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61.
62.
Revealing the Diversity of Natural Hydrologic Regimes in California with Relevance for Environmental Flows Applications 下载免费PDF全文
Belize A. Lane Helen E. Dahlke Gregory B. Pasternack Samuel Sandoval‐Solis 《Journal of the American Water Resources Association》2017,53(2):411-430
Alterations to flow regimes for water management objectives have degraded river ecosystems worldwide. These alterations are particularly profound in Mediterranean climate regions such as California with strong climatic variability and riverine species highly adapted to the resulting flooding and drought disturbances. However, defining environmental flow targets for Mediterranean rivers is complicated by extreme hydrologic variability and often intensive water management legacies. Improved understanding of the diversity of natural streamflow patterns and their spatial arrangement across Mediterranean regions is needed to support the future development of effective flow targets at appropriate scales for management applications with minimal resource and data requirements. Our study addresses this need through the development of a spatially explicit reach‐scale hydrologic classification for California. Dominant hydrologic regimes and their physio‐climatic controls are revealed, using available unimpaired and naturalized streamflow time‐series and generally publicly available geospatial datasets. This methodology identifies eight natural flow classes representing distinct flow sources, hydrologic characteristics, and catchment controls over rainfall‐runoff response. The study provides a broad‐scale hydrologic framework upon which flow‐ecology relationships could subsequently be established towards reach‐scale environmental flows applications in a complex, highly altered Mediterranean region. 相似文献
63.
借鉴美国加州南岸空气质量预报经验,特别是其运行管理模式对于现阶段中国城市环境空气质量预测预报具有极高的参考价值。简要介绍了加州南岸空气质量管理局(SCAQMD)空气质量预报业务流程、技术方法、信息发布方式和预报效果评估策略。建议从4个方面借鉴SCAQMD经验:(1)建立相对完善的空气质量预报体系,分层级自上而下指导预报工作;(2)选择合适的空气质量预报方法,综合统筹成本-效益评估工作;(3)评估预报效果进而提高预报准确率;(4)在优化空气质量预报能力的基础上,有序开展预警协同控制工作。 相似文献
64.
Geoffrey Wandesforde-Smith Iara Verocai Dias Moreira 《Environmental Impact Assessment Review》1985,5(3):223-238
EIA has been instituted in developing countries in the last decade largely in response to outside pressures. Governments have been quick to initiate reforms rather than jeopardize projects that might be key to national development plans. At the subnational level, most projects are not financed by foreign aid. The application of EIA at this level is often the result of pressure exerted on policy elites by the bureaucracy. This paper describes the reorganization of environmental protection agencies in the state of Rio de Janeiro in Brazil. This reorganization provided the setting for a bureaucratic initiative on EIA. The authors also analyze two cases in which EIA was applied unsatisfactorily and comment on the political realites of implementing EIA at the subnational level. 相似文献
65.
Differing Effects of Cattle Grazing on Native and Alien Plants 总被引:5,自引:0,他引:5
Abstract: Habitat managers use cattle grazing to reduce alien plant cover and promote native species in California grasslands and elsewhere in the western United States. We tested the effectiveness of grazing as a restoration method by examining the effects of herbivory on native and alien plants. At Carrizo Plain National Monument, California, we surveyed native and alien species cover in adjacent grazed and ungrazed areas. We also established experimental plots in which plants were clipped or mulch (dead biomass) was removed. In addition, we clipped plants grown in pots and plants in the field that grew with and without competitors. Native species were negatively affected by clipping in 1999, 2000, and 2001, whereas alien species were unaffected. In the experimental field plots, the European annual forb Erodium cicutarium compensated in growth and reproduction following simulated herbivory. In contrast, growth and reproduction of the native perennial bunchgrass Poa secunda were reduced 1 year after clipping. In pots, E. cicutarium overcompensated and grasses undercompensated. In the field, European grasses were unaffected by the removal of competitors. It is unclear by what mechanism E. cicutarium was able to compensate, but the ability may be related to its basal rosette growth form and indeterminately growing inflorescences. The native California grassland community assembled in the absence of grazing herds, whereas invasive European species have been exposed to grazing for centuries. It may be that these invaders have adaptations that better enable them to recover from grazing. In the grassland we studied, the strategy of livestock grazing for restoration is counterproductive. It harms native species and promotes alien plant growth. 相似文献
66.
Lynn L. Bergeson 《环境质量管理》2019,28(3):141-144
In the recent past, two important states—California and New York—have launched extensive and precedent‐setting ingredient disclosure laws regarding cleaning products with the clear goal of prompting the deselection of certain chemical substances and forcing product reformulation. Industry prefers to refer to this trend as “ingredient communication,” a goal we can all agree is desirable. By whatever name, these state measures will have a significant impact on ingredient disclosure trends across product lines, likely well beyond their stated application to cleaning products. These state laws are summarized below, followed by a discussion of their similarities, key differences, and their implications. 相似文献
67.
