共查询到18条相似文献,搜索用时 231 毫秒
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台湾桂竹一元重量表是地方性用表 ,通过研究永泰县台湾桂竹胸径与重量的相关关系编制出永泰县台湾桂竹一元重量表 ,该表经检验系统误差在±2%范围 ,可以适用于永泰县 相似文献
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利用回归方程建立杉木地径与胸径、树高曲线方程,并结合福建省杉木二元材积公式和出材率表编制了红旗林场杉木地径一元材积表和出材率表,经检验,其精度符合要求,适合红旗林场杉木林分使用. 相似文献
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尤溪国有林场杉木人工林林分材种出材率表的编制 总被引:1,自引:0,他引:1
采用尤溪国有林场近年来伐区调查设计资料,选择杉木林分平均胸径和平均高为辅助因子,应用多方程分析对比法研制杉木人工林林分一元和二元材种出材率表。结果表明,林分材种出材率与平均胸径D及D2H之间的关系,以Y=aeb/x方程效果最佳,但规格材的拟合效果不如总出材率;采用平均胸径和平均高2个因子编制的林分二元材种出材率表,精度要高于只用平均胸径1个因子的林分一元材种出材率表。所编数表简便实用,在森林资源调查中有应用价值。 相似文献
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华北落叶松天然林立木重量表的试编 总被引:2,自引:0,他引:2
本文根据立木生物量(W)与树木胸径(D)、树高(H)和材积(V)间存在的相关关系,建立了最优经验方程,试编了华北落叶松天然林一元和二元立未重量表,並阐述了编表的具体步骤和应用方法。 相似文献
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应用古田县近年来伐区调查实际造材数据,以林分平均胸径和平均高为自变量,分别以林分总出材率和规格材出材率为因变量,选择理查德方程建立马尾松人工林分一元和二元材种出材率模型。经拟合结果分析,以林分平均胸径D和平均高H的组合D2H作为自变量,其拟合效果和预估精度要高于只用一个平均胸径或平均高的单因子林分材种出材率模型。并编制了林分一元和二元材种出材率表。 相似文献
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谭俊 《中南林业调查规划》1993,(4):54-56,58
立木生物量(W)与树木胸径(D),树高(H)和材积(V)间存在的相关关系,建立最优经验方程,可编制天然林一元和二元立木重量表。在大比例尺的航片上,可判读量测出胸径,树高,冠幅和株数,根据这些判读因子查立木重量表,再利用测定林分单位面积生物量方法之一的略算法,即可实现估算林分单位面积生物量之目的。 相似文献
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利用我国湿地松分布区内222个气象站点的10a气候资料的平均值,用主成分分析法,将湿地松栽培区划分为4个立地气候区,即:Ⅰ.南亚热带、热带沿海立地气候区;Ⅱ.中亚热带丘陵立地气候区;Ⅲ.暖温带、北亚热带丘陵、平原、岗地立地气候区;Ⅳ.湘、鄂、川接壤山地,四川盆地,黔东南立地气候区.再在各气候区内实测有代表性的8~10a的湿地松标准地171块,分别采用平均胸径、平均树高、平均单株材积证实各气候区内湿地松生长差异.这4个立地气候区可作为湿地松人工林立地类型划分、立地质量评价等经营数表编表单元的依据. 相似文献
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天然沙罗竹生物学特性和个体结构规律的研究 总被引:3,自引:0,他引:3
沙罗竹是我国南部热带地区分布较广,具有多种经济价值较高的大型丛生竹,本文论述了天然沙罗竹的分布和生物学特性,揭示了沙罗竹的秆形、秆壁厚度、秆材含水率的变化规律和个体结构特点,用实测材料拟合了秒结构因子之间相关关系的回归方程,编制了供天然沙罗竹林资源调查和规划使用的计量数表,为天然丛生林资源调查计量标准和科学经营的依据。 相似文献
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Growth and yield models were developed for individual tress and stands based on336 temporary plots with 405 stem analysis trees of dahurian larch(Larix gmelinii(Rupr.)Rupr.)plantations throughout Daxing’anling mountains.Several equations were selected using nonlinearregression analysis.Results showed that the Richards equation was the best model for estimatingtree height,stand mean helght and stand dominant height from age; The Power equation was thebest model for prediction tree volume from DBH and tree height; The logarithmic stand volumeequation was good for predicting stand volume from age,mean height,basal area and other standvariables.These models can be used to construct the volume table, the site index table and other for-estry tables for dahurian larch plantations. 相似文献
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IntroductionDahurianlarch(L8risgmeliniiRupr.)isoneofthemostimportanttimberspeciesinChina.AsaresuItofovercuttingforseveraIdecades,thenaturaIDahurianIarchforestresourcesaredecliningrapidly.PIantationsofdahurianIarchhavebecomeanimportantpartofforestpreserveresourcesinDaxing'anMountains.ConsequentIystudyingthegroWthofDahurianlarchandformingtheforesttabfesareofsignrficancetofor-estproduction.ThispaperpresentsinformationongroWthandyieIdmodeIsofDahurianlarchpIantations.MethodsDataof4O5stema… 相似文献
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In Europe yield tables are frequently used to get informationon future total crops as well as on current and future incrementsper hectare and thus the database for forest valuations, decisionson allowable cut and other management decisions. These yieldtables usually claim to describe potential growth and yieldper hectare of even-aged pure species stands. As a prerequisiteto the use of these yield tables in mixed species, even-agedstands, the area to which every species has to be related needsto be known. The way to calculate this area is to split up thearea of the mixed stand into areas each of which is occupiedby a fully stocked pure stand of one species.Stocking is measured in terms of observed basal area versusbasal area given by the yield tables. Thus the species proportionby area is calculated from the ratios between the observed andthe respective yield table basal areas. In order to obtain thenecessary sample size for a given precision of the species proportionby area, its variance is calculated from Gauss's law of errorpropagation with the species proportion by basal area and theratio between the respective basal areas as they are given byan appropriate yield table as independent variables. Estimatesof these variables indicate that 3 to 12 angle counts per stand(basal area factor BAF = 4 m2 ha1) are sufficient fora standard error of ±10 per cent for the species proportionby area, and 9 to 50 angle counts for one of ±5 per cent. 相似文献
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E. K. Marsh 《Southern Forests》2013,75(1):2-8
The methods employed in the construction of new metric volume and percentage utilization tables for Eucalyptus grandis, based on 1 378 sample trees are described. Most of the complicated volume calculations were executed on a computer. Because of this, the formula for a frustum of a cone was used to calculate volumes of log sections. The logarithmic volume equation was used for the construction of the general volume table. It was found that bark thickness had a significant effect on the variation of tree volume. Therefore, volume tables for various bark thickness classes have been prepared in addition to a general table for average bark thickness. The relationship between breast height diameter and the percentage of the total volume to 2 inches tip represented by a given tip diameter class can be explained satisfactorily by regression of the probit transformation of the percentage volume on a polynomial of the reciprocal of breast height diameter. For metric conversion, the tip diameter class was introduced as an additional variable and the relationship was expressed by one equation for all the tip diameter classes combined. Imperial as well as metric equivalents of all equations established are given. 相似文献