美国齿小蠹的研究

齿小蠹属（Ips）是世界范围的森林害虫，其很多各类能直接危害活树，是先锋害虫，该文从鉴定检索、分布范围、危害寄主三方面对美国30种齿小蠹做了介绍。     

Consumer willingness to pay price premiums for environmentally certified wood products in the U.S.

Since its inception nearly 15 years ago, environmental certification has become an important issue in the wood products industry. One research question that has been examined is the potential willingness for supply chain participants to pay a premium for certified products or raw materials to offset certification costs. This study examines stated willingness to pay for four wood products from the perspective of U.S. consumers. Data was collected in 1995 and 2005 from the population of U.S. residential consumers to detect changes in willingness to pay for certified wood products along time and increase the statistical strength of the model. Results of an ordered probit model suggest that higher probabilities of paying a premium are associated to consumers who seek out certified products and who believe certification can lessen environmental impacts such as tropical deforestation. There is also a strong relationship between respondent income and willingness-to-pay. Despite the current industry structure in the U.S. that has adopted a mass-certification strategy that does not place price premiums on certified products, results suggest that such premiums may exist for imported certified tropical wood products. Analysis of marginal effects suggests consumers' willingness to pay a 10% premium for three of the four certified items studied. Niche markets may potentially be exploited in the U.S. and price premiums captured by wood products manufacturers in tropical regions and/or American importers.     

International expectations for sustainable forestry: a view from the U.S. forest industry

Today several global forces are raising expectations that forestry must be practiced on a sustainable basis. This is true for forestry as practiced in tropical, temperate, and boreal regions, as well as in developed and developing countries. Several institutional processes are in place to develop criteria for and indicators of sustainable forestry. As customers and consumers have become more knowledgeable, they are becoming more demanding about the environmental attributes of the products they buy. Forest products companies and forest landowners who wish to maintain access to these more demanding markets will need to provide assurances of their commitment to sustainable forestry practices.Forest landowners and forest products manufacturers in Washington, Oregon, and California are currently better positioned to meet these expectations than are producers in other regions. In these western states, state forest practices laws and regulations are generally consistent with emerging international criteria and indicators of sustainable management.However, U.S. competitors in such countries as Canada and Sweden are acting rapidly to establish sustainable forestry practices, and to communicate their commitments to their stakeholders and customers. The assurance of sustainable forestry practices is now the latest means by which environmentally aware and demanding customers and consumers differentiate among forest products producers.     

Event analysis of the impact of mergers and acquisitions on the financial performance of the U.S. forest products industry

The U.S. forest products industry has witnessed an unprecedented period of mergers and acquisitions (M&As) in recent years. In this study, the impact of 70 M&As from 1990 to 2004 on the financial performance of 85 publicly traded forest firms was evaluated. The examination of abnormal returns revealed that the equity market had responded to these M&As. The average cumulative abnormal returns for all the firms as a group ranged from 1.66% for the 15-day event window to 3.03% for the 3-day event window. From the cross-sectional regressions, the position as a target firm and the relative transaction size explained a large portion of the variations of the individual firms' cumulative abnormal returns. Finally, risk analyses through the Capital Asset Pricing Model showed that the risk for some of the selected 14 acquiring firms had changed after the M&As.     

Impact of alternative livelihood interventions on household welfare: Evidence from rural Ethiopia

Livelihoods of a large number of households in Ethiopia depend on environmental resources. On the other hand, excessive reliance of households on environmental resources for their sustenance has already lead to high rates of deforestation and forest degradation in Ethiopia. A project was set out to provide alternative livelihood activities in order to improve the welfare of vulnerable families who derive their livelihoods mainly from selling firewood and charcoal. The project provided support to women groups to engage in income generating activities that create alternative means of livelihoods. This paper assesses the impacts of participating in alternative livelihood activities on household welfare and environmental protection in rural Ethiopia. The paper uses data from cross-sectional survey involving 450 sample households to examine the difference in household welfare between project participants and non-participants using propensity score matching and inverse probability weighting estimator with regression adjustment. Empirical results show that participation in alternative livelihood activities has contributed to increment in total grain production, increased household income and adoption of natural resources management technologies. Project households consumed more diverse food across food groups and earned an extra $35 per month from local market sales of tree and fruit seedlings. The result was robust and consistent across models. The findings support the notion that new streams of income generating activities can lead to improvements in household's well-being as well as reduction in environmental degradation.     

