美国的城市林业

本文介绍了城市林业的内涵以及在美国的发展简史。作者还对其经营范围、法规制定、价值计算、行道树管理、教育和科学研究等作了阐述。     

美国西部生物质能源的利用

美国林产品杂志58卷1、2期合刊发表了David L．Nicholls等人的一篇关于森林生物质能源利用的论文。     

State policies for agroforestry in the United States

Existing state legislation and programs pertaining to agroforestry were determined in a 1995 nationwide survey of state- employed natural resource professionals in the United States. At that time, only 20 of the 50 states had legislation that could be identified as pertaining to any of the five major agroforestry practices: windbreaks, riparian buffers, alley-cropping, silvopasture, or forest farming. Nine states had direct legislation specifically referring to one or more of these agroforestry practices, while the remaining 11 states had indirect legislation that could be construed as pertaining to agroforestry. Cost-sharing was the most commonly employed incentive in the direct legislation states and windbreaks were the most common practice in those states. Tax incentives and cost-sharing were the most favored approaches in the 11 states with indirect legislation. This revised version was published online in June 2006 with corrections to the Cover Date.     

现代花艺之装饰美

现代花艺（也称为现代花卉装饰艺术）是区别于传统的西方式插花和传统东方式插花的花卉装饰艺术。它出现于上世纪60-70年代。最先在欧美流行。上世纪初,世界各国的政治、经济、文化等都在短时间内经历了巨变。在这种动荡不安、纷繁复杂的社会环境下,各种新奇的、另类的艺术理论应运而生。传统的文化观、审美观受到了严重的冲击,各艺术门类的全新的艺术尝试层出不穷,而且备受追捧,各种流派不断涌现。     

广西太平狮山国家森林公园旅游资源评价与规划设计

对广西太平狮山国家森林公园的资源特色、资源等级以及风景质量的分析评价的基础上,提出该森林公园规划的思路和规划方案。     

美国的山区流域管理

作者介绍了流域的概念和定义以及流域管理的起因,论述了美国山区流域管理所面临的问题和采取的治理措施,并阐述了流域管理中森林水文学的作用和效益。认为,美国的流域管理已经从单一的水资源调控发展到对整个流域以水土资源为核心的再生自然资源的保护、改良和多目标利用,以达到流域的可持续发展的目的。     

美国耐旱景观实践及启示

在水资源日益紧缺的背景下,耐旱景观在世界范围内受到重视,其原则广泛应用于干旱地区的景观营造并获得了巨大收益。文中介绍美国耐旱景观及其原则,解析耐旱景观的内涵,列举美国耐旱景观实践的具体做法,希望通过美国耐旱景观的实践能够让更多地区的景观建设获得启示并从中受益。     

Phylogeographic patterns of Armillariaostoyae in the western United States

Nuclear ribosomal DNA regions (i.e. large subunit, internal transcribed spacer, 5.8S and intergenic spacer) were sequenced using a direct‐polymerase chain reaction method from Armillaria ostoyae genets collected from the western USA. Many of the A. ostoyae genets contained heterogeneity among rDNA repeats, indicating intragenomic variation and likely intraspecific hybridization. Intragenomic variation was verified by visually editing base‐sequence offsets in regions with insertions/deletions, and using sequence‐specific internal primers to resequence heterogeneous regions. Phylogenetic analyses with Bayesian Inference methods were used to define groups within A. ostoyae. Analysis of A. ostoyae from outside the western USA indicated the presence of a Circumboreal group of A. ostoyae that also occurs in Utah; two other phylogeographic groups were associated with the Rocky Mountain and Pacific Northwest regions of the USA. Mixed sequence types, an indication of intraspecific hybrids, were common in some geographic regions. Hybridization events may have influenced species evolution, contributing to variation in pathogenicity and virulence. The occurrence of these groups and intraspecific hybrids also indicates that paleogeography and paleoclimate may have influenced the phylogeography of A. ostoyae. In addition, other Armillaria species were examined for evolutionary relationships with the groups of A. ostoyae. These findings will provide a basis for future research relating ecological function to genetic diversity within A. ostoyae.     

