落叶松林木枯损模型

林木枯损模型是林木生长模型系统的重要组成部分。根据来自吉林省汪清林业局森林经理调查的１２个落叶松复位样地的１３１个径阶组数据,应用Ｌｏｇｉｓｔｉｃ型回归式建立了落叶松林木枯损模型。自变量有径阶、相对直径、每公顷株数、每公顷断面积、平方平均直径、郁闭度和大于所估径阶的林木直径平方和。考虑模型的相关指数和各参数的变动系数,得出仅包含相对直径、郁闭度、平方平均直径３个自变量的经验方程。该经验方程具有形式简单、测算容易、无需年龄和地位质量指标、参数稳定性好等特点,可用于落叶松径阶枯损比率和单木枯损概率的预估。     

基于空间结构参数的大兴安岭天然落叶松单木直径生长模型

[目的 ]研究林分空间结构对兴安落叶松单木直径生长的影响,为大兴安岭天然落叶松次生林的有效恢复提供理论依据和技术支撑。[方法 ]以大兴安岭天然落叶松次生林为研究对象,基于塔河林业局盘古林场50株兴安落叶松解析木数据,采用S-Plus软件中的NLS函数对8种常用的林木生长模型进行拟合优度评价,进而确定最优基础模型;通过再参数化方法,考虑常用林分因子、单木因子、物种多样性以及林分空间结构等参数对林木直径生长的影响;最终,采用NLME函数构建兴安落叶松单木直径生长的最优混合效应模型,并系统评价不同模型的拟合优度。[结果 ]兴安落叶松单木直径生长的最优基础模型为Mitscherlich方程(调整系数Ra2=0.628 5),其参数a分别与林分平均树高、单木胸径、混交度和角尺度显著相关,而参数b则与林分平均胸径和竞争指数显著相关;据此,建立的兴安落叶松广义直径生长模型的Ra2值相较基础模型提升约31%(Ra2=0.826 4);通过引入随机参数(参数a1)、异方差函数(幂函数varPower)、时间序列函数(高斯结构corGaussian),单木水平的混合效应模型进一步将Ra2值提升约17%(Ra2=0.971 0);五折交叉检验结果表明,混合模型的调整系数、平均绝对误差和均方根误差分别为0.983 8、0.56 cm和0.72 cm,能够满足单木直径生长预测的需要。模型模拟结果表明,单木直径生长量随着单木胸径、角尺度和混交度的增加而增加,但随着林分平均胸径、平均树高和竞争指数的增加而减小;当各变量数值每增加10%时,其对应的胸径生长量依次为:+0.45 cm、+3.62 cm、+4.71 cm、-0.34 cm、-0.21 cm和-0.73 cm,但取决于不同的林分特征和生长阶段。[结论 ]林分角尺度、混交度和竞争水平对兴安落叶松单木直径生长具有显著作用,在后续森林经营中应通过合理的采伐来降低林木的竞争水平,并注重创建和维护林木的随机分布格局和混交程度。     

塞罕坝华北落叶松林生长模型的研究

收集了塞罕坝机械林场内的160株华北落叶松解析木数据,使用理查德方程、逻辑斯蒂方程、单分子曲线以及严格舒马克曲线4个理论生长方程分别拟合出塞罕坝地区华北落叶松人工林的胸径、树高和材积生长模型。结果表明：4个理论方程均适合华北落叶松林的生长过程,但是理查德方程拟合精度最高,与林木实际生长情况最符合,它拟合得到的决定系数均在0．998以上;其次是逻辑斯蒂方程,得到的决定系数在0．988以上。因此,建议在以后华北落叶松人工林林木生长模型的研究中使用理查德方程。     

玄武岩落叶松母树林的生态特点及抚育间伐的效果

介绍了玄武岩落叶松母树林的生态特点及林分类型，并从树冠生长、直径生长、树高生长、结实、林木抗性及环境条件影响和经营效益6个方面对抚育间伐的效果进行了讨论。     

关于落叶松同令林胸径分布规律的探讨

林分生产力与林分结构有密切关系。其中林木直径的分布规律是林分结构的基本规律。在同令林中,随着林令的增长,林木胸径的生长速度,出现差异,致使各径阶株数发生变化。其中,大多数林木位于林分平均直径附近,最粗和最细的林木较少。这是林木株数按径阶分布的一般规律。然而不同地区、不同树种的具体分布规律,仍然有所区别。为探明不同地区落叶松人工林不同生长阶段的胸径分布规律,对我省的净月潭、土们岭、松花湖、桦甸、蛟河、敦化、延吉、龙井、安图、通化、东丰等地的林分,做了如下分析。     