The long-run determinants of U.S. lumber imported from Canada revisited

This paper examines the effects of the lumber price, the housing starts, and the bilateral exchange rate on U.S. softwood lumber imports from Canada in a cointegration framework. To that end, the Phillips-Hansen fully-modified cointegration (FM-OLS) procedure is applied to monthly data for the period from January 1994 through June 2009. Results show that there exists the long-run equilibrium relationship between the U.S. lumber imports from Canada and the selected macroeconomic and market variables. We also find that the U.S. lumber price and housing starts are more important than the bilateral exchange rate in influencing U.S.-Canada softwood lumber trade.     

引进美国葡萄柚果实营养分析

以云南省普文县生长的9个葡萄柚品种的果实为试材,主要对果实的性状和综合营养品质进行分析,结果表明,不同品种的单果重、可食率、总糖、含酸量、可溶性固形物、Vc和含汁量的差异明显,其变幅依次为301．30～366．42g、62．58％～71．11％、3．26％～5．34％、0．92％～1．32％、6．42％～8．86％、20．84～26．71mg／100g、53．4％～70．3％,其他性状差异不明显。综合营养品质较好的品种是里约红,哈路比、帕利斯、里德马叙,营养品质较差的是矮化。     

美国进口变色栎木上的长喙壳类真菌种类鉴定

经分离培养从美国进口变色栎木上获得5个长喙壳状分离菌株,通过形态学比较,鉴定为4个种,1个为常见种,另3个属我国的新记录种,即拟薄粘束长喙壳(Grosmannia leptographioides),念珠长喙壳(Ceratocystis moniliformis),异同长喙壳(C.variospora).而常见种甘薯长喙壳(C.fimbriata)是一种重要的木材变色菌.并对此4种的形态特征作了全面系统的描述.     

美国胶合板市场:1.针叶材胶合板

在过去10～15年里,美国的针叶材胶合板的市场份额已经有很大一部分为定向刨花板(OSB)取代。预测,到2007年针叶材胶合板产量会跌至1130万m~3,而 OSB 产量会达到2470万m~3。     

从苏联林业改革中我国可以借鉴什么

本刊1988年第4期发表了"苏联林业改革的核心问题"。一年来,苏联围绕经济核算制与林业、森工两张皮的问题仍在热烈争论。新中国林业50年代完全以苏联为榜样,因此现在听听他们的代表人物关于林业改革的议论是有益的。作者浏览了1988-1989年苏联林业主要报刊关于改革的文章,尽可能结合中国实际摘了10个问题。应当承认,苏联林业改革尚无实质性进展。     

美国林业NGO在林业管理中的作用

美国有8万多个行业协会和社会中介组织(NGO),作为政府工作的补充,在美国社会经济发展中发挥了重要的作用。本文介绍的5个组织,虽然只是美国众多林业NGO中的一小部分,但他们在美国林业管理中特别是森林可持续经营中发挥着重要的作用。     

Determinants of Vietnam’s wood products trade: application of the gravity model

ABSTRACT

This study applied a gravity model estimation using panel data in order to analyze the impact of the determinants of Vietnam’s wood products trade from 2001 to 2016.The gravity estimates imply the importance of size of the economies, distance, level of openness of the economy, population, forest resource endowments of Vietnam’s trade partners, Vietnam’s logging restrictions policy, common border, free trade agreement, and exchange rates as determinants of Vietnam’s wood products trade. These variables were found to have different effects on the export and import of wood products. Vietnam’s access to the WTO and APEC did not help either its imports or exports in wood products. The results of this study also indicate that the Government of Vietnam needs to implement policies to increase investment in the wood processing industry, develop high quality wood materials from domestic plantations, and take advantage of trade preferences from new free trade agreements in order to promote wood product trade. The results of this study have implications for trade policy, resource-based economic development, and Vietnam’s forest resource conservation.     

