用全林整体模型计算林分纯生长量的方法及精度分析*

全林整体生长模型对总蓄积的估计与对生长量的估计是相容的，可以用来计算林分生长率。基于全林整体模型和马什假设的名义年龄法是一种估算林分类型纯生长量的好方法，本文详细介绍了此法的计算步骤。大青山实验局两个树种的实验表明，此法给出生长率的无偏估计。对一个林分类型生长率的估计，其精度大致相当于１～４个固定样地的估计精度。因而特别适于对含有多种林分类型林区综合生长率的估计。     

度量误差对全林整体模型的影响研究

唐守正(1991)提出的全林整体模型,是一项将生长收获模型作为系统来进行研究的重要成果,在此基础上展开了一系列的应用研究。李希菲(1991)年建立了大青山主要树种的全林整体模型并进行了精度验证,洪玲霞(1993)给出了由全林整体生长模型推导林分密度控制图的方法,唐守正等(1995)对用全林整体模型计算林分纯生长量的方法及精度分析进行了研究。建立全林整体模型时,首先对林分每公顷株数、平均直径、林分优势高、林分平均高和形高5个因子进行观测,然后利用最小二乘法,由自稀疏方程估计出自稀疏指数γ、自稀疏率β、完满立木度林分的密度指数Sf[…     

北京落叶松人工林全林分模型研建

以北京森林资源一类调查中侧柏的数据为基础,以Rechards方程为模版,通过spss统计建模工具进行拟合,建立了包括落叶松的树高模型、立地指数、林分密度、断面积指数、全林收获模型、林分生长模型在内的全林分模型。林分生长模型保持了与收获模型的相容性,在此基础上利用林分生长模型,可根据某一时期的林分收获量预知未来某一时期的林分蓄积。通过检验证明,此北京落叶松人工林全林分的林分生长模型有很强的适用性,为有关林业部门确定最优密度指数、立地指数等因子来改善落叶松的经营方式提供了依据。     

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。     

杉木、落叶松断面积模型参数比较

断面积模型是全林模型系统中最重要的模型。本文应用南方５省（区）杉木、北方３省长白落叶松标准地，分别建立了１０组断面积模型，进行比较。结果表明，杉木按立地区建模时，虽然优势高生长过程相似，但断面积生长过程却不同，不能使用同一模型参数。杉木按产区建模时，虽属同区同带，断面积生长过程差异仍很大，因此杉木产区也不是建模的依据。东北３省长白落叶松建模结果表明，各省优势高和断面积生长过程接近，模型参数差异不大。     

杉木林分自然生长和人为控制密度生长模型研究

在会同杉木人工林林分全林整体模型的基础上,分析并建立了会同杉木人工林完满立木度林分自然生长和一般林分的自然生长的规律和模型,并采用人工神经网络方法建立了会同杉木人工林人为控制密度生长过程模型.检验结果表明,这组生长模型可以满足林业生产和科研的精度要求.     

Integrated Stand Growth Model of Mongolian Oak and It’s Application

利用汪清林业局1997年、2007年森林经理调查的61块蒙古栎林的固定样地数据建立了蒙古栎林全林整体模型.全林整体模型是一组非线性联立方程组,它由8个非线性模型组成.利用Forstat2.0软件中的“非线性误差变量联立方程组”方法求解模型参数,保证了模型的无偏性.“刀切法”检验结果表明各林分因子的平均相对误差和相对均方误差均在15％以下.应用全林整体模型可以进行不同初始条件林分的生长分析及制定不同立地条件的林分密度控制图,为蒙古栎林的经营提供参考.     

