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为建立适用于甘肃省的立木材积模型,获取更为准确的材积表,以甘肃省山杏、山杨为研究对象,采用电子经纬仪进行无损立木精测获取数据,并通过误差变量联立方程组方法,建立了两个树种的二元立木材积方程、一元立木材积方程以及树高-胸径回归模型,为准确估计相应树种的森林蓄积量提供了科学依据。利用经典的二元材积模型山本和藏式及指数树高模型进行联立得到相容性立木材积方程,通过6项指标对所得模型进行综合评价,结果表明:二元材积模型、一元材积模型都能取得良好效果,其中山杏二元材积表、胸径一元材积表的平均预估误差分别为2.12%,2.58%;山杨二元材积表、胸径一元材积表的平均预估误差分别为1.57%,2.01%;所建相容性一二元材积模型可用于甘肃省山杏山杨蓄积量估计。 相似文献
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根据抚宁县林木生长现状与河北省一元立木材积表的差异,选择合适的H-D数字曲线方程,用图解法检验调整,用部颁二元立木材积表材积经验式导算出一元立木材积表。 相似文献
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<正> 泡桐是华北平原农区重要的速生用材树种,其原木是我国传统出口商品。但从六十年代以来,国内外均提出用我国现行原木材积表(LY 108-61)衡测泡桐原木材积误差过大,外贸部门和外商反映尤为强烈。为了解运用原木材积表衡测泡桐原木材积的误差状况,我们随机抽取了兗州、成武,烟台和民权等县、市的泡桐原木1,050根,以实测材积(一米区分段求积法)和查LY 108-61原木材积表所获数据相比较,并计算了误差(见表1)。 相似文献
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<正> 一个林区一般都生长着几个甚至几十个树种的林木。在具体林分中,有的为纯林,有的则为混交林。为调查立木材积,一般都编制地方性一元材积表。这种材积表又可分两种:一种是多树种混合材积表,如过去东北地区用的针叶树材积表和阔叶树材积表;另一种是分别树种编制的单一树种材积表。前者简便,但误差较大。如根据我们的分析,在直径相同时,榆树的材积仅为山杨材积的77.6%,黑桦材积仅为枫桦材积的79.8%;后者精度较高,但由于表格过多,容易造成混乱而出现错误。因此,在一个林区范围内,有必要编制出一套具 相似文献
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一、原条材积表的编制我国原条材积的测算方法历经三十余年的实施,已知误差较大。故从1985年12月1日起限制其使用范围,并将检径固定在离大头水眼内侧(斧口或锯口内侧)2.5m处,而改用下式计算杉原条材积: V=0.39(d+3.5)~2(L+0.48)/10000 (1) 其他树种原条材积可借用(1)式或沿用旧法查表。但(1)式须经大量实测数据导出,精度始有保证。而本文提出的方法,只须从二元材积表或树高级材积表算出干形指数r,再用下法即可成表。该表可提供各检径、不同高度且经过修匀的单株去皮树干材积,再按原条造材规格将 相似文献
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皖北杨树二元立木材积表的编制 总被引:2,自引:0,他引:2
以安徽省杨树人工林为研究对象,按照立木材积表编制要求,随机抽取329棵杨树伐倒木材积资料.以300棵样木资料为编表样本,选用3种数学模型为二元材积的候选模型,利用非线性麦夸特迭代求解法确定各模型参数、剩余标准差、相关指数.根据相关指数和剩余标准差,确定最优二元材积模型为:V=0.000 096 93d2.0123h0.6147".以29棵样木资料为验表样本,分别计算二元材积模型理论材积与实际材积的平均相对误差、平均绝对相对误差和系统误差,计算结果为:二元材积表分别是2.7%、8.6%、0.1%.各种材积误差均满足林业生产材积估算误差要求. 相似文献
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中国森林认证产销监管链标准与《欧盟木材法》关于合法性的比较分析 总被引:1,自引:1,他引:0
2010年颁布的《欧盟木材法》要求所有进入欧盟市场的木材产品都必须具有合法性,而我国则在2012年出台了关于森林认证的2个国家标准——《GB/T 28951-2012中国森林认证森林经营》和《GB/T 28952-2012中国森林认证产销监管链》。文中通过对《欧盟木材法》和中国森林认证产销监管链标准关于木材合法性的比较分析提出,开展产销监管链认证或尽职调查是应对《欧盟木材法》的一种现实选择,但林产品外贸企业应以《欧盟木材法》实施为契机,进一步加强对林产品供应链的监管以确保木材来源的合法性,提升经营管理水平。 相似文献
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On mechanical behavior of traditional timber shear wall in Taiwan I: background and theory derivation 总被引:1,自引:0,他引:1
The objectives of this study were to explore the mechanical behavior of traditional timber shear walls in Taiwan and to propose
a theoretical model to predict their lateral force resistance. An extensive field investigation was conducted, and the dimensions,
tectonic detail, and materials used were recorded. The data collected were used as the reference for theoretical derivation
and experimental design. In the theoretical model, the moment resistance of entire shear walls was derived from the contributions
of the moment-resisting capacity supplied not only by embedment and friction action between board units and beams but also
the dowel action of bamboo nails. Timber shear walls with various geometric conditions and material properties are considered.
The theoretical model demonstrated in this study can be used to predict the mechanical behavior of timber shear walls and
will be verified by experiments in our next article. 相似文献
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The US and EU markets are the main destinations of Chinese forest products.Through analyzing the similarities and differences between the US Lacey Act Amendment and the EU Timber Regulation,the paper focused on how to realize better compatibility and practicality of Chinese timber legality verification scheme in terms of verification standard setting,verification procedures,pilot work of timber legality verification scheme,capacity-building trainings and studies on key problems. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(4):328-335
Timber quality and increment of Scots pines were analysed in two adjacent stands in northern Sweden. One stand originated from advance growth, and one from planted seedlings. Height increment of advance growth that was higher than 1.3 m when released was slow compared with advance growth lower than 1.3 m and planted trees. Timber quality of advance growth, > 1.3 m at release, was poor due to high incidence of stem damage, most likely inflicted during the logging operation. Potential timber quality of planted Scots pines was better among dominated than dominating trees. Volume production was more than twice as high in the plantation as in the stand originating from advance growth. Slash burning after clear felling had a positive effect on production in the plantation. 相似文献
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Forestland tenure institutions and patterns are in a period of rapid change in the USA. Historically dominant forestland tenures
are disappearing, and new tenures are emerging. Traditional, vertically integrated forest products firms have shed their forestland
holdings which have been picked up by Timber Investment Management Organizations (TIMOs) and Real Estate Investment Trusts
(REITs). Increasing numbers of private individuals and families are purchasing small rural tracts and some communities are
developing innovative means to gain control over nearby forestlands in order to protect these lands from commercial real estate
development. Within this context of rapid ownership change, small-scale forest owners including families and communities find
themselves at a competitive disadvantage, relative to large corporate owners, in wood commodity markets. This paper considers
how small-scale forest tenures, relative to large corporate tenures, may be advantageous to society with regard to selected
ecological, social, and economic factors. While the paper primarily draws upon illustrations from the US Pacific Northwest,
its themes are global in nature. 相似文献
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木结构建筑可以发挥优良的固碳作用,促进生态环境的和谐健康和可持续发展。木结构建筑的使用维护阶段是其生命周期中持续时间最长、对碳排放影响最大的阶段。基于生命周期分析法研究了木结构建筑在使用过程中影响其碳排放的主要因素和量化方法,在此基础上针对性地提出了减少碳排放的措施。 相似文献