在行山刺槐人工林直径分布规律及产量预测模型的研究

该文运用ｗｅｉｂｕｌｌ分布、正分布、对数正态分布、ｔ分布和β分布来拟事河北省太行山刺槐人工林的直径分布规律。结果表明：ｗｅｉｂｕｌｌ分布和β分布的拟合效果好，且前者优于后者。同时运用ｗｅｉｂｕｌｌ分布函数建立了预测林分结构与产量的模型系统，包括单木材积方程、树高曲线方程、密度转换方程等。使用该模型系统时，只需输入林分特征因子系统，则可以预测出该林分各径株数、平均树高及林分材积等信息。误差检验结果表     

太行山刺槐人工林直径分布规律及产量预测模型的研究

该文运用ｗｅｉｂｕｌｌ分布、正态分布、对数正态分布、τ分布和β分布来拟合河北省太行山刺槐人工林的直径分布规律。结果表明：ｗｅｉｂｕｌｌ分布和β分布的拟合效果好，且前者优于后者。同时运用ｗｅｉｂｕｌｌ分布函数建立了预测林分结构与产量的模型系统，包括单木材积方程、树高曲线方程、密度转换方程等。使用该模型系统时，只需输入林分特征因子系统，则可以预测出该林分各径阶株数、平均树高及林分材积等信息。误差检验结果表明，该模型系统精度高。     

林分直径枯损模型分析与研究

林分株数分布函数和林木生长模型在预估直径生长、径阶株数分布方面已经得到广泛的应用。本文在综合分析各种直径枯损模型的基础上，全面比较和检验了各种模型的适用性和预测精度。结果表明，利用林分株数分布函数或林木生长模型预估林分直径枯损分布，具有结构合理、适用性强及预测精度高等特征，成为预估林分枯损的最佳模型之一。     

以相对直径为竞争指标的单木直径生长模型研究

选择了Richards,Logistic,Mitscherlich,Gompertz,Modified-Weibull 5个最为常用的单木直径生长理论方程作为基础方程,采取再次参数化的方法将与林木生长密切相关的地位指数(SI)、林分密度(N)、单木竞争指标——相对直径(RD)等因子引入方程,对马尾松人工林的单木直径生长模型进行了研究。结果表明,采用该方法得到的单木直径生长方程具有很好的适应性和很高的预估精度,因为该方程中包含了林木的相对直径RD,当令RD等于1.0时,单木的直径生长模型就反映了林分的平均直径生长,这为从单木生长模型向全林分生长模型的耦合提供了一条途径。     

信州落叶松人工林生长模型及其系统收获表的研究

系统收获表能预测现实林分在各种经营体系下的生长过程和收获量。本文根据信州落叶松人工林固定标准地观测数据，从林分和单木两个水平分析和建立了生长模型，在此基础上编制了信州落叶松人工林系统收获表，提出系统收获表的一般编制方法。本研究的特点是以现实林分为研究对象，建立全林分生长模型和林分径阶生长模型，将前者的总生长量通过后者分配给各直径阶和树高阶，以保证林分水平的预测结果和单木水平的生长是相容的。     

林分生长和收获模型整体化思路探讨

介绍了林分生长和收获模型的概念、分类及模型整体化研究的内涵,以单木直径生长模型作为基础模型,提出了单木直径、树高、断面积、材积模型之间,林分平均直径、断面积、材积模型之间以及单木生长模型、全林分模型和径阶分布模型之间的耦合思路,对于解决不同水平模型之间的相容性、一致性及内部结构的统一具有一定意义.     

