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601.
Sullivan TJ Moore JA Thomas DR Mallery E Snyder KU Wustenberg M Wustenberg J Mackey SD Moore DL 《Environmental management》2007,40(6):958-965
An experimental study was conducted in Tillamook, Oregon, USA, to quantify the effectiveness of edge-of-field vegetated buffers
for reducing transport of fecal coliform bacteria (FCB) from agricultural fields amended with dairy cow manure. Installation
of vegetated buffers on loamy soils dramatically reduced the bacterial contamination of runoff water from manure-treated pasturelands,
but the size of the vegetated buffer was not an important determinant of bacterial removal efficiency. Only 10% of the runoff
samples collected from treatment cells having vegetated buffers exhibited FCB concentrations >200 colony forming units (cfu)/100
mL (a common water quality standard value), and the median concentration for all cells containing vegetated buffers was only
6 cfu/100 mL. The presence of a vegetated buffer of any size, from 1 to 25 m, generally reduced the median FCB concentration
in runoff by more than 99%. Results for FCB load calculations were similar. Our results suggest that where substantial FCB
contamination of runoff occurs from manure-treated pasturelands, it might be disproportionately associated with specific field
or management conditions, such as the presence of soils that exhibit low water infiltration and generate larger volumes of
runoff or the absence of a vegetated buffer. Buffer size regulations that do not consider such differences might not be efficient
or effective in reducing bacterial contamination of runoff. 相似文献
602.
Assessment of Eutrophication in Estuaries: Pressure–State–Response and Nitrogen Source Apportionment 总被引:1,自引:0,他引:1
Whitall D Bricker S Ferreira J Nobre AM Simas T Silva M 《Environmental management》2007,40(4):678-690
A eutrophication assessment method was developed as part of the National Estuarine Eutrophication Assessment (NEEA) Program.
The program is designed to improve monitoring and assessment of eutrophication in the estuaries and coastal bays of the United
States with the intent to guide management plans and develop analytical and research models and tools for managers. These
tools will help guide and improve management success for estuaries and coastal resources. The assessment method, a Pressure-State-Response
approach, uses a simple model to determine Pressure and statistical criteria for indicator variables (where applicable) to
determine State. The Response determination is mostly heuristic, although research models are being developed to improve that
component. The three components are determined individually and then combined into a single rating. Application to several
systems in the European Union (E.U.), specifically in Portugal, shows that the method is transferable, and thus is useful
for development of management measures in both the Unites States and E.U. This approach identifies and quantifies the key
anthropogenic nutrient input sources to estuaries so that management measures can target inputs for maximum effect. Because
nitrogen is often the limiting nutrient in estuarine systems, examples of source identification and quantification for nitrogen
have been developed for 11 coastal watersheds on the U.S. east coast using the WATERSN model. In general, estuaries in the
Northeastern United States receive most of their nitrogen from human sewage, followed by atmospheric deposition. This is in
contrast to some watersheds in the Mid-Atlantic (Chesapeake Bay) and South Atlantic (Pamlico Sound), which receive most of
their nitrogen from agricultural runoff. Source identification is important for implementing effective management measures
that should be monitored for success using assessment methods, as described herein. For instance, these results suggest that
Northeastern estuaries would likely benefit most from improved sewage treatment, where as the Mid and South Atlantic systems
would benefit most from agricultural runoff reductions. 相似文献
603.
Yellow starthistle (Centaurea solsitialis L.) is an invasive weed that creates problems for the management of Idaho's rangelands. A bioeconomic approach combined with an input-output economic model is used to estimate direct and secondary economic costs of the weed in relation to its interference with agricultural and non-agricultural benefits that rangelands provide. Direct economic costs of the infestations were estimated to be of 8.2 million '05 dollars per year, and secondary costs of 4.5 million '05 dollars per year, for a total of 12.7 million '05 dollars; agricultural related economic impacts accounted for 79% of this total cost, and non-agricultural for 21%. 相似文献
604.
