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971.
We conducted field surveys and laboratory analyses to test the effects of soil characteristics in habitat mitigation sites and natural sites on the growth and condition of blue elderberry (Sambucus mexicana), which is the sole host plant for the federally threatened Valley elderberry longhorn beetle (Desmocerus californicus dimorphus). Thirty mitigation and 16 natural sites were selected throughout the range of the beetle. We found that although plant relative growth rates were comparable between mitigation sites and a natural site, mitigation sites contained substantially less soil nutrients than mitigation sites. Within mitigation sites, elderberry health and growth were positively correlated with the amount of total nitrogen in soils and less strongly with other soil nutrients and soil moisture. Analyses demonstrated reductions in the relative growth rate of elderberry as mitigation sites aged, and that soil nutrients and soil moisture became depleted over time. For mitigation sites, it took approximately seven years to develop basal stem diameters that have been linked to successful beetle colonization. Mitigation sites have smaller shrubs than natural sites and growth slows as mitigation sites age, thus delaying convergence of conditions between natural and mitigation sites. Analyses of soil particle size and whether sites were within the 100-year floodplain (as an indicator of riparian conditions) were inconclusive. We recommend investigating fertilizing and optimum planting densities for elderberry at restoration and mitigation sites, as well as increasing the duration of irrigation and monitoring.  相似文献   
972.
973.
We conducted case studies of three successful examples of collaborative, community-based natural resource conservation and development. Our purpose was to: (1) identify the functions served by interactions within the social networks of involved stakeholders; (2) describe key structural properties of these social networks; and (3) determine how these structural properties varied when the networks were serving different functions. The case studies relied on semi-structured, in-depth interviews of 8 to 11 key stakeholders at each site who had played a significant role in the collaborative projects. Interview questions focused on the roles played by key stakeholders and the functions of interactions between them. Interactions allowed the exchange of ideas, provided access to funding, and enabled some stakeholders to influence others. The exchange of ideas involved the largest number of stakeholders, the highest percentage of local stakeholders, and the highest density of interactions. Our findings demonstrated the value of tailoring strategies for involving stakeholders to meet different needs during a collaborative, community-based natural resource management project. Widespread involvement of local stakeholders may be most appropriate when ideas for a project are being developed. During efforts to exert influence to secure project approvals or funding, however, involving specific individuals with political connections or influence on possible sources of funds may be critical. Our findings are consistent with past work that has postulated that social networks may require specific characteristics to meet different needs in community-based environmental management.  相似文献   
974.
Inter-seasonal studies on the trace metal load of surface water, sediment and Tympanotonus fuscatus var. radula of Iko River were conducted between 2003 and 2004. The impact of anthropogenic activities especially industrial effluent, petroleum related wastes, gas flare and episodic oil spills on the ecosystem are remarkable. Trace metals analyzed included cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), vanadium (V) and zinc (Zn). Sediment particle size analysis revealed that they were characteristically psammitic and were predominantly of medium to fine grained sand (>73%), less of silt (<15%) and clay (<10%). These results correlated with low levels of trace elements such as Pb (0.03 ± 0.02 mg kg−1), Cr (0.22 ± 0.12 mg kg−1), Cd (0.05 ± 0.03 mg kg−1), Cu (0.04 ± 0.02 mg kg−1) and Mn (0.23 ± 0.22 mg kg−1) in the sediment samples. This observation is consistent with the scarcity of clayey materials known to be good scavengers for metallic and organic contaminants. Sediments indicated enhanced concentration of Fe, Ni and V, while other metal levels were relatively low. The concentrations of all the metals except Pb in surface water were within the permissible levels, suggesting that the petroleum contaminants had minimal effect on the state of pollution by trace metals in Iko River. Notably, the pollutant concentrations in the sediments were markedly higher than the corresponding concentrations in surface water and T. fuscatus tissues, and decreased with distance from point sources of pollution.  相似文献   
975.
Wastewater management in small and medium-sized enterprises representing the chemical and food industries was investigated. The results showed that wastewater discharged from an ink-production factory was highly contaminated with organic pollutants. Anaerobic biological treatment followed by chemical coagulation using ferric chloride aided with lime proved to be very effective and produced an effluent that complied with national regulatory standard for wastewater discharge into public sewage network. Also, management of wastewater from a confectionery factory representing the food sector was carried out. Aerobic biological treatment using plastic-packed trickling filter proved to be an effective treatment method. However, application of in-plant control measures alleviated the requirement for the construction of a wastewater treatment plant. The applied pollution prevention and cleaner production measures involved good housekeeping, recovery of spent chocolate, modification of floor cleaning and installation of suction devices for the removal of sugar and starch powders. All improvement measures were documented by cost/benefit analysis.  相似文献   
976.
