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<正> 蓄积量通过样地每木调查,用一元材积表测算,是目前我国和其它国家最常用的一种调查方法。随着经营强度和调查技术的提高,越来越对一元材积表测算蓄积量提出了疑异或否定,若用二元材积表,虽能提高样地蓄积量的调查精度,但需要测定30—40株立木的树高来反映待测样地胸径与树高的数量关系,使外业工作量增加很多,而未被广泛采用。本文根据3P抽样理论,提出在样地每木调查基础上, 相似文献
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以我国南方地区最重要的针叶树种杉木(Cunninghamia lanceolata)为研究对象,采用误差变量联立方程组方法,建立了相容性二元立木材积方程、胸径和地径一元立木材积方程、树高胸径回归模型及地径胸径回归模型。利用3种树高模型和2种地径模型组合了4个相容性立木材积表系列模型联立方程组,通过6项指标进行综合评价,结果表明由最简单的树高模型和地径模型构成的相容性系列材积模型就能取得良好效果,其二元材积表、胸径一元材积表和地径一元材积表的平均预估误差分别为1.31%、3.66%和7.39%,可用于不同目的的杉木林蓄积量估计。 相似文献
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可变参数相对树曲线模型及其应用研究 总被引：7，自引：0，他引：7
用我国现行一元立木材积表估计林分或样地的立木材积偏差很大，而直接利用二元木材积表，则野外实测树高的工作量又太大。本研究针对这一实际问题，提出了通过建立可变参数相对树高曲线模型，将二元立木材积表直接用于林分或样地立木材积估计的方法，其 估计精度可达到接近实测树高曲线法的水平。 相似文献
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以我国南方地区最重要的针叶树种杉木（Cunninghamia lanceolata）为研究对象,采用误差变量联立方程组方法,建立了相容性二元立木材积方程、胸径和地径一元立木材积方程、树高胸径回归模型及地径胸径回归模型。利用3种树高模型和2种地径模型组合了4个相容性立木材积表系列模型联立方程组,通过6项指标进行综合评价,结果表明由最简单的树高模型和地径模型构成的相容性系列材积模型就能取得良好效果,其二元材积表、胸径一元材积表和地径一元材积表的平均预估误差分别为1.31%、3.66%和7.39%,可用于不同目的的杉木林蓄积量估计。 相似文献
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在采伐现场根据伐桩和相关信息测算已采伐林木蓄积,可采用的方法很多,通过不同测算方法的应用表明:用回归分析法建立根径、胸径、树高的回归方程,并用二元立木材积式计算采伐木蓄积,其结果比较真实可靠。 相似文献
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相对树高曲线模型的建立与应用 总被引：1，自引：0，他引：1
利用标准地调查资料建立相对树高曲线模型，将此模型与二元立木材积表相结合，用于林分和样地立木材积的估计。其估计精度可达到近似实测树高曲线法的水平，又不增加野外工作量，避免了利用一元立木材积表估计林分或样地立木材积偏差太大的问题。 相似文献
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沙县杉木、马尾松、阔叶树地径一元材积表编制的研究 总被引：1，自引：0，他引：1
地径材积表是林业生产、科研和管理的基础工具。本文结合县级森林资源连续清查样地调查,通过样木地径、胸径成对值测定,建立地径——胸径回归关系,并利用现有省定的一元立木材积表,编制了沙县杉木、马尾松、阔叶树地径一元材积表。 相似文献
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间伐对人工林生长及木材质量具有重要影响。在浙江开化开展了间伐强度（强度、中度和对照）和间伐方式（间伐1次,间伐2次）对杉木人工林生长及出材量等的影响研究,第1试验区大径材培育林分在第7年和第14年进行了2次间伐,第2试验区中径材培育林分仅在第12年时进行1次间伐。结果表明：22年生大径材培育林分和19年生中径材培育林分不同间伐处理之间树高、总断面积的差异均不显著。间伐显著增加了林木胸径的生长,大径材培育林分强度和中度间伐处理的平均胸径分别比对照增加13.78%和9.69%,中径材培育林分强度和中度间伐处理的平均胸径分别比对照增加12.28%和7.02%。间伐显著促进了林木单株材积的增加,2组试验林分活立木材积随着间伐强度的增加而降低,第1试验区22年生林分不同间伐强度之间活立木材积的差异不显著（P>0.05）,第2试验区强度间伐活立木材积显著低于对照（P<0.05）,中度间伐林分活立木材积与对照和强度间伐之间的差异不显著（P>0.05）。2组试验林分总蓄积和出材量也随着间伐强度的增加而降低,二者在3种间伐处理之间均没有显著差异（P>0.05）。间伐强度不能有效增加林分活立木材积和林分出材量,间伐次数对林分出材量及出材规格有重要影响。试验区杉木大径材培育以2次间伐,总间伐强度50%左右较为适宜,而中径材培育则以1次中度间伐（约25%）为宜。 相似文献
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A forest biomass yield table based on an empirical model 总被引：1，自引：0，他引：1
Tomohiro Nishizono Toshio Iehara Hirofumi Kuboyama Miki Fukuda 《Journal of Forest Research》2005,10(3):211-220
We report an empirical model for estimating unutilized wood biomass, and its application to Cryptomeria japonica D. Don and Larix kaempferi in Tohno City, Iwate Prefecture, northeast Japan. Outputs from the model are the quantity of unutilized wood biomass and merchantable volume produced by timber harvest. The unutilized wood biomass is divided into stumps, tops, branches, foliages, small trees, and unutilized stems due to their defects. Inputs to the model are mean diameter at breast height (DBH), mean tree height, trees per unit area, and timber utilization standards. DBH distribution, DBH–height curve, stem form, bark thickness, and relationship