Agroforestry and forestry-related practices in the Midwestern United States

A survey, conducted in 1990–1991 on agroforestry and forestry-related systems in eight Midwestern states, showed that three traditional and three nontraditional agroforestry systems are practiced in the region. Of 46 traditional systems reported, most common was agrisilviculture (28), then silvipasture (12) and agrisilvipasture (6). These systems often involved corn, soybeans, and hay planted with tree species for nut, timber, or Christmas tree production, and cattle. Non-traditional agroforestry systems were field windbreaks/shelterbelts (29), treeshrub intercropping systems (21), and boundary plantings (11). These systems involved a variety of northern hardwood species evergreens, and shrubs. There was also a preponderance of specialized systems (97) of growing trees with the production of mushrooms, nuts, syrup, wildlife, and other nonwood products. The survey is exploratory in nature and, although the results may not represent a complete count of people involved with agroforestry in the region, the numbers reported may indicate where a practice may be prevalent. The results reflect the fact that much work still needs to be done by agroforesters in this region. They also provide some basis for further research on more suitable systems, and for identifying other researchable questions on agroforestry for the region. The methodology also made possible a bigger nucleus for networking of agroforesters and other interested people in the Midwest. Finally, although not normally considered as agroforestry, the significance of the other specialized systems reported in this survey is that they offer varied ways of connecting forestry with other activities in a largely agricultural landscape, and that they may even be seen as opportunities for easier transition into agroforestry.     

美国森林的水文效应

详尽综述了美国森林在涵养水源、改良水质和保障人民健康方面的作用和贡献,集中分析了国有林在水供给方面所扮演的重要角色——包括数量、质量、时空分布及防洪减灾等方面的经济价值.     

美国国有森林系统规划管理

美国的森林资源丰富且国有森林经营管理水平较高,其国有森林的权属清晰,管理理念先进,管理体系规范,法律法规健全,科学化经营程度高,森林多功能经营完善。美国最新的国有森林系统规划管理是在吸取了几十年的经验和教训之后提出的,旨在为人们和社区提供生态系统服务和多种用途,为当前和未来提供一系列的社会、经济和生态效益。文中介绍美国国有森林系统规划管理的背景和规划框架,分析其规划管理特点,总结其现行管理体系,并提出对我国国有林经营管理的借鉴意义。     

为林业生产服务的美国林业科技体制

本文着重介绍了美国林业科技队伍状况、科研经费来源、选题和科技成果推广体系。并结合中国国情提出了具体建议。     

Silvopasture practices and perspectives in the Northeastern United States

The use of silvopasture systems on farms in the Northeastern United States has never been documented. Our objective was to gather baseline data to describe silvopasture practices and perspectives in the Northeastern United States. To accomplish this, we investigated the structure, management of, and reasons for use of silvopastures in New York state and New England through a series of interviews and inventories on 20 farms purposefully chosen as practicing silvopasture. Thematic content analysis was conducted to summarize interview results and identify trends related to silvopasture practices. Three farmers in this study had been practicing silvopasture on their farms over 30 years; the rest were new to silvopasture in the past 10 years. Only three of 20 farmers interviewed in this study had experience practicing silvopasture prior to implementing it on their farms. Forest conversion to silvopasture was the primary starting point for silvopastures observed on regional farms. Orchard, open field edge, outdoor living barn, and plantation silvopastures were also documented on multiple farms. Shade and a desire to maximize use of farm woodlands were primary reasons for silvopasture utilization. This research provides evidence that silvopastures are being used to diversify regional farms. For the practice to be advanced in the region further research is needed on the topic.     

Forestland ownership changes in the United States and Sweden

This article examines the changing structure and ownership of the forest products industry in North America and the Nordic countries. The authors explore company-specific perspectives on why some private forest products companies divest themselves of timberland ownership and others do not. The focus is on the United States, where the forest products industry has divested itself of substantial amounts of timberland, and on Sweden, where divestitures have been smaller. In both the United States and Sweden, forest products industries are large and forestland ownership has traditionally been an important component of the portfolio of an integrated forest products firm. The analysis presented here is based in part on literature about the vertical integration of markets.