青海华北落叶松林直径结构及生长模型研究

根据青海海东地区华北落叶松林区30个标准地调查所得数据,分析各主要调查因子间相关关系,研究落叶松直径分布结构并建立落叶松直径结构模型、树干材积生长模型及林分蓄积生长模型。结果表明:青海海东地区华北落叶松直径分布运用β分布函数的拟合效果最好;青海互助北山林场华北落叶松整体处于中龄林且直径分布较为稳定集中;树干材积生长模型运用理查德模型(Richards)方程拟合效果最好,方程为:V=7485.5×(1-e~(-0.001T))~(2.99);皮尔森相关系数分析得出:林分平均直径、林分平均高度、林分平均年龄3个因子与林分蓄积生长相关性最为显著,拟合得蓄积量生长模型为:V=18.752×LnD+5.647×T+15.836×H-28.349。研究结果可为青海高寒地区华北落叶松科学化管理提供参考。     

华北落叶松天然次生林单木冠幅模型构建

以山西省庞泉沟自然保护区华北落叶松天然次生林为研究对象,基于1 531株单木冠幅实测数据,对华北落叶松天然次生林单木冠幅预测模型展开研究。首先从9个常见的冠幅-直径候选模型中选出一个拟合精度较高的模型作为构建冠幅模型的基础模型;接着从林分测树因子、立地因子和林分竞争指标中选出与冠幅相关性较强的因子作为模型自变量进行建模;最后利用偏差、剩余均方根误差R和决定系数并结合似然比检验对模型进行检验与评价。结果为:三参数的逻辑斯蒂形式的冠幅-直径模型拟合精度较高,并且模型参数可解释,因此把该模型作为构建华北落叶松单木冠幅模型的基础模型;对象木冠长、林分密度和林木竞争压力指数与冠幅相关性较强,当基础模型中考虑这些因子时能进一步提高预测精度。所构建的冠幅模型可为华北落叶松天然次生林的科学经营提供理论基础和技术依据。     

冀北山地桦落混交林空间结构与直径生长关系研究

林分空间结构是森林经营管理过程中的重要因子。大小比数是林分空间结构的主要参数,对林木生长与竞争有重要影响。该研究以冀北山地典型森林类型桦落混交林为对象,以中心树与周围最近4株相邻木为空间结构单元,以林木年轮宽度确定直径生长,研究大小比数与直径生长的关系。结果表明:对于大小比数为0.5的空间结构单元,与相邻最粗树比较,桦树和落叶松的中心树直径生长过程基本一致,分3种情况:1一直处于劣态。2前后期处于劣态,中期竞争生长。3前期处于劣态,中后期竞争生长。不同大小比数木的林木之间的竞争主要集中于8~15a,此期间是对林分进行抚育采伐、调整林分密度的最佳时期。     

兴安落叶松人工林生长分析及模型研究

以黑龙江省拜泉县为试验点,对兴安落叶松人工林的生长及生长模型进行研究,目的在于确定它的适宜生长环境、生长高峰期及生长规律,使林木在最有价值期获得管护。结果表明,兴安落叶松人工林适合阴坡湿润的环境,5～10年为生长高峰,材积平均生长量采用V=a+b1A+b2A2模型。     

鄂西山区日本落叶松林相容性单株生物量模型研究

在收集的36块标准地资料和建立的单株生物量模型基础上,基于非线性度量误差模型方法,对鄂西山区日本落叶松林相容性单株生物量模型进行研究。结果表明,鄂西山区日本落叶松单株生物量平均分配规律呈树干生物量树根生物量树冠生物量;所构建的日本落叶松相容性单株生物量模型,确定系数和预估精度均在0.90以上,模型拟合效果较好,预估精度较高,较好地解决了传统模型不相容问题;各组分生物量占总生物量的比例随直径的增大呈不同变化特点,客观反映了林木生物量随直径生长的变化规律。     

冀北山地华北落叶松人工林与天然次生油松林不同坡位生长状况研究

在冀北木兰围场自然保护区内,通过对比华北落叶松[Larixgmellini（Rupr．）Rupr]人工林与天然次生油松（P／nustabulaeformiscarr）林不同坡位的连年生长量与平均生长量,建立生长过程曲线方程并拟合树高与胸径之间的关系,分析两种林型内乔木树种的生长过程。结果表明：（1）落叶松人工林不同坡位样地内,标准木的拟合生长模型基本相似;材积连年及平均生长速率排序为：坡底落叶松〉坡中落叶松〉坡顶落叶松。（2）天然次生油松林不同坡位样地内材积平均生长量均随着年龄的增长而增加,油松标准木的生长过程基本相同,且标准木的拟合生长模型基本相似。但坡中油松立木材积平均生长量高于坡地和坡顶。（3）相同坡位样地内人工林与天然林间的连年生长曲线存在明显差异性。油松林生理年龄高于落叶松林,标准木达到材积数量成熟的年龄比落叶松大,单株立木材积量较大。（4）人工落叶松林和天然油松次生林内乔木树种的胸径与树高问存在密切的相关性,其相关系数均达到0．9以上。     

