免疫进化算法在建立地位指数曲线模型中的应用

选择Schumacher方程构建优势高和地位指数均能写成显式表达式的多形地位指数曲线模型,以同时兼顾优势高和地位指数的估测误差最小为目标函数,采用免疫进化算法求解参数．实例分析表明：该文建立的多形地位指数曲线模型能够客观地反映不同立地下优势高的生长规律,且误差小,应用方便．     

地形因素对桤木人工林生长和树干公定容重的影响

本文应用四个地形因子在两个水平下的正交试验设计方法,系统分析了13年生桤木人工林胸径和树高生长以及树干公定容重的变化规律。结果表明,影响桤木人工林胸径和树干公定容重的首要地形因子是坡形,其次是坡向,再者是坡位,而小于45°的坡度影响不显著;影响桤木人工林树高的首要地形因子是坡形,其次是坡位,再者是坡向,小于45°的坡度影响同样不显著。     

包含哑变量的黑龙江省落叶松人工林碳储量预测模型系统

利用2005—2010年两期黑龙江省落叶松人工林固定监测样地数据,分析黑龙江省落叶松人工林各林分变量因子之间的关系,建立地位级指数曲线模型和林分密度指数模型,采用两步最小二乘的方法建立预测包含林分平均断面积和林分碳储量的联立方程组,将以上所构建的模型统称为黑龙江省落叶松人工林碳储量预测模型系统.同时将龄组和区域作为哑变量加入到预测模型中.结果表明: 模型系统中除地位级指数曲线模型之外,剩余模型的确定系数(R²)均大于0.98,均方根误差均小于4,而加入哑变量的模型R²有所增加,均方根误差均小于3,说明模型稳定性较好,预估参数较为精确.各模型的平均相对误差均小于2%,大部分模型平均相对误差绝对值小于15%,模型精度均在95%以上,研究结果可以对黑龙江省不同区域和龄组的落叶松人工林林分平均树高进行精确拟合.根据地位级指数曲线模型和联立方程组的拟合参数进行分析,当调查样地在同一区域时,林分年龄越大,林分平均树高、林分平均断面积和林分碳储量越大,符合实际生长规律;而在林分年龄相同、区域不同时,不同区域林分平均树高由大到小的排列顺序为: 平原地区、小兴安岭南坡地区、张广才岭东坡地区、完达山地区、张广才岭西坡地区、小兴安岭北坡地区.不同区域林分断面积和林分碳储量由多到少的排列顺序为: 张广才岭东坡地区、小兴安岭北坡地区、张广才岭西坡地区、小兴安岭南坡地区、完达山地区、平原地区.     

吉林省长白山区胡桃楸天然次生混交林立地指数模型

依据吉林省长白山胡桃楸天然次生混交林12个典型区域的坡向、坡位分布,结合胡桃楸龄级,布设样地109块,以年龄-树高数据为材料,编制了吉林省东部山区胡桃楸天然次生混交林立地指数表.结果表明: 应用3倍树高标准差法剔除异常数据,最终得到80块379对胡桃楸不同龄级的年龄与树高数据,运用7个数学模型进行比较,确定了单形立地指数导向曲线方程式: H=28.0181(1-e^-0.0341A)^1.0503,决定系数R²为0.85,残差平方和为0.89,基准年龄为50年,指数级距为2 m,得到了16～28 m的7条立地指数曲线.根据不同立地类型,建立了多形立地指数模型,幂函数拟合效果较好,即H=B₀t^B1,其中B₀=10^-9e^0.9213SI,B₁=-0.2139SI+5.6183,最终得到了多形立地指数模型方程式H=10^-9e^0.9213SIt^{-0.2139SI+5.6183}.指数级差法和落点检验法对2种立地指数模型的精度检验表明,多形立地指数的精确度较高,能够准确地反映胡桃楸不同立地类型间树高生长的差异,可用于吉林省长白山区胡桃楸天然次生混交林立地质量评价.     

