Vintage capital,market structure and productivity in an evolutionary model of industry growth

This paper examines the effects of inter-firm variation in vintage equipment replacement policies on industry productivity and structure using an evolutionary model based on Nelson-Winter. Traditional industry productivity measures assume a graduated replacement policy with low variation across firms in the average age of the capital stock. This approach allows for inter-firm policy variation. The first part reviews the neoclassical treatment of vintage capital investment; the second part outlines an evolutionary model of vintage replacement in the context of industry growth; and the third part presents results of simulation experiments focused on the relationship between vintage replacement patterns and industry productivity growth. Findings suggest that inter-firm differences in vintage capital investment policies may account for significant shifts in the rates of industry productivity growth and changes in market structure.     

企业集团内部资本市场最优规模设计

企业集团内部形成的资本市场具有降低交易成本、进行有效监督、优化资本配置、放松外部融资约束等方面的优势。但内部资本市场规模并非越大越好，超过一定规模会降低企业集团整体的运作效率。因此，探究企业集团内部资本市场的最优规模，以达到集团整体效用最大化有着十分重要的意义。     

Reconciling economic and biological modeling of migratory fish stocks: Optimal management of the Atlantic salmon fishery in the Baltic Sea

The paper puts forward a model of the Atlantic salmon fishery in the Baltic Sea that integrates the salient biological and economic characteristics of migratory fish stocks. Designed to be compatible with the framework used for actual stock assessments, the model accounts for age-structured population dynamics, the seasonal harvest and competing harvesting by commercial and recreational fishermen. It is parameterized for the Simojoki River stock. The socially optimal policy for maximizing discounted net benefits from the fishery within an uncertain environment is determined using a dynamic programming approach and numerical solution method. Our results indicate that substantial economic benefits could be realized under optimal management without compromising stock sustainability.     

Economic policy with bounded controls

When investigating optimal policies for macroeconomic models, it is common practice to modify the objective function so that the resulting optimal control trajectories become acceptable from a practical point of view. In this paper we argue that the sole purpose of the objective function should be to express the preference of the decision makers, and that explicit bounds on the controls should be used to ensure that the optimal controls will be practical. Using a piece-wise quadratic objective function involving only the unemployment and inflation rates, which are state (endogenous) variables, we first develop a discrete minimum principle, giving necessary and sufficient optimality conditions. Then we perform various bounded control experiments with the 35-equation quarterly CLEAR model of the Canadian economy, which is very briefly described. The empirical results which were obtained using a version of the GRG algorithm are discussed in view of the conclusions that might be drawn for a real-world practical policy analysis.     

林纸工业之我见—兼论瓶颈矛盾的突破

本文在分析云南省森林资源特点的基础上，提出调整资源利用结构，发展阔叶树材制浆造纸和结合灭荒建立纸浆专用林基地等政策性建议。     

An investment-function-based measure of capacity utilisation.: Potential output and utilised capacity in the Bank of Italy's quarterly model

Measures of potential output and the output gap are increasingly being developed and used to concisely quantify and monitor the risk of price accelerations stemming from rises in aggregate demand that are not met by a corresponding increase in supply. They often play a prominent role in the price determination mechanisms of macroeconometric models. In this paper we build a measure of potential private-sector value added for the Italian economy that is consistent with the capital accumulation process in the Banca d'Italia's Quarterly Model — and more generally with the rest of the supply-side block of that model. More specifically, we exploit the fact that the investment function can be thought of as a relationship transforming desired gross additions to capacity output into capital accumulation by means of a conversion factor (the optimal capital/output ratio). Thus, if one removes the component of investment decisions that stems from changes in the relative price of the production factors, (i.e. in the optimal capital/output ratio), then a measure of the desired gross addition to capacity may be constructed. The results draw a cyclical picture of the degree of capacity utilisation for the period 1970–1997 that is roughly in line with those produced by the Wharton and Hodrick–Prescott filter approaches, as well as with the pictures resulting from the ISAE, IMF, European Commission and OECD measures of the output gap. Our investment-function-based measure appears to be a promising indicator of the pressure exerted on prices by demand accelerations. Its empirical properties are, on the whole, acceptable and plausible.     

