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101.
Fred J. Brenner William Kanour Bruce Weston Gerald Valerio Kenneth R. Grayburn 《Environmental management》1986,10(2):241-253
A study of the impact of two flood control reservoirs and pollution influx was conducted on two streams within the Sandy Creek Watershed, Mercer County, Pennsylvania, USA. Fecal coliforms were significantly reduced in the outflows without affecting water chemistry, thereby improving the overall water quality. The size and composition of the aquatic communities as well as stream metabolism varied seasonably among the different sampling stations. Pollution influx primarily from communities and agricultural drainage had a greater impact on the stream ecosystem than did impounding of the streams. Natural wetlands and riparian vegetation were important factors in reducing the pollution load in these streams. The reestablishment and maintenance of riparian vegetation should therefore be an integral part of the land-use plan for watersheds in order to improve water quality and wildlife habitats. In the future, the maintenance of riparian vegetation should be given prime consideration in the development of watershed projects. 相似文献
102.
Gerald F. Gifford William Humphries Richard A. Jaynes 《Journal of the American Water Resources Association》1984,20(2):181-186
ABSTRACT: Heat pulse velocity techniques were developed for effective monitoring of water movement in aspen (Populus tremuloides), subalpine fir (Abies lasiocarpa), and Englemann spruce (Picea engelmannif). Water loss was monitored in replicated trees of each species for one year. These data were used to modify the plant activity index (a reflection of the ability of plants to transpire water at various times during a year) and the crop coefficient (a reflection of differences in consumptive use rates of water by different vegetation types when all other factors are held constant) for each species within the model ASPCON, a deterministic, lumped-parameter model describing the hydrology of aspen to conifer succession. Results of the modeling in dicate 18.6 cm net loss of moisture available for streamflow when spruce replaced aspen, and a loss of 7.2 cm when fir forests replaced aspen. The aspen to conifer successional trend appears, therefore, to be significantly reducing water yields in the western United States. 相似文献
103.
R. Gerald Wright 《Environmental management》1984,8(2):121-124
Legislation settling the Alaska Native Lands Claims also resulted in the establishment of ten new parks and preserves in Alaska. This settlement was the result of a long and often bitter legislative struggle between pro- and antidevelopment groups. The planning history of the Wrangell-St. Elias National Park and Preserve is used as a case example of this debate. One particular source of conflict was the curtailment of sport hunting that would result under national park classification. A preserve classification was introduced to resolve this conflict. Data on wildlife resources and sport hunting were instrumental in defining the areas so classified. 相似文献
104.
Bronwen Jones 《Natural resources forum》2006,30(2):124-135
The UK reviewed its National Sustainable Development Strategy during 2003 and 2004, and produced a new strategy — the third for the UK — in March 2005. Having established that the main weakness of the previous strategy was in its delivery, the review and the resulting new strategy set out to put a much stronger emphasis on delivery mechanisms. In support of this, the process included more participative ways for those involved in delivering to contribute their views and ideas, including web‐based dialogue, participative events and seminars, and community level discussions. The key points for the success of the project were the involvement of stakeholders; project management of the process; a marketing and communications strategy; cross‐departmental governance; and involvement of an external challenge function (fulfilled in the UK by the Sustainable Development Commission). 相似文献
105.
106.
Recovery of temperate-stream fish communities from disturbance: A review of case studies and synthesis of theory 总被引:3,自引:0,他引:3
Naomi E. Detenbeck Philip W. DeVore Gerald J. Niemi Ann Lima 《Environmental management》1992,16(1):33-53
To evaluate the relative effect of autecologic factors, site-specific factors, disturbance characteristics, and community
structure on the recovery of temperate-stream fish communities, we reviewed case histories for 49 sites and recorded data
on 411 recovery end points. Most data were derived from studies of low-gradient third- or fourth-order temperate streams located
in forested or agricultural watersheds. Species composition, species richness, and total density all recovered within one
year for over 70% of systems studied. Lotic fish communities were not resilient to press disturbances (e.g., mining, logging,
channelization) in the absence of mitigation efforts (recovery time >5 to >52 yr) and in these cases recovery was limited
by habitat quality. Following pulse disturbances, autecological factors, site-specific factors, and disturbance-specific factors
all affected rates of recovery. Centrarchids and minnows were most resilient to disturbance, while salmonid populations were
least resilient of all families considered. Species within rock-substrate/nest-spawning guilds required significantly longer
time periods to either recolonize or reestablish predisturbance population densities than did species within other reproductive
guilds. Recovery was enhanced by the presence of refugia but was delayed by barriers to migration, especially when source
populations for recolonization were relatively distant. Median population recovery times for systems in which disturbances
occurred during or immediately prior to spawning were significantly less than median recovery times for systems in which disturbances
occurred immediately after spawning. There was little evidence for the influence of biotic interactions on recovery rates. 相似文献
107.
