刺槐根径立木材积表的编制

刺槐根径立木材积表的编制薛海军（国营凌源市欺天林场）为掌握辽西地区刺槐人工林资源的消长变化，必须对过去的采伐量、误伐量、盗伐量等进行估测。估测一般要通过根径调查来实现。因此，本文研究了根径与胸径的相关规律，推算立木材积，编制出刺槐人工林根径立木材积表...     

毁林案件的采伐量调查

伐根检尺是测定毁林案件采伐量的常用方法，选择相似林分调查并且建立胸径──-根径关系式和树高曲线，间接应用二元立木材积表计算蓄积可提高伐根测定采伐蓄积的准确性。     

辽宁落叶松人工林根径材积表的研制

在林业科研和生产中,要经常估测已伐林木的材积。特别是在森林资源消长变化调查中,经常用根径推算立木材积,以便测定以往的采伐量、误伐量和滥砍盗伐量。目前,最好的办法,是对树木根径的调查,然后通过根径与胸径的相关关系,导算出胸径,再根据胸径与单株材积的样木,编制根径立木材积表。     

根径材积外业调查的蓄积误差

1问题产生的原因在森林资源蓄积调查时,一般采用胸径测量法,然后根据一元立木材积表的对应数值计算立木蓄积。1986年12月,黑龙江省森工总局又编制了黑龙江省森工林区根径立木材积表,目的是在森林采伐更新和林政管理中,准确估测采伐量,特别是盗伐、滥伐和误差量。森林采伐规程中规定,采伐时,被伐木伐根的高度一般不允许超过10 cm,但超过10 cm的伐根数量在15%以内也视为合格,而且按此伐根所测得的蓄积,与采代前利用胸径测得的立木蓄积的误差不大。然而,随着天然林资源保护工程的施实和伐区质量管理的加强,新规程对伐根的采伐高度要求为0 cm,也…     

关于盗伐、滥伐林木材积测定问题的解答

一、根径材积表的编制方法同一元材积表(胸径材积表)是否一样?根据一个因子(根径或胸径)与树干带皮材积的函数关系[V=F(D)]而编制的数表称为一元材积表。一元材积表有根径材积表和胸径材积表之分。日常工作中，若不加说明，一元材积表指胸径材积表。无论那种一元材积表，它们的编表方法基本一样：首先伐倒一定数量的林木，实测材积及对应的根径或胸径；然后用多种函数表达式，求解系数值，以剩余平方和最小者为优；     

黑龙江省国有林区根径立木材积表编制的研究

<正> 在不断加强采伐更新和林政管理的进程中,估测采伐量,特别是盗伐、滥伐、误伐量的要求日益增长。然而,作为计测对象的立木已从林地消失,唯有伐桩可见。因此,利用根径估测立木材积,即编制根径立木材积表的工作提到日程。1986年12月,经省森工总局主管领导同意,全省森工企业伐区调查设计工作会议商定,从整个林区收集数据,编制黑龙江省森工林区根径立木材积表。     

山西省天然油松林根径立木材积表的编制

通过采集山西省天然油松林的根径、胸径样本数据，依据《根径立木材积表编制技术规程》的技术要求，利用数理统计和回归关系建立天然油松林根径-胸径数学模型，同时进行数学模型检验，最后建立根径材积表，以达到支持生产的目的。     

沭阳县黑杨派无性系杨树一元立木材积表的编制

通过对黑杨派无性系杨树胸径—树高,根径—胸径关系的分析,用平均实验形数法编制了可供使用的沭阳县杨树胸径—根径一元立木材积表。     

基于平板采集系统编制根径立木材积表研究

2018年山西省开展了《主要树种(油松)根径立木材积表编制》试点工作,以满足林业生产应用对根径材积表的需求。其主要目的是填补山西省无"根径立木材积表"的空白;扩编山西省主要树种立木一元材积表大径阶部分;为森林资源调查监测、森林抚育、资产评估、盗伐滥伐和火烧林木案件司法鉴定等提供技术支撑。主要方法是根据目前国内、省内材积表编制相关技术规程和参考资料,通过现地林分样木调查,建立根径-胸径数学模型,编制立木材积基础数表。通过平板数据采集程序直接编制根径立木材积表是本文的一个主要创新点,有一定参考意义和推广价值。     