Radiative forcing and the optimal rotation age

Forests help mitigate climate change by sequestering atmospheric carbon. However, boreal and high-latitude temperate forests may also contribute to global warming due to the albedo effect. The relative effects of carbon sequestration and albedo can be quantified in terms of radiative forcing. We present a stylized, stand-level analysis to determine the optimal rotation age when considering a tax/subsidy scheme based on radiative forcing and the notion of equivalent carbon emissions. Additional management decision variables considered include species choice and regeneration effort, since these can impact the albedo effect. We demonstrate analytically that the optimal rotation length is likely shortened when albedo-related equivalent emissions are incorporated, relative to a policy based only on carbon. Empirical results indicate that rotation ages do decrease relative to a “carbon only” policy, and approach the traditional (timber only) Faustmann rotation age as equivalent emission rates increase. Our results suggest that forestation does not necessarily provide climatic benefits in all circumstances, and that, at the margin, other opportunities for carbon reduction (e.g. abatement), or pursuing forestation in other locations, become more attractive.     

论森林生态产品的外在性

文章运用现代经济学的外部性理论系统分析了森林生态产品外部性的表现形式。在分析森林生态产品外部性的特点和本质的基础上提出解决这种外部性的最佳途径是由政府提供森林生态产品这种公共产品。     

The Legislator as Political Entrepreneur: Investment in Political Capital

This paper applies the standard Austrian theory of capital investment to the standard interest group model of legislator behavior. Distinguishing between reputational capital and representative capital as interdependent forms of political capital, I argue that legislator behavior (specifically roll call voting) can be explained as entrepreneurial investment in political capital under uncertainty. I discuss several examples in which this approach can potentially add predictive power regarding legislative voting.     

信息不对称条件下林产品营销风险及防范

市场经济条件下普遍存在的信息不对称现象给林产品营销带来了很多风险,诸如：低质量林产品驱逐高质量林产品、林产品市场缩小或使市场不存在,等,制约了营销目标的实现。林产品经营者和政府,必须树立林产品品牌形象,创新林产品企业营销方式,构筑林产品市场营销预警系统与信息反馈系统,加强市场信用机制建设,努力培育林产品企业的商誉,增强政府对林产品市场的服务功能,以防范信息不对称给林产品营销带来的风险,促使林产品营销的顺利开展。     

Protecting Forests Through Farming. A Dynamic Model of Nontimber Forest Extraction

Forest resource extraction by local communities has been cited as a major impediment to the efficient management of protected forests. This paper develops a two sector dynamic model for farming and forest resource extraction by communities living in the forest periphery. The model assumes that land under forestry is constant and households allocate their time to farming and forestry. Comparative dynamic results suggest that higher prices for agriculture output, lower input prices, better knowledge of farming techniques and a lower discount rate may result in a higher equilibrium stock of forest resources. Tobit analysis with primary data collected from the Sinharaja forest in Sri Lanka provides supportive empirical evidence.     

Another reconciliation between economists and forestry experts: OLG-arguments

Foresters often claim that the goal of good forest policy is to have a sustained forest yield, or even a maximum sustainable yield. They also claim that people wish to save a few extra trees for their children. This bequest motive is not modelled in the standard approach to the optimal rotation problem. In this paper, we present a standard version of an overlapping generation model augmented with a simple tree technology. We show in particular that the market equilibrium can be dynamically inefficient, and that a bequest motive in terms of trees can correct for the overaccumulation of capital that causes the inefficiency. The bequest motive also enables us to account for a harvesting intensity varying with age (young people typically cut more than elderly people) in spite of a perfect capital market.The crux of the argument is that a bequest motive is likely to increase the equilibrium interest rate and move the economy away from a maximum sustainable yield policy. It, however, improves efficiency and is able to explain empirical regularities that are not easily explained by a traditional perfect capital market approach to forestry.The author acknowledges comments from Karl-Göran Mäler, Stockholm School of Economics, participants in the economics-forestry economics seminar at the University of Umeå, and two anonymous referees.