The principal–agent model with multilateral externalities: An application to climate agreements

We consider contracting of a principal with an agent if multilateral externalities are present. The motivating example is that of an international climate agreement given private information about the willingness-to-pay (WTP) for emissions abatement. Due to multilateral externalities the principal uses her own emissions besides subsidies to incentivize the agent and to assure his participation. Optimal contracts equalize marginal abatement costs and, thus, can be implemented by a system of competitive permit trading. Moreover, optimal contracts can include a boundary part (i.e., the endogenous, type dependent participation constraint is binding), which is not a copy of the outside option of no contract. Compared to this outside option, a contract can increase emissions of the principal for types with a low WTP, and reduce her payoff for high types. Subsidies can be constant or even decreasing in emission reductions, and turn negative so that the agent reduces emissions and pays the principal.     

A Revealed Preference Approach to Estimating Supply Curves for Ecosystem Services: Use of Auctions to Set Payments for Soil Erosion Control in Indonesia

Abstract:  To supply ecosystem services, private landholders incur costs. Knowledge of these costs is critical for the design of conservation-payment programs. Estimating these costs accurately is difficult because the minimum acceptable payment to a potential supplier is private information. We describe how an auction of payment contracts can be designed to elicit this information during the design phase of a conservation-payment program. With an estimate of the ecosystem-service supply curve from a pilot auction, conservation planners can explore the financial, ecological, and socioeconomic consequences of alternative scaled-up programs. We demonstrate the potential of our approach in Indonesia, where soil erosion on coffee farms generates downstream ecological and economic costs. Bid data from a small-scale, uniform-price auction for soil-conservation contracts allowed estimates of the costs of a scaled-up program, the gain from integrating biophysical and economic data to target contracts, and the trade-offs between poverty alleviation and supply of ecosystem services. Our study illustrates an auction-based approach to revealing private information about the costs of supplying ecosystem services. Such information can improve the design of programs devised to protect and enhance ecosystem services.     

The additionality problem with offsets: Optimal contracts for carbon sequestration in forests

Carbon offsets are a frequently discussed tool for reducing the costs of an emissions reduction policy. However, offsets have a basic problem stemming from asymmetric information. Sellers of offsets have private information about their opportunity costs, leading to concerns about whether offsets are additional. Non-additional offsets can undermine a cap-and-trade program or, if the government purchases them directly, result in enormous government expenditures. We analyze contracts for carbon sequestration in forests that mitigate the asymmetric information problem. Landowners are offered a menu of two-part contracts that induces them to reveal their type. Under this scheme, the government is able to identify ex post how much additional forest each landowner contributes and minimize ex ante its expenditures on carbon sequestration. To explore the performance of the contracting scheme, we conduct a national-scale simulation using an econometric model of land-use change. The results indicate that for an increase in forest area of 61 million acres, government expenditures are $5.3 billion lower under the contracting approach compared to a uniform subsidy offered to all landowners. This compares to an increase in private opportunity costs of just $110 million dollars under the contracts. Thus, the contracting scheme is preferable from society's perspective.     

Suitability of short or long conservation contracts under ecological and socio-economic uncertainty

Acquisition of land rights has become a primary tool used to protect terrestrial biodiversity. Fixed length contracts are often used when trying to secure conservation benefits on private land in agri-environment schemes and payment for environmental services schemes, but the duration of the conservation contracts used in different programmes varies. To date, very little research has been undertaken to determine the situations in which contracts of differing lengths are optimal or when conservation agencies or groups should use a portfolio of different contract lengths rather than relying on a single type. Using stochastic dynamic programming and related heuristic methods, we investigate how the choice between short or long conservation contracts is affected by uncertainty regarding the future availability of sites and their ecological condition. We also examine the benefits offered by using a portfolio of different contract lengths. Conservation agencies must pay private landowners a premium to secure longer agreements and because of this, shorter contracts are advantageous if sites are likely to remain available for conservation in the future. Long contracts are preferred when future site availability becomes more unlikely. In contrast to uncertainty over site availability, uncertainty over future ecological conditions has little effect on contract selection and only markedly influences the choice between short and long contracts when there is heterogeneity across sites in expected conservation outcomes and future availability of sites is also uncertain. Finally, when future site availability is unlikely, the use of a portfolio of short and long contracts would offer greater conservation gains than using either type in isolation, even though this option is not yet one that is commonly found in conservation practice.     