天然白桦林直径分布规律的研究

在林分生长模型研究中，选择描述林分直径分布的函数是至关重要的。本文对来自于内蒙古地区的天然白桦林林分用不同的函数对直径分布进行验证，根据检验结果表明：正态分布接受率最高；同时对结果也做了分析，探讨了不同年龄、不同立地指数对正态分布接受率的影响；并对不接受分布的原因进行了简单的分析。     

基于林木多期直径测定数据的异龄林年龄估计方法

基于固定样地多期直径测定数据,拟合直径与年龄相关的生长模型,为异龄林年龄结构的确定提供估计方法。通过为第一期林木设置不同年龄初值的方法采集样地内各树种的直径与年龄坐标信息,采用不同直径生长方程对数据进行模拟,依据树高生长至1.3 m时的年龄t0,将拟合曲线在坐标内准确定位并用生长方程估计单木、径阶以及林分的平均年龄,对结果进行适用性检验和评价。结果表明:运用Richards方程分别拟合青冈栎、杉木、马尾松的直径与年龄的生长关系时,模型的相关指数R2分别为0.93、0.91、0.97,剩余标准差分别为1.18、0.78、0.37,平均绝对误差分别为0.80、0.61、0.31;该估计方法预测林分平均年龄的绝对误差最大值为2 a,相对误差最大值为8.2%;预测径阶年龄的绝对误差最大值为3 a,相对误差最大值为12.5%,平均绝对百分误差为5.1%;预测单木年龄的绝对误差最大值为7.0 a,相对误差最大值为29.3%,平均绝对百分误差最大值为14.8%。Richards方程在参数生物学意义以及模型拟合精度方面能较好地反映出各树种的直径与年龄生长的关系。研究提出的依据林木多期直径测定数据估计异龄林年龄的方法,预测林分平均年龄与径阶年龄的平均绝对百分误差小于10%,预测效果较好,其估计方法可以应用于科研和生产实践。     

中亚热带杉阔混交林直径分布研究

以中亚热带杉阔混交林固定样地的调查数据,用偏度、峰度和变动系数为指标研究了杉阔混交林直径株数分布特征,运用Normal分布、Lognormal分布、Weibull分布、Gamma分布、Logistic分布、负指数分布等6种概率密度函数对杉阔混交林林分的直径分布规律进行了分析研究,并利用χ2检验法来检验6种概率分布的拟合效果。结果表明:杉阔混交林林分平均胸径为14.2 cm,在5.2~40 cm之间变动,径阶分布范围不大;林分直径分布曲线为左偏态,中小径阶林木株数居多数;林分直径主要分布在6~28 cm径阶,株数累积百分比高达90%以上;6种分布函数中,以Logisti c分布函数模拟杉阔混交林直径分布的效果最好,可用于杉阔混交林的直径分布和生长预测,为杉阔混交林的科学经营提供理论依据。     

蒙古栎林分直径Weibull分布参数估计和预测方法比较

【目的】比较Weibull直径分布参数估计和预测的不同方法在蒙古栎次生林经营中的适用性和精确性,为更好开展蒙古栎林经营提供理论依据和技术参数。【方法】以吉林省157块蒙古栎纯林为研究对象,运用Kolmogorov-Smirnov(K-S)检验和误差指数比较最大似然法、矩法和百分位法估计和预测蒙古栎纯林分Weibull三参数的优劣。首先分析评价最大似然法、矩法和百分位法3种参数估计方法;然后为预测林分分布变化,建立参数预测法、参数回收法和参数百分位法的估计参数与林分年龄、平均高、优势高和林分密度等林分因子之间的回归模型;最后将回归方程计算得出的各参数代入Weibull分布,以预测直径分布变化趋势。【结果】最大似然法、矩法和百分位法均较好地估计了蒙古栎纯林的直径分布,K-S检验的接受率在82.80%~96.18%之间,其中最大似然法的接受率最高;通过配对t检验比较3种估计方法,最大似然法的误差指数平均数在显著水平为0.05时显著性地小于其他2种方法。在预测蒙古栎林分直径分布时,通过K-S检验可知,百分位法的接受率为64.45%,均高于其他2种方法;通过配对t检验比较3种预测方法,参数百分位法在显著水平为0.1时比参数预测法和参数回收法更加精确。【结论】在估计蒙古栎林分直径分布时,最大似然法较矩法和百分位法效果好;在预测蒙古栎林分直径分布时,参数百分位法较参数预测法和参数回收法效果好。     

