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721.
以上海市为例总结了生活垃圾分类工作的发展历程,分析了生活垃圾分类减量工作的重要意义,对上海市2011年以来生活垃圾分类减量工作的目标、方法、存在问题等进行阐述,并提出了下一步加强生活垃圾分类减量工作的发展方向和对策措施。 相似文献
722.
中国西北地区农林复合经营的保护与发展 总被引:1,自引:0,他引:1
中国西北地区深居内陆,区域生态系统脆弱,干旱、水土流失和风沙灾害等问题频繁,严重影响了区域社会经济的发展与生态文明建设进程。发展复合农林业是林业发展的新思路,是解决区域生态环境与落后社会经济问题恶性循环的有效途径。论文根据西北地区特殊的自然、经济、社会条件以及农林复合经营发展现状,结合农林复合系统科研、生产实践及农村经济发展的需要,将西北干旱地区农林复合经营划分为草原风沙区、荒漠绿洲区、黄土高原区和青藏高原区4个类型区,并分析概述了各类型区复合农林业发展的现状和特点。根据农林复合系统多层次、多组分、多功能和多目标的特点,提出了基于林分起源、生物组分、生长周期和主导功能标尺的农林复合经营类型划分方法。对目前西北地区农林复合经营发展中存在的规划、理论研究和推广应用等问题提出了相应对策,以期为区域农林复合经营的保护与发展提供借鉴。 相似文献
723.
Spectrally Driven Classification of High Spatial Resolution,Hyperspectral Imagery: A Tool for Mapping In-Stream Habitat 总被引:1,自引:0,他引:1
Legleiter CJ 《Environmental management》2003,32(3):399-411
Streams represent an essential component of functional ecosystems and serve as sensitive indicators of disturbance. Accurate mapping and monitoring of these features is therefore critical, and this study explored the potential to characterize aquatic habitat with remotely sensed data. High spatial resolution, hyperspectral imagery of the Lamar River, Wyoming, USA, was used to examine the relationship between spectrally defined classes and field-mapped habitats. Advantages of this approach included enhanced depiction of fine-scale heterogeneity and improved portrayal of gradational zones between adjacent features. Certain habitat types delineated in the field were strongly associated with specific image classes, but most included areas of diverse spectral character; spatially buffering the field map polygons strengthened this association. Canonical discriminant analysis (CDA) indicated that the ratio of the variability among groups to that within a group was an order of magnitude greater for spectrally defined image classes (20.84) than for field-mapped habitat types (1.82), suggesting that unsupervised image classification might more effectively categorize the fluvial environment. CDA results also suggested that shortwave-infrared wavelengths were valuable for distinguishing various in-stream habitats. Although hyperspectral stream classification seemed capable of identifying more features than previously recognized, the technique also suggested that the intrinsic complexity of the Lamar River would preclude its subdivision into a discrete number of classes. Establishing physically based linkages between observed spectral patterns and ecologically relevant channel characteristics will require additional research, but hyperspectral stream classification could provide novel insight into fluvial systems while emerging as a potentially powerful tool for resource management. 相似文献
724.
Uranov (1975) formulated a theory of the age structure of plant populations and, in particular, defined the index of ageness . On the basis of this theory, the concepts of the energy efficiency of plants in a certain ontogenetic state and the average efficiency of a population () are introduced. A new classification of populations with respect to the types of age structure is proposed which is based on both the and values and, accordingly, is named the delta–omega classification. The notion of effective population density is defined. This parameter takes into account different loads of plants in different ontogenetic states on the environment and is quantitatively equal to the product of the population density and . The proposed approaches and methods are illustrated by data on the distribution of age states in different plant species. 相似文献
725.
中国灾害学图书简索(一) 总被引:1,自引:0,他引:1
本文搜集整理了1990年以来国内出版的有关灾害研究方面的图书,并简要介绍了其主要内容。这对了解灾害学图书的出版状况,掌握灾害科研成果的最新动向将起到一定的作用。 相似文献
726.