滨海湿地类自然保护区的成本-效益研究——以江苏盐城湿地珍禽国家级自然保护区为例

以江苏盐城湿地珍禽国家级自然保护区为例,分析了滨海湿地生态系统所提供的生态系统服务及保护该系统所产生的成本.采用市场价值法、影子工程法和专家评估法估算了保护区内滨海湿地生态系统服务价值.2010年盐城保护区内滨海湿地生态系统产生的保护成本为8.18× 109元,其中管理成本为1.95× 107元,机会成本为8.16× 109元;保护区产生的效益为1.83× 1010元.结果表明,盐城保护区获得的效益远大于其付出的成本,盐城保护区的存在具有经济学上的收益优势.因此,在盐城滨海湿地建立自然保护区具有巨大的生态效益,这种优势更多地体现为长期的综合效益,且难以用货币形式直接兑现.对待自然保护区建设与管理应形成整体、长期的理念,不能因短期利益和局部利益而牺牲自然保护区,真正做到对保护区的永久保护和持续利用.     

Contract renegotiation and rent re-distribution: Who gets raked over the coals?

Policy shocks affect the rent distribution in long-term contracts, which can lead to such contracts being renegotiated. We seek an understanding of what aspects of contract design, in the face of a substantial policy shock, affect the propensity to renegotiate. We test our hypotheses using data on U.S. coal contracts after the policy shock of the 1990 Clean Air Act Amendments. Contracts are divided into two categories, those that were renegotiated following the shock and those that were not. Characteristics of the contract are used to explain whether or not the contract was ultimately renegotiated. Results provide guidance on rent re-distribution and contract renegotiation more generally and are applicable to contemporary policy issues such as climate change legislation.     

滨海地区湿地重建的生态工程范例

在天津泰达区盐田上通过淡水浸泡、消浪墙构建、土壤更换、水生植物引种等措施，重建了湿地生态系统的结构。结果表明，人工湿地在初期阶段是成功的。     

Alternative transportation fuel standards: Welfare effects and climate benefits

This paper develops an integrated model of the fuel and agricultural sectors to analyze the welfare and greenhouse gas emission (GHG) effects of the existing Renewable Fuel Standard (RFS), a Low Carbon Fuel Standard (LCFS) and a carbon price policy. The conceptual framework shows that these policies differ in the incentives they create for the consumption and mix of different types of biofuels and in their effects on food and fuel prices and GHG emissions. We also simulate the welfare and GHG effects of these three policies which are normalized to achieve the same level of US GHG emissions. By promoting greater production of food-crop based biofuels, the RFS is found to lead to a larger reduction in fossil fuel use but also a larger increase in food prices and a smaller reduction in global GHG emissions compared to the LCFS and carbon tax. All three policies increase US social welfare compared to a no-biofuel baseline scenario due to improved terms-of-trade, even when environmental benefits are excluded; global social welfare increases with a carbon tax but decreases with the RFS and LCFS due to the efficiency costs imposed by these policies, even after including the benefits of mitigating GHG emissions.     