It is common to use the results of various solid-phase and aqueous-fraction toxicity tests as part of the decision-making
process for selecting disposal options for dredged sediments. The mere presence of toxicity, however, does not provide a logical
basis for selecting economical, environmentally protective disposal techniques. To achieve this, it is necessary to be able
to identify specific compounds responsible for sediment toxicity. Toxicity identification evaluation (TIE) procedures, originally
developed for complex effluents, represent a useful approach for identifying acutely toxic compounds in dredged materials.
Herein we present a conceptual overview for TIE use in part of the decision-making framework for selecting dredged material
disposal options; included are discussions concerning appropriate test fractions and species for TIE analyses, and specific
TIE manipulations useful for ascertaining whether toxicity is due to any of a number of common sediment contaminants including
ammonia, hydrogen sulfide, metals, or nonpolar organics. 相似文献
108.
Gerald Pollio 《Natural resources forum》1993,17(3):191-197
Energy finance has resurfaced as a major issue in energy and energy policy debates. These concerns arise from the recent dismal performance of the private oil industry, and the growing financial demands of the former Soviet Union and other emerging markets. These growing financial imbalances are seen as jeopardizing the continued smooth growth of the world's petroleum industry. However, this paper stresses that the financial difficulties being experienced by publicly held oil companies are due, primarily, to the current economic recession. As economic growth recovers, and owing to recent substantial cost reductions, the balance sheets of the private oil industry will improve. Among state energy companies, recent structural and financial reforms mean that such companies will be able to retain more cash flow than was true historically. Moreover, many national oil companies are again able to access funds on international financial markets and generally at increasingly attractive spreads. And finally, there is the growing importance of financial innovation that is already having a positive impact on the level and pace of petroleum development worldwide. 相似文献
109.
This study investigated the potential for wildlife feeding to artificially increase population densities of the Australian brush-turkey, Alectura lathami and assessed the indirect adverse effects that this may have on surrounding forest floor vegetation. Census counts and observations of feeding activity conducted in recreation areas of Australia's Gold Coast hinterland confirmed that brush-turkey population densities were significantly elevated by the provision of food by humans. Brush-turkey densities were high at sites where birds are actively fed, moderate at sites where birds feed opportunistically and low at sites where humans have negligible impact on local food availability. Brush-turkeys caused significant environmental impact at sites where their population densities have been substantially elevated by active feeding. Across all sites, increases in brush-turkey density were accompanied by a significant decline in ground cover, leaf litter weight, seed density and seedling density. Natural environmental variables such as gradient, vegetation type and canopy cover did not explain the observed impacts. The impacts were consistent with those described in trampling studies and suggest that at high density, even small animals can have significant trampling impacts on their local environment. This study demonstrates that wildlife feeding can have detrimental impacts on the integrity of local environments and recommends greater consideration of small animals and their potential indirect impacts when regulating wildlife feeding in National Parks and other nature conservation areas. 相似文献
110.
This study investigates the relationship between characteristics of environmental policy statements and the reputations of ISO 14001 registrars who had performed certification audits of firms operating in mainland China. Three characteristics of environmental policy statements were examined: (1) The conformance of the policy to strict interpretations of the international standard; (2) The policy statement's adherence to the good practice guidelines specified in ISO 14004; and, (3) Self-reported evaluations of the policy statement's effectiveness as implemented. Data from 106 facilities in Beijing, Shanghai and Guangzhou reveal that registrar quality has a relatively weak, positive relationship with conformance to both ISO 14001 standards and to ISO 14004 guidelines, but no relationship was observed with the self-reported data. Additional findings are that the use of foreign registrars is significantly associated with the adoption of ISO 14004 guidelines and that conformance with ISO 14001 standards is somewhat higher for international joint ventures and foreign-owned firms than for state-owned enterprises. 相似文献