Response of branch growth and mortality to silvicultural treatments in coastal Douglas-fir plantations: Implications for predicting tree growth

Static models of individual tree crown attributes such as height to crown base and maximum branch diameter profile have been developed for several commercially important species. Dynamic models of individual branch growth and mortality have received less attention, but have generally been developed retrospectively by dissecting felled trees; however, this approach is limited by the lack of historic stand data and the difficulty in determining the exact timing of branch death. This study monitored the development of individual branches on 103 stems located on a variety of silvicultural trials in the Pacific Northwest, USA. The results indicated that branch growth and mortality were significantly influenced by precommercial thinning (PCT), commercial thinning, fertilization, vegetation management, and a foliar disease known as Swiss needle cast [caused by Phaeocryptopus gaeumannii (T. Rohde) Petr.]. Models developed across these datasets accounted for treatment effects through variables such as tree basal area growth and the size of the crown. Insertion of the branch growth and mortality equations into an individual-tree modeling framework, significantly improved short-term predictions of crown recession on an independent series of silvicultural trials, which increased mean accuracy of diameter growth prediction (reduction in mean bias). However, the static height to crown base equation resulted in a lower mean square error for the tree diameter and height growth predictions. Overall, individual branches were found to be highly responsive to changes in stand conditions imposed by silvicultural treatments, and therefore represent an important mechanism explaining tree and stand growth responses.     

白桦人工林单木生长的人工神经网络模型研究

以东北林业大学帽儿山实验林场白桦人工林为研究对象,采用MATLAB中log-sigmoid型函数（logsig）和线性函数（purelin）为神经元的作用函数,用林分内单木相对直径、林分密度指数、林分地位指数和林分年龄作为输入变量,以单木胸径生长量作为输出变量,构建了4：n：1的单木生长的BP人工神经网络模型。用200组单木生长数据对网络模型进行训练和检验,得最适宜的网络结构为4：3：1,均方误差函数mse=0．00160179,总体拟合精度为96．86％。本模型在充分跟踪样本数据的同时,又保持树木生长方程的规律性,可供同类条件的林分在进行经营设计时进行分析、计算和模拟和预测等使用。     

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.     

天然林区小班森林资源数据的更新模型

以吉林省汪清林业局为例,根据１９９７年森林经理调查的８４８块固定样地数据,与全林整体模型方法相结合,建立了适合于天然林区林业局（场）无人为干预小班森林资源数据更新的林分级生长模型组。该组模型包括林分密度指数,平均高,断面积,形高,郁闭度等林分测算因子的生长或变化模型。     

Generalized height–diameter models—an application for major tree species in complex stands of interior British Columbia

Using permanent sample-plot data, selected tree height and diameter functions were evaluated for their predictive abilities for major tree species in complex (multiple age, size and species cohort) stands of interior British Columbia (BC), Canada. Two sets of models were evaluated. The first set included five models for estimating height as a function of individual tree diameter, the second set also included five models for estimating height as a function of individual tree diameter and other stand-level attributes. The inclusion of the BAL index (which simultaneously indicates the relative position of a tree and stand density) into the base height–diameter models increased the accuracy of prediction for all species. On average, by including stand level attributes, root mean square values were reduced by 30.0 cm. Based on the residual plots and fit statistics, these models can be recommended for estimating tree heights for major tree species in complex stands of interior BC. The model coefficients are documented for future use.     

A growth model for Pinus radiata D. Don stands in north-western Spain

A dynamic whole-stand growth model for radiata pine (Pinus radiata D. Don) stands in north-western Spain is presented. In this model, the initial stand conditions at any point in time are defined by three state variables (number of trees per hectare, stand basal area and dominant height), and are used to estimate total or merchantable stand volume for a given projection age. The model uses three transition functions derived with the generalized algebraic difference approach (GADA) to project the corresponding stand state variables at any particular time. These equations were fitted using the base-age-invariant dummy variables method. In addition, the model incorporates a function for predicting initial stand basal area, which can be used to establish the starting point for the simulation. Once the state variables are known for a specific moment, a distribution function is used to estimate the number of trees in each diameter class by recovering the parameters of the Weibull function, using the moments of first and second order of the distribution. By using a generalized height-diameter function to estimate the height of the average tree in each diameter class, combined with a taper function that uses the above predicted diameter and height, it is then possible to estimate total or merchantable stand volume.     

