Amenity values of proximity to National Wildlife Refuges: An analysis of urban residential property values

This research quantifies the property value benefits of National Wildlife Refuges near urban areas on the eastern coast of the U.S.A. Our approach is made possible through access to confidential U.S. Census data identifying property values surrounding all refuges with high geographic resolution. Results from hedonic property value models suggest that the amenity values of refuges located near urbanized areas are capitalized into the value of homes in very close proximity, averaging $11 million per refuge. These capitalized values add directly to the local tax base and are considerable complements to the annual economic value created by the refuge system.     

Testing whether waterfowl hunting benefits increase with greater water deliveries to wetlands

The change in waterfowl hunting benefits due to an increase in water deliveries to the levels required for biologically optimal wildlife refuge management at California's San Joaquin Valley National Wildlife Refuges are estimated with the Travel Cost Method, using both ordinary least squares and Poisson count data estimators. To test whether these increases were statistically significant, the Krinsky and Robb technique was used to find confidence intervals around the consumer surplus point estimates. The increases in consumer surplus were found to be statistically significant in 5 of the 6 refuges based on OLS regression estimates and in all 6 refuges using Poisson count data regression estimates. In addition, a comparison of the marginal value of an acre-foot of water in consumptive recreational use versus agriculture use is made, with the finding that the marginal value of water in waterfowl hunting was greater than the marginal value of water in agriculture for one of the six refuges.     

The costs and benefits of refuge requirements: The case of Bt cotton

Refuge requirements have been the primary regulatory tool to delay pest resistance to Bt crops. This paper presents a simple method to estimate the annual cost of refuges to producers, applying it to Bt cotton. It also examines broader welfare impacts, estimating how Bt cotton acreage restrictions affect producer surplus, consumer surplus, seed supplier profits, and commodity program outlays. The implications of grower adoption behavior — partial adoption, aggregate adoption, and refuge choice — for regulatory costs are examined. Empirical examples illustrate how providing multiple refuge options significantly reduces regulatory costs.     

Refugee Immigration and Total Factor Productivity

This paper uses panel cointegration and causality techniques to examine the long-run relationship between refuge immigration and total factor productivity (TFP), a relationship that has not yet been examined in the literature. It is found that refugee immigration has, on average, a positive long-run effect on TFP, suggesting that refuge immigration increases the diversity of skills and ideas available to society as a whole, which in turn promotes specialization and innovation. It is also found that causality is unidirectional from refugee immigration to TFP, suggesting that refugees are primarily motivated by the push factor of persecution in the source country rather than by productivity (and hence welfare) gains as a potential pull factor in the destination country.     

对我国特殊普通合伙会计师事务所若干问题的思考

文章对推行特殊普通合伙会计师事务所可能出现的问题进行了较全面的分析,认为会计师事务所的转制不应采取一刀切的做法;应在对合伙人的保护与对债权人、公众的利益保护之间寻求平衡;特殊普通合伙并非是合伙人的防风港与避难所;特殊普通合伙解决不了理念、管理落后的顽症;特殊普通合伙会加剧合伙人之间的矛盾;特殊普通合伙中合伙人重大过失的判断标准并不清晰。     

Conserving metapopulations in human-altered landscapes at the urban–rural fringe

The conversion of natural areas to human-dominated land uses results in loss, degradation, and fragmentation of wildlife habitat which often lead to species endangerment and local extinction. The risk of endangerment may be particularly acute for species that exist as metapopulations in which viability of the species is contingent upon dispersal of individuals among local sub-populations. This paper uses an optimization framework to investigate the problem of conserving metapopulations residing in areas at the urban–rural fringe. We compare the optimal allocation of preservation to outcomes of four other policy alternatives including the reserve-site-selection option that fully preserves habitat patches while allowing full development of the intervening dispersal matrix. In general, the optimal allocation includes some amount of preservation in both habitat patches and dispersal matrix, with the level of protection typically greater in habitat patches. The reserve-site-selection conservation option is optimal in only a few cases. Heterogeneity in terms of land use and landscape structure adds complexity to the optimal solution such that no one policy works well across all land units and in situations where the landscape structure is skewed, full protection of some land units and full development of others becomes more common.     

Allocation of emission permits with leakage through capital markets

This paper analyses how tradable emission permits should be allocated to firms when capital is internationally mobile. When international environmental problems are attempted solved through uncoordinated policies between countries, it might be desirable for the home country to issue free emission permits in proportion to the use of capital in order to prevent leakage through international capital movements. The desirability of free emission permits will however be reduced if capital also can be employed in a domestic non-polluting sector. In this case, it may even be optimal to tax the use of capital in the polluting sector. It is also shown that it is always optimal to subsidise the use of capital in the polluting sector if the use of labour is taxed at an optimal rate. Finally, leakage does not affect the optimal domestic emission limit as long as appropriate capital subsidies and labour taxes are implementeed.     

