大型露天煤矿生态重建的效益分析

本文讨论了黄土区大型露天煤矿生态重建效益产生的特点及其量化分析的方法。矿区生态重建的效益体现为生态效益、经济效益、社会效益的配比与统一,这种配比主要取决于三项因素,它们依次是：（1）矿区生态重建目标,（2）矿区生态重建系统建设和演变,（3）生态重建措施。当前矿区生态重建的主要任务是土地的再利用,土地的利用状况。本文选择“土地利用结构”指标,以平朔安太堡露天煤矿生态重建为例,简要地揭示了生态重建效益的动态增长过程。     

唐山市采煤下沉区植物资源生态分析

采煤下沉区是矿区在剧烈的人为干扰下形成的一种特殊景观,其生态结构与功能退化严重,使用价值和美学价值被破坏.通过生态恢复和植被重建,促使采煤下沉区的生态与经济价值再生,对区域生态系统的健康、地方经济可持续发展以及人民的生活水平提高具有十分重要的意义.本文主要通过对唐山市南部采煤下沉区景观生态特征和环境影响的调查分析,阐述了采煤下沉区南湖公园的建设成果,并提出了采煤下沉区植物资源生态恢复和重建的生物措施.     

大型露天矿区农村生态经济系统重建模式研究——以平朔矿为例

凡是以开采矿产资源为主的地区都要面临资源枯竭后如何发展经济的问题。本文以正处于生产鼎盛期的全国大型露天煤矿——平朔矿为例,针对其与农村生态经济紧密相关的特点,分析农村生态经济可持续发展方面存在的问题,提出矿区农村生态经济系统重建的三方面模式:一是通过工业生态经济链发展提供资金,减少污染。二是要建立基于矿区复垦地的小杂粮生产、林木培育、牧草种植、中草药种植的多元农业生态经济园区。三是矿区农村生态经济重建,需要通过股份制联合开发复垦土地,建立失地农民基本生活保障制度,并推进农村城镇化建设等。     

煤矿塌陷区土地复垦与生态补偿优化设计

本文在综合分析煤炭开采的生态环境效应基础上,提出了煤矿塌陷区土地复垦与生态补偿优化设计的原则,并指出在土地复垦时进行生态补偿应从经济、社会、工程三个方面优化设计,以取得社会、生态与经济效益双赢的良好效果,对实现矿区可持续发展有重要意义,对我国矿区土地复垦有一定借鉴意义.     

矿区土地复垦与土地利用变化分析

以鸡东县四海矿区为研究对象,对矿区土地复垦前后土地利用结构变化进行分析,结果表明:四海矿区采矿用地总面积为236.03hm2,土地复垦采矿用地为183.10hm2,废弃的采矿用地主要复垦为旱地、有林地等用地类型,此项研究将为今后编制土地复垦规划提供科学依据。     

煤炭矿区复合生态系统及其耦合机理研究

以复合生态系统理论为基础,系统研究了煤炭矿区复合生态系统的涵义、组成结构、功能、特征及生态管理目标,论述了煤炭矿区复合生态系统资源—经济—社会—环境各子系统的耦合机理,分析了复合生态系统内物质流、能量流、价值流和信息流的交换机制;煤炭矿区复合生态系统管理所面对的主要问题包括矿区地面塌陷和土地压占、水资源污染和水系破坏、植被破坏和水土流失、大气污染和废渣污染;为此,应实施生态系统保护和维持性策略、生态修复和生态重建等策略。     

城市景观生态

本文分析了中国城市化及城市扩张所带来的城市景观现状问题，通过对景观生态学原理的简单阐述，运用城市景观生态规划原理来指导城市景观生态建设，并提出了五大城市景观生态发展战略。     

浅谈煤矿开采后的复垦技术

本文对煤矿塌陷区土地复垦进行了分类,介绍了塌陷区土地复垦的工程技术及生物复垦措施.开采沉陷是造成矿区环境地质灾害的直接原因,有效控制和减轻地面沉陷程度是避免开采沉陷环境灾害的基本途径.充填采煤法是减少地表下沉效果作好的方法.文章针对煤矿开采对矿区环境、地表破坏的影响,以减轻危害程度为目标,提出合理的采矿方法和工艺.     