美国葡萄柚营养成分分析与评价

对西双版纳普文林场引种的葡萄柚品种进行外观性状及化学成分分析,并对其营养品质进行了综合分析。结果表明,不同品种的单果质量、可食率、可溶性固形物含量、柠檬酸含量、总糖含量、和维生素C含量的差异明显,其变化幅度依次为350~550 g,70%~75%,7%~11%,0.9%~1.7%,3.49%~6.03%,20~30 m g/(100 g)。不同品种的果形指数差异较小。由此得出哈路比、亨路比、里德马叙、里约红、星路比的综合营养品质较好,矮化、火焰的综合营养品质较差。以期为开展葡萄柚品种区划及制定分级标准提供必要的参考和依据。     

美国林务局机载红外林火探测系统综述

详述了机载红外林火探测系统的分类指标以及类型,对主要机载红外林火探测系统的研发背景、工作成本和相关性能进行了介绍。     

美国试验林网络体系建设和发展

长期定位观测网络是各国科研人员在研究与揭示生态系统结构与功能变化规律时采用的重要方法,是阐明生态系统内在机制、动态平衡以及生物化学循环过程不可替代的研究手段。世界各国都建立了生态资源与环境监测网络,是目前长期定位观测发展的主流方向。文中介绍了美国试验林网络体系（EFRs）的背景与起源、任务目标、网络构架、运行机制、研究内容、贡献与成就,以及在其发展过程中存在的问题;希望通过分析美国试验林网络体系的建设和发展,为我国未来林业生态观测网络建设提供参考。     

Disintegration of the U. S. Industrial Forest Estate: Dynamics,Trajectories, and Questions

In the past decade ownership of the corporate forestry sector in the USA has undergone remarkable transformation. Corporate consolidation, separation of processing capacity ownership from timberland ownership, and disinvestment from timberland ownership altogether have occurred rapidly and on a global scale. Vertically-integrated forest products companies, once the standard model for publically-traded corporations, have all but disappeared. A new class of timberland investors now dominates the timberland estate. These new owners can be viewed as the most recent manifestation of capital from the core seeking rent in the distant periphery. While in this respect they resemble their industrial forestry predecessors, they differ markedly with regard to landholding objectives, time horizons, management capacities and other characteristics. This transformation has created new challenges and opportunities for other forest owners and for rural communities. Many timber processing mills have closed, restricting markets for smallholder wood. While much former industrial timberland remains in industrial-style timber management, some has been subdivided for ‘highest and best use,’ and conservation buyers have assumed control of a few large blocks. Further fragmentation of the industrial forest estate is anticipated, presenting both challenges and opportunities to small-scale forest owners and rural communities. This paper outlines the dynamics of forest ownership restructuring, posits alternative future scenarios for small-scale forestry, and points to potentially useful future research.     

Status and trends of the processed wood products trade in Ethiopia

ABSTRACT

Information on the trends of the processed wood products (PWP) trade in Ethiopia is lacking. Therefore, the objectives of this article are (a) to evaluate the trends of expenses from importing and incomes generated from exporting different PWP, (b) to assess the PWP trade balance, and (c) to forecast future ex-penses in importing PWP. To achieve the objectives, import and export data of PWP in the years of 2005–2013 were collected. The data were analyzed using Pearson’s correlation. The trend of expenses was analyzed using Excel and future expenditures were forecasted by models for each PWP, independently. The result indicated that, Ethiopia spent on average, US$55.2 million/yr to import different PWP. The trend of expenses to import different PWP increased by 13% each year. There was a strong and positive correlation between the average yearly expenses to import different PWP with that of the population of the country in different years’ time (R² = .80) and also the GDP of the country in different years’ time (R² = .87). Overall, the results showed the self–insufficiency of the country in producing different PWP and the heavy expenditure to import wood products to fill the gap.     

北美杂交杨无性系扦插苗生长比较

在北京对新引进的30个杂交杨无性系1 a生扦插苗的生长进行了初步研究。依据苗高、地径和树干生物量3指标可将引种无性系分为4组:第1组由XMH-11、XMH-12、DMH-4、DMH-3组成,其高生长快,地径生长慢,生物量低;第2组包括XMH-7、HE-1、HE-3、MH-8、MH-5、MH-2、XMH-4、XMH-10、HY-1共9个无性系,其生长特点是:苗高、地径生长快,生物产量高;第3组包括HE-4、XMH-8、MH-3、MH-7、MH-4、MH-8、MH-35、MH-6、XMH-9、MH-9共10个无性系,其苗高、地径和生物量处于中等;第4组包括DMH-1、XMH-5、XMH-6、HE-2、XMH-3、MH-1、DMH-2共7个无性系,它们的苗高、地径和生物量均小。从第12、组中选育适生优良无性系的机会较大,可将这13个无性系列为重点试验对象;第3组的无性系在生长方面的表现中等,可结合其他育种目标进行良种选育。