中国森林火灾研究综述 总被引:15,自引:0,他引:15
概述了中国森林火灾方面的研究成果,包括森林火灾的分级和分类、影响因素、研究内容、预报方法等,重点论述了中国森林火灾的研究内容,尤其是中国森林火灾的发生规律及学者们对森林火灾原因的看法。最后提出了防治森林火灾的指导思想。 相似文献
727.
Field assessments of impacted streams require a control or at least an unbiased estimate of attainable conditions. Control sites, such as upstream/downstream or wilderness sites, have proven inadequate for assessing attainable ecological conditions where the control streams differ naturally from the impacted streams to a considerable degree or where different disturbances exist than those being studied. Relatively undisturbed reference sites with watersheds in areas having the same land-surface form, soil, potential natural vegetation, and land use as are predominant in large, relatively homogeneous regions are suggested as alternative control sites. These areas are considered typical of the region and therefore the sites also are considered typical of the region because their watersheds exhibit all the terrestrial variables that make that region a region. The logical basis for developing regional reference sites lies in the ability to group watersheds and common stream types into regions by integrating available maps of terrestrial variables that influence streams. Relatively undisturbed reference sites can be selected from typical areas of the regions and from transition zones where one or two of the terrestrial variables are not the predominant one(s) of the region. These reference sites are useful for estimating attainable conditions, for evaluating temporal and spatial changes in ecological integrity, for classifying attainable uses of streams, and for setting biological and environmental criteria. 相似文献
728.
Robert L. Vertrees 《Journal of the American Water Resources Association》1985,21(1):115-134
ABSTRACT: A matrix was developed of problems with the functional use of water resources (rows) and functions served by water resources research (columns). A classification of water problems and a classification of research fields also were developed to accompany the matrix. The matrix and classification schemes were used when preparing the five-year research and development plan of the Water Resources Center of The Ohio State University. They were used: (1) to classify each research project that had been supported by the Water Resources Center from 1965 through 1980, (2) to guide interviews with personnel of federal and state agencies and university faculty who assisted in defining Ohio's water research needs, (3) to organize responses received during these interviews, and (4) to arrive at a selected list of ten problems with the functional use of Ohio's water resources that were prioritized based upon opinions received from water-related officials throughout the state. Other matrices and classification schemes are reviewed that were revised and expanded upon when formulating the ones used in Ohio. Suggestions are given regarding further development of the functional matrix and accompanying classifications as well as their use in administration of the cooperative federal-state water resources research program and other federal water resources research programs. 相似文献
729.
ABSTRACT: At a time when productive water resources research is essential to protecting the quality of and wisely using our limited water resources, pervasive trends toward consumerism, fiscal restraint, centralized management, and using research for other social objectives threaten research productivity. The research prioritization and management structure that these trends have created was examined in the microcosm of its application at the Utah Water Research Laboratory. The result indicated that ephemeral prioritization and the failure of research users to target researchers to their own particular needs is diluting productivity. Incremental research prioritization and greater use of advisory councils in facilitating user-researcher interaction are suggested as corrective approaches, but the only firm conclusion at this point in time must be that empirical studies of the performance of alternatives in research management structure are solely needed. 相似文献
730.
Recreation use was studied on a diverse state river system to test the hypothesis that recreation use patterns vary systematically by river type. River segments were classified into representative river types through application of a two-fold classification system. The first classification factor, generalized geomorphology, defines and groups the dominant resource bases of which rivers are comprised. The second classification factor, cultural setting, defines the land use and settlement patterns in which each river type is found. Significant differences were found among resulting river types with respect to the nature and intensity of recreation activity, desired use density, and user perceived problems and conflicts. Management recommendations were developed, based on study findings, for each river type. It is concluded that when both environmental attributes and cultural setting are taken into account, regularities appear with respect to the way in which river resources are used and perceived by recreationists. Further exploration and expansion of such recreation-resource relationships to other activities and environments may hold substantial implications for the allocation and management of outdoor recreation resources. 相似文献