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381.
土地资源的多级网格数据结构建立与应用研究 总被引:1,自引:0,他引:1
传统的基于行政区的土地统计数据不能完全表现区域内部土地利用的空间分异特征,以武汉市为实验区,对基于网格的统计信息算法STING(Statistical Information Grid-based method)进行扩展,以景观多样性指数为定量化指标对实验区进行四叉树划分生成不均匀多级网格,建立一种拟合了行政区划界线的不均匀的多级网格结构来存储、管理和分析土地数据。并以此多级网格数据结构为平台计算和生成实验区人口密度空间分异渲染图,初步抽取了人口分布与土地利用之间的关系。实验表明,基于多级网格的统计方法能更好地表达土地利用及其相关数据的空间分异性,利于对土地资源数据的进一步挖掘以抽取所需知识。 相似文献
382.
Sergio Castellano Valentina Marconi Valeria Zanollo Giulia Berto 《Behavioral ecology and sociobiology》2009,63(8):1109-1118
As in many lekking anurans, Italian treefrog males use two mating tactics: they can attract females by calling vigorously
or be satellites, that is, they can remain silent in proximity of a calling male and try to intercept females attracted by
their neighbour. We investigated the factors that affected the expression of this mating tactic. Consistent with the conditional
mating tactic hypothesis, satellites were smaller than average and smaller than their parasitised calling males. They spent
a larger-than-average number of nights at the breeding site, where most of them were also observed calling. Moreover, satellites
showed lower call rates and lower mating success than those of males they parasitise but not lower than those of males they
did not parasitise. Overall, these results, together with those derived from the analyses of the seasonal and spatial distribution
of males, provide evidence for a non-random association between satellites and calling males and are consistent with the hypothesis
that satellites have spectral and temporal acoustic preferences that parallel those of females. By adopting the less-successful
satellite mating tactic, competitively inferior males can nevertheless maximise their potential reproductive fitness by sexually
parasitising the most attractive chorusing males. 相似文献
383.
Modelling habitat suitability of semi-aquatic vertebrates for large scale conservation purposes is a particularly challenging task, due to the fine-scale linearity of riverine habitats, and to the ecological continuum represented by the riparian and the aquatic ecosystems, on one side, and by a river and its tributaries, on the other. 相似文献
384.
Sensitivity Analyses of Spatial Population Viability Analysis Models for Species at Risk and Habitat Conservation Planning 总被引:3,自引:0,他引:3
ILONA R. NAUJOKAITIS-LEWIS§ JANELLE M. R. CURTIS† PETER ARCESE JORDAN ROSENFELD‡ 《Conservation biology》2009,23(1):225-229
Abstract: Population viability analysis (PVA) is an effective framework for modeling species- and habitat-recovery efforts, but uncertainty in parameter estimates and model structure can lead to unreliable predictions. Integrating complex and often uncertain information into spatial PVA models requires that comprehensive sensitivity analyses be applied to explore the influence of spatial and nonspatial parameters on model predictions. We reviewed 87 analyses of spatial demographic PVA models of plants and animals to identify common approaches to sensitivity analysis in recent publications. In contrast to best practices recommended in the broader modeling community, sensitivity analyses of spatial PVAs were typically ad hoc, inconsistent, and difficult to compare. Most studies applied local approaches to sensitivity analyses, but few varied multiple parameters simultaneously. A lack of standards for sensitivity analysis and reporting in spatial PVAs has the potential to compromise the ability to learn collectively from PVA results, accurately interpret results in cases where model relationships include nonlinearities and interactions, prioritize monitoring and management actions, and ensure conservation-planning decisions are robust to uncertainties in spatial and nonspatial parameters. Our review underscores the need to develop tools for global sensitivity analysis and apply these to spatial PVA. 相似文献
385.
Conservation Threats Due to Human-Caused Increases in Fire Frequency in Mediterranean-Climate Ecosystems 总被引:1,自引:0,他引:1
Periodic wildfire is an important natural process in Mediterranean-climate ecosystems, but increasing fire recurrence threatens the fragile ecology of these regions. Because most fires are human-caused, we investigated how human population patterns affect fire frequency. Prior research in California suggests the relationship between population density and fire frequency is not linear. There are few human ignitions in areas with low population density, so fire frequency is low. As population density increases, human ignitions and fire frequency also increase, but beyond a density threshold, the relationship becomes negative as fuels become sparser and fire suppression resources are concentrated. We tested whether this hypothesis also applies to the other Mediterranean-climate ecosystems of the world. We used global satellite databases of population, fire activity, and land cover to evaluate the spatial relationship between humans and fire in the world's five Mediterranean-climate ecosystems. Both the mean and median population densities were consistently and substantially higher in areas with than without fire, but fire again peaked at intermediate population densities, which suggests that the spatial relationship is complex and nonlinear. Some land-cover types burned more frequently than expected, but no systematic differences were observed across the five regions. The consistent association between higher population densities and fire suggests that regardless of differences between land-cover types, natural fire regimes, or overall population, the presence of people in Mediterranean-climate regions strongly affects the frequency of fires; thus, population growth in areas now sparsely settled presents a conservation concern. Considering the sensitivity of plant species to repeated burning and the global conservation significance of Mediterranean-climate ecosystems, conservation planning needs to consider the human influence on fire frequency. Fine-scale spatial analysis of relationships between people and fire may help identify areas where increases in fire frequency will threaten ecologically valuable areas. 相似文献
386.
关于中国企业品牌战略的研究 总被引:2,自引:0,他引:2
陈威 《湖南环境生物职业技术学院学报》2009,15(1):39-42
为使中国企业更好的应对国外品牌的竞争,稳健的实施企业品牌战略,该文就我国企业实施品牌战略的现状以及存在的问题进行了分析,有针对性的提出了具体在实施品牌战略过程中应特别注意并实行有效调控的对策。参4. 相似文献
387.
388.
现代绿色物流管理及其策略研究 总被引:35,自引:0,他引:35
陈达 《中国人口.资源与环境》2001,11(2):111-113
现代绿色物流管理作为一种新的物流管理方式,符合时代发展的要求和类生存发展的利益,因而代表了未来物流管理发展的方向和趋势。本文探讨了现代绿色物流管理的可持续发展、生态经济学和生态伦理学理论基础,分析了现代物流管理中影响环境的非绿色因素,接着从政府、企业和消费者三个角度提出了现代绿色物流管理的策略,最后指出21世纪绿色物流管理的特征。 相似文献
389.
经济战略研究与可持续发展的若干思考 总被引:3,自引:1,他引:2
冯之浚 《中国人口.资源与环境》2001,11(2):1-5
本文分析了战略研究演化的轨迹,揭示了可持续发展的深刻内涵,指出了21世纪我国可持续发展面临的机遇。 相似文献
390.
赵彦修 《中国人口.资源与环境》2001,11(2):14-17
邓小平同志关于发展的理论中,包含了丰富的具有中国特色的可持续发展思想,以江泽民同志为核心的第三代领导集体,丰富和发展着邓小平理论。深入学习邓小平理论,对我国实施可持续发展战略,有重要的意义。 相似文献