蒙古栎林全林整体生长模型及其应用

利用汪清林业局1997年、2007年森林经理调查的61块蒙古栎林的固定样地数据建立了蒙古栎林全林整体模型。全林整体模型是一组非线性联立方程组,它由8个非线性模型组成。利用Forstat2.0软件中的"非线性误差变量联立方程组"方法求解模型参数,保证了模型的无偏性。"刀切法"检验结果表明各林分因子的平均相对误差和相对均方误差均在15%以下。应用全林整体模型可以进行不同初始条件林分的生长分析及制定不同立地条件的林分密度控制图,为蒙古栎林的经营提供参考。     

马尾松人工纯林全林整体生物量模型的构建

以湖南省会同县马尾松纯林为研究对象,采用两阶段度量误差模型法对马尾松林分蓄积量与各组分生物量回归模型和全林整体生长模型进行融合,并对模型的参数进行重新估计,得到马尾松纯林全林整体生物量模型,经检验模型精度较高,适用性强。     

由全林整体生长模型推导林分密度控制图的方法*

本文以杉木为例，介绍了由全林整体生长模型推导林分密度控制图的方法。指出由全林整体生长模型推导出的林分密度控制图与由它推导出的多种常用林分表如标准表、正常收获表；不同初植密度林分的自然生长过程表、可变密度收获表等之间是相容的。     

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.     

A reduced growth model based on stand basal area. A case for hybrid poplar plantations in northeast Spain

Whole-stand models normally require data on initial stand basal area and dominant height. Dominant height measurements are time-consuming and often imprecise, compromising subsequent predictions. Poplar plantations provide a special case where basal area correlates with site index; a whole-stand model could thus be based on stand basal area. We report a static model constructed by the generalized algebraic difference approach (GADA) for poplar plantations for three different hybrid poplars (Populus × euramericana (Dode) Guinier “I-214”, “MC”, and “Luisa Avanzo”) in northeast Spain. The transition function was based on current stand basal area and was fitted with data from 158 permanent plots ranging from 1- to 17-year-old plantations. Merchantable stand volume was estimated by a volume equation where height was predicted by a height–basal area relationship based on 458 temporary plots. The model differences between clones were compared using the nonlinear extra sum of squares method. Significant differences were detected, while Luisa Avanzo presented the highest merchantable volume at the end of the rotation. Errors in basal area predictions were below 20% within 6 years in the case of Luisa Avanzo and MC clones, and within 3 years in the case of I-214. Our research showed that satisfactory predictions can be obtained using GADA with a single transition function based on an easily measurable variable such as stand basal area.     

A first-approximation simple dynamic growth model for forest teak plantations in Gujarat state of India

Tectona grandis (teak) is one of the most important tropical timber species occurring naturally in India. In India, teak is the single most important commercial timber species. Scientifically sound growth models, based on advanced modelling techniques, are often not available, although they are necessary for the successful management of teak stands in the country. Long-term forest planning requires mathematical models. In this paper, an attempt is made to develop a dynamic growth model based on the limited data, consisting of three annual measurements, collected from 15 teak sample plots in Gujarat state of India. A biologically consistent whole-stand growth model is presented, which uses the state-space approach for modelling rates of change of dominant height, stand density and stand basal area. A simple model containing few free parameters performed well and is particularly well suited to situations where available data are scarce.     

基于树高和树冠因子的立木材积模型研究

[目的]由于激光雷达技术已经能准确测定立木树高及相关树冠因子,应用该技术建立基于树高和树冠因子的立木材积模型,为激光技术在森林蓄积估计中提供技术支撑.[方法]利用云杉、冷杉、栎树、桦树4个树种组的3 010株实测样木数据,分析了立木材积与胸径、树高、树冠因子之间的相关关系;并通过对数回归方法构建了基于树高和树冠因子的立木材积模型,用确定系数R²和平均预估误差MPE等6项指标对模型进行评价.[结果]表明,立木材积与单一因子之间的相关,以胸径最为紧密,其次是树高,再次是冠长和冠幅.基于树高和树冠因子的立木材积模型中,以树高和冠幅作为解释变量的二元模型效果较好,再增加冠长因子的三元模型改进不大.云杉、冷杉、栎树、桦树4个树种组基于树高冠幅的立木材积模型,其R²分别为0.81、0.80、0.76和0.77,MPE分别为4.7%、5.3%、5.4%和5.3%,模型预估精度均能达到95%左右.[结论]本文对材积与林木因子之间相关关系的定量分析,建立了云杉、冷杉、栎树、桦树4个树种的立木材积模型,模型预估精度高.为激光雷达技术定量估测森林参数提供了依据.     