Ecological drivers of group living in two populations of the communally rearing rodent, Octodon degus

Intraspecific variation in sociality is thought to reflect a trade-off between current fitness benefits and costs that emerge from individuals' decision to join or leave groups. Since those benefits and costs may be influenced by ecological conditions, ecological variation remains a major, ultimate cause of intraspecific variation in sociality. Intraspecific comparisons of mammalian sociality across populations facing different environmental conditions have not provided a consistent relationship between ecological variation and group-living. Thus, we studied two populations of the communally rearing rodent Octodon degus to determine how co-variation between sociality and ecology supports alternative ecological causes of group living. In particular, we examined how variables linked to predation risk, thermal conditions, burrowing costs, and food availability predicted temporal and population variation in sociality. Our study revealed population and temporal variation in total group size and group composition that covaried with population and yearly differences in ecology. In particular, predation risk and burrowing costs are supported as drivers of this social variation in degus. Thermal differences, food quantity and quality were not significant predictors of social group size. In contrast to between populations, social variation within populations was largely uncoupled from ecological differences.     

Ecological constraints on group size: an analysis of spider monkey and chimpanzee subgroups

The social organization of spider monkeys (Ateles geoffroyi) and chimpanzees (Pan troglodytes) appear remarkably similar. In this paper, field studies of these two species were used to (1) test a model of ecological constraints on animal group size which suggests that group size is a function of travel costs and (2) assess ecological and social factors underlying the social organization of these two species. Spider monkeys were studied over a 6-year period in Santa Rosa National Park, Costa Rica, and chimpanzees were studied for 6 years in Kibale National Park, Uganda. Adults of both species spent their time in small subgroups that frequently changed size and composition. Thus, unlike most primate species, spider monkeys and chimpanzees were not always in a spatially cohesive social group; each individual had the option of associating in subgroups of a different size or composition. Both species relied on ripe fruit from trees that could be depleted through their feeding activity. However, spider monkey food resources tended to occur at higher densities, were more common, less temporally variable, and did not reach the low levels experienced by chimpanzees. Analyses of the relationship between subgroup size and the density and distribution of their food resources suggested that travel costs limit subgroup size. However, these ecological factors did not influence all age/sex classes equally. For example, the number of adult males in a subgroup was a function of food density and travel costs. However, this was not the case for female chimpanzees, suggesting that the benefits of being in a subgroup for females did not exceed the costs, even when ecological conditions appeared to minimize subgroup foraging costs. Therefore, it seems likely that social strategies influenced the relationship between food resource variables and subgroup size.     

Female encounter rates and fighting costs of males are associated with lek size in Drosophila mycetophaga

Male costs and benefits associated with male display size in field populations of an Australian lekking Drosophila species were examined. Results suggested that male mating success increased with display size, since matings appeared to be more common in large displays, and since the probability of males encountering a female increased as displays contained more males. Female encounter probabilities did not increase once about 20 males or more were present on a display. Male size and fighting costs tended to increase with display size. The distribution of males among displays did not follow the ideal free distribution in the sense that each male did not have equal mating opportunity per unit time. Deviation from an ideal free distribution may have been due to female preference for mating in aggregations rather than with solitary males, since in a field experiment females were more willing for mating in an aggregation of five males than with solitary males. Received: 22 May 1997 / Accepted after revision: 1 November 1997     

Maintenance of variable responses for coping with wetland drying in freshwater turtles

Aquatic animals inhabiting temporary wetlands must respond to habitat drying either by estivating or moving to other wetlands. Using radiotelemetry and capture mark recapture, we examined factors influencing the decisions made by individuals in a population of freshwater turtles (Chelodina longicollis) in response to wetland drying in southeastern Australia. Turtles exhibited both behaviors, either remaining quiescent in terrestrial habitats for variable lengths of time (terrestrial estivation) or moving to other wetlands. Both the proportion of individuals that estivated terrestrially and the time individuals spent in terrestrial habitats increased with decreasing wetland hydroperiod and increasing distance to the nearest permanent wetland, suggesting behavioral decisions are conditional or state dependent (i.e., plastic) and influenced by local and landscape factors. Variation in the strategy or tactic chosen also increased with increasing isolation from other wetlands, suggesting that individuals differentially weigh the costs and benefits of residing terrestrially vs. those of long-distance movement; movement to other wetlands was the near universal strategy chosen when only a short distance must be traveled to permanent wetlands. The quality of temporary wetlands relative to permanent wetlands at our study site varies considerably and unpredictably with annual rainfall and with it the cost-benefit ratio of each strategy or tactic. Residency in or near temporary wetlands is more successful during wet periods due to production benefits, but movement to permanent wetlands is more successful, or least costly, during dry periods due to survival and body condition benefits. This shifting balance may maintain diversity in response of turtles to the spatial and temporal pattern in wetland quality if their response is in part genetically determined.     

