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961.
The Lower Rio Grande Valley (LRGV) of south Texas is an agriculturally rich area supporting intensive production of vegetables, fruits, grain sorghum, and cotton. Modern agricultural practices involve the combined use of irrigation with the application of large amounts of agrochemicals to maximize crop yields. Intensive agricultural activities in past decades might have caused potential contamination of soil, surface water, and groundwater due to leaching of pesticides in the vadose zone. In an effort to promote precision farming in citrus production, this paper aims at developing an airborne multispectral technique for identifying tree health problems in a citrus grove that can be combined with variable rate technology (VRT) for required pesticide application and environmental modeling for assessment of pollution prevention. An unsupervised linear unmixing method was applied to classify the image for the grove and quantify the symptom severity for appropriate infection control. The PRZM-3 model was used to estimate environmental impacts that contribute to nonpoint source pollution with and without the use of multispectral remote sensing and VRT. Research findings using site-specific environmental assessment clearly indicate that combination of remote sensing and VRT may result in benefit to the environment by reducing the nonpoint source pollution by 92.15%. Overall, this study demonstrates the potential of precision farming for citrus production in the nexus of industrial ecology and agricultural sustainability.  相似文献   
962.
Numerous road and railway construction projects include costly mitigation measures to offset the barrier effect produced on local fauna, despite the scarcity of data on the effectiveness of such mitigation measures. In this study, we evaluate the utility of different types of crossing structures. Vertebrate use of 43 transverse crossing structures along the A-52 motorway (north-western Spain) was studied during spring 2001. Research centered on wildlife passages (9), wildlife-adapted box culverts (7), functional passages (6 overpasses, 7 underpasses) and culverts (14), with marble dust being used to record animal tracks. A total of 424 track-days were recorded, with most of the larger vertebrate groups present in the area being detected. All crossing structure types were used by animals, although the intensity of use varied significantly among them (Kruskal-Wallis test, p<0.05); culverts were used less frequently than other structures. Crossing structure type and width were identified as the most important factors in their selection for use. Wildlife passages and adapted culverts allowed crossing by certain species (wild boar, roe deer, Eurasian badger), which do not tend to cross elsewhere. These results highlight the importance of using both mixed-type structures and wildlife passages in reducing the barrier effect of roads.  相似文献   
963.
Agricultural landscapes illustrate the impact of human actions on physical settings, and differential human pressures cause these landscapes to change with time. Our study explored changes in the terraced landscapes of Nisyros Island, Greece, focusing on the socioeconomic aspects during two time periods using field data, cadastral research, local documents, and published literature, as well as surveys of the islanders. Population increases during the late 19th to early 20th centuries marked a significant escalation of terrace and dry stone wall construction, which facilitated cultivation on 58.4% of the island. By the mid-20th century, the economic collapse of agricultural activities and consequent emigration caused the abandonment of cultivated land and traditional management practices, dramatically reducing farm and field numbers. Terrace abandonment continued in recent decades, with increased livestock grazing becoming the main land management tool; as a result, both farm and pasture sizes increased. Neglect and changing land use has led to deterioration and destruction of many terraces on the island. We discuss the socioeconomic and political backgrounds responsible for the land-use change before World War II (annexation of Nisyros Island by the Ottoman Empire, Italy, and Greece; overseas migration opportunities; and world transportation changes) and after the war (social changes in peasant societies; worldwide changes in agricultural production practices). The adverse landscape changes documented for Nisyros Island appear to be inevitable for modern Mediterranean rural societies, including those on other islands in this region. The island’s unique terraced landscapes may qualify Nisyros to become an archive or repository of old agricultural management techniques to be used by future generations and a living resource for sustainable management.  相似文献   
964.
Changes in agricultural policy have traceable effects on landscape aesthetics. For the catchment area of Lake Greifensee, an economic land-use model predicted land-use changes caused by agricultural policy. Three scenarios implementing different direct payment schemes show that land-use intensity will decrease by 2011 compared with the ‘reference status’ 2000.The output of the economic land-use model is explicit in space. It was assessed by the ‘naturalness’ perception factor of the method proposed by Hoisl et al. [1989. Landschaftsästhetik in der Flurbereinigung. Materialien zur Flurbereinigung—Heft 17. Bayerisches Staatsministerium für Ernährung, Landwirtschaft und Forsten, München] with regard to landscape aesthetics. Even though lower land-use intensity is generally predicted by 2011, the values of the ‘naturalness’ perception factor do not significantly improve if the payment scheme remains unchanged, or if the payment scheme is amended by incentives for specific location of the ecological compensation areas (ECAs). A significant reduction in the values of the ‘naturalness’ perception factor was found when subsidies for ECA's were cancelled. This leads us to the conclusion that in order to keep Swiss landscapes as attractive as they are at present, policy must sustain incentives for low-intensity land-use types.  相似文献   
965.
以底栖动物为指示物种对长江流域水生态进行评价   总被引:5,自引:0,他引:5  
采用底栖动物作为指示物种对长江流域的水生态进行了调查研究和生态评价。在长江上游支流、中下游干流及沿江湖泊上选取36个代表性样点进行生态考察和底栖动物采样、鉴定和分析。采用Hilsenhoff生物指数和水化学分析对样点水质进行评价,对比分析了各样点底栖动物的结构组成及多样性。上游支流大部分样点水质清洁;中游干流及沿江湖泊水质受到轻度到中度污染;下游干流水质污染加重。底栖动物多样性在上游支流中最高,中游湖泊较高,干流中下游较低。总结得出了4种河床演变条件下的底栖动物群谱。上游支流河床稳定的河流底栖动物密度较大,物种丰富,多样性高;侵蚀下切的河流底栖动物密度、物种数和多样性较低;淤积抬升的河流底栖动物密度、物种数和多样性更低一些;河势散乱且河床运动剧烈的支流物种丰度和密度均很低甚至为零,生态条件差。  相似文献   
966.
