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101.
Abstract

The current pressure on production resources of North China Plain, such as land and water to feed the growing population, necessitates the assessment of the sustainability of farming practices. This study focuses on the sustainability of farming practices related to groundwater and soil fertility management. The assessment is based on selected site-specific key indicators and their established threshold limits. The current farming practices in the study area are clearly unsustainable. Only about 6% of the surveyed farm households practice sustainable farming. The study stresses that farming practice, which is economically sustainable, should not be promoted at the cost of environment. Holistic strategies need to be developed and implemented that aim at balanced use of inputs, which satisfy both productivity and environmental concerns.  相似文献   
102.
This paper explores, explains and discusses issues around the dilemma between local conservation of natural resources (often, endangered species and habitats) and tourism needs in Africa. Often and in constitutional terms, local people have a right to exploit and use resources endowed in their local area. However, tourists often are interested in viewing the vegetation and animal resources undisturbed. Inevitably, there is an undeclared animosity of values and interests between local communities and tourists and state agencies. As a result, the dilemma is thus of governance. The purpose of this paper is to demonstrate the governance dilemma of resource utilization and tourism in Africa in a bid to create an informed stewardship framework for sustainability. This is achieved by way of case studies and narratives from Africa. As such, this paper will be a review literature on how different communities perceive tourism and derive livelihoods from their immediate environment. It also explains how the external factors influence local needs and interests. A more sustainable and operational framework that reduces friction among stakeholders is suggested.  相似文献   
103.
Due to the important role that the agricultural sector plays in sustaining growth and reducing poverty in developing countries, the adoption of practices that have the potential to simultaneously improve agricultural productivity while minimizing environmental impacts is essential. This paper examines the determinants of farmers’ perceptions of climate change and subsequent adoption of sustainable land management practices in the Niger basin of Benin. Binary and multivariate probit models are applied in a two‐stage regression procedure to cross‐sectional data collected through a survey of 545 randomly selected farm households in 28 villages. The findings indicate that there are substitutabilities among three pairs of sustainable land management practices being used by the farmers. Climate change perception is positively related to land tenure, experience in farming, number of relatives, tractor use, and membership in farmers’ organizations, and negatively related to household size, remoteness, and plough use. Moreover, the findings reveal that the uptake of land management practices is related to assets, land tenure, education level of the household head, remoteness, social network, non‐irrigated land size, having a farm located near a river/lake/stream, tractor and plough use, being a subsistence farmer or not, and memberships in farmers’ organizations. The adoption of sustainable land management practices could be encouraged through improving access to markets, adequate roads, and technologies, as well as by promoting membership in farmers’ organizations.  相似文献   
104.
In response to federal and state clean water laws, forestry best management practices (BMPs) have been developed and implemented to prevent nonpoint source water pollution. Ellefson and Miles (1985) found that estimated BMP costs in the Midwest could amount to more than half of the net returns on national forest timber sales. Henly et al. (1988) found that government costs to implement forest practice rules ranged from as little as $100,000 per year in Idaho and Nevada to more than $4 million annually in California. A review of studies in the South indicates that estimated BMP costs have increased over time. Lickwar et al. (1992) estimated Southeast average costs of $12.45 per acre, $2.34 per MBF, or 2.87% of gross stumpage values based on 1987 BMPs and prices. Woodman and Cubbage (1994) estimated Georgia average BMP costs of $24.33 per acre or $3.02 per MBF for forest industry lands and $41.65 per acre or $5.39 per MBF for NIPF lands. For Virginia, Shaffer et al. (1998) estimated median BMP costs of $18.90 per acre. These moderate cost increases could be attributed to a higher level of standards in the revision of each state BMP guidelines manual, as well as moderate price inflation. BMPs such as better road construction, water bars, culverts, and broad-based dips have been most expensive so far. To date streamside zones have not been very expensive because the rules allow most of the valuable residual tees to be harvested as long as heavy equipment does not operate near the streams. However, this limitation may become much more difficult and costly – as indicated by Kluender et al. (2000) – as fewer chainsaw fellers and cable skidders are available. Stricter BMPs, such as those already adopted to implement forest certification standards in the South or those used to protect salmon habitat in the West, could prompt more expensive southern BMPs for landowners and state agencies in the future.  相似文献   
105.