Assessment of the Water Quality and Ecosystem Health of the Great Barrier Reef (Australia): Conceptual Models 总被引:3,自引:0,他引:3
Haynes D Brodie J Waterhouse J Bainbridge Z Bass D Hart B 《Environmental management》2007,40(6):993-1003
Run-off containing increased concentrations of sediment, nutrients, and pesticides from land-based anthropogenic activities
is a significant influence on water quality and the ecologic conditions of nearshore areas of the Great Barrier Reef World
Heritage Area, Australia. The potential and actual impacts of increased pollutant concentrations range from bioaccumulation
of contaminants and decreased photosynthetic capacity to major shifts in community structure and health of mangrove, coral
reef, and seagrass ecosystems. A detailed conceptual model underpins and illustrates the links between the main anthropogenic
pressures or threats (dry-land cattle grazing and intensive sugar cane cropping) and the production of key contaminants or
stressors of Great Barrier Reef water quality. The conceptual model also includes longer-term threats to Great Barrier Reef
water quality and ecosystem health, such as global climate change, that will potentially confound direct model interrelationships.
The model recognises that system-specific attributes, such as monsoonal wind direction, rainfall intensity, and flood plume
residence times, will act as system filters to modify the effects of any water-quality system stressor. The model also summarises
key ecosystem responses in ecosystem health that can be monitored through indicators at catchment, riverine, and marine scales.
Selected indicators include riverine and marine water quality, inshore coral reef and seagrass status, and biota pollutant
burdens. These indicators have been adopted as components of a long-term monitoring program to enable assessment of the effectiveness
of change in catchment-management practices in improving Great Barrier Reef (and adjacent catchment) water quality under the
Queensland and Australian Governments’ Reef Water Quality Protection Plan. 相似文献
605.
Using GIS to Generate Spatially Balanced Random Survey Designs for Natural Resource Applications 总被引:2,自引:0,他引:2
Theobald DM Stevens DL White D Urquhart NS Olsen AR Norman JB 《Environmental management》2007,40(1):134-146
Sampling of a population is frequently required to understand trends and patterns in natural resource management because financial
and time constraints preclude a complete census. A rigorous probability-based survey design specifies where to sample so that
inferences from the sample apply to the entire population. Probability survey designs should be used in natural resource and
environmental management situations because they provide the mathematical foundation for statistical inference. Development
of long-term monitoring designs demand survey designs that achieve statistical rigor and are efficient but remain flexible
to inevitable logistical or practical constraints during field data collection. Here we describe an approach to probability-based
survey design, called the Reversed Randomized Quadrant-Recursive Raster, based on the concept of spatially balanced sampling
and implemented in a geographic information system. This provides environmental managers a practical tool to generate flexible
and efficient survey designs for natural resource applications. Factors commonly used to modify sampling intensity, such as
categories, gradients, or accessibility, can be readily incorporated into the spatially balanced sample design. 相似文献
606.
Jeffrey D. Fore Scott P. Sowa David L. Galat Gust M. Annis David D. Diamond Charles Rewa 《Environmental management》2014,53(3):567-582
Managers can improve conservation of lotic systems over large geographies if they have tools to assess total watershed conditions for individual stream segments and can identify segments where conservation practices are most likely to be successful (i.e., primary management capacity). The goal of this research was to develop a suite of threat indices to help agriculture resource management agencies select and prioritize watersheds across Missouri River basin in which to implement agriculture conservation practices. We quantified watershed percentages or densities of 17 threat metrics that represent major sources of ecological stress to stream communities into five threat indices: agriculture, urban, point-source pollution, infrastructure, and all non-agriculture threats. We identified stream segments where agriculture management agencies had primary management capacity. Agriculture watershed condition differed by ecoregion and considerable local variation was observed among stream segments in ecoregions of high agriculture threats. Stream segments with high non-agriculture threats were most concentrated near urban areas, but showed high local variability. 60 % of stream segments in the basin were classified as under U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) primary management capacity and most segments were in regions of high agricultural threats. NRCS primary management capacity was locally variable which highlights the importance of assessing total watershed condition for multiple threats. Our threat indices can be used by agriculture resource management agencies to prioritize conservation actions and investments based on: (a) relative severity of all threats, (b) relative severity of agricultural threats, and (c) and degree of primary management capacity. 相似文献
607.