单木生长模型边缘误差的传播规律*

研究提出了生长模拟保护带应由边缘效应带和误差阻尼带两部分构成。边缘效应带的宽度等于林分平均优势木影响圈半径的２倍，阻尼带的宽度可根据模拟分期数和模拟精度估计。样地边缘误差呈衰减趋势由外向内逐级传播，各环带中树木竞争指数的系统误差，可根据其与样地边缘的距离近似估计。利用生长模型一般形式推导出了竞争指数相对误差与生长模拟相对误差的转换函数，证明由边缘效应造成的不同位置树木生长模拟系统误差是可估的。该研究为单水生长模型生长模拟保护带宽度的确定提供了理论依据和实用的估计方法。     

Individual tree aboveground biomass for <Emphasis Type="Italic">Castanopsis indica</Emphasis> in the mid-hills of Nepal

Quantitative information of tree biomass is useful for management planning and monitoring of the changes in carbon stock in both forest and agroforestry systems. An estimate of carbon stored in these systems can be useful for developing climate change mitigation strategies. A precise estimate of forest biomass is also important for other issues ranging from industrial forestry practices to scientific purposes. The individual tree-based biomass models serve as fundamental tools for precise estimates of carbon stock of species of interest in forest and agroforestry systems. We developed individual tree aboveground biomass models for Castanopsis indica using thirty-six destructively sampled tree data covering a wide range of tree size, site quality, growth stage, stand density, and topographic characteristics. We used diameter at breast height (DBH) as a main predictor and height-to-DBH ratio (a measure of tree slenderness) and wood density (a measure of stiffness and cohesiveness of wood fibres) as covariate predictors in modelling. We, hereafter, termed the biomass models with former two predictors as first category models (density independent models) and the models with all three predictors as second category models (density dependent models). Among various functions evaluated, a simple power function of the form \(y_{i} = b_{1} x_{i}^{{b_{2} }}\), in each category, showed the best fits to our data. This formulation, in each category, described most of the biomass variations (\(R_{adj}^{2}\) > 0.98 and RMSE < 72.2) with no significant trend in the residuals. Since both density dependent and density independent models exhibit almost similar fit statistics and graphical features, one of them can be applied for desired accuracy, depending on the access of the input information required by the model. Our biomass models are site-specific, and their applications should therefore be limited to the growth stage, stand density, site quality, stand condition, and species distribution similar to those that formed the basis of this study. Further research is recommended to validate and verify our model using a larger dataset with a wider range of values for site quality, climatic and topographic characteristics, stand density, growth stage, and species distribution across Nepal.     

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。     

A process‐based model for the dimensional growth of even‐aged stands

An individual tree, process‐based stand growth model is presented. It is based on the carbon balance, according to which tree growth depends on the activities of photosynthesis, respiration and senescence. A simple model is specified for each component of the carbon balance. Next, equations for the tree structure, in which e.g. pipe‐model theory is utilized, are presented. The growth model for dry‐weights of tree compartments based on the carbon balance is transformed using these equations to allow the expression of growth in terms of diameter and height. It is also possible to aggregate a number of physiological and biometrical coefficients into a small number of generalized coefficients of the dimensional growth model. Additional components, including the equations for recession of the crown base and tree survival that are necessary for a stand growth model, are specified. Comparison of the stand growth model with a yield table and a growth model for a sapling stand suggests that the model is capable of accounting for the basic features of stand growth. Furthermore, simulations with varying initial density and some of the model's coefficients indicate that the stand growth model is approximately consistent with the so‐called self‐thinning rule.