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941.
942.
The conversion of landscapes by human activities results in widespread changes in landscape spatial structure. Regardless of the type of land conversion, there appears to be a limited number of common spatial configurations that result from such land transformation processes. Some of these configurations are considered optimal or more desirable than others. Based on pattern geometry, we define ten processes responsible for pattern change: aggregation, attrition, creation, deformation, dissection, enlargement, fragmentation, perforation, shift, and shrinkage. A novelty in this contribution is the inclusion of transformation processes causing expansion of the land cover of interest. Consequently, we propose a decision tree algorithm that enables detection of these processes, based on three parameters that have to be determined before and after the transformation of the landscape: area, perimeter length, and number of patches of the focal landscape class. As an example, the decision tree algorithm is applied to determine the transformation processes of three divergent land cover change scenarios: deciduous woodland degradation in Cadiz Township (Wisconsin, USA) 1831–1950, canopy gap formation in a terra firme rain forest at the Tiputini Biodiversity Station (Amazonian Ecuador) 1997–1998, and forest regrowth in Petersham Township (Massachusetts, USA) 1830–1985. The examples signal the importance of the temporal resolution of the data, since long-term pattern conversions can be subdivided in stadia in which particular pattern components are altered by specific transformation processes. 相似文献
943.
944.
945.
以人权原则以及现代工业的理念 ,从现代安全管理体系和方法的新要求入手 ,站在长久安全和可持续发展战略的高度 ,探求新的安全管理理念和模式 ;进一步研讨了区域战略安全管理模式 ,并归纳出其类型与层次 ;概述了国内外安全管理模式的发展历程 ,对我国战略安全管理的现状和对新模式的探索过程进行了分析 ,归纳出国内外战略安全管理新理念构架 ;重点阐述了HSE(健康、安全、环境 ) ,QHSE(质量、健康、安全、环境 ) ,OHS(职业健康安全 )管理体系战略、安全文化战略以及美国和欧共体战略安全管理等先进理念 ;最后提出了闭环控制的滚动式战略安全管理技术构思和战略安全管理的国内外发展趋势。区域战略安全管理模式的应用与发展将使现代安全管理提高到一个新的高度。 相似文献
946.
Land Resource Sustainability for Urban Development: Spatial Decision Support System Prototype 总被引:1,自引:0,他引:1
Banai R 《Environmental management》2005,36(2):282-296
Land resource sustainability for urban development characterizes the problem of decision-making with multiplicity and uncertainty. A decision support system prototype aids in the assessment of incremental land development plan proposals put forth within the long-term community priority of a sustainable growth. Facilitating this assessment is the analytic hierarchy process (AHP), a multicriteria evaluation and decision support system. The decision support system incorporates multiple sustainability criteria, weighted strategically responsive to local public policy priorities and community–specific situations and values, while gauging and directing desirable future courses of development. Furthermore, the decision support system uses a GIS, which facilitates an assessment of urban form with multiple indicators of sustainability as spatial criteria thematically. The resultant land-use sustainability scores indicate, on the ratio-scale of AHP, whether or not a desirable urban form is likely in the long run, and if so, to what degree. The two alternative modes of synthesis in AHP—ideal and distributive—provide assessments of a land development plan incrementally (short-term) and city-wide pattern comprehensively (long-term), respectively. Thus, the spatial decision support system facilitates proactive and collective public policy determination of land resource for future sustainable urban development. 相似文献
947.
Runoff and soil loss from steep slopes treated with low cost bioengineering measures 总被引:1,自引:0,他引:1
Soil loss and surface runoff patterns were studied in erosion plots developed on manmade steep slopes (60 percent) over three years (1997–2000) in which rainfall ranged from 1338.4 to 1429.2 mm/year. Surface runoff and soil loss was examined under three different rainfall intensity classes. Runoff was mainly controlled by the rainfall distribution pattern on the seasonal scale. The soil loss was influenced by runoff during the first year. Both soil loss and runoff were reduced due to bioengineering measures in the first year irrespective of species planted. In the third year, combined effects of growth of grasses on protected plots, soil compaction and sediment exhaustion was noticed on runoff and soil loss. This was reflected by reduction in the runoff and soil loss from untreated and treated plots. In the high intensity class, reduction in runoff in treated plots was about 50 percent in three years and reduction in soil loss ranged between 94–95 percent in all plots. Physical treatment with brushwood structures was more efficient in erosion control in the low intensity class. 相似文献
948.