Gina M. Skurka Darin Steve Schoenig Jacob N. Barney F. Dane Panetta Joseph M. DiTomaso 《Journal of environmental management》2011
Large geographic areas can have numerous incipient invasive plant populations that necessitate eradication. However, resources are often deficient to address every infestation. Within the United States, weed lists (either state-level or smaller unit) generally guide the prioritization of eradication of each listed species uniformly across the focus region. This strategy has several limitations that can compromise overall effectiveness, which include spending limited resources on 1) low impact populations, 2) difficult to access populations, or 3) missing high impact populations of low priority species. Therefore, we developed a novel science-based, transparent, analytical ranking tool to prioritize weed populations, instead of species, for eradication and tested it on a group of noxious weeds in California. For outreach purposes, we named the tool WHIPPET (Weed Heuristics: Invasive Population Prioritization for Eradication Tool). Using the Analytic Hierarchy Process that included expert opinion, we developed three major criteria, four sub-criteria, and four sub-sub-criteria, taking into account both species and population characteristics. Subject matter experts weighted and scored these criteria to assess the relative impact, potential spread, and feasibility of eradication (major criteria) for 100 total populations of 19 species. Species-wide population scores indicated that conspecific populations do not necessarily group together in the final ranked output. Thus, priority lists based solely on species-level characteristics are less effective compared to a blended prioritization based on both species attributes and individual population and site parameters. WHIPPET should facilitate a more efficacious decision-making process allocating limited resources to target invasive plant infestations with the greatest predicted impacts to the region under consideration. 相似文献
68.
Abstract: Current conservation mitigation plans often fail to ensure full in-kind habitat replacement for endangered species, which suggests the need for improved methods for calculating mitigation credits. A simple, yet biologically meaningful method for calculating mitigation credits would be to let the number of mitigation credits assigned to a parcel of land scale with the reproductive value of the individuals occupying that parcel. This can be accomplished by dividing the population into 2 or more subdivisions with different reproductive values, calculating the densities of these subdivisions as a function of one or more habitat parameters, and then forming a weighted sum of these densities such that each density distribution is weighted by the reproductive value of its respective subdivision of the population. This weighted sum is the density distribution of reproductive value, and by integrating it over a particular parcel, one can determine the mitigation value of that parcel. We carried out this procedure for a population of California tiger salamanders ( Ambystoma californiense ), with distance from breeding site as our habitat parameter and the 3 visually identifiable age classes (adults, juveniles, and metamorphs) as our population subdivisions. This led to a density distribution of reproductive value that decreased exponentially with increasing distance from a breeding site. Mitigation strategies derived from this function will be more likely to ensure the persistence of California tiger salamander populations than current approaches, which assign all land within 1.6 km of a breeding site the same mitigation value. Use of the density distribution of reproductive value as a basis for mitigation plans is a procedure that can be applied to all endangered species, and it should improve the quality of mitigation decisions. 相似文献
69.
All JD 《Environmental management》2007,40(1):7-11
In this issue of Environmental Management, Glenn and others posit that a previous study had analytical and interpretive errors
in analysis of shrimp fishing in the Upper Gulf of California, Mexico. Unfortunately, much of their evidence is too indirect
and of insufficient scale to address the central question of salinity in the Upper Gulf. Also, many of their suppositions
did not include direct interviews with local officials or a robust understanding of remote sensing literature. This response
to their rebuttal presents a set of figures and analysis demonstrating that the Colorado River flows into a closed evaporative
basin known as the Laguna Salada and thus cannot flow into the Gulf of California. Readers are asked to examine the images
and interpret their meaning for themselves. 相似文献
70.
Many California streams have been adversely affected by sedimentation caused by historic and current land uses, including
timber harvesting. The impacts of timber harvesting and logging transportation systems on erosion and sediment delivery can
be directly measured, modeled, or inferred from water quality measurements. California regulatory agencies, researchers, and
land owners have adopted turbidity monitoring to determine effects of forest management practices on suspended sediment loads
and water quality at watershed, project, and site scales. Watershed-scale trends in sediment discharge and responses to current
forest practices may be estimated from data collected at automated sampling stations that measure turbidity, stream flow,
suspended sediment concentrations, and other water quality parameters. Future results from these studies will provide a basis
for assessing the effectiveness of modern forest practice regulations in protecting water quality. At the project scale, manual
sampling of water column turbidity during high stream flow events within and downstream from active timber harvest plans can
identify emerging sediment sources. Remedial actions can then be taken by managers to prevent or mitigate water quality impacts.
At the site scale, manual turbidity sampling during storms or high stream flow events at sites located upstream and downstream
from new, upgraded, or decommissioned stream crossings has proven to be a valuable way to determine whether measures taken
to prevent post-construction erosion and sediment production are effective. Turbidity monitoring at the project and site scales
is therefore an important tool for adaptive management. Uncertainty regarding the effects of current forest practices must
be resolved through watershed-scale experiments. In the short term, this uncertainty will stimulate increased use of project
and site-scale monitoring. 相似文献