污水湿地处理工艺优化组合设计

污水湿地处理系统是利用土壤、作物、微生物自然净化功能的生态工程技术。主要有水面湿地和渗滤湿地两种类型,在天津城市污水土地处理与利用系统研究的基础上,将两种工艺的优点进行优化组合,并应用于大港油田等污水湿地处理工程,运行结果表明：将水面湿地和渗滤湿地工艺优化组合设计的示范工程,具有提高水力负荷、减少运行费用、节省工程投资、处理效果稳定等特点,有利于处理工程的长期稳定运行。     

Generating spatially optimized habitat in a trade‐off between social optimality and budget efficiency

Auctions have been proposed as alternatives to payments for environmental services when spatial interactions and costs are better known to landowners than to the conservation agency (asymmetric information). Recently, an auction scheme was proposed that delivers optimal conservation in the sense that social welfare is maximized. I examined the social welfare and the budget efficiency delivered by this scheme, where social welfare represents the difference between the monetized ecological benefit and the conservation cost incurred to the landowners and budget efficiency is defined as maximizing the ecological benefit for a given conservation budget. For the analysis, I considered a stylized landscape with land patches that can be used for agriculture or conservation. The ecological benefit was measured by an objective function that increases with increasing number and spatial aggregation of conserved land patches. I compared the social welfare and the budget efficiency of the auction scheme with an agglomeration payment, a policy scheme that considers spatial interactions and that was proposed recently. The auction delivered a higher level of social welfare than the agglomeration payment. However, the agglomeration payment was more efficient budgetarily than the auction, so the comparative performances of the 2 schemes depended on the chosen policy criterion–social welfare or budget efficiency. Both policy criteria are relevant for conservation. Which one should be chosen depends on the problem at hand, for example, whether social preferences should be taken into account in the decision of how much money to invest in conservation or whether the available conservation budget is strictly limited.     

Regulation with direct benefits of information disclosure and imperfect monitoring

We model the optimal design of programs requiring heterogeneous firms to disclose harmful emissions when disclosure yields both direct and indirect benefits. The indirect benefit arises from the internalization of social costs and resulting reduction in emissions. The direct benefit results from the disclosure of previously private information which is valuable to potentially harmed parties. Previous theoretical and empirical analyses of such programs restrict attention to the former benefit while the stated motivation for such programs highlights the latter benefit. When disclosure yields both direct and indirect benefits, policymakers face a tradeoff between inducing truthful self-reporting and deterring emissions. Internalizing the social costs of emissions, such as through an emissions tax, will deter emissions, but may also reduce incentives for firms to truthfully report their emissions.     

Optimal resource extraction and uncertainty about new technology

The optimal extraction policy of a known resource stock in an economy which has imperfect information about existence of a new technology is discussed. The optimal program is shown to depend on the remaining stock and the current information about existence of the new technology (which is updated every period). For two special forms of social welfare function, the optimal extraction policy is shown to be more conservative than in the situation of perfect information. The effects of improved information and greater availability of the known stock on the optimal extraction policy are also investigated.     

拉萨巴嘎雪湿地土壤重金属分布及生态风险评价

巴嘎雪湿地是西藏拉萨河流域的代表性湿地之一.文章为了解巴嘎雪湿地的重金属分布特征,在2018年10月采集了巴嘎雪湿地的表层土壤样品,对土壤中的Cu、Zn、Cr、Ni、Pb、Cd、As、Hg重金属的含量进行了检测.巴嘎雪湿地表层土壤的重金属污染评价采用的方法主要包括内梅罗综合污染指数法、地积累指数法和潜在生态风险指数法....     