A comprehensive synthesis of data from empirically based published studies and a widely used stormwater best management practice (BMP) database were used to assess the variability in nitrogen (N) removal performance of urban stormwater ponds, wetlands, and swales and to identify factors that may explain this variability. While the data suggest that BMPs were generally effective on average, removal efficiencies of ammonium (NH4), nitrate (NO3), and total nitrogen (TN) were highly variable ranging from negative (i.e., BMPs acting as sources of N) to 100%. For example, removal of NO3 varied from (median ±1 SD) ?15 ± 49% for dry ponds, 32 ± 120% for wet ponds, 58 ± 210% for wetlands, and 37 ± 29% for swales. Across the same BMP types, TN removal was 27 ± 24%, 40 ± 31%, 61 ± 30%, and 50 ± 29%. NH4 removal was 9 ± 36%, 29 ± 72%, 31 ± 24%, and 45 ± 34%. BMP size, age, and location explained some of the variability. For example, small and shallow ponds and wetlands were more effective than larger, deeper ones in removing N. Despite well‐known intra‐annual variation in N fluxes, most measurements have been made over short time periods using concentrations, not flow‐weighted N fluxes. Urban N export is increasing in some areas as large storms become more frequent. Thus, accounting for the full range of BMP performance under such conditions is crucial. A select number of long‐term flux‐based BMP studies that rigorously measure rainfall, hydrology, and site conditions could improve BMP implementation.  相似文献   
106.
This literature review addresses how wide a streamside forest buffer needs to be to protect water quality, habitat, and biota for small streams (≤~100 km2 or ~5th order watershed) with a focus on eight functions: (1) subsurface nitrate removal varied inversely with subsurface water flux and for sites with water flux >50 l/m/day (~40% avg base flow to Chesapeake Bay) median removal efficiency was 55% (26‐64%) for buffers <40 m wide and 89% (27‐99%) for buffers >40 m wide; (2) sediment trapping was ~65 and ~85% for a 10‐ and 30‐m buffer, respectively, based on streamside field or experimentally loaded sites; (3) stream channel width was significantly wider when bordered by ~25‐m buffer (relative to no forest) with no additional widening for buffers ≥25 m; (4) channel meandering and bank erosion were lower in forest but more studies are needed to determine the effect of buffer width; (5) temperature remained within 2°C of levels in a fully forested watershed with a buffer ≥20 m but full protection against thermal change requires buffers ≥30 m; (6) large woody debris (LWD) has been poorly studied but we infer a buffer width equal to the height of mature streamside trees (~30 m) can provide natural input levels; (7, 8) macroinvertebrate and fish communities, and their instream habitat, remain near a natural or semi‐natural state when buffered by ≥30 m of forest. Overall, buffers ≥30 m wide are needed to protect the physical, chemical, and biological integrity of small streams.  相似文献   
107.
This paper presents a study on the use of best management practices (BMPs) for controlling nonpoint pollution in the Xikeng Reservoir watershed located in Shenzhen, China. A BMP treatment train design, including a pond, a wetland, and a buffer strip placed in series was implemented at the reservoir location. A separate grass swale was also constructed at the site. Low impact development (LID) BMPs, namely a planter box and bioboxes, were used at the parking lot of the reservoir’s Administration Building. Samples were collected during storm events and were analyzed for total suspended solids (TSS), biochemical oxygen demand (BOD5), ammonia nitrogen (NH3—N), and total phosphorus (TP). The removal efficiencies of both BMP systems were evaluated using the Efficiency Ratio (ER) method based on the event mean concentration (EMC) data. In summary, the pond/wetland treatment train removed 70%―90% of TSS, 20%―50% of BOD5, and 30%―70% of TP and NH3—N. The swale removed 50%―90% of TSS, 30%―55% of BOD5, −10%―35% of NH3—N, and 25%―70% of TP. For the planter box and biobox, the ranges of removal rates were 70%―90%, 20%―50%, and 30%―70% for TSS, BOD5, and ammonia and phosphorus, respectively.  相似文献   
108.