立地条件对米老排人工林生长和材质的影响

对不同立地条件(不同地带和地形)下米老排(Mytilaria laosensis Lecomte)人工林胸径和树高生长以及木材品质的差异进行了比较分析.结果表明:相同地形条件下生长于南亚热带的米老排人工林林分胸径和树高以及木材密度、顺纹抗压强度和抗弯强度大于生长于中亚热带的,而木材尺寸稳定性小于生长于中亚热带的.相同地带内山谷中的米老排人工林林分胸径和树高以及木材尺寸稳定性大于山脊上的; 木材密度、顺纹抗压强度和抗弯强度则小于山脊上的.差异显著性t检验表明:立地条件(地带和地形)对米老排人工林林分胸径和树高影响均极显著,对米老排人工林的木材密度、顺纹抗压强度和抗弯强度影响极显著或显著;地形对米老排人工林的木材差异干缩影响极显著或显著,地带的影响不显著.研究结果为米老排人工林培育和木材合理利用提供科学依据.     

灰色模型应用于估测落叶松林分生长量的研究

本文用灰色GM（1,1）模型对林分平均生长过程进行模拟,给出落叶松人工林林分在树高、胸径、材积3个指标上平均总生长量的灰色模型,经过检验,估测效果好．     

塞罕坝华北落叶松人工林地位指数模型

运用传统地位指数模型来估计不同立地类型人工林立地指数是非常困难的,本文主要目的是建立适用于不同立地条件的地位指数模型,并对其立地质量进行评价.以两类调查数据和173块临时样地数据为基础,构建基于数量化理论方法I的非线性混合地位指数生长模型.结果表明： 海拔、坡向、土层厚度及土壤类型是影响华北落叶松人工林优势高生长的主要限制性因子;建立了主要限制性立地因子与林分优势高的线性回归方程,确定系数为0.912;确定华北落叶松人工林基准年龄为20年,对主要立地类型非线性地位指数混合模型参数进行了估计,模型确定系数R²均大于0.85,预测值与真实值绝对误差（e）在-0.43～0.45范围内,平均均方根误差（RMSE）在0.907～1.148范围内,模型拟合精度较高;主要立地类型优势高预测值与实际值估计误差在\[-0.95,0.95\]置信区间内,其中高海拔 阴坡 砂壤 中土层类型立地质量最高,其次为高海拔-阳坡-砂壤-中土层、低海拔-阴坡-砂壤-中土层,低海拔-阳坡-砂壤-中土层类型立地质量最差.     

长白山主要针叶树种胸径和树高变异系数与竞争因子的关系

选取长白山地区8个皆伐标准地的1139株标准木,利用变异系数(CV)分析了云杉、冷杉和红松3个主要针叶树种的胸径和树高随龄阶、树高随径阶的变化.结果表明：在研究地区,3个主要针叶树种树高随径阶的变异相对较小,胸径和树高随龄阶的变异较大,胸径随龄阶的变异系数最大.在天然林中,传统的以径阶为自变量的树高曲线能较好地反映实际生长,以龄阶为自变量的胸径和树高生长模型对实际生长程度的反映较差.竞争是引起树高和胸径变动的主要因子.若将竞争因子添加到传统的生长方程和树高曲线中,可以大幅度提高模型的精度.     

基于枝条木材密度分级的鼎湖山南亚热带常绿阔叶林树高曲线模型

如何便捷准确地测量树高一直是林学及群落生态学所关心的问题。由于木材密度与树木生长密切相关, 因此基于木材密度建立树高曲线模型能够为测量树高提供新的方法。本文以鼎湖山南亚热带常绿阔叶林1.44 ha塔吊样地内119个物种的4,032个个体为研究对象, 利用树高、胸径和木材密度数据来探究基于枝条木材密度分级的树高曲线模型。首先, 对个体进行随机抽样, 将其划分为建模样本(占总样本量的70%)和检验样本(占总样本量的30%), 并通过聚类分析将所有个体的木材密度划分为4级。其次, 基于建模样本利用常见的5种理论生长方程(Richards、Korf、Logistic、Gompertz和Weibull方程)对不同分级建立树高-胸径模型; 基于检验样本检验模型精度, 并确定各分级的最适模型。最后, 构建基于物种分类的树高曲线模型, 并比较其与木材密度分级模型的差异。结果表明: 基于木材密度分级的模型, 各分级小组检验样本的平均绝对误差(MAE)和均方根误差(RMSE)最小值所对应的模型类型与建模样本结果一致, 确定Gompertz模型和Weibull模型为鼎湖山南亚热带常绿阔叶林最适树高模型类型。比较基于木材密度分级的模型与基于物种分类的模型, 发现二者的MAE、RMSE指数差异小。综上, 基于木材密度分级的树高曲线模型对树高估测精度高, 使用方便, 为树高预测提供了新方法, 可以更好服务森林调查等生产实践。     

