 0.60). These trends indicate that DOC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg(Ⅱ)_(RED) in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DOC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.     

试论衡水湖湿地生态旅游开发

衡水湖国家级自然保护区不仅具有丰富的生物多样性、优美的自然风光,还有悠久的历史文化,具备开展生态旅游得天独厚的先决条件。本文初步探讨了衡水湖开展湿地生态旅游的优势和原则。