Stem and Crown Relations in Four Species from an Evermoist Forest in Sri Lanka

Abstract

The volume of a tree's crown represents the accumulated historic crown surfaces integrated over time and environmental conditions. As such the crown volume of a tree should be correlated to the stem diameter, which represents accumulated historic wood increment. This study examines the relationship between crown and stem metrics of four tree species, Macaranga peltata, Schumacheria castaneifolia, Shorea megistophylla, and Shorea trapezifolia, from an evermoist forest in southwestern Sri Lanka. Shorea megistophyllahad the highest correlation between crown volume and stem diameter of the four species (r² = 0.55). The addition of an inverted parabola, to represent historic crown surfaces not included by the current crown volume, improved correlations with stem diameter significantly, especially in the flat-topped pioneer species, Macaranga peltata. Schumacheria castaneifoliashowed poor correlations between stem and crown dimensions, suggesting that allocation to fruit and flower production may receive higher priority than diameter growth. The relative importance of current crown volume and cumulative crown volume in explaining variation in stem diameter offers insight into species life-history patterns.     

The privatisation of New Zealand forests

During the 1980s and early 1990s, the New Zealand economy went through radical economic changes, overhauling almost all aspects of economic policy. The New Zealand Forest Service was not exempt from these changes. This paper describes two major aspects of that change: the way the New Zealand Forest Service, like many other state trading activities, was restructured first through corporatisation under the State-Owned Enterprises Act 1986 which has ultimately led to privatisation; and secondly through the enactment of the New Zealand Resource Management Act 1991 which has fundamentally altered environmental management in New Zealand. The Act's underlying principle is based on the principle of sustainable management. This principle forms the foundation of forest management in New Zealand. Whether the restructuring and privatisation will produce a more efficient forestry sector is an issue that the author does not address. The Crown Assets sales are an ongoing and dynamic process which still have not been completed. This is a shortened version of a chapter originally presented in her LL.M. Thesis in 1995.     

美国农产品产地直销支持政策对中国的启示

美国2014农业法案,在营养援助计划、信贷支持、农村发展和园艺支持计划中增加了一些新的支持产地和区域农产品直销的政策和规定.通过对“农民-消费者”和“农场-厂商”包括机构、学校、农场地零售店、餐厅等食品销售渠道的支持,旨在加强消费者与本地和地区食品市场的连接.在整理美国新农业法案对产地和区域食物直销支持政策内容的基础上,对其影响进行评价,进而结合目前我国农产品直销支持政策存在的问题提出其对我国的启示.     

从“66任务”到《荒野法》美国关于国家公园游憩与保护的争议及启示

美国国家公园因二战时期预算不足导致缺乏维护,发展陷于停滞,无法满足战后民众飞速增长的户外游憩空间需求。国家公园局局长康拉德·沃斯在1956年向总统艾森豪威尔提出“66任务”,旨在到1966年以现代化手段全面翻新、修建公园基础设施并提升公园服务水准。该项目共修筑了超过数千英里的国家公园内部道路和100多个现代化游客中心。然而,“66任务”因其现代主义风格的建筑和过度开发遭到环保组织反对,批评人士认为公路和带有玻璃幕墙的游客中心破坏了国家公园的自然美景,枉顾公园的自然承载力。这背后的深层矛盾是国家公园在游憩与保护间的冲突。在此背景下,诞生了主要以服务大众游憩为主的《户外游憩法》和以生态学为指导主张完整保护的《荒野法》,美国国家公园保护体系向多元化迈进。我国在国家公园体制建设上应积极吸取其经验教训,平衡游憩与保护的关系,完善国家公园法律体系,大力提升国家公园的科教功能。     

应对国际林产品贸易面临的新挑战

伴随着林产品贸易规模的扩大, 中国林产品贸易环境面临不断恶化的风险。金融危机、森林认证和雷斯法案构成了中国林产品贸易环境变化的主要因素。如何应对林产品贸易面临的新挑战成为制约中国林产品贸易发展的首要问题。文中首先分析中国林产品贸易环境的构成因素并简要介绍各个因素产生和发展的背景; 在此基础上, 结合中国林产品贸易的实际情况, 对不同因素的影响分别予以分析; 最后, 针对贸易环境不同层次的特点, 提出应对国际林产品贸易环境变化的系统性的政策建议。     

《雷斯法案》修正案对中美木质家具出口影响及对策分析

首先分析美国<雷斯法案>修正案的历史沿革、出台的背景以及修订的主要内容;接着从中美木质家具贸易现状出发,研究<雷斯法案>修正案对中美木质家具出口的影响,指出由于出口难度加大、出口成本提高和贸易保护主义等原因,将减少我国木质家具出口.在此基础上,文章最后针对我国家具出口企业如何应对挑战提出了一些合理化建议.     

Evaluating the Relative Roles of Ecological Regions and Land-cover Composition for Guiding Establishment of Nutrient Criteria

The continuing degradation of United States surface waters by excessive nutrient loads has motivated the establishment of nutrient criteria for streams, lakes, and estuaries as a means to protect aquatic resources. Nutrient criteria have been established based on ecoregional differences, recognizing that geographic variation in climate, topography, geology, and land use require use of different criteria values for different regions of the continental United States. Several studies have demonstrated that land-cover composition also strongly influences nutrient concentrations and yields. We examined the relative importance of ecoregions and watershed land-cover composition in explaining variability in nitrogen (N) and phosphorus (P) concentrations by re-analyzing the National Eutrophication Survey (NES) data reported by Omernik (1977). The variance of N concentrations among land-cover composition classes within ecoregions was six times larger than the variance among ecoregions. For P concentrations, land-cover composition within ecoregions accounted for three times more variance than ecoregions themselves. Variance across ecoregions was only weakly significant after accounting for variance in land-cover composition within ecoregions. The results suggest that the relationship between land-cover composition and nutrient concentrations in aquatic systems should also be used to help guide establishment of nutrient criteria.     

农民工行使选举权的现状与对策分析

对农民工行使选取权的现状进行了深入地分析,指出导致农民工选举权搁浅的原因是因为现行户籍制度的束缚、现行选举法的滞后性和不可操作性以及农民工自身参政意识的薄弱。针对这些因素,提出改革现行户籍制度、推进选举法的修改和完善、通过各种渠道加强农民工的参政意识等对策。