大青山实验局森林资源的动态分析及其SD模型

本文运用系统动力学(System Dynamics,简称SD)方法,并结合统计方法,通过对广西大青山实验局森林资源的系统分析,建立了大青山实验局森林资源SD动态仿真模型。该模型由34个水平变量、300个方程式描述,包括杉木面积子块、杉木蓄积子块、马尾松面积子块、马尾松蓄积子块、阔杂面积子块、阔杂蓄积子块、其它地类面积子块、其它地类蓄积子块及抚育间伐子块等9个子块。并在此基础上,研究了抚育间伐对林分生长的影响。运用所建立的SD模型,可对该地区森林资源的动态行为作多种模拟实验研究,同时为分析经营方案对森林资源的影响提供了一种可行的手段。     

以“3S”为基础的森林蓄积动态监测系统研究

1　系统研究的目的以“3S”为基础的森林蓄积动态监测系统 ,即利用遥感 ( RS)、地理信息系统 ( GIS)及全球卫星定位系统 ( GPS)信息 ,结合少量地面样地资料 ,建立以像元为单位的森林蓄积估测方程 ,进行蓄积预报。其主要目的是 :尽量减少地面调查的工作量 ,快速、准确进行森林总蓄积预报 ;通过少量的地面调查资料或地面临时样地资料 ,对林班或小班的蓄积进行估测 ,以提高局部地段蓄积可信度。2　系统组成及功能如图 1所示 ,整个系统包括 :RS及 GIS信息提取、变量优选、蓄积估测 3大部分。图 1　系统组成2 .1　 RS及 GIS信息提取如图 …     

应用数学模型测定林分蓄积的探讨

华东森林经理1991年第1期刊登了汪国良同志的《数学模型及其林分蓄积测定应用的探讨》一文,文章中指出了应用标准木法和数表法测定林分蓄积存在的问题,并提出了应用数学模型测定林分蓄积的设想,笔者认为此法可行。为了进一步验证这一理论,探索一种林分蓄积量测定的新方法,本人结合教学实习,对应用数学模型测定林分蓄积作了初步试验,现将建模方法及其应用作一简述和讨论。     

基于混合效应模型的杉木人工林蓄积联立方程系统

建立江西杉木人工林基于非线性混合效应方法的林分优势木平均高和断面积模型以及基于对数形式线性混合效应蓄积模型的联立方程组,利用验证数据与传统模型回归方法的模拟结果进行比较分析。结果表明,优势木平均高是联立方程组最基本的组成部分。通过考虑优势木平均高和林分断面积模型中参数的随机效应以及3个因变量间的相关性,则蓄积模型中参数的随机效应可以忽略。优势木平均高决定着林分断面积预测的准确性,而优势木平均高和林分断面积又是预测蓄积的主要误差来源。基于混合效应模型方法的模拟结果明显好于传统回归估计方法。进行预测时,通过解释联立方程组中因变量相互间的相关性,利用已被观测的变量能够提高未观测变量的估计精度。     

湖南楠木次生林生长与收获预估模型

[目的]建立湖南省楠木次生林林分断面积与蓄积相容性生长收获预估模型,为林分的生长预测和经营决策提供理论依据.[方法]以湖南省1989—2014年6期一类清查样地中的楠木次生林为研究对象,建立其林分断面积和蓄积生长的联立方程组,在此基础上,加入样地效应,构建基于混合效应的联立方程系统.[结果]基础模型包括3个含林分变量的...     

CASIO fx-4500PA计算器在森林资源二类调查中的应用

CASIO fx-4500PA计算器在云南省森林资源调查中使用广泛，针对二类调查小班蓄积及样地蓄积等因子计算的需要，分别编写了计算程序，列出了程序清单，并对程序的使用作了说明。     

异龄林最适立木蓄积和择伐周期的确定

本文采用使林价最大化的方法来确定西部黄松异龄林的最适立木蓄积和择伐周期,分析说明了林价的最大化与土地期望价最大化是一致的。并由此提出了一个既适合于同龄林又适合于异龄林的经营方法,而且对最适立木蓄积和最适择伐周期作了经济上的解释。较差静态分析证明:最适立木蓄积和择伐周期对利率的变化比较敏感,同时对立木价的变化也很敏感。     