矿业开发密集地区的景观生态重建刍议

本文针对矿业开发密集地区的特点,从尾矿综合利用、土壤重建、植被重建、生态农业建设、矿业生态园区建设及全方位生态建设六个层次论述了该类地区的景观生态建设。     

自然价值的保护与利用——华中农业大学 校园规划15年

针对已完成的华中农业大学校园规划进行反馈调 查，分析校园生态规划设计理论方法的实施效果，提出对总体 格局进一步优化以及生物多样性保护的具体改进措施。即以最 优景观格局理论对校园进行格局优化，以景观生态效应理论建 设生态廊道，采取紧凑式建筑布局减少建筑占地，在规划设计 中保护并利用多种景观边界。以栖息地保护为核心，通过修复 校园自然景观要素、重建部分栖息地以及引入城市农业等措 施，将校园生物多样性维持在一个较高的水平上。     

Forecasting the price of gold

This article seeks to evaluate the appropriateness of a variety of existing forecasting techniques (17 methods) at providing accurate and statistically significant forecasts for gold price. We report the results from the nine most competitive techniques. Special consideration is given to the ability of these techniques to provide forecasts which outperforms the random walk (RW) as we noticed that certain multivariate models (which included prices of silver, platinum, palladium and rhodium, besides gold) were also unable to outperform the RW in this case. Interestingly, the results show that none of the forecasting techniques are able to outperform the RW at horizons of 1 and 9 steps ahead, and on average, the exponential smoothing model is seen providing the best forecasts in terms of the lowest root mean squared error over the 24-month forecasting horizons. Moreover, we find that the univariate models used in this article are able to outperform the Bayesian autoregression and Bayesian vector autoregressive models, with exponential smoothing reporting statistically significant results in comparison with the former models, and classical autoregressive and the vector autoregressive models in most cases.     

Planned adaptation in risk regulation: An initial survey of US environmental, health, and safety regulation

In principle, we want regulatory programs to be based on current realities, as reflected for example in the best knowledge of relevant experts. That would imply that old rules now on the books should be consistent with today's knowledge base, not just what was known when a rule or standard was originally set. This paper reports on a survey of US programs, examining how often existing rules are actually updated in light of better knowledge, and identifies five programs that attempt to make policy routinely adaptive. These programs exhibit what we term Planned Adaptation: they both revise rules when relevant new knowledge appears, and take steps to produce such improved knowledge. While Planned Adaptation is rare, it is used in several nationally prominent programs, including air pollution, airplane safety, and drug safety. Planned Adaptation is a policy tool that deserves more attention.     

The greenhouse effect: Damages,costs and abatement

The buildup of so-called greenhouse gases in the atmosphere — CO₂ in particular-appears to be having an adverse impact on the global climate. This paper briefly reviews current expectations with regard to physical and biological effects, their potential costs to society, and likely costs of abatement. For a worst case scenario it is impossible to assess, in economic terms, the full range of possible non-linear synergistic effects. In the most favorable (although not necessarily likely) case (of slow-paced climate change), however, it seems likely that the impacts are within the affordable range, at least in the industrialized countries of the world. In the third world the notion of affordability is of doubtful relevance, making the problem of quantitative evaluation almost impossible. We tentatively assess the lower limit of quantifiable climate-induced damages at $30 to $35 per ton of CO₂ equivalent, worldwide, with the major damages being concentrated in regions most adversely affected by sea-level rise. The non-quantifiable environmental damages are also significant and should by no means be disregarded.The costs and benefits of (1) reducing CFC use and (2) reducing fossil fuel consumption, as a means of abatement, are considered in some detail. This strategy has remarkably high indirect benefits in terms of reduced air pollution damage and even direct cost savings to consumers. The indirect benefits of reduced air pollution and its associated health and environmental effects from fossil-fuel combustion in the industrialized countries range from $20 to $60 per ton of CO₂ eliminated. In addition, there is good evidence that modest (e.g. 25%) reductions in CO₂ emissions may be achievable by the U.S. (and, by implication, for other countries) by a combination of increased energy efficiency and restructuring that would permit simultaneous direct economic benefits (savings) to energy consumers of the order of $50 per ton of CO₂ saved. A higher level of overall emissions reduction — possibly approaching 50% — could probably be achieved, at little or not net cost, by taking advantage of these savings.We suggest the use of taxes on fossil fuel extraction (or a carbon tax) as a reasonable way of inducing the structural changes that would be required to achieve significant reduction in energy use and CO₂ emissions. To minimize the economic burden (and create a political constituency in support of the approach) we suggest the substitution of resource-based taxes in general for other types of taxes (on labor, income, real estate, or trade) that are now the main sources of government revenue. While it is conceded that it would be difficult to calculate the optimal tax on extractive resources, we do not think this is a necessary prerequisite to policy-making. In fact, we note that the existing tax system has never been optimized according to theoretical principles, and is far from optimal by any reasonable criteria.During the academic year 1989–90 Dr. Ayres was at the International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.During the summer of 1989 Mr. Walter was a member of the Young Scientists' Summer Program at IIASA.     

