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91.
应用树干分段的二元形数函数的削度方程、商品材材积方程和树干总材积方程的一致性方程系统编制明溪县杉木、马尾松的商品材立木材积表。既能充分利用公开发表的有效的测树信息和数表 ,又能结合区域的资源调查信息估测一致性系统中的参数 ,且编表的误差分布均匀 ,绝对误差和相对误差小  相似文献   
92.
Within the European Union there exist three different frameworks for forest accounting at the national level. For purposes of the national accounts, the regulations of the European System of Integrated Economic Accounts (ESA) have to be observed. They require a distinction between forestry and logging and provide specific guidelines for the valuation of standing timber. In recognition of the special character of forests and forestry production, two satellite accounts are devoted to forestry: the Economic Accounts for Forestry (EAF) and the European Framework for Integrated Environmental and Economic Accounting for Forests (IEEAF). Although they were designed as complementary to the national accounts and refer to the same basic methodologies, the guidelines for forest accounting provided by the three manuals are not fully compatible. Just recently, a further integration and harmonization of the concepts for forest accounting has been proposed. Austria has implemented the valuation of the increment as an output of forestry as requested by ESA and produces the EAF tables on a regular basis. The possibilities for extending forest accounting to natural resource accounts for standing timber and the IEEAF have been investigated in terms of pilot studies. The Austrian experiences and results exemplify the problems and possible solutions associated with the adoption of the different European schemes. Data deficits and valuation issues restrict the significance of respective results to some degree, especially as regards forestry-specific extensions of the accounting schemes.  相似文献   
93.
姚雪刚 《林业科技》2005,30(4):17-20
通过分析,确定了小陇山林区日本落叶松人工商品林抚育间伐的时间,抚育间隔期及抚育强度,预测了抚育间伐的经济效益。  相似文献   
94.
The historical transition of timber distribution pattern in China was presented firstly with main parts of timber flows in China, which included timber markets, timber transport system and regulations of timber transport. Based on the overview on tropical timber flows in China, the trade flows of tropical timber from production and imports of tropical timber to export of tropical timber products were analyzed by vivid illustrations. At the same time, problems in timber trade flows in China were analysed in the end.  相似文献   
95.
During the early eighties farmers in north-west India planted Eucalyptus on a massive scale for sale as poles and pulpwood. However, after 1986 farmers in this region have almost stopped growing Eucalyptus, as their experience with its marketing was not a happy one. The pole market got saturated, paper mills did not pay a remunerative price, and fuelwood prices were low and uneconomical. More important, because of legal restrictions on the transport and sale of wood, and other institutional factors, the gap in the farmgate price and the consumer price remained very wide. Wood markets have, on the whole, exploited the farmers, rather than helped them. Due to this, the short period of flirtation with tree crops seems to be over for at least resident farmers in those very areas in north-west India where they had so enthusiastically planted Eucalyptus in the early 1980s.Abbreviations BDO Block Development Officer - Headloaders poor people who collect firewood on their heads from forest lands for consumption and sale - m ha million hectares - Rs Indian Rupee 16 Rs = 1 US Dollar in 1989 - panchayat elected village organisation - pradhan village chief On study leave from the Government of India to the Oxford Forestry Institute, South Parks Road, Oxford, OX1 3RB, U.K. Present address: 17 Ponnappa Road, Allahabad 211001, India  相似文献   
96.
本文阐述了锯材在干燥过程中出现的干裂问题及产生的原因和防止办法。  相似文献   
97.
Lifting for handling and flatbed truck transportation to the job site are important processes during manufacture of prefabri-cated wooden construction units like mini homes and building modules. Significant damage can occur to sections or components of units during these operations. Although damage usually will not impair its structural safety, it is costly to fix and causes the public to perceive prefabricated wooden buildings as low quality products. Field observations and preliminary numerical models for prefabri-cated units subject to lifting and transportation forces are summarized here. Once fully developed and verified, models will support the creation of damage mitigation strategies centered on structural details indicating how units are to be supported during lifting and transportation.  相似文献   
98.
本文针对GB/T114-1995《原木检验》标准中,有关针叶树材的活节,检量颜色较深,质地较硬部分(似黑眼珠)的尺寸问题,认为颜色较深、质地较硬是构造特征,节子尺寸应含最外圈年轮。检量似黑眼珠不符合国际惯例。  相似文献   
99.
罗建才 《福建林业科技》1995,22(2):79-80,36
杉木小径材胶拼技术以6-12cm的衫木小径材为原料,通过制材、胶拼、干燥和加工等工艺,生产出较大规格的板方材,可代替杉木中、大径材用于家俱、建筑等行业。  相似文献   
100.
我国50~60年代初期,林业部综合队曾编制红松(Pinus koraiensis Sieb.et Zucc.)、云杉(Picea spp.)、马尾松(Pinus massoniana Lamb.)、兴安落叶松(Larix gmelini(Rupr.)Rupr.)、白桦(Betula platyphylla Suk.)等树种材种出材量表,70~80年代各省(区)市、规划院、科研等单位对杉(Cunninghamia lanceolata Hook.)、落叶松、山杨(Populus davidiana  相似文献   
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