Recycling and conservation efforts for water are the need of the day because of the lack of new water sources and the ever-increasing demand for drinking water. Seedlings of Acacia nilotica L. were irrigated with: canal water (T1, control); municipal effluent (T2); textile effluent (T3); steel effluent (T4); textile + municipal effluent in 1:1 ratio (T5); steel + municipal effluent in 1:2 ratio (T6); steel + textile in 1:2 ratio (T8) and steel + municipal + textile in 1:2:2 ratio (T7) with views to observe effluents effect on the seedlings and its adaptability and to recommend safe disposal of these effluents. Seedlings in T6, T7 and T8 showed 50% lesser height and collar diameter than those in control. Seedlings in T2 attained greatest height, collar diameter, numbers of branches and produced 140 g dry biomass seedling−1. Highest concentration of manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn) and lowest concentration of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) in the seedlings of T4, T6, T7 and T8 resulted in nutritional imbalance, mineral toxicity and reduction in photosynthetic (Pn) and transpiration (E) rates and caused seedling mortality. Seedlings of T3 had highest sodium concentration and low concentration of Ca, Mg and micronutrients resulting in nutritional imbalance, augmented chlorosis and reduced gas exchange and biomass by half as compared to control. Increased growth, Pn and E and biomass in seedlings of T5 over T3 and survival period in T6, T7 and T8 seedlings suggested a beneficial effect of effluents mixing. Unscientific disposal should be avoided and toxic concentration of metal ions␣may be reduced for long-term application and harmless disposal of effluents in afforestation and urban development.  相似文献   
977.
ABSTRACT: Forest land managers are concerned about the effects of logging on soil erosion, streamflow, and water quality and are promoting the use of Best Management Practices (BMPs) to control impacts. To compare the effects of BMP implementation on streamwater quality, two of three small watersheds in Kentucky were harvested in 1983 and 1984, one with BMPs, the other without BMPs. There was no effect of clearcutting on stream temperatures. Streamflow increased by 17.8 cm (123 percent) on the BMP watershed during the first 17 months after cutting and by 20.6 cm (138 percent) on the Non-BMP watershed. Water yields remained significantly elevated compared to the uncut watershed 8 years after harvesting. Suspended sediment flux was 14 and 30 times higher on the BMP and Non-BMP Watersheds, respectively, than on the uncut watershed during treatment, and 4 and 6.5 times higher in the 17 months after treatment was complete. Clearcutting resulted in increased concentrations of nitrate, and other nutrients compared to the uncut watershed, and concentrations were highest on the non-BMP watershed. Recovery of biotic control over nutrient losses occurred within three years of clearcutting. The streamside buffer strip was effective in reducing the impact of clearcutting on water yield and sediment flux.  相似文献   
978.
This paper develops a methodology for integrating a land-use forecasting model with an event scale, rainfall-runoff model in support of improving land-use policy formulation at the watershed scale. The models selected for integration are loosely coupled, structured upon a common GIS platform that facilitates data exchange. The hydrologic model HEC-HMS is calibrated for a specific storm event that occurred within central Washington State. The land-use forecasting model, What If? is implemented to forecast future spatial distributions of low-density residential land-uses under low and high population growth estimates. Forecasted land-use distribution patterns for the years 2015, 2025, and 2050 are then used as land-use data input for the calibrated hydrologic model, keeping all other parameters constant. Impacts to the stream discharge hydrograph are predicted as the study area becomes increasingly developed as forecasted by What If?. The initial results of this integration process demonstrate the synergy that can be generated through the linkage of the selected models. The ability to quantifiably forecast the potential hydrologic implications of proposed land-use policies before their implementation offers land-use decision-makers a valuable tool for discerning which proposed land-use alternatives will be effective at minimizing storm water runoff.  相似文献   
979.
This research has demonstrated that even in a small urbanised country like Britain, communities can still be remote. The paper analyses the nature of remote settlements and suggests that beyond the rural idyll, there are deprived communities. In order to obtain real data, a study area in the North Pennines was selected. The types of remote communities were evident throughout the study area and one of each type was selected for further study. It became clear that villages with an industrial base had most potential, due to high energy demand, vulnerability and community involvement. A village with a high measure of multiple deprivation and suffering from fuel poverty was chosen for a more detailed investigation. Energy demand profiles were developed and candidate technologies nominated. The latter were tested by filters that assessed fitness for application, robustness and autonomy. The most appropriate combinations of technologies were proposed. The residents and their community representatives were involved in the process and recognised the benefits of the proposals to themselves and others.  相似文献   
980.
Tourism and landscape are interdependent concepts. Nature- and culture-based tourism are now quite well developed activities and can constitute an excellent way of exploiting the natural resources of certain areas, and should therefore be considered as key objectives in landscape planning and management in a growing number of countries. All of this calls for careful evaluation of the effects of tourism on the territory. This article focuses on an integrated spatial method for landscape analysis aimed at quantifying the relationship between preferences of visitors and landscape features. The spatial expression of the model relating types of leisure and recreational preferences to the potential capacity of the landscape to meet them involves a set of maps showing degrees of potential visitor satisfaction. The method constitutes a useful tool for the design of tourism planning and management strategies, with landscape conservation as a reference.  相似文献   
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