Restoring prairie on formerly cultivated land begins by selecting propagule seed sources and the diversity of species to reintroduce. This study examined the effects of dominant grass propagule source (cultivar vs. non-cultivar) and sown propagule diversity (grass:forb sowing ratio) on plant community structure. Two field experiments were established in Kansas and Illinois consisting of identical split plot designs. Dominant grass source was assigned as the whole-plot factor, and sown dominance of grasses (five levels of seeded grass dominance) as the subplot factor. Species density, cover, and diversity were quantified for 5 years. The effect of dominant grass source on the cover of focal grasses, sown species, and volunteer species was contingent upon location, with variation between dominant grass sources observed exclusively in Kansas. Species density and diversity showed regionally convergent patterns in response to dominant grass source. Contrary to our hypotheses, total species density and diversity were not lower in the presence of grass cultivars, the grass source we had predicted would be more competitive. Sown grass dominance effects on the cover of the focal grass species were contingent upon location resulting from establishment corresponding better to the assigned treatments in Illinois. All other cover groups showed regionally convergent patterns, with lower cover of volunteers and higher cover of sown forbs, diversity, and species density in the lowest sown grass dominance treatment in both sites. Thus, decisions regarding the diversity of propagules to reintroduce had more consequence for plant community structure than cultivar or non-cultivar source of dominant grasses. 相似文献
608.
Vehicles on beaches cause numerous deleterious effects to coastal wildlife. These impacts may, hypothetically, be lessened if drivers act to reduce disturbance. Since it is unknown to what extent such behavior occurs, and whether it can reduce disturbance, we quantified the behavior of drivers who encountered birds on open-coast, sandy beaches in eastern Australia and the consequent bird responses. Drivers of commercial tourist buses never slowed or altered course (“evaded birds”) to avoid disturbing birds; conversely, 34 % of drivers of private cars did evade birds. Drivers of vehicles with fishing rod holders tended (P = 0.09) to evade birds more frequently than non-fishing vehicles. Evasion, when it occurred, was modest, and did not significantly decrease the intensity of bird response or the probability of escapes on the wing. Voluntary behavioral adjustments to alleviate impacts on wildlife may be unworkable, suggesting that other solutions (e.g., beach closures) might be the only effective and feasible way to reduce disturbance to birds on ocean beaches. 相似文献
609.
Robin Hickman Patricia Austin David Banister 《Journal of Environmental Policy & Planning》2014,16(3):419-435
AbstractA number of cities around the world are associated with very high levels of private motor car usage, and Auckland provides an example of one of these ‘hyperautomobile’ cities. There are many problems with this system of transportation and dependence on the private car, including environmental, social and city design dimensions. Though there is a clear aspiration to move towards reduced levels of car usage in the city's transport and spatial planning strategies, there are major difficulties in implementation terms. We develop and consider future scenarios to 2041 to reduce these levels of motorization, and subsequent transport CO2 emissions, with a much greater use of public transport, walking and cycling, urban planning, and low emission vehicles. The current implementability of such a ‘sustainable mobility’ future is however questioned in the current political and social context, and critically debated in terms of the available governance mechanisms and the limited attempts to shape the behaviour of the public. We conclude by calling for a reconsideration of the policy measures being considered, including the range and levels of application and investment; with a much wider framing of the transport planning remit, and carried out within a much stronger participatory framework for decision-making. 相似文献
610.
For species that form multi-generational and territorial family groups, resource-rich areas are predicted to support family dynasties in which one genetic lineage continuously occupies an area and may even expand to occupy surrounding areas. Data from a long-term study of Tasmanian native hens (Gallinula mortierii) support this prediction. The reproductive success and dispersal patterns of 18 hen lineages were monitored for seven breeding seasons and over several generations. The founder group with the highest average territory quality produced the highest total number of fledged young and the highest number of fledged linear descendants, accounting for 24% of the combined reproductive output of these 18 lineages. In the space of 6 years, this single genetic lineage expanded from one territory to occupy 12 of the 47 territories present in the population. This rate of expansion was over four times the population average for the same period. A multivariate analysis revealed that the success of a genetic lineage depended only on the number of high-quality territories surrounding the founder group. These results further demonstrate the resource-dependent nature of reproductive success in this species, and also highlight the potential importance of family dynasties in other cooperative species with complex social dynamics and dispersal patterns. 相似文献