用航空像片判读分解法推算小班蓄积

少林地区二类调查要提供小班蓄积和有关因子,以作今后森林经营安排的依据。而少林地区的次生林的林相比较单纯,并且大多在中幼龄阶段,单株材积变化不大,林地呈团状分布,生长好坏与局部立地条件相关紧密。这种林块集团镶嵌是造成小班蓄积差异的主要因素。针对这种特点,抓住影响蓄积变动的主要矛盾,首先分析确定各树种不同立地类型的平均蓄积(标准蓄积u_im～3/h_a),再通过像片判读,判定每个小班的立地类型、林地与空地的比例K(简称林空比)和小班内各树种林冠面积比例(P_i),按公式X_i=u_iKp_i计算小班各树种每公顷蓄积,再累加得小班平均每公顷蓄积,就可以计算出小班蓄积。基于上述认识,在山西省蒲县克城林场朝阳经营区二林班进行了像片判读分解法试验。限于时间紧迫,未做全面实地验证;特别由于试验人员无该地实践经验,有关判读特征都是     

云南松天然林最适保留密度的探讨

云南松天然林最适保留密度的探讨杨再强（西昌农业高等专科学校）谢以萍（四川西昌市林业局云南松（Ｐｉｎｕｓｙｕｎｎａｎｅｎｓｉｓ）是四川西南山地主要森林植被，活立木蓄积占全省森林总蓄积的２０％。凉山州云南松森林面积达７３．３万公顷。目前云南松天然林经营作...     

天然林保护工程对黑龙江省林区社会影响的预测

我国森林以天然林为主,按森林面积统计,全国森林总面积为１０８６７４万ｈｍ２,天然林与人工林比例为８：２;按森林蓄积统计,全国森林总蓄积为９０８３７１７万ｍ３,天然林与人工林比例为９：１。如按森林的经济、生态、社会综合效益统计,目前天然林在我国的作...     

遂川天然次生林干材收获模型

根据天然次生林中收集的样本资料,以样地中检尺乔木树干材积为基准变量Ｙ,以平均林龄,平均胸径,株数、乔木种数、郁闭度为说明变量,建立不同的干材收获模型。『     

Survey Study of Moso Bamboo Management Techniques Dissemination in Zhejiang

By PRA survey to 1 245 farmer households of 10 key Moso bamboo (Phyllostachys pubescens) production counties, the source and demand of the management techniques in Zhejiang were studied. The conducted principal factor analysis revealed that experience and traditional knowledge are currently major technical sources of farmer households' Moso bamboo forest management techniques and that the demonstrative household is a highly expected technical source, in which the prime factor is interpersonal dissemination ...     

四川桤木立木干材材积收获模型

根据 16 0株样木资料 ,以年龄 (X1)、胸径 (X2 )、树高 (X3 )、枝下高 (X4 )、冠幅 (X5)为说明变量 ,建立以立木干材材积 (Y)为基准变量的收获模型。     

Stem volume models for Cryptomeria japonica of Jeju Island,Korea

The accurate estimation of the stem volume of trees is an important task for forest managers. Two common variables used in stem volume models are the diameter at breast height (DBH) and the total height of a tree. These two variables can be used together, or only the DBH can be used. The present study was conducted to develop a simple volume model for Cryptomeria japonica found in Jeju Island, South Korea. The performance of six models using only the DBH and using both the DBH and total height as variables were evaluated. Fit statistics including coefficient of determination (R²), standard error of the estimate (SEE), mean bias (ē), absolute mean difference (AMD), Akaike information criterion (AIC), and Akaike weight (AIC_w) were used to evaluate the models. Lack-of-fit statistics were also used for further evaluation. The results showed that the models using the DBH and total height as variables performed better than the models using only the DBH as a variable.     

Modeling compatible single-tree aboveground biomass equations for masson pine (Pinus massoniana) in southern China

Because of global climate change,it is necessary to add forest biomass estimation to national forest resource monitoring.The biomass equations developed for forest biomass estimation should be compatible with volume equations.Based on the tree volume and aboveground biomass data of Masson pine(Pinus massoniana Lamb.) in southern China,we constructed one-,two-and three-variable aboveground biomass equations and biomass conversion functions compatible with tree volume equations by using error-in-variable simultaneous equations.The prediction precision of aboveground biomass estimates from one variable equation exceeded 95%.The regressions of aboveground biomass equations were improved slightly when tree height and crown width were used together with diameter on breast height,although the contributions to regressions were statistically insignificant.For the biomass conversion function on one variable,the conversion factor decreased with increasing diameter,but for the conversion function on two variables,the conversion factor increased with increasing diameter but decreased with increasing tree height.     

