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141.
John C. Clausen Kenneth N. Brooks 《Journal of the American Water Resources Association》1983,19(5):769-772
ABSTRACT The impacts of milled peat mining on runoff quality in northern Minnesota were determined using a multiple watershed approach. The frequency distributions of water quality constituents were used to detect whether runoff from a mined bog differed from that of 15 unmined (control) bogs. Peat mining increased water temperature, suspended sediment, specific conductance and concentrations of acidity, iron, sodium, and nitrogen species, although drinking water standards were not exceeded (α= 0.05). The method presented may be applicable for other nonpoint pollution investigations. 相似文献
142.
Human-induced impacts from recreational use of wilderness continue to be a significant management challenge, threatening the integrity of the wilderness resource and the quality of visitor experiences. Campsite impacts are of particular concern to managers. One approach to this problem is the Limits of Acceptable Change (LAC) planning system, which focuses attention on the question, “How much change in wilderness conditions is acceptable?” The research reported here compares and contrasts wilderness manager and visitor perceptions of theacceptability of different levels of campsite impacts,amount of impact, and perceptual zoning of wilderness. The results reinforce previous findings regarding differences between managers and visitors. Management implications are discussed. 相似文献
143.
Fred R. Kuss 《Environmental management》1986,10(5):637-650
This article reviews some of the more important factors found to influence the susceptibility of plants to trampling impacts associated with recreational use of natural areas. A three-way interaction mediates plant responses to impacts: plant x environment x stress level(s). Plant responses vary in part according to the genetic constitution of the plant, life and growth form, the adaptive flexibility of the plant, and anatomical differences inherent to growth habit and morphology. Other factors that influence plant sensitivities to impacts are the habitat environments in which plants grow, since a number of conditions such as moisture excesses or deficiencies, nitrogen or oxygen starvation, late frosts, etc., cause physiological injury and may increase plant sensitivity to impacts. Among the environmental factors that may increase or lessen plant sensitivities to impacts are soil moisture levels, canopy density, elevation, aspect, microclimate, soil drainage, texture, fertility and productivity. Seasonal influences also bear consideration since environmental changes and phonological and physiological events are mediated by time of year. Stresses are caused by both direct and indirect forms of impact and vary according to season of use, frequency and amount of use, and the type of activity. These interactions are further complicated by evidence that inter- and intraspecific competition, antagonism, and commensalism may influence differences in the sensitivity of plant communities to impacts. 相似文献
144.
G. Mathias Kondolf J. Warren Webb Michael J. Sale Thomas Felando 《Environmental management》1987,11(6):757-769
As the number of proposals to divert streamflow for power production has increased in recent years, interest has grown in predicting the impacts of flow reductions on riparian vegetation. Because the extent and density of riparian vegetation depend largely on local geomorphic and hydrologic setting, site-specific geomorphic and hydrologic information is needed. This article describes methods for collecting relevant hydrologic data, and reports the results of such studies on seven stream reaches proposed for hydroelectric development in the eastern Sierra Nevada, California, USA. The methods described are: (a) preparing geomorphic maps from aerial photographs, (b) using well level records to evaluate the influence of streamflow on the riparian water table, (c) taking synoptic flow measurements to identify gaining and losing reaches, and (d) analyzing flow records from an upstream-downstream pair of gages to document seasonal variations in downstream flow losses. In the eastern Sierra Nevada, the geomorphic influences on hydrology and riparian vegetation were pronounced. For example, in a large, U-shaped glacial valley, the width of the riparian strip was highly variable along the study reach and was related to geomorphic controls, whereas the study reaches on alluvial fan deposits had relatively uniform geomorphology and riparian strip width. Flow losses of 20% were typical over reaches on alluvial fans. In a mountain valley, however, one stream gained up to 275% from geomorphically controlled groundwater contributions. 相似文献
145.
Jeffrey M. Klopatek 《Environmental management》1988,12(5):703-711
Problems of using food chain support as a functional attribute of a wetland are discussed. It is suggested that primary production may not be the metric that best evaluates food chain support. Environmental constructs of the wetland and resultant habitat variables appear to yield more information on life-support functions. A landscape-oriented approach is derived to separate hierarchically the wet-lands into ecological regions and landscape elements. This classification scheme allows for predetermination of environmental constraints and the possible natural limits of wetland food chain support. It is proposed that models derived from spatial location theory be used to determine the movement of animals from wetland patches experiencing impacts on food chain support. Patch size, distance between patches, habitat diversity, and environmental constraints are incorporated in these models. 相似文献
146.