An application of mixed-effects model to evaluate the effects of initial spacing on radial variation in wood density in Japanese larch (Larix kaempferi)

The effects of initial tree spacing on wood density at breast height were examined for 22-year-old Japanese larch (Larix kaempferi). The experiment involved the use of three plots with different initial tree spacing densities (300, 500, and 1000 trees/ha). For five trees selected from each plot, the total tree height, diameter at breast height, height to the base of the live crown, and crown diameter were measured. Ring width and wood density for individual growth rings were determined by X-ray densitometry. A mixed-effects model was applied for fitting the radial variation in wood density in relation to initial spacing. Models having various mean and covariance structures were tested in devising an appropriate wood density model. The model, consisting of the mean structure with quadratic age effects and heterogeneous first-order autoregressive covariance, was able to describe the radial variation in wood density. Closer spacing of trees (1000 trees/ha) resulted in a faster increase in wood density from the pith outward than for more widely spaced trees, indicating that initial tree spacing may influence the age of transition from juvenile to mature wood.     

Prediction of annual tree growth and survival for thinned and unthinned even-aged maritime pine stands in Portugal from data with different time measurement intervals

An annual individual tree survival and growth model was developed for pure even-aged stands of maritime pine in Portugal, using a large data set containing irregularly time-spaced measurements and considering thinning effects. The model is distance-independent and is based on a function for diameter growth, a function for height growth and a survival function. Two approaches are compared for modeling annual tree growth. The first approach directly estimates a future diameter or height using well-known growth functions formulated in difference form. The second approach estimates diameter or height using a function in differential form estimating the increment over a year period. In both approaches, the function parameters were related to tree and stand variables reflecting the competition status of the tree as well as of a thinning response factor. Variable growth and survival rates were assumed in the modeling approaches. An iterative method was used to continuously update tree and stand attributes using a cut-off to convert the survival probability for a living or a dead tree. The individual tree diameter growth model and the survival probability model were fitted simultaneously using seemingly unrelated regression (SUR). Parameters of the height function were obtained separately as the number of observations for height was much lower than the number of observations for diameter, which may affect the statistical inference and the estimation of contemporaneous cross-equation error correlation inherent to the system of equations. PRESS residuals were used to evaluate the predictive performance of the diameter and the height growth functions. Additional statistics based in the log likelihood function and also in the survival probability were computed to evaluate the survival function. The second modeling approach, which integrates components of growth expansion and decline, performed slightly better than the first approach. A variable accounting for the thinning response that was tested proved to be significant for predicting diameter growth, even if the model already included competition-related explanatory variables, namely the basal area of trees larger than the subject tree. However, this thinning response factor was not significant for predicting height growth.     

一种与直径分布型无关的预测林分直径累积分布的方法

本文推导出一组联系林分平均直径生长和直径累积分布生长之间的方程式。根据这些方程建立的全林分生长模型和径阶模型或与距离无关的单木模型之间的关系，可以指导由林分断面积总生长向单木直径生长的分配。采用这一组方程，根据二个不同时间点上算术平均直径和均方平均直径回收生长模型和枯损模型中的参数，保证林分水平预测的结果和径级水平或单木水平预测的结果相容。采用一个误差函数来刻化相同直径林木在生长过程中的分化，证明了忽略这项误差函数可能导致预测的直径分布范围小于实际的范围。因此，加上一个误差函数预测直径分布在一定程度上提高了直径分布预测的精度。最后一个实例说明计算过程。     

A basal area increment model for individual trees in mixed continuous cover forests in Iranian Caspian forests