天然长白松干形的研究

长白松是我国特有的松科松属植物,仅见于长白山海拔630~1 400 m之间,因其特殊的分类地位和优良的遗传性而受到普遍关注。本文对第一代天然长白松林的干形进行了分析研究,结果表明:正形数的变动系数最小,相对比较稳定;从正形率系列看,q0.7以下的变动系数均小于10%,随着直径上移,变动系数增大;形数随形率增大而增加,且相关关系紧密;利用样条函数理论,拟合出长白松干形曲线的样条函数方程组,利用计算机程序可容易地计算出立木材积,与实测值相比较80%样木的误差小于3%,精度较高。海拔700 m处的长白松立木干形优于海拔1 100 m处的干形,尖削度小,干形圆满,出材率高。     

福安市马尾松林分密度效应的研究

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。     

Goal programming approach for sustainable forest management （case study in Iranian Caspian forests）

We used a goal programming technique to determine the optimal harvest volume for the Iranian Caspian forest. We collected data including volume, growth, wood price at forest roadside, and variable harvesting costs. The allometric method was used to quantify seques- trated carbon. Regression analysis was used to derive growth models. Expected mean price was estimated using wood price and variable harvesting costs. Questionnaire was used to determine the constraints and the equation coefficients of the goal programming model. The optimal volume was determined using the goal programming method according to multipurpose forest management. LINGO software was used for analysis. Results indicated that the optimum volumes of species were 250.25 m3.ha-1 for beech, 59 m3.ha-1 for hornbeam, 73 m3.ha-1 for oak, 41 m3.ha-1 for alder, and 32 m3.ha-1 for other species. The total optimum volume is 455.25 m3.ha-1.     

江南油杉人工林生长规律研究

【目的】研究了江南油杉人工林生长规律,以期为江南油杉人工林合理经营提供科学依据。【方法】在全面调查广西林科院老虎岭实验林场27年生江南油杉人工林基础上,在不同的3个标准样地内选择了12株平均木进行树干解析,深入分析其树高、胸径、单株材积生长规律及形数变化规律。并采用6种林木生长经验模型进行回归分析和比较,选出合适的生长模型。【结果】27年生江南油杉树高、胸径、材积的总生长量随着年龄的增加而增加,其中,树高生长总量为16.9 m,胸径生长总量为20.3 cm,材积生长总量为0.283 685 m^3。江南油杉胸高形数是随着年龄的增加先急剧增加,然后再缓慢下降,形数曲线呈反"J"型变化,胸高形数在第7年后小于1,第24年后曲线变化趋于平稳状态,保持在0.52左右。【结论】1)树高在6~14 a和18~24 a处于较高的增长水平,是江南油杉树高生长的速生期。胸径生长的速生期在6~16 a和18~27 a出现。树高和胸径的连年生长量随年龄的增加而增高增粗,树高的高生长期比胸径高生长期早2 a,树高与胸径的低生长期出现在同年。材积的第1个生长高峰期在1~14 a,在第26年后是材积的第2个生长高峰期。各龄阶胸高形数表明江南油杉的胸高形数大,树高尖削度小。2)通过比较分析6种生长模型对江南油杉胸径、树高和材积的实测值的拟合情况,苏玛克(Schumacher)模型可作为江南油杉树高和胸径生长模型,韦布尔(Weibull)模型可作为材积生长模型。经检验,预测值和实测值的残差及相对总误差均较小,模型精度较高,证明所选择的数学模型预测值与实际生长规律基本吻合。3)27年生江南油杉材积的连年生长量和平均生长量曲线经27 a生长仍未相交,说明江南油杉在27 a内尚未达到数量成熟。通过材积生长模型的推算结果,江南油杉材积年平均生长量与连年生长量相交于48~49 a间,即江南油杉数量成熟年龄为49 a,此时的江南油杉材积生长量为0.942 460 m^3。     

THE POSSIBILITIES AND LIMITATIONS OF SILVICULTURAL TREATMENT IN PLANTATIONS IN SOUTH AFRICA

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.