论赤水河流域资源环境的开发与保护   总被引:14,自引:2,他引:14  
通过对赤水河流域的资源环境综合考察,提出赤水河流域在资源环境方面的价值归结为生态河、美景河、美酒河和英雄河四大特点,具有重要的保护价值。从长江流域水资源开发、利用和保护的角度和视野.建议在长江流域选择1~2条自然生态支流,在开发利用长江水资源的同时,给长江留下1~2条不修大坝的自然生态河流。分析认为,赤水河具备了作为自然生态河流的条件和优势。在此基础上,提出建立具有流域性和综合性为特点的“赤水河流域综合性自然保护区”,保护对象包括赤水河两岸的陆生植物、水生生物特别是鱼类、自然景观和人文景观。从多个层面和角度阐明了建立流域性和综合性自然保护区的意义和作用。分析了当前赤水河流域开发和保护面临的主要矛盾,提出了“赤水河流域综合性自然保护区”的主要内容。最后,提出了国家应加强对赤水河流域的支持力度的具体措施。  相似文献   
967.
An examination of ecological risk assessment and management practices   总被引:5,自引:0,他引:5  
Ecological risk assessment has grown and evolved since the 1980s, as have new challenges (e.g. global climate change, loss of habitat and biodiversity and the effects of multiple anthropogenic chemicals on ecological systems) that need to be factored into the risk assessment processes. There is also an on-going shift from evaluating adverse health impacts on particular, often small scale, environments to undertaking more complex ecological assessments of whole populations and communities across ecologically meaningful landscapes. These trends are generating an increased demand for much more complex ecological assessments, making it increasingly clear that to achieve its potential as a management tool, methods must be developed to apply ecological risk assessment to larger and more complex scales. This paper reviews the development of the ecological risk assessment paradigm in the United States, identifies ways it is being applied and adapted in other countries, explores future research needs and practice improvements, and examines current issues that need to be considered in taking forward the scientific development of ecological risk assessment as a useful environmental management tool.  相似文献   
968.
生态学范式下的清洁生产、产业生态和循环经济分析   总被引:2,自引:0,他引:2  
运用生态学理论,从个体生态、种群生态、群落生态和生态系统生态4个生态学尺度上对清洁生产、产业生态和循环经济进行类比分析,论述了清洁生产与个体生态学、生态产业与种群生态学和群落生态学、循环经济与生态系统生态学的内在联系及3者之间的相容和递进关系,指出当前清洁生产和产业生态研究与实践中存在的局限性,认为提高清洁生产实施的层次,扩大清洁生产实施的范围,将产业生态研究上升到产业生态系统层面是清洁生产和产业生态未来研究和实践的方向,3者在不同层面的实践将最终推动人类不断接近可持续发展的理想目标.  相似文献   
969.
To balance trade-offs between livestock’s negative environmental impacts and their positive contributions (e.g. maintaining semi-natural grasslands, varied agricultural landscapes and crop rotations), a better understanding is needed of how the supply of ecosystem services differs across farms. We analysed a suite of indicators for non-provisioning ecosystem services on a large subset of Swedish farms (71% of farms, covering 82% of agricultural land) and related these to farm type, farm size and livestock density. The analysed indicators exhibited clear geographical patterns with hotspots especially in less productive regions. Controlling for this spatial variation we still found that small-scale and ruminant farms were associated with more varied landscapes, small-scale habitats, semi-natural grasslands and better crop sequences compared to nearby farms specialised in crop production, while farms specialising in monogastric livestock were associated with less varied landscapes and inferior crop sequences. Results for cultural ecosystem services indicated that farms with more semi-natural grassland were associated with more visitors and more likely located within designated recreation or nature conservation areas.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01726-y.  相似文献   
970.
本文以“要素—领域—任务”国家生态环境规划体系的形成过程为切入点,回顾了新中国成立以来特别是“十一五”之后我国生态环境规划的发展历程。研究表明,在“要素—领域—任务”体系构建完善的关键阶段,即“十一五”到“十二五”,我国的生态环境规划体系在“污染减排”的基础上,明确提出“质量改善”“风险防范”和“公共服务”三大领域,战略领域的划分逐步明确,环境规划要素逐渐充实,落实任务更加精细。而在“要素—领域—任务”体系的充实提高过程中,即“十二五”到“十三五”,进一步提出“绿色发展”“生态修复”“制度创新”三大领域。要素方面,通过推进“三大污染防治行动计划”,使气、水、土三要素治理纲举目张。任务的重心则向生态环境综合治理、区域统筹协调发展转变。为更好地发挥“要素—领域—任务”体系优势,支撑我国现代环境治理体系的构建,本文提出,“十四五”规划应在要素层面全面覆盖且重点突出,领域层面系统整合并统筹协调,任务层面具体落实且创新机制,助力建成适应美丽中国建设要求的生态环境管理体系新格局。  相似文献   
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