The aim of this study was to develop and test a new basal area growth model in mixed species continuous cover forests in northern Iran.Weanalyzed 421 core samples from 6 main species in the forest area to develop our growth model.In each plot,we measured variables such as total tree height(m),diameter at breast height(DBH)(cm)and basal area of larger trees as cumulative basal areas of trees(GCUM)ofDBH[5 cm.The empirical data were analyzed using regression analysis.There was a statistically significant nonlinear function between the annual basal area increment,as the dependent variable,and the basal area of the individual trees and competition as explanatory variables.Reference area from the largest trees,was circular plot with area of 0.1 ha.GCUM was estimated for trees of DBH>5 cm.Furthermore,we investigated the dependencies of diameter growth of different species on stand density at different levels of competition,and diameter development of individual trees through time.The results indicate that competition caused by larger neighborhood trees has a negative effect on growth.In addition,the maximum diameter increment is affected by competition level.Therefore,the maximum diameter increment of species occurs when the trees are about 35–40 cm in dense-forest(40 to 0 m^2 per ha)and when the trees are about 60 to 70 cm in very dense forest(60 to 0 m^2 per ha)which is more likely to Caspian natural forests with high level density due to uneven-aged composition of stands.     

Estimation of a basal area growth model for individual trees in uneven-aged Caspian mixed species forests

The aim of this study was to estimate a basal area growth model for individual trees in uneven-aged Caspian forests. A survey was conducted in order to find a natural forest without any harvesting activities, a so called ‘untouched forest’ and an area was selected from the Iranian Caspian forest. Three sample plots in the same aspect and of the same forest type were selected. In each plot, total tree height, diameter at breast height, distance of neighbor trees and azimuth were measured. Thirty trees were selected and drilled with increment borer to determine the increment model. Regression analysis was used to estimate the growth model. Results show that, for individual trees, there is a significant nonlinear relationship between the annual basal area increment, as the dependent variable, and the basal area. The results also show that the basal area of competing trees has a positive influence on growth. That the increment is higher with more competing neighboring trees is possibly because plots with higher volume per hectare and more competition, most likely also have higher site index or better soil or better site productivity than the plot with lower volume per hectare.     

塞罕坝林区低密度经营对华北落叶松林分生长的影响

为了给坝上塞罕坝林区低密度经营提供依据,以华北落叶松人工林为研究对象,对不同林分密度条件下(150株/hm~2、225株/hm~2、300株/hm~2和375株/hm~2)华北落叶松林分的生长情况进行分析,研究低密度经营对华北落叶松生长的影响,提出培育华北落叶松大径级用材林的技术体系。结果表明:林分密度对胸径、树高和单株材积总生长量、平均生长量、连年生长量都有一定程度的影响,影响程度按照胸径、单株材积、树高顺序递减;林分密度过大或过小均影响华北落叶松林分的生长,林分密度控制在225~300株/hm~2时,华北落叶松胸径、树高和单株材积总生长量、平均生长量、连年生长量最大。     

Individual tree diameter increment model for managed even-aged stands of ponderosa pine throughout the western United States using a multilevel linear mixed effects model

A diameter increment model is developed and evaluated for individual trees of ponderosa pine throughout the species range in the United States using a multilevel linear mixed model. Stochastic variability is broken down among period, locale, plot, tree and within-tree components. Covariates acting at tree and stand level, as breast height diameter, density, site index, and competition indices are included in the model as fixed effects in order to explain residual variability. The data set used in this study came from long-term permanent research plots in even-aged, pure stands both planted and of natural origin. The data base consists of six levels-of-growing stock studies supplemented by initial spacing and other permanent-plot thinning studies for a total of 310 plots, 34,263 trees and 153,854 observations. Regression analysis is the preferred technique used in growth and yield modeling in forestry. We choose the mixed effects models instead of the regression analysis approach because it allows for proper treatment of error terms in a repeated measures analysis framework. Regional growth and yield models exist for ponderosa pine. However, data collection and analysis procedures differ. As a result, comparisons of growth responses that may be due to geographic variation of the species are not possible. Our goal is to present a single distance-independent diameter increment model applicable throughout the geographic range of ponderosa pine in the United States and by using only data from long-term permanent plots on sites capable of the productivity estimated by Meyer [Meyer, W.H., 1938. Yield of Even-Aged Stands of Ponderosa Pine. US Department of Agriculture Technical Bulletin 630].     

大兴安岭松岭大扬气林场落叶松生长规律研究

树木生长量的大小及生长速率,一方面受树木本身遗传因素的影响,另一方面也受所处环境条件的制约。以大扬气林场的兴安落叶松为研究对象,基于其37株标准木的树干解析、生长数据,利用线性模型、对数模型、多项式模型、指数模型研究不同测树因子(胸径、树高等)之间的关系,分析模拟其生长规律。结果表明:在研究区域内,多项式模型模拟所得到的相关系数相对较高,因此可以利用此模型来预估此区域落叶松的生长规律。