Sustainability of Nations

SUMMARY

A method is presented to interrelate the development of economy, environment and social quality in communities. Economy and environment, in initial development stages, oppose each other. Social welfare and economy generally develop simultaneously. To assess overall progress in sustainable development, an integrated and quantifiable framework is presented which defines five levels of sustainability. Increasing sustainability is characterized by growing responsibility for the impacts of man's actions in space and time. Through increased eco-efficiency and changed awareness, nations and companies arrive at a synergistic relationship between environment and economy. It is indicated that social security benefits expenditure increases by a factor 3.5 and carbon dioxide emissions per capita decreases by a factor 3 at each higher level of sustainability. Quantified differences in sustainability levels of 24 nations are shown. Priorities for improving and safeguarding sustainability are indicated.     

Perceived barriers to and drivers of community participation in protected‐area governance

Protected areas (PAs) are a frequently used conservation strategy, yet their socioeconomic impacts on local communities remain contentious. A shift toward increased participation by local communities in PA governance seeks to deliver benefits for human well‐being and biodiversity. Although participation is considered critical to the success of PAs, few researchers have investigated individuals’ decisions to participate and what this means for how local people experience the costs and benefits of conservation. We explored who participates in PA governance associations and why; the perceived benefits and costs to participation; and how costs and benefits are distributed within and between communities. Methods included 3 focus groups, 37 interviews, and 217 questionnaire surveys conducted in 3 communities and other stakeholders (e.g., employees of a nongovernmental organization and government officials) in PA governance in Madagascar. Our study design was grounded in the theory of planned behavior (TPB), the most commonly applied behavior model in social psychology. Participation in PA governance was limited by miscommunication and lack of knowledge about who could get involved and how. Respondents perceived limited benefits and high costs and uneven distribution of these within and between communities. Men, poorer households, and people in remote villages reported the highest costs. Our findings illustrate challenges related to comanagement of PAs: understanding the heterogeneous nature of communities; ensuring all households are represented in governance participation; understanding differences in the meaning of forest protection; and targeting interventions to reach households most in need to avoid elite capture.     

芜湖市龙窝湖湿地土壤重金属污染特征及潜在生态风险评价

分析了不同人类活动方式下芜湖市龙窝湖湿地土壤镍（Ni）、铬（Cr）、镉（Cd）、铅（Pb）、铜（Cu）和锌（Zn）含量差异,采用污染指数法、潜在生态风险指数法和沉积物质量基准（SQG）比较法对湿地土壤重金属污染特征和潜在生态风险进行评价。结果表明：6个样地土壤重金属含量只有Cd含量（0．76—3．67mg／kg）显著超过土壤环境质量二级标准（GB15618—1995）;6个样地土壤Cd和Cu含量与塘式水产养殖湿地、网式水产养殖湿地、垃圾倾倒地下游湿地和垃圾倾倒地土壤Pb和Zn含量超过土壤背景值,而6个样地土壤Ni和Cr含量与湖泊底泥和耕地土壤Ph和Zn含量未超标;土壤6种重金属综合污染指数为垃圾倾倒地下游湿地（25．4）〉网式水产养殖湿地（25．3）〉塘式水产养殖湿地（23．1）〉垃圾倾倒地（19．2）〉耕地（8．2）=湖泊底泥（8．2）;土壤6种重金属综合潜在生态风险指数为网式水产养殖湿地（603．6）〉垃圾倾倒地下游湿地（595．5）〉塘式水产养殖湿地（538．4）〉垃圾倾倒地（439．9）〉耕地（145．6）〉湖泊底泥（136．6）。土壤cd含量高是导致湿地土壤重金属较高污染（Cd单项污染指数占综合污染指数：49％～76％）和存在严重潜在生态风险（Cd单项潜在生态风险指数占综合潜在生态风险指数：88％～96％）的关键元素。基于沉积物质量基准比较法的潜在风险评价结果表明湿地土壤存在M、Cd和Cu污染的中等潜在生态风险。