The nutrient and pesticide abatement efficiency of varying mixtures was examined in a vegetated free water surface constructed wetland. Three different agricultural chemical pollutant mixture conditions were assessed: nutrients only (N and P); pesticides only (atrazine, S-metolachlor and permethrin); and a mixture of nutrients and pesticides. With nutrients only, 672 h nutrient mitigation of 77–91% total phosphorous (TP) and 74–98% total nitrogen (TN) was associated with distance from the injection point and rainfall, whereas with nutrient and pesticide mixtures, 672 h nutrient mitigation of 11–71% TP and 84–98% TN were associated with distance and time. With pesticides only, 672 h pesticide mitigation of 50–99% was associated with distance and time, whereas with nutrients and pesticide mixtures, 672 h pesticide mitigation of 48–99% was associated primarily with distance. Dissipation half-lives were 2–10 times greater for P and 1.5–5 times greater for N when pesticides were present. Pesticide dissipation half-lives showed no clear differences with or without nutrients. While vegetated free water surface constructed wetlands can be effective best management practice tools to trap and abate agricultural run-off during rainfall events, efficiencies can be affected by different types of complex pollutant mixtures and wetland design and implementation should accommodate varying efficiencies.  相似文献   
109.
Manufacturing firms are striving to improve their sustainable performance in order to satisfy multiple stakeholders. Eco-innovation is a promising approach that decreases environmental impact and helps firms to increase their business value. There are several antecedents which help the firms to innovate and improve their triple bottom line performance. Among the antecedents, management and innovative practices are directly related to eco-innovation. It is not well known what practices and innovations help the firms to eco-innovate as well as to improve sustainable performance. Hence, the research objective of this paper is to identify the suitable combination of management and innovative practices that help firms to eco-innovate as well as to achieve overall sustainable performance. The paper develops an eco-innovation conceptual model which relates the management and innovative practices (antecedents) and overall sustainable performance (consequences) of eco-innovation using institutional theory. Using Indian manufacturing sector’s empirical data and Structural Equation Modelling (SEM) approach, this paper determines the effect of eco-innovation’s antecedents and consequences. In the Indian context, this study suggests that the role of management practice is more significant towards eco-innovation than innovative practices. The results reflect practitioners’ view on how to increase innovation rate and to focus more on social aspects. The finding suggests that training on environmental related practices could tackle innovation and social aspects in the Indian manufacturing sector context.  相似文献   
110.
Managed forests generally produce high water quality, but degradation is possible via sedimentation if proper management is not implemented during forest harvesting. To mitigate harvesting effects on total watershed sediment yield, it is necessary to understand all processes that contribute to these effects. Forest harvesting best management practices (BMPs) focus almost exclusively on overland sediment sources, whereas in‐and‐near stream sources go unaddressed although they can contribute substantially to sediment yield. Thus, we propose a new framework to classify forest harvesting effects on stream sediment yield according to their direct and indirect processes. Direct effects are those caused by erosion and sediment delivery to surface water from overland sources (e.g., forest roads). Indirect effects are those caused by a shift in hydrologic processes due to tree removal that accounts for increases in subsurface and surface flows to the stream such that alterations in water quality are not predicated upon overland sediment delivery to the stream, but rather in‐stream processes. Although the direct/indirect distinction is often implicit in forest hydrology studies, we have formalized it as a conceptual model to help identify primary drivers of sediment yield after forest harvesting in different landscapes. Based on a literature review, we identify drivers of these effects in five regions of the United States, discuss current forest management BMPs, and identify research needs.  相似文献   
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