Determination of number of stems in coniferous forest stands by means of aerial photo‐interpretation

Two models for determination of the number of stems per hectare in forest stands (N) from attributes derived by aerial photo‐interpretation were developed. The models relied on the assumption that N could be determined by dividing the total stand volume per hectare with the volume of the “average tree”; defined by stand mean height and the diameter corresponding to mean basal area of a stand. Input variables of the models were stand mean height, crown closure and site quality. Additionally, model II required input of average stand volume per hectare and average mean diameter derived from stratified field sample plot inventories. Material for 143 coniferous stands was used for the testing of the models. The stands were recorded by intensive field measurements. Aerial photographs at the approximate scale of 1:15 000 were used for photo‐interpretation. The N value was underestimated in model I by 5.4–47.0%. The standard deviation for the differences was 15.2–26.2% for mature stands and 41.4–44.2% for young thinning phase stands. For model II, the mean difference between the predicted and observed N value was in the range ‐16.1% to 12.2%.     

Total tree,merchantable stem and branch volume models for miombo woodlands of Malawi

The objective of this study was to develop general (multispecies) models for prediction of total tree, merchantable stem and branch volume including options with diameter at breast height (dbh) only, and with both dbh and total tree height (ht), as independent variables. The modelling data set was based on destructively sampled trees and comprised 74 trees from 33 tree species, collected from four forest reserves located in different ecological zones of Malawi. The dbh and ht ranges for the data set were 5.3–111.2?cm and 3.0–25.0?m, respectively. A number of alternative model forms were tested and the final model selection was based on root mean square error (RMSE) values calculated using a leave-one-out cross-validation procedure. The model performances and the evaluations of the finally selected models (R? 2 range 0.72 to 0.92; RMSE range 38% to 71%; mean prediction errors range ?1.4% to 1.3%) suggest that all models can be used over a wide range of geographical and ecological conditions in Malawi with an appropriate accuracy in predictions. The appropriateness of the developed models was also supported by the fact that the mean prediction errors of these models were much lower than the mean prediction errors (range ?23.6% to 48.9%) of some previously developed models tested on our data.     

混合效应模型在森林生长模型中的应用

对以往生长和收获模型存在的问题及混合效应模型在森林生长模型研究中的意义进行描述,分别介绍线性混合效应模型和非线性混合效应模型的表达形式和算法,对国内外利用混合效应模型研究林分的树高、断面积和蓄积的研究进展情况进行详细的综述,最后对混合效应模型目前存在的问题和应用前景进行简单的探讨.     

Models for the estimation of single tree volume in four Miombo woodland types

Single tree volume estimation models are produced for four Julbernardia-Brachystegia woodlands in Malawi. The estimation models are based on the regression of volume on one or a number of independent variables derived from diameter and height. In total, 1282 trees from 46 species were felled and individually measured. Site-specific models were produced for the dominant species and important species groups, with separate models for canopy and under-storey species groups from three sites. Compared to diameter, height was a poor predictor of volume and only derivations of diameter were used wherever possible. The models may have wider applicability, particularly in woodlands with similar structure, climatic and edaphic conditions, but should be validated since their applicability outside of the four sample sites has not yet been tested.     

GROWTH AND YIELD MODELS FOR DAHURIAN LARCH PLANTATIONS

Growth and yield models were developed for individual tress and stands based on336 temporary plots with 405 stem analysis trees of dahurian larch(Larix gmelinii(Rupr.)Rupr.)plantations throughout Daxing’anling mountains.Several equations were selected using nonlinearregression analysis.Results showed that the Richards equation was the best model for estimatingtree height,stand mean helght and stand dominant height from age; The Power equation was thebest model for prediction tree volume from DBH and tree height; The logarithmic stand volumeequation was good for predicting stand volume from age,mean height,basal area and other standvariables.These models can be used to construct the volume table, the site index table and other for-estry tables for dahurian larch plantations.