of stem biomass to foliage and branch biomass could be described by the proposed model, indicating its validity. The proposed model enables us to develop the forest biomass yield tables modified from the existing stem volume yield tables. The developed forest biomass yield tables indicated that the unutilized wood biomass due to defects accounted for the largest part of the whole unutilized wood biomass, and that the ratio of unutilized parts in stem volume to total stem volume could vary with stand age and site productivity class. Based on a comparison of the developed forest biomass yield tables with those reported previously, we concluded that the proposed model-based forest biomass yield table would be useful for estimating the quantity of unutilized wood biomass. 相似文献
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Juliana Menegassi LeoniJochen Schöngart 《Forest Ecology and Management》2011,261(1):62-67
The long-term success of forest management depends primarily on the sustainability of timber production. In this study we analyse the population structure, tree age and wood increment of Malouetia tamaquarina (Aubl.) (Apocynaceae) to define a species-specific minimum logging diameter (MLD) and felling cycle by modelling volume growth. Contrary to other timber species in the nutrient-rich white-water floodplains forests (várzea), M. tamaquarina grows in the subcanopy of old-growth várzea forests. The wood of this species is utilized by local inhabitants in the floodplains for handicraft. In 35 plots of 25 m × 50 m we measured diameter at breast height (DBH) and tree height of all trees taller than 150 cm height. From 37 individuals with DBH > 15 cm we sampled two cores by increment borers to determine the wood density, tree age and diameter increment rates. In the management area of a várzea settlement with about 150 ha recently harvested trees of M. tamaquarina have been recorded and DBH was measured. The species presents an inverse J-shaped diameter distribution indicating that the species is obviously regenerating in the old-growth forests. Tree-ring analysis indicates a mean age of 74.5 years for a DBH of 22.7 cm for a studied population comprising 37 trees with maximum ages of up to 141 years for an individual with a DBH of 45.7 cm. The tree species has low annual diameter increment rates (3.16 ± 0.6 mm) despite a low wood density (0.36 ± 0.05 g cm−3). The volume growth model indicates a MLD of 25 cm and a felling cycle of 32.4 years. In the management area 35 trees with a mean DBH of 24 cm were recorded, similar to the defined MLD. The abundance of trees above the MLD is 2.7 trees ha−1, or 405 trees, when extrapolated to the whole management area. Considering a felling cycle of 32.4 years (annual production unit of 4.63 ha) this results in total of 12.5 harvestable trees, almost three times less than actually harvested. The actual practice of harvesting M. tamaquarina risks the overexploitation of this slow-growing species. 相似文献
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运用随机抽样法抽取马尾松成熟林分50个小班,调查胸径、树高、单位蓄积量及密度等测树因子,运用回归分析法进行测树因子相关性分析,结果表明,林分蓄积量对于密度、胸径、树高之间存在显著线性关系,其相关性数学模型可用三元线性回归方程y=b0+b1x1+b2x2+b3x3表示,其中,密度是影响林分蓄积量的主导因素。相关性变化趋势分析表明,在兼顾林分产量和林木径级的情况下,合理保留密度每667 m2为105株。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):121-126