林木伐根根径、胸径与树高的相关关系在伐区检查中的应用

目前，利用伐根与胸径的相关关系来测算立木材积，倍受林业科技工作者的关注。之前，采伐量的确定就是利用伐区作业现场遗留的根径来推算立木胸径，然后，通过胸径测算出立木材积的。其首推出伐根与胸径的相关关系经验式：D1．3=0．84D0—1．346。此式虽广泛应用于天山中东部各林区，但对于我区各局部地区而言，得出的结果往往与实际有一定的出入。     

利用Excel软件辅助林木采伐作业设计

论述了利用Excel的插入函数功能设计蓄积量、出材率、采伐强度和综合计算等函数表达式,制作林木采伐作业调查设计表,解决了采伐作业设计中查数表繁琐、内业计算和采伐强度控制难等问题。     

太行山南麓连香树的生长过程分析

对连香树人工群落平均木个体的地径、胸径、树高和材积的生长规律进行了研究,其结果显示人工种植的连香树在树龄为6年后即开始郁闭,连香树生长极快,6年可郁闭成材。另外,连香树地径生长高峰期在第6～7年龄、胸径生长高峰在第5～6年龄、树高生长高峰在第4～5年龄,材积生长高峰期在第8～9年龄。建立了地径、胸径、树高和材积4个生长模型,均达到极显著水平。     

基于卫星图像的立木材积表编制编程实现

介绍了以编程实现编制卫星图像立木材积表的过程,着重介绍了使用最小二乘法计算经验模型中参数的算法及部分代码,并以北京市密云县雾灵山的落叶松为例,利用软件建立了胸径和冠幅的一元回归模型：D1.3=3.301 4＋6.312 2Ck,并据此编制了一元卫星图像立木材积表。     

小兴安岭低质林改造后小径木和采伐剩余物综合利用探讨

通过对小兴安岭低质林改造过程中产生的中小径木和采伐剩余物研究,分析中小径木和采伐剩余物的产生量,提出其利用途径和价值。结果表明：改造采伐时产生的大径木、中径木、小径木、短小材和薪材的出材量分别为1.13m^3/hm^2、32.15m^3/hm^2、38.30m^3/hm^2、4.79m^3/hm^2和12.68 m^3/hm^2,中小径木和薪材的出材量较高;改造地每公顷中小径木直接出售可获得6.5万元的收入。采伐剩余物总量为16.92 m^3/hm^2。小径木除了直接销售外,还可加工成拼版材、压缩木、重组木和单板层积材等。采伐剩余物可加工成木片,再根据不同的工艺加工成刨花板、纤维板、木丝板及纸张等用途。中小径木和采伐剩余物的综合利用可有效利用林区资源,提高林区经济效益。     

巨尾桉人工林地径与胸径、树高相关模型的研究

根据巨尾桉人工林样木的地径D0、胸径D及树高H观测数据,采用多模型选优法和逐步回归法求解方程,经分析对比后分别建立了地径与胸径、地径与树高相关的2个数学模型:lnD=3.7275-18.6673/D0;H=32.0925-244.050 3/D0。应用这2个模型,配合一元材积表或二元材积表就可测定被伐木的材积。     

Modelling the long-term impacts of selective logging on genetic diversity and demographic structure of four tropical tree species in the Amazon forest

In the last three decades, Amazon tropical forests have experienced high rates of deforestation, both by clearing for agriculture and by logging. In this study, we use computer simulations to examine the potential effects of forest logging on genetic diversity and demographic recovery (basal area development) of four neotropical tree species over a time frame reflecting multiple logging events. The study species, Bagassa guianensis Aubl., Hymenaea courbaril L., Manilkara huberi (Ducke) Chevalier, and Symphonia globulifera L.f., are all taxa which are commonly exploited for timber in the Brazilian Amazon. The simulations were parameterized using empirical data from field studies in the Tapajós National Forest, Pará State, Brazil, including genotypes at microsatellite loci, demography, ecology and growth for each species. Eight scenarios, combining two different cutting cycles and two minimum cutting diameters, were examined for each of the four species. The scenarios represent the actual forest practices used in Brazil and French Guiana (cutting diameter 45 and 60 cm, and cutting cycle of 30 and 65 years, respectively). Logging scenarios were applied for six cutting cycles, and final genetic and demographic data were compared to baseline data from corresponding control scenarios. At the end of the simulated period the basal area was strongly reduced under all conditions in B. guianensis, H. courbaril, and M. huberi. In only two scenarios was a species able to recover its basal area following logging (S. globulifera with both 45- and 60-cm cutting diameters under a 65-year cutting cycle). In the logging scenarios, all species showed a loss of alleles and genotypes and an increased genetic distance (calculated between each population at the start and the end of the simulations). These effects were higher under the most intensive logging cycles (30 years, 45 cm). However, effective number of alleles, expected and observed heterozygosities, and the fixation index were little affected by the logging simulations. Over all, we conclude that, even under very optimistic conditions for growth and recruitment, current logging practices are not sustainable in terms of basal area. Our simulations show that different species respond differently to logging, both demographically and genetically. No single set of logging parameters can be applied to the forest as a whole. Rather, forest management practices must be species-specific, taking into account not only growth parameters but also ecological and reproductive variables, in order to move toward long-term forest sustainability.     