Optimal taxation of car ownership, car use and public transport: Insights derived from a discrete choice numerical optimization model

We formulated and numerically evaluated a model of car ownership, car use and public transport use for peak and off-peak hours of the day. The model was used to study the optimal tax structure for passenger transport in Belgium, with special emphasis on the optimal tax treatment of diesel versus gasoline cars. We obtained a number of interesting results. First, if the government can set all fixed and variable transport taxes optimally, the higher marginal external cost of diesel use implies that the optimal tax per kilometre for the use of a diesel car is higher than for the use of a gasoline car. Moreover, high congestion implies that the taxes on car use in the peak period are more than twice their current levels. However, the optimal tax on ownership of a diesel car is some 200€ below its current level. Second, if the government uses kilometre taxes that do not differentiate between fuel types, the optimal ownership tax on a diesel car is twice as high as the tax on a gasoline car. Furthermore, if political constraints restrict user taxes to their current levels, we find that optimal ownership taxes on diesel cars double, whereas those on gasoline cars rise by 30%. Finally, subsidies to public transport are found to be optimal as long as variable car taxes are not differentiated between periods.     

Regulation of a Spatial Externality: Refuges versus Tax for Managing Pest Resistance

We examine regulations for managing pest resistance to pesticide varieties in a temporally and spatially explicit framework. We compare the performance of the EPA’s mandatory refuges and a tax (or subsidy) on the pesticide variety under several biological assumptions on pest mobility and the heterogeneity of farmers’ pest vulnerability. We find that only the tax (or subsidy) restores efficiency if pest mobility is perfect within the area. If pest mobility is imperfect and when farmers face identical pest vulnerability, only the refuge might restore efficiency. With simulations we illustrate that complex outcomes may arise for intermediate levels of pest mobility and farmers’ heterogeneity. Our results shed light on the choice of regulatory instruments for common-pool resource regulations where spatial localization matters.     

中国最优财政支农支出研究

由于"三农"问题的重要性和特殊性,政府不断增加财政支农支出是必然选择.但是,政府财政支农支出不能无限增加,必须确定其最优规模和结构,提高资金使用效率.既要不断加大财政支农生产性支出,也要增加财政支农非生产性支出,提高基层财政公共服务能力,提供更多有利于农业生产和农民身心健康的公共产品和公共服务.     

Fishing Technology and Optimal Distribution of Harvest Rates

This paper examines the problem of the optimal management of a joint-ownership fishing exploitation, where agents use different fishing gears. We consider a model in which the fishing activity may affect resource growth, not only through the harvest function but also through the natural growth rate of the resource. This allows us to capture the fact that some fishing gears alter the natural growth rate of the resource. We find that when the natural growth of the resource is altered by the fishing technology, the optimal stock is not independent of how harvest quotas are distribute among the agents. As a result, a fishing policy that firstly determines the optimum stock and, secondly, decides how to distribute the harvest among the different agents, will not be efficient. We also analyze the joint determination of optimal stock and harvest quotas and show that positive harvest quotas will only be optimal when countries are characterized by certain asymmetries.     

满足消费最大化的最优居民收入差距研究

本文运用中国20年来的数据,估算了使居民消费最大化的城乡、城镇内部收入差距的最优路径.研究发现我国实际城乡、城镇内部收入差距不仅高于最优路径,而且偏离最优路径的程度正在扩大.城镇内部收入差距对最优路径的偏离超过了城乡收入差距对最优路径的偏离,而且城镇内部收入差距正在以更快的速度偏离最优路径,这说明城镇内部收入差距抑制消费需求的强度更大.要扩张居民消费,就必须采取措施缩小居民收入差距,尤其是缩小城镇内部收入差距.本文的实证分析为缩小居民收入差距的方向和力度提供了一个客观的、可操作的参照系.     

Optimal growth theory: Challenging problems and suggested answers

We argue that optimal economic growth is confronting serious applicability problems, having nothing to offer in these days of high public deficits accompanied by high unemployment rates. In particular, the theory is not capable of indicating optimal savings rates; those are systematically in ranges that can be considered as unacceptable, or are accompanied by unrealistically high real growth rates. Faulty is the systematic use of arbitrary utility functions, which turn out to be contradictory to competitive equilibrium. We then show how relying on the hypothesis of competitive equilibrium yields reasonable, perfectly acceptable numbers for the optimal savings rate.     