The aim of the study was to develop methods for estimating the taper curves for trees tallied in a forest inventory. The average stem form in a stand was described by the principal components of the stand effects in the stem dimensions measured in the polar coordinate system. Measurements of diameter at breast height, diameter at a height of 6 meters, and height taken from trees on the sample tree plots were used for determining the first four principal components. Regression models were derived to predict the principal components from the site and growing stock variables. These models were used to estimate the taper curves of the tallied trees. Use of the principal components estimated by the regression models gave less reliable results than use of the principal component estimates based on measurement of the height of one randomly chosen tree on the sample plot. The best result was found with combined use of the principal component estimates and one height measurement per sample plot. 相似文献
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在内蒙古赤峰市敖汉旗小流域选择小叶杨、白榆、油松为研究对象,采用样地法和标准木树干解析木法,对标准地内林木进行每木检尺,同时对标准木树干解析,从而对流域内3种人工造林树种进行树高、胸径以及材积生长过程分析。结果表明:立地条件对不同人工林都存在明显的生长抑制作用。(1)小叶杨在种植19年后,树高、胸径、材积量生长均出现下降或减缓;从材积生长来看,第5~19年时为小叶杨的速生期;(2)白榆在种植后9~10年间树高和胸径生长速度开始降低,树高连年生长量与平均生长量相交于10年。材积量的快速积累可达22年;(3)油松在种植后14~19年开始出现树高和胸径生长降低现象,种植后19年是油松生长的转折期,应在此时实施疏伐调整。从材积生长来看,第7~20年时为油松的速生期。 相似文献
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不同种源马尾松造林效果及经济效益对比分析 总被引：9，自引：0，他引：9
分不同地位指数级，对比分析了广西容县种源和贵州龙里种源马尾松人工林的林分结构和生长效果的差异。以现实林分蓄积量为基础，结合材种出材量（率）预测模型和研究区的技术经济指标，用动态分析方法进行了经济效果评价。结果表明，在贵州引种广西容县种源是可行的，在相同立地条件，容县种源林分生产力高于贵州龙里种源，树高、胸径、蓄积量分别高１５．０—２１．７％、５．４—１９．１％和２８—４０％。经济效益、净现值高３８．９６—６１．２８％和６９．７８—９１．７６％。两种源单株材积随林龄加大，差异增大，但增长百分比随之减少。经济效益、净现值、益本比均随地位指数的增大而加大。 相似文献
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Han Y.H. Chen Songling Fu Robert A. Monserud Ian C. Gillies 《Forest Ecology and Management》2008,255(12):3980-3984
Tree mortality is a poorly understood process in the boreal forest. While large disturbances reset succession by killing all or most trees, background tree mortality was hypothesized to be affected by competition, ageing, and stand composition. We tested these hypotheses on jack pine (Pinus banksiana Lamb.) mortality using data from long-term repeatedly measured permanent sample plots collected between 1952 and 1989 in Ontario, Canada. The probability of mortality over a 5-year period was modeled using logistic regression with the maximum likelihood estimation employed for parameter estimation. Relative competitiveness measured as the ratio of individual tree diameter at breast height (DBH) to mean stand DBH explained more variation in mortality than stand age did. Mortality increased rapidly with decreasing DBH ratio. A U-shaped mortality pattern with stand age was found while stand composition had no effect on mortality. Developed by using a residual sequential regression approach, our final mixed-effects model with a 81% model correctness of mortality prediction conclusively demonstrated that relative competitiveness is the key determinant for jack pine mortality. 相似文献