James A. Bradbury S. Lawrence Dingman Barry D. Keim 《Journal of the American Water Resources Association》2002,38(5):1287-1299
ABSTRACT: To provide a basis for regional hydroclimatic forecasting, New England (NE) precipitation and streamflow are compared with indices for the El Niño/Southern Oscillation, the Pacific North American (PNA) pattern, and the North Atlantic Oscillation (NAO). Significant positive correlations are found between the NAO index and monthly streamflow at western inland locations, with the strongest seasonal correlations occurring in winter. Smoothed records for the winter NAO and winter streamflow are highly correlated at some sites, suggesting that interrelationships are most significant in the low frequency spectrum. However, correlations between the NAO and precipitation are not significant, so further examination of other factors is needed to explain the relationship between the NAO and streamflow. NAO related regional air temperature, sea surface temperature (SST), storm tracking, and snowfall variability are possible mechanisms for the observed teleconnection. Exceptionally cool regional air temperatures, and SSTs, and unique regional storm track patterns characterized NE's climate during the famous 1960s drought, suggesting that concurrent (persistent) negative NAO conditions may have contributed to the severity of that event. Monthly and winter averaged regional streamflow variability are also significantly correlated with the PNA index. This, along with results from previous studies, suggests that tropospheric wave character and associated North Pacific SST anomalies are also related to NE regional drought conditions. 相似文献
949.
Peter?M.?KappelerEmail author Hans?G.?Erkert 《Behavioral ecology and sociobiology》2003,54(4):359-369
Whether animals are active at night or during the day has profound consequences for many aspects of their behavioral ecology. Because of ecological and physiological trade-offs, most animals, including primates, are either strictly nocturnal or diurnal. However, a few primate species exhibit cathemeral activity, i.e., their activity is irregularly distributed throughout the 24-h cycle. Details and determinants of this unusual activity pattern are poorly understood because long-term 24-h observations are not feasible in the field. We therefore used small data loggers to record the activity of cathemeral redfronted lemurs (Eulemur fulvus rufus) from several neighboring groups quantitatively and continuously over a complete annual cycle in order to evaluate various proposed proximate and ultimate determinants of cathemeral activity. Activity data were examined for variation as a function of ambient temperature, time of day, lunar phase, and season. We found that cathemeral activity occurred year-round and that, on average, 3.5 times more activity occurred during the day. Total and diurnal activity increased during the long days of the austral summer. Nocturnal activity increased during the longer nights of the cool dry season. Irrespective of season, lunar phase had a significant effect on the distribution of activity across the 24-h cycle, with most nocturnal activity recorded during parts of the night with greatest brightness. These data indicate that light availability is the primary proximate determinant for the patterning of cathemeral activity. Several lines of evidence suggest that cathemerality in lemurs has evolved from nocturnal ancestors and that it represents a transitory state on the way to the diurnal niche.Communicated by F. Trillmich 相似文献
950.
针对现有人工湿地硝化效能低、占地面积大的问题,研究污水处理厂尾水人工湿地高效硝化深度处理技术,采用序批式深床人工湿地反应器(DSCW),考察进水方式及其运行工况对硝化效能的影响。结果表明,进水方式、进水时间和闲置时间对湿地硝化效能影响显著。进水方式采用"连续进水-间歇出水"较连续进出水运行工况NH_4~+-N去除率高39.69%。连续进水时间为5.5 h、7.5 h、11.5 h时,NH_4~+-N去除率分别为81.82%、88.12%、89.91%;闲置时间为0、2 h、4 h时,NH_4~+-N去除率分别为88.12%、94.46%、92.60%。反应器在水温(20±3)℃、负荷35.56 g NH_4~+-N/(m2·d)、连续进水7.5 h-间歇出水0.5 h-排空闲置2 h运行工况下,出水NH_4~+-N为0.91 mg/L,去除率为94.46%,系统NH_4~+-N去除效能大幅提高。 相似文献