SCIENCE AND INDUSTRY: TRACING THE FLOW OF BASIC RESEARCH THROUGH MANUFACTURING AND TRADE

This paper describes flows of basic research through the US economy during the late 20th century. In addition, the paper studies the effect of the flows on scientific papers in industries and fields. This article differs from others in its use of measures of science rather than technology. Together, its results present a picture of the structure of basic research flows in a modern, science-intensive economy. Basic research flows are large within petrochemicals and drugs, and within software and communications. Flows of chemistry, physics, and engineering are common throughout all industries – biology and medicine are almost confined to petrochemicals and drugs; and computer science is nearly as restricted to software and communications. In general, basic research flows are more concentrated within scientific fields than within industries. Our findings concerning the production of scientific papers indicate that the effect of a 1% change in academic R&D spillovers significantly exceeds that of industrial spillovers. In addition, within-field effects exceed effects between-fields, while within- and between-industry effects are roughly equal. It follows that scientific fields limit basic research flows more than industries do, perhaps because large firms implicitly span a range of industries.     

Valuing Mangrove-Fishery Linkages – A Case Study of Campeche, Mexico

This paper explores the value of mangrove systems as a breeding and nursery habitat for off-shore fisheries, focusing on mangrove-shrimp production linkages in Campeche State, Mexico. We develop an open access fishery model to account explicitly for the effect of mangrove area on carrying capacity and thus production. From the long-run equilibrium conditions of the model we are able to establish the key parameters determining the comparative static effects of a change in mangrove area on this equilibrium. We then estimate empirically the effects of changes in mangrove area in the Laguna de Terminos on the production and value of shrimp harvests in Campeche over 1980–90. Our findings suggest that mangroves are an important and essential input into the Campeche shrimp fishery, but that the low levels of deforestation between 1980 and 1990 mean that the resulting losses to the shrimp fishery are still comparatively small. Over-exploitation of the fishery due to open access conditions remains the more pervasive threat, and without better management any long-run benefits of protecting mangrove habitat are likely to be dissipated.     

An Economic Analysis and Simulation of Woodfuel Management in the Sahel

This paper presents an economic framework and a computationalmethodology for assessing the evolution of woodfuel supply costsand the spatial distribution of biomass in a Sahelian woodlandsetting. Spatial data on standing stock and the costs oftransport to market are used to construct a supply curve for fuelto a fuel-consuming location. Given an exogenously specifieddemand, the model simulates, period by period, the extraction,regeneration, and transport of wood fuels. The model is appliedto evaluate the benefits and ecological impacts of scenarios forwoodland management around the city of N'Djamena, Chad.     

Zvi Griliches's contributions to the economics of technology and growth*

Zvi Griliches's contributions to the economics of technology and growth are identified. Included is a discussion of his contributions on: the determinants of differences in speed of adoption of innovations; the use of patents to measure technology; the private and social returns to R&D; and spillover effects from R&D. Griliches's own evaluation of his research contribution is compared to the evaluation of others in the field, using as evidence citation counts of his works collected from the online Web of Science. Griliches's most important contribution is his 1957 Econometrica hybrid corn paper that is a foundation of the economics of technological innovation. Remarkably, the trend in annual citations to the paper has continued to increase for over 40 years. Finally, we summarize Griliches's most recent views on the practice of economics and on the most important unanswered questions in the economics of technology and growth.     

Evidence on the impact of R&D and ICT investments on innovation and productivity in Italian firms

Both research and development (R&D) and information and communication technology (ICT) investment have been identified as sources of relative innovation underperformance in Europe vis-à-vis the USA. In this article, we investigate the R&D and ICT investment at the firm level in an effort to assess their relative importance and to what extent they are complements or substitutes. We use data on a large unbalanced panel data sample of Italian manufacturing firms constructed from four consecutive waves of a survey of manufacturing firms, to estimate a version of the CDM model of R&D, innovation, and productivity [Crépon–Duguet–Mairesse 1998. Research, innovation and productivity: An econometric analysis at the firm level. Economics of Innovation and New Technology 7, no. 2: 115–58] that has been modified to include ICT investment and R&D as the two main inputs into innovation and productivity. We find that R&D and ICT are both strongly associated with innovation and productivity, with R&D being more important for innovation, and ICT investment being more important for productivity. For the median firm, rates of return to both investments are so high that they suggest considerably underinvestment in both these activities. We explore the possible complementarity between R&D and ICT in innovation and production, but find none, although we do find complementarity between R&D and worker skill in innovation.     

新员工主动社会化行为与组织承诺关系研究——以社会资本为中介变量

为了探索新员工主动社会化行为影响组织承诺的过程,本文对来自企业的401个有效样本进行了实证分析。本研究运用层级回归的方法,控制了人口统计变量的影响后,发现员工的搜寻信息和搜寻绩效反馈行为对组织承诺有直接的正面影响,同时,通过员工社会资本对员工组织承诺产生了间接的正面影响。社会资本在员工搜寻信息和搜寻绩效反馈行为影响组织承诺的机制中起部分中介作用。员工的关系构建行为对组织承诺没有显著影响,但对员工社会资本存在显著的正面影响。