Optimal Dutch disease

Growth models of the Dutch disease explain why resource abundance may reduce growth. The literature, however, also raises a new question: if the use of resource wealth hurts productivity growth, how should such wealth be optimally managed? This question forms the topic of the present paper. We show that the assumptions in the previous literature imply that the optimal share of national wealth consumed in each period needs to be adjusted down. Some Dutch disease, however, is always optimal. Thus, lower growth in resource-abundant countries may not be a problem in itself, but may be part of an optimal growth path. The optimal spending path of the resource wealth may be increasing or decreasing over time. What might be contrary to intuition is that the bigger is the growth generating traded sector, the more of the resource income should be spent in early periods.     

Optimal Dutch disease

Growth models of the Dutch disease explain why resource abundance may reduce growth. The literature, however, also raises a new question: if the use of resource wealth hurts productivity growth, how should such wealth be optimally managed? This question forms the topic of the present paper. We show that the assumptions in the previous literature imply that the optimal share of national wealth consumed in each period needs to be adjusted down. Some Dutch disease, however, is always optimal. Thus, lower growth in resource-abundant countries may not be a problem in itself, but may be part of an optimal growth path. The optimal spending path of the resource wealth may be increasing or decreasing over time. What might be contrary to intuition is that the bigger is the growth generating traded sector, the more of the resource income should be spent in early periods.     

The Optimal Linear Income Tax Model: Utility or Equivalent Income?

This paper compares the use of equivalent income with that of utility, in the social welfare function, in optimal income tax models. Equivalent income is a money metric welfare measure that, unlike utility, is not affected by monotonic transformations of utility. The use of equivalent income is found to produce an optimal tax rate that is more sensitive to the degree of inequality aversion, compared with the use of utility. With Cobb-Douglas and CES utility functions, the optimal tax rate is the same for utility and equivalent income where relative inequality aversion is unity. When using equivalent incomes, the case for high marginal rates does not depend on the assumption of a very low elasticity of substitution between consumption and leisure.     

On the spatial nature of the groundwater pumping externality

Most existing economic analyses of optimal groundwater management use single-cell aquifer models, which assume that an aquifer responds uniformly and instantly to groundwater pumping. In this paper, we develop an economic model of groundwater management that explicitly incorporates spatial dynamic groundwater flow equations. Calibration of our model to published economic studies of specific aquifers demonstrates that existing studies generally incorrectly estimate the magnitude of the groundwater pumping externality relative to spatially explicit models. In particular, for large aquifers with surface areas of thousands of square miles, the marginal pumping externality predicted by single-cell models may be orders of magnitude less than that predicted by a spatially explicit model, even at large distances from a pumping well. Conversely, for small aquifers with areas of a few hundred square miles or less, single-cell models reasonably approximate the pumping externality. Application of single-cell models to inappropriate settings may result in misleading policy implications due to understatement of the magnitude and spatial nature of the groundwater externality.     

Bioeconomic modeling for control of weeds in natural environments

When a weed invasion is first discovered a decision has to be made on whether to attempt to eradicate it, contain it or do nothing. Ideally, these decisions should be based on a complete benefit-cost analysis, but this is often not possible. A partial analysis, combining knowledge of the rate of spread, seedbank longevity, costs of control and techniques of economic analysis, can assist in making a good decision. This paper presents a decision model to determine when immediate eradication of a weed should be attempted, or more generally whether weed control should be attempted at all. The technique is based on identifying two ‘switching points’: the invasion size at which it is no longer optimal to attempt eradication but where containment may be an option; and the invasion size at which it becomes optimal to apply no form of control at all. The model is applied to a woody perennial weed in a natural environment. The results show that seedbank longevity is the main constraint on the maximum eradicable area and spread rate is the main constraint on the maximum containment area. Stochastic simulations are undertaken to derive probability distributions of costs which are than used to evaluate the effect of budget constraints on areas that can be eradicated. We find that, in the absence of a budget constraint, it may be desirable to eradicate invasions from areas as large as 8000 ha, but when budget constraints typical of those faced by agencies in Australia are introduced, feasible eradicable areas are less than 1000 ha.     

西部河谷型城市人口容量研究——以天水市为例

人口容量是河谷型城市发展的战略性议题。在总结相关研究基础上,分析了其主要影响因素,构建基于河谷用地空间、可供水资源及生态环境三个影响因素下的人口容量测算方法。以典型河谷型城市天水市为例,计算出上述三个因素下的各自适度人口容量和最大人口容量分别为:73.5万和109.8万;77.66万和211.39万;73.37万和116.96万。根据木桶原理“最短边”因素发现,现有发展条件下天水市适度人口容量应为73.37万、最大人口容量为109.8万。     

A simple proof of the monotonicity of the state trajectories in autonomous control problems

This paper deals with the question whether in optimal control problems with one state variable cyclical solutions and other nonmonotonicities can be optimal. It is shown that this can only occur if exogeneous shocks are brought into the model while for autonomous problems the state trajectory must always be monotonic. The proof also applies for nondifferentiable control problems as it does not use any regularity assumptions for the model functions.