我国原木、木浆进口数量与价格变化及其影响因素分析

原木和木浆是我国进口林产品中的大宗商品.进入新世纪以来,我国的原木和木浆进口数量和进口额迅速增长,对外依存度逐年提高.近年来,受供求关系、进口品种、进口渠道、汇率、石油价格变化等影响,导致我国原木、木浆进口价格上涨.     

中国原木进口对洲际森林生态足迹的影响

运用生态足迹模型测度了1995～2007年中国原木进口引起的森林生态足迹转移,特别关注了中国原木进口的森林生态足迹与全球森林生态足迹和承载力的比较。结果表明:虽然从欧洲原木进口的森林生态足迹输入有明显增长,但中国原木需求更多依赖本国供给,对亚洲、大洋洲及非洲等区域影响较小,并没有证据表明中国原木进口严重威胁到世界森林资源。     

Convergence clubs in Latin America

The aim of this work is to identify convergence clubs in 17 Latin American countries in terms of GDP per capita during the period 1990–2014. To do this, we apply the methodology developed by Phillips-Sul in order to identify the different convergence clubs on the path of growth in the Latin American economy over this period. The empirical results strongly support the existence of convergence clubs, indicating that the Latin American economy consists of four groups, each converging towards its own steady-state path, with two countries being divergent.     

A bivariate infinitely divisible law for modeling the magnitude and duration of monotone periods of log‐returns

The focus of this article is modeling the magnitude and duration of monotone periods of log‐returns. For this, we propose a new bivariate law assuming that the probabilistic framework over the magnitude and duration is based on the joint distribution of (X,N), where N is geometric distributed and X is the sum of an identically distributed sequence of inverse‐Gaussian random variables independent of N. In this sense, X and N represent the magnitude and duration of the log‐returns, respectively, and the magnitude comes from an infinite mixture of inverse‐Gaussian distributions. This new model is named bivariate inverse‐Gaussian geometric ( in short) law. We provide statistical properties of the model and explore stochastic representations. In particular, we show that the is infinitely divisible, and with this, an induced Lévy process is proposed and studied in some detail. Estimation of the parameters is performed via maximum likelihood, and Fisher's information matrix is obtained. An empirical illustration to the log‐returns of Tyco International stock demonstrates the superior performance of the law compared to an existing model. We expect that the proposed law can be considered as a powerful tool in the modeling of log‐returns and other episodes analyses such as water resources management, risk assessment, and civil engineering projects.     

Accounting Ratios and the Cross‐section of Expected Stock Returns

Under clean‐surplus accounting, the log return on a stock can be decomposed into a linear function of the contemporaneous log return on equity, the contemporaneous log dividend–price ratio (if the stock pays a dividend), and both the contemporaneous and lagged values of the log book‐to‐market equity ratio. This paper studies the implications of this decomposition for the cross‐section of conditional expected stock returns. The empirical analysis reveals that the log accounting ratios capture cross‐sectional variation in both the conditional mean and conditional variance of log stock returns, which is consistent with the decomposition. It also brings fresh insights to the relation between firm size (market equity) and conditional expected stock returns. The evidence indicates that the conditional median return increases with firm size, while the conditional return skewness decreases with firm size. Empirically, the skewness effect outweighs the median effect, leading to the well‐documented inverse relation between size and average returns. The results of out‐of‐sample tests suggest that investors could use the information provided by the observed values of the log accounting ratios to formulate more effective portfolio strategies.     

东北红松阔叶混交林的特点及其分布规律

红松阔叶混交林在东北东部山区分布极为广泛，是该地区水平地带性和垂直地带性森林；将东北红松阔叶混文林分为3部分：典型阔叶红松混交林，河岸、河谷阶地阔叶红松混交林和山脊、陡坡阔叶红松混交林；介绍了红松阔叶温交林组成、分布规律及其地势的特点。     

Generalized Hyperbolic Diffusion Processes with Applications in Finance

A special class of diffusion processes, the generalized hyperbolic diffusion processes, is introduced. As a byproduct we present a technique for the construction of one-dimensional ergodic diffusion processes with a predetermined stationary density. We specifically study the application of this new type of diffusion process to financial data, especially U.S. stock prices. It is seen that in addition to confirming stylized features of the financial market, a key explanation concerning thick-tailed log returns is provided.     

Dynamic correlation multivariate stochastic volatility with latent factors

Modeling the correlation structure of returns is essential in many financial applications. Considerable evidence from empirical studies has shown that the correlation among asset returns is not stable over time. A recent development in the multivariate stochastic volatility literature is the application of inverse Wishart processes to characterize the evolution of return correlation matrices. Within the inverse Wishart multivariate stochastic volatility framework, we propose a flexible correlated latent factor model to achieve dimension reduction and capture the stylized fact of ‘correlation breakdown’ simultaneously. The parameter estimation is based on existing Markov chain Monte Carlo methods. We illustrate the proposed model with several empirical studies. In particular, we use high‐dimensional stock return data to compare our model with competing models based on multiple performance metrics and tests. The results show that the proposed model not only describes historic stylized facts reasonably but also provides the best overall performance.     

基于原木法估算立木收益价值的实证研究

以林木市场价格为基础,采用原木法对杉木人工林的经济收益价值的估算进行实证分析,并对其应用范围和应用价值进行了研究,为林木经营者提供了做出最佳林木产出决策的思路和建议。     

我国原木进口变化趋势及其影响因素

随着我国经济飞速发展,国内对木材的需求不断增长,而我国木材产量无法满足国内旺盛的需求,木材供求矛盾日益突出。因此,近10年来我国木材进口量大幅增长,特别是原木的进口量占了很大比重。文章先简要介绍了我国木材产量和原木进口情况,然后分别描述了木材产品进口结构的变化和原木进口来源地的变化,最后分析了影响原木进口变化的诸多因素,指出生产效率、社会政策和便利性是促使我国原木进口高速增长的主要因素。