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491.
/ The management of riverine wetlands, recognized as a major component of biodiversity in fluvial hydrosystems, is problematic. Preservation or restoration of such ecosystems requires a method to assess the major ecological processes operating in the wetlands, the sustainability of the aquatic stage, and the restoration potential of each riverine wetland. We propose a method of diagnosis based on aquatic macrophytes and helophytes. Plant communities are used because they are easy to survey and provide information about (1) the origin of a water supply (i.e., groundwater, seepage, or surface river water) and its nutrient content, (2) effects of flood disturbances, and (3) terrestrialization processes. The novelty of the method is that, in contrast to available typologies, it is based on the interference of gradients resulting from several processes, which makes it possible to predict wetland sustainability and restoration potential. These predictions result from knowledge of the processes involved in terrestrialization, i.e., the influence of flood disturbances, occurrence of groundwater supplies, trophic degree, and water permanency of the habitat during a yearly cycle. The method is demonstrated on five different river systems. 相似文献
492.
493.
Timothy D. Mayer Seth W. Naman 《Journal of the American Water Resources Association》2011,47(4):724-738
Mayer, Timothy D. and Seth W. Naman, 2011. Streamflow Response to Climate as Influenced by Geology and Elevation. Journal of the American Water Resources Association (JAWRA) 47(4):724‐738. DOI: 10.1111/j.1752‐1688.2011.00537.x Abstract: This study examines the regional streamflow response in 25 predominately unregulated basins to warmer winter temperatures and snowpack reductions over the last half century in the Klamath Basin of California and Oregon. Geologic controls of streamflow in the region result in two general stream types: surface‐dominated and groundwater‐dominated basins. Surface‐dominated basins were further differentiated into rain basins and snowmelt basins on the basis of elevation and timing of winter runoff. Streamflow characteristics and response to climate vary with stream type, as discussed in the study. Warmer winter temperatures and snowpack reductions have caused significantly earlier runoff peaks in both snowmelt and groundwater basins in the region. In the groundwater basins, the streamflow response to changes in snowpack is smoothed and delayed and the effects are extended longer in the summer. Our results indicate that absolute decreases in July‐September base flows are significantly greater, by an order of magnitude, in groundwater basins compared to surface‐dominated basins. The declines are important because groundwater basins sustain Upper Klamath Lake inflows and mainstem river flows during the typically dry summers of the area. Upper Klamath Lake April‐September net inflows have decreased an estimated 16% or 84 thousand acre‐feet (103.6 Mm3) since 1961, with the summer months showing proportionately more decline. These changes will exacerbate water supply problems for agriculture and natural resources in the region. 相似文献
494.
Species with partial migration, where a portion of a population migrates and the other remains residential, provide the opportunity to evaluate conditions for migration and test mechanisms influencing migratory decisions. We conducted a five-year study of two populations of red-spotted newts (Notophthalmus viridescens), composed of individuals that either remain as residents in the breeding pond over the winter or migrate to the terrestrial habitat. We used multistate mark-recapture methods to (1) test for differences in survival probability between migrants and residents, (2) determine if migrants breed every year or skip opportunities for reproduction, and (3) estimate the frequency of individuals switching migratory tactic. We used estimates of life history parameters from the natural populations in combination with previous experimental work to evaluate processes maintaining partial migration at the population level and to assess mechanisms influencing the decision to migrate. Based on capture-recapture information on over 3000 individuals, we found that newts can switch migratory tactics over their lifetime. We conclude that migrants and residents coexist through conditional asymmetries, with residents having higher fitness and inferior individuals adopting the migrant tactic. We found that newts are more likely to switch from residency to migrating than the reverse and males were more likely to remain as residents. Migration differences between the sexes are likely driven by reproduction benefits of residency for males and high energetic costs of breeding resulting in lower breeding frequencies for females. Environmental conditions also influence partial migration within a population; we found support for density-dependent processes in the pond strongly influencing the probability of migrating. Our work illustrates how migration can be influenced by a complex range of individual and environmental factors and enhances our understanding of the conditions necessary for the evolution and maintenance of partial migration within populations. 相似文献
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496.
Oruko Richard O. Edokpayi Joshua N. Msagati Titus A.M. Tavengwa Nikita T. Ogola Henry J.O. Ijoma Grace Odiyo John O. 《Environmental science and pollution research international》2021,28(31):42135-42149
Environmental Science and Pollution Research - To mitigate the negative environmental and public health concerns associated with increased industrial discharges amid the rapid industrial growth,... 相似文献
497.
In recent years, commodity markets show a large amount of volatility and substantial price jumps, indicating an increasing economic scarcity in many cases. As this scarcity makes commodity procurement a critical issue for national economies, industry sectors and manufacturing companies, a number of criticality indices have been presented and utilized in science as well as in practice. These indices are mostly based on an aggregation of different key figures, both qualitative and quantitative. However, the weighting of the different factors is in most cases arbitrary or based on rough estimates. 相似文献
498.
Smart growth policies direct development towards existing communities already served by roads, sewer systems and other infrastructure. The increased development in these communities in turn should enable them to benefit from a stronger tax-base, more efficient use of their schools and other public facilities, and the renewed economic vitality of their urban centres. These goals and objectives appear to complement and support the efforts of urban mayors to attract new property tax rateables and better-paying jobs, but they may conflict with the desires of residents to reduce densities and improve the quality of life. We use a visual GIS-based model to assist five small contiguous older suburbs individually and collectively to evaluate their current redevelopment plans and to understand the implications of their land-use decisions on the quality of life in their communities. By bringing them together as a group, and our raising broader redevelopment and impact issues, they have begun to rethink how these properties could be best used to meet the community's needs and to see them in the context of similar redevelopment plans within their mini-region. One of the changes emerging is a greater role for certain types of residential development and a concurrent reduction in the amount of commercial space being considered. The authors would like to thank the Geraldine R. Dodge Foundation for funding this project, the Somerset County Planning Board and mayors of the five towns for actively supporting and participating in the study and the Regional Planning Partnership for its co-operation and assistance in refining its GOZ model to promote regional planning from the bottom up. The authors accept full responsibility for the ideas and recommendations in this report. 相似文献
499.
Henry Musoke Semakula 《中国人口.资源与环境(英文版)》2013,11(3):59-66
Abstract The health impacts of tobacco consumption are well documented and have gained acceptance worldwide. Today, a substantial, preventable burden of tobacco attributable diseases exists in most countries, though in most of the cases, unknown. Smoking accounts for almost half of the deaths in middle age in some regions. In Uganda, translating findings into policy action is slow and involves several stakeholders. It will continue to require support from tobacco control campaign groups. This paper analyses secondary literature on tobacco smoking and later provides an appropriate medium based communication strategy that can be adopted to counteract the persuasive smoking evil adverts of tobacco companies as well as creating awareness among the population of the health impacts caused by smoking. 相似文献