粮食增产寄希望于中低产田改造

广东省增加粮食产量的关键是提高单产，改造中低产田是提高单产的最有效途径．本文回顾了一年来广东省农建改低的工作，指出今后应进一步提高认识，高标准搞好农田基本建设，为广东农业实现现代化打下坚实的基础．为搞好农田基本建设，必须切实加强领导．有计划有步骤地认真做好各方面的工作．     

A comparative study of the costs of alternative mayfly oviposition behaviors

Oviposition behavior of insects has associated fitness costs related to the probability that females survive to oviposit. During summer 2003, we observed the oviposition behavior and compared the mortality rates of females of 17 mayfly species in one western Colorado watershed. We dissected adult females collected on terrestrial sticky traps, in drift nets submerged in streams, and in stomachs of brook trout to determine whether the mayflies had oviposited before capture, drowning, or consumption. Females oviposited by either splashing on the water surface releasing all their eggs (splashers), dropping their eggs from the air (bombers), dipping their abdomens multiple times releasing a few eggs at a time (dippers), landing on rocks and ovipositing on the undersides (landers), or floating downstream while releasing their eggs (floaters). Almost 100% of lander and 50% of dipper females had not oviposited when captured on sticky traps, increasing their vulnerability to preoviposition mortality by aerial predators compared to mayflies with other behaviors. In contrast, most females had laid their eggs before drowning or being eaten by a fish (50–90%). However, groups with oviposition behaviors most exposed to the water surface (floaters, then splashers, dippers, and landers) were more vulnerable to drowning before completing oviposition. In addition, splashers and floaters were most vulnerable to predation by brook trout before ovipositing. These data suggest that fitness costs associated with preoviposition mortality may be considerable depending on mayfly oviposition behavior. Furthermore, previously demonstrated benefits of low predation rates on eggs of lander species may be offset in part by costs to female survival. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Plant vintage, technology, and environmental regulation

We use data on productivity and pollution abatement costs at individual pulp and paper mills to test whether the impact of environmental regulation on productivity differs by plant vintage and technology. Plants with higher pollution abatement costs have significantly lower productivity levels. This relationship differs greatly based on a plant's technology, with productivity at integrated mills being greatly affected by abatement costs, while the impact at non-integrated mills is negligible. Plant vintage does not seem to matter, with older and newer plants showing similar impacts. Reported abatement costs appear to substantially understate the true costs of abatement. Accounting for the impact of technology differences makes some difference in the estimated overall impact of environmental regulation.     

劳资关系的分配视角分析

从历史发展进程的角度分析了劳资关系及其变化问题,并重点探讨劳动与资本之间分配关系的动态变化．“资本雇佣劳动”这种制度安排有其历史发展过程中的“路径依赖”特征,各种不同经济与法律环境对其形成与存在提供基础,而今后经济发展的复杂化将对传统的劳资关系产生重要的影响．劳资之间分配关系是劳资关系中最为重要而根本性的体现,劳资关系的变迁对于其分配关系也将产生影响,使劳资之间的分配模式从传统的“以物质资本为中心”的分配模式向新型的“以人力资本为中心”的分配模式转化．     

Project-Based Emissions Trading: The Impact of Institutional Arrangements on Cost-Effectiveness

In this paper we demonstrate that the institutionalarrangement (or: design) of Joint Implementation (JI) and the CleanDevelopment Mechanism (CDM) has a decisive impact on theircost-effectiveness. We illustrate our arguments by statistically analyzing thecosts from 94 Activities Implemented Jointly (AIJ) pilot phase projects aswell as by adjusting these data on the basis of simple mathematicalformulas. These calculations explicitly take into account the institutionaldifferences between JI (sinks, no banking) and the CDM (banking, no sinks)under the Kyoto Protocol and also show the possible effects on credit costsof alternative design options. However, our numerical illustrations shouldbe viewed with caution, because AIJ is only to a limited extentrepresentative of potential future JI and CDM projects and because creditcosts are not credit prices. Some of the main figures found in this study are:an average cost figure per unit of emission reduction for AIJ projects of 46dollar per ton of carbon dioxide equivalent ($/Mg CO₂-eq), anaverage potential JI credit cost figure which is lowered to 37$/Mg CO₂-eq by introducing banking and an average of 6$/Mg CO₂-eq per credit for potential low-cost CDM projects whichincludes sinks. However, at CoP6 in November 2000 in The Hague (TheNetherlands), the Parties to the Framework Convention on Climate Change(FCCC) did not (yet) reach consensus on the institutional details of theproject-based mechanisms, such as the possible arrangement of early JIaction or the inclusion of sinks under the CDM.     