大兴安岭不同生态区域兴安落叶松树高曲线的研究

以大兴安岭3个不同生态区域的兴安落叶松伐倒木为对象,基于2 272株实测树高—胸径数据,分别选用12种树高曲线模型,对模型参数进行求解,并采用确定系数（R²）、误差(Bias)、均方根误差（RMSE）对模型精度进行检验。结果表明,Korf方程,唐守正方程和Hossfeld方程能较好地描述区域1和区域3的落叶松树高曲线;Richard方程,Weibull方程和Mitscherlich方程能较好地描述区域2的落叶松树高曲线。采用限制模型和无限制模型的假设检验方法对所选模型进行区域性检验。结果表明,任何2个区域的树高曲线都有显著不同,且区域2与区域1和区域3的树高曲线相差较大,区域1和区域3的树高曲线相差较小。不同生态区域树高曲线的错误应用会导致较大的预测误差。     

Tree vigor and height growth in Black Spruce

Summary The relationship between tree height and tree vigor was examined in order to test the hypothesis that increased height results in a reduction in photosynthate availability for growth due to an increase in respiratory load of the sapwood. Various vigor indices were measured on black spruce [Picea mariana (Mill.) B. S. P.] trees on a wide range of sites and ages. The relationship between these vigor indices and tree height and site quality were then evaluated through correlation and regression analyses. Vigor indices based on meristematic activity such as specific volume increment and height growth rate were generally more strongly correlated than foliage based indices (i.e. Waring vigor estimates). Both tree height and site index were found to have a significant effect on specific volume increment and height growth rate. However the height effect decreased with a decrease in site quality, and became insignificant (P <0.05) on the poorer sites. The full regression model, allowing the height effect to vary between different site quality groups, explained 82% and 72% of the variability in specific volume increment and height growth rate, respectively. The results support the hypothesis that increases in the ratio of respiration to photosynthesis in trees as they increase in size is largely a function of tree height. Possible explanations for the decreased height effect on poor sites are also discussed.     

A Study of Stand Growth Model for Pinus yunnanensis (Pinaceae) Based on Plots Data——A Case Study in Yangliu Township,Baoshan, Yunnan Province

Pinus yunnanensis is one of most important timber species in Yunnan Province, and widely distributed in southwest China. Studies on growth model have been reported, however, most of which focused on a specific part of growth model. To build detailed, easily used and accurate empirical stand growth model from the same dataset, a case study was conducted in Yangliu Township, Baoshan, Yunnan Province. A total of 86 sample plots data were collected using two stages sampling design. Several popular non-linear growth functions were fitted and compared, including Chapman-Richards, Mitscherlich, Schumacher, Gompertz, Logistic, Korf and Allometric function. Models of site index, density index, average diameter at breast height (DBH) and stock volume growth model were fitted respectively. The different models performed more or less similarly in terms of coefficients of determination and root mean square error (RMSE). However, empirical growth function “Schumacher” had lower coefficient of variation for all parameters than other models. Schumacher function was the most suitable one for site index, average DBH and stock volume growth model in all alternative functions.     

Selection for Annual Growth Curves in NICOTIANA TABACUM L

The cumulative growth of a plant is the result of interrelated processes, and response to selection for changes in the annual growth curve requires many physiological adjustments. Selection to modify the entire annual growth curve may therefore not be as effective as linear models may predict. Periodic growth of a population of Nicotiana tabacum L. was estimated to have heritabilities increasing from 7% up to 31% for successive heights, with positive genetic and phenotypic correlations among all periods. Two selection experiments on this population indicate the difficulties of using simple index selection to raise the entire growth curve. A selection index of eight periodic heights resulted in a gain in all periods for the first cycle of selection but mixed losses and gains in subsequent cycles for a small net gain after four cycles of selection. A selection index of three parameters of a nonlinear height growth function resulted in a consistent change in the growth curves over the four cycles of selection but a net loss in early growth and a large net gain in late-season growth.     