What loggers leave behind: Impacts on big-leaf mahogany (Swietenia macrophylla) commercial populations and potential for post-logging recovery in the Brazilian Amazon

The sustainability of current harvest practices for high-value Meliaceae can be assessed by quantifying logging intensity and projecting growth and survival by post-logging populations over anticipated intervals between harvests. From 100%-area inventories of big-leaf mahogany (Swietenia macrophylla) covering 204 ha or more at eight logged and unlogged forest sites across southern Brazilian Amazonia, we report generally higher landscape-scale densities and smaller population-level mean diameters in eastern forests compared to western forests, where most commercial stocks survive. Density of trees ≥20 cm diameter varied by two orders of magnitude and peaked at 1.17 ha⁻¹. Size class frequency distributions appeared unimodal at two high-density sites, but were essentially amodal or flat elsewhere; diameter increment patterns indicate that populations were multi- or all-aged. At two high-density sites, conventional logging removed 93–95% of commercial trees (≥45 cm diameter at the time of logging), illegally eliminated 31–47% of sub-merchantable trees, and targeted trees as small as 20 cm diameter. Projected recovery by commercial stems during 30 years after conventional logging represented 9.9–37.5% of initial densities and was highly dependent on initial logging intensity and size class frequency distributions of commercial trees. We simulated post-logging recovery over the same period at all sites according to the 2003 regulatory framework for mahogany in Brazil, which raised the minimum diameter cutting limit to 60 cm and requires retention during the first harvest of 20% of commercial-sized trees. Recovery during 30 years ranged from approximately 0 to 31% over 20% retention densities at seven of eight sites. At only one site where sub-merchantable trees dominated the population did the simulated density of harvestable stems after 30 years exceed initial commercial densities. These results indicate that 80% harvest intensity will not be sustainable over multiple cutting cycles for most populations without silvicultural interventions ensuring establishment and long-term growth of artificial regeneration to augment depleted natural stocks, including repeated tending of outplanted seedlings. Without improved harvest protocols for mahogany in Brazil as explored in this paper, future commercial supplies of this species as well as other high-value tropical timbers are endangered. Rapid changes in the timber industry and land-use in the Amazon are also significant challenges to sustainable management of mahogany.     

荔浦县伐区马尾松树高回归曲线研制

根据国家林业局《森林采伐限额执行情况检查方案》的技术要求,通过实地测树调查,应用二次抛物线回归技术,研制了荔浦县伐区马尾松的树高回归曲线,为创建当地马尾松地径材积表提供了一条途径。     

黔西北杉木防护林间伐强度试验

为探讨黔西北杉木防护林的经营度,从2000年开始,对贵州省织金、纳雍县1991和1992年营造的杉木林进行不同强度的间伐试验。结果认为,初植密度对胸高直径、树高、蓄积量的影响随密度的增加而减少。而中度间伐可以提高生长量为胸径128%、材积71%、蓄积29%。首次林分间伐后密度以保留3 000株.hm-2为宜。间伐初期容易导致水土流失。     

用正形数胸高形数和经验回归方程编制人工林立木材积表

用正形数、胸高形数和经验回归方程３种方法编制的樟子松人工林二元材积表，其精度比较的结果表明，正形数法最优，其次是胸高形数法。直接用经验回归方程编制的一元材积表和利用树高曲线把胸高形数二元材积表导算成一元材积表的精度比较结果表明，后者优于前者．因此，利用胸高形数是编制材积表的有效方法。