Frederick M. Fisher Kenneth L. Dickson John H. Rodgers Keith Anderson John Slocomb 《Journal of the American Water Resources Association》1988,24(5):1017-1026
ABSTRACT: A method to partition the variation in concentrations of water chemistry parameters in a river is described. The approach consists of fitting a family of curves for each chemical parameter. Each curve indicates the response of the parameter to river flow for a particular time period or location. An analysis of covariance is then used to identify statistically significant differences between curves. Such differences result largely from two factors: (1) the discharge of effluents and (2) river flow-concentration relationships. The deviations from the fitted curves indicate month-to-month variations unrelated to river flow that are controlled by factors such as temperature-related seasonal patterns. Underlying statistical assumptions are discussed with respect to water chemistry data. The technique is applied to a data set consisting of monthly samples of 22 water chemistry parameters from the Sulphur River of Texas and Arkansas. Several patterns of response to river flow and to two effluent discharges were revealed. 相似文献
147.
Impacts of Recreation Trails on Exotic and Ruderal Species Distribution in Grassland Areas Along the Colorado Front Range 总被引:1,自引:0,他引:1
This study examines the establishment patterns of exotic and ruderal species along trail corridors in grassland areas of the Colorado Front Range. The effects of trail presence, trail age, and trail traffic levels on exotic and ruderal species establishment are explored to ascertain the potential impacts of trails on surrounding vegetation. Established trails exhibited a greater presence of exotic and ruderal species along the immediate trailside, showing that disturbed trailsides tend to encourage the growth of these species over time. Furthermore, the established trails exhibited significantly less native, nonruderal, and overall species richness at the trailside. These trailside patterns did not show a significant spread away from the trail edge, even after prolonged time periods. Finally, higher trail use tended to hasten the establishment of exotic species along the trailside. The trails did not introduce new species to the recreation areas; rather they acted as reorganizational tools for species that were already present in the study sites. 相似文献
148.
Socio-Ecological Impact and Risk Assessments in the Urban Environment: A Multidisciplinary Concept from Hong Kong 总被引:1,自引:0,他引:1
L.M. Marafa 《The Environmentalist》2002,22(4):377-385
This paper discusses the increasing importance of the environment to social scientists. A multidisciplinary approach is highlighted and it is argued that the social sciences have a more significant role to play in understanding and responding to environmental deterioration than has hitherto been the case. The need for harmonizing multidisciplinarity in appreciating impact assessments is emphasized. A framework for analyzing and containing environmental impacts in Hong Kong is also proposed. 相似文献
149.
This study examined the comparability of onsite and offsite methods for measuring norms for trail impacts using photo/survey
techniques. A total of 449 subjects participated in a study of Mudeung-Mountain Provincial Park, Gwang-Ju, Korea. For the
overall photo evaluation method (OPEM), respondents rated the acceptability of bare soil area for each of a series of photographs.
For the specific photo evaluation method (SPEM), respondents selected a photograph that illustrated the largest acceptable
proportion of bare soil area from a series of 10 photographs. Overall, there were no substantial differences in maximum acceptable
impacts between onsite (onsite-I visitor group surveyed at the actual trail points and onsite-II departing visitor group surveyed
at the exit area) and offsite (students surveyed in a laboratory setting) groups for the two norm measurement alternatives
(OPEM and SPEM). Subjects’ difficulty ratings were low for both methods, and there were no substantial differences in norms
between individuals with high and low levels of experience at the park. The offsite method appears to be substitutable for
onsite methods in this particular study area, which is a frontcountry setting with a relatively simple range of recreation
opportunities. Implications and further studies are discussed. 相似文献
150.
Fast economic and social changes in recent years in China have brought massive expansion, redevelopment, and restructuring
of cities. These changes offer cities the opportunity to improve environmental quality through urban green spaces (UGSs) and
to address the challenges of meeting community aspirations. This study explored peoples’ minds concerning UGSs in Guangzhou
city in south China in relation to the following: (1) knowledge and perception of 25 ecosystem services and 8 negative impacts;
(2) attitude toward site condition and management; (3) expectation of landscape design; and (4) preference ranking of venues.
A questionnaire was designed to solicit opinions from 340 respondents randomly chosen from residents living in the study area.
The results indicated widespread recognition of ecosystem services and strong support of UGS programs. Negative responses
were weakly expressed. Amelioration of urban microclimate and environmental quality were emphasized. Environmental functions
stressed in publicity programs, together with aggravating environmental problems in the city, tended to focus respondents’
attention on UGS benefits. Wildlife habitat, species conservation and other natural ecosystem services drew limited concerns.
Awareness of economic benefits was very low. Visual-landscape contributions with strong preference for naturalistic design
and recreational benefits were highlighted. Compared with other countries, Guangzhou residents were characterized by visual–scenic–recreation
orientation and pragmatic–utilitarian perception of UGSs, reflecting underlying differences in the understanding of inherent
ecosystem services of green spaces. Relevant UGS policies and practices could adopt the approaches of market survey, citizen
participation, and precision planning in order to meet increasingly mature and refined demands. Citizens’ understanding of
high-order ecosystem services could be enhanced to encourage appreciation of nature and their associated benefits. 相似文献