抚育间伐对侧柏人工林及林下植被生长的影响

抚育间伐是森林经营管理措施之一,是对森林生态系统的人为干扰。研究不同抚育方式、强度和频率对森林生态系统的干扰对重建、恢复森林生态系统固有功能及实现森林可持续经营管理有重要意义。以31块北京地区侧柏人工林样地对不同抚育强度后侧柏林生长、林下植被生长及林下植物多样性变化进行了研究。研究结果表明:侧柏林分经不同强度抚育后单木胸径、树高、冠幅和林分蓄积生长均增加,不同抚育强度下单木胸径、树高、冠幅生长量和林分蓄积生长量与立地条件有关,好的立地条件宜采取强度抚育,较差立地条件宜采取中弱度抚育;侧柏林分经弱度、中度抚育后林下植物种类增加,经强度抚育后减少;不同强度抚育后林下植物Simpson多样性指数和Shannon-Wiener多样性指数随时间增大,后者对抚育强度更为敏感;林下灌草生物量随抚育强度增大而增加,并随时间增加;侧柏人工林生态系统种间竞争程度与立地条件有关,好的立地条件能够经受较强的人为干扰,差的立地条件受弱度干扰就会打破种间生长平衡。     

Nonlinear growth generates age changes in the moments of the frequency distribution: the example of height in puberty

Higher moments of the frequency distribution of child height and weight change with age, particularly during puberty, though why is not known. Our aims were to confirm that height skewness and kurtosis change with age during puberty, to devise a model to explain why, and to test the model by analyzing the data longitudinally. Heights of 3245 Christ's Hospital School boys born during 1927-1956 were measured twice termly from 9 to 20 years (n=129508). Treating the data as independent, the mean, standard deviation (SD), skewness, and kurtosis were calculated in 40 age groups and plotted as functions of age t. The data were also analyzed longitudinally using the nonlinear random-effects growth model H(t)=h(t-epsilon )+alpha, with H(t) the cross-sectional data, h(t) the individual mean curve, and epsilon and alpha subject-specific random effects reflecting variability in age and height at peak height velocity (PHV). Mean height increased monotonically with age, while the SD, skewness, and kurtosis changed cyclically with, respectively, 1, 2, and 3 turning points. Surprisingly, their age curves corresponded closely in shape to the first, second, and third derivatives of the mean height curve. The growth model expanded as a Taylor series in epsilon predicted such a pattern, and the longitudinal analysis showed that adjusting for age at PHV on a multiplicative scale largely removed the trends in the higher moments. A nonlinear growth process where subjects grow at different rates, such as in puberty, generates cyclical changes in the higher moments of the frequency distribution.     

Regionalizing Nutrient Values of Vegetation to Assess Site Fertility of Mountain Forests in the Bavarian Alps

Height growth and productivity of forests depend on temperature, water and nutrients. Ellenberg indicator values that summarize vegetation response to growth factors are suited to predict site fertility. Macronutrients (NPK), as represented by N-values, are a crucial component of site fertility and susceptibility towards biomass extraction. Based on 1,500 vegetation plots from an inventory stratified over all important forest types of the Bavarian Alps we regionalized Ellenberg N-values against area-wide soil, climate and relief predictors including a spatial effect at a scale of 1 : 25,000, resulting in a general additive model (GAM) with eight predictors and an explained deviance of 53 % on test data. The N-value layer was combined with other regionalized indicator values (temperature, reaction, moisture) to predict height of Norway spruce at reference age (site index) of an independent forest inventory data set, resulting in a GAM with an explained deviance of 35 %. After temperature the nutrient value was the second most important predictor of site index and clearly superior to soil reaction. It can be concluded that forest growth is sensitive to reductions of NPK-availability through whole tree harvesting and that maps of N-values deliver important information for planning sustainable harvesting.