长春市水环境生态系统服务功能价值评估

生态系统服务不是无偿提供的，而是用货币量算，价值不菲。对长春市水生态系统的5项服务功能进行估算累加。可以得出目前长春市水生态系统服务每年价值在62599．35万元之上。比1990年的水生态系统服务价值有所削减。也就是说，在过去10a间，长春市水生环境给人们提供的福利在减少。因为各技术和学科本身的局限，所得值只能作为决策者的参考，而更精确的结果需要更合理的方法和更深入广泛的研究。     

Measuring forest ecosystem sustainability: A resource accounting approach

A new environmental paradigm has emerged, reflecting a change in the public's understanding of resource sustainability. Forest policy makers need to be better informed about such changes to achieve economic, social, and environmental objectives in a manner that balances human needs and aspirations with ecosystem constraints. As an aid to this task, a forest resource accounting system based on the key concept of natural capital could help reshape forest policies to provide an even wider spectrum of benefits for both present and future generations by maintaining and enhancing the productive capacity of forest capital. Such a resource accounting system would provide a tool for integrating multidimensional information requirements in measuring the health of both forest ecosystems and economic systems. This paper outlines some of the features of this accounting system and proposes and framework that would integrate economic and ecological characteristics of natural resources. Forest resource accounting is urgently needed to achieve the sustainability goals of ecosystem management.     

Environmental and social implications of waste in U.S. agriculture and food sectors

Because the agriculture/food sectors appear to be driven by short-term economic and political forces, cheap energy, and agricultural-chemical technologies, waste and environmental/social problems in the agricultural/food sectors are estimated to cost the nation at least $150 billion per year. Most of the waste and environmental/social problems can be eliminated through better resource management policies and the adoption of sustainable agricultural practices.Based on a paper entitled Waste in U.S. Agricultural and Food Sectors—Environmental and Social Costs presented at the Gross National Waste Product Forum, Washington, D.C.     

EFFECT OF SYSTEM LAYOUT ON SUBSURFACE DRAINAGE COST IN FLAT IRRIGATED LAND1

ABSTRACT: The economic feasibility of large-scale subsurface drainage projects in irrigated land is affected by construction costs. This study was conducted to evaluate the effect of two different types of subsurface drainage system layout on construction costs for a 1000 ha pilot area located in the Nile Delta of Egypt. The two types of layout studied were the conventional layout currently used in Egypt and the modified layout that was developed for reducing water losses from rice fields. When compared to the conventional layout, the modified layout resulted in a reduction of 6.74 percent in construction costs (714,464 US$ versus 766,142 US$). This cost reduction is explained by the need for lesser lengths of large diameter collector pipes with the modified layout, which results from the smaller drainage area of subsurface drainage systems (average 23.7 versus 30.8 ha). We have found that the cost of subsurface drainage can be minimized by reducing the area drained by each subsurface drainage system.     

WATER QUALITY MONITORING NETWORK DESIGN: A PROBLEM OF MULTI-OBJECTIVE DECISION MAKING1

ABSTRACT: Hydrologic data network design is a fairly complicated problem where questions as to the number of gages required, time frequencies to be selected, and benefits/costs of monitoring still remain unresolved. These issues are intensified in case of water quality variables as they are more error-prone, costly, and time consuming to sample. The basic difficulty underlying the design and evaluation of monitoring systems is the lack of an objective criterion to assess: (a) the efficiency, and (b) cost-effectiveness of a network. A statistical procedure based on the entropy principle of information theory is proposed to address the evaluation of both factors. Efficiency is measured quantitatively in terms of the information produced by a network. Similarly, benefits of monitoring are described by informative measures for an objective evaluation of cost-effectiveness. The study presented demonstrates the applicability of the entropy method in assessing the efficiency and the benefits of an existing water quality monitoring network. The method is applied for temporal and spatial features of monitoring, handled as both separate and combined problems. The results are shown in the case of the highly polluted Porsuk River in Turkey. The strengths and shortcomings of the proposed methodology are discussed, with recommendations for future research on the application of the entropy principle in network design.