A flexible regression model for diameter prediction

We present a functional regression model for diameter prediction. Usually stem form is estimated from a regression model using dbh and height of the sample tree as predictor. With our model additional diameter observations measured at arbitrary locations within the sample tree can be incorporated in the estimation in order to calibrate a standard prediction based on dbh and height. For this purpose, the stem form of a sample tree is modelled as a smooth random function. The observed diameters are assumed as independent realizations from a sample of possible trajectories of the stem contour. The population average of the stem form within a given dbh and height class is estimated with the taper curves applied in the national forest inventory in Germany. Tree deviation from the population average is modelled with the help of a Karhunen–Loève expansion for the random part of the trajectory. Eigenfunctions and scores of the Karhunen–Loève expansion are estimated through conditional expectations within the methodological framework of functional principal component analysis (FPCA). In addition to a calibrated estimation of the stem form, FPCA provides asymptotic pointwise or simultaneous confidence intervals for the calibrated diameter predictions. For the application of functional principal component analysis modelling the covariance function of the random process is crucial. The main features of the functional regression model are discussed informally and demonstrated by means of practical examples.     

Juvenile genetic parameter estimates for vigour,stem form,branching habit and survival in three radiata pine (<Emphasis Type="Italic">Pinus radiata</Emphasis> D.Don) progeny tests in Galicia,NW Spain

Individual and family heritabilities, as well as phenotypic and genetic correlations were estimated 2 and 3 years after plantation, in progeny tests carried out in plantations of open-pollinated Pinus radiata D.Don progeny located at three different sites in Galicia (NW Spain). The following factors were considered: survival, growth (free growth, height, diameter, volume, height/diameter ratio), form (number of branches, number of whorls, number of branches per whorl, number of branches per tree height meter, number of ramicorn branches, diameter of the thickest branch, internode length, branch angle, stem straightness, stem sinuosity, number of forks) and resistance (frost and insect resistance). Each plantation contained 50 female parents that had been selected as plus trees in genetically unimproved plantations in Galicia, as well as 6 female parents selected from the radiata pine breeding programme in the Basque Country (northern Spain) and two commercial lots of seed from Galicia, as controls. Individual heritabilities varied from low to high levels for each trait studied. Family heritabilities followed similar trends for individual heritabilities, but were of much greater magnitude. The results suggested that all traits except the number of branches per whorl and insect resistance could be expected to respond to selection based on individual performance. The less heritable traits could be improved by progeny testing. Height and diameter were strongly and positively correlated, and both traits were also correlated with the number of branches, the number of whorls and the branch diameter. The results are compared with previously published data and discussed in relation to the implications for breeding activities.     

白花泡桐树冠结构、生长性状的选择对于形改良的影响

为了改良白花泡桐的干形，对树冠结构、生长性状与干形的遗传相关进行了剖析和通径分析，计算出主要树冠性状、生长性状对干形的６３个选择指数方程。结果表明，胸径、小枝数、分枝总长、冠表面积和树高对形数、圆满度的决定系数在０．４０５～０．９４０和０．４２６～１．０６４之间。由以上５性状和形数或圆满度组成的综合选择指数方程效果最好。对形数选择的遗传进度、相对效率分别为０．１５５和１５９．０１５７％。对圆满度选择的遗传进度、相对效率分别为０．１７４和１２８．３６７９％。     

白花泡桐树冠结构、生长性状的选择对于形改良的影响*

为了改良白花泡桐的干形，对树冠结构，生长性状与干形的遗传相关进行了剖析和通径分析，计算出主要树冠性状、生长性状对于干形的６３个选择指数方程。结果表明，胸径、小枝数、分枝总长、冠表面积和树高对形数，圆满度的决定系数在０．４０５～０．９４０和０．４２６～１．０６４之间。由以上５性状和形数或圆满度组成的综合选择指数方程效果最好。对形数选择遗传进度，相对效率分别为０．１５５和１５９．０１５７％。对圆满度选     

Biomass,stem basic density and expansion factor functions for five exotic conifers grown in Denmark

Adequate allometric equations are needed for estimating carbon pools of fast growing tree species in relation to international reporting of CO₂ emissions and for assessing their possible contribution to increasing forest biomass resources. We developed models for predicting biomass, stem basic density and expansion factors of stem to above-ground biomass for five fast growing conifers. Data included destructive measurements of 236 trees from 14 sites, covering a wide range of growth conditions. To ensure model efficiency, models for predicting stem, crown and total above-ground biomass for the five species were estimated simultaneously using a linear, mixed effects model that allowed contemporaneous correlations between the different tree components. Models differed among species and included dbh and tree height. The models explained more than 98% of the variation in above-ground biomass and reflected differences in the allometry between tree species. Stem density differed among species but generally declined with increasing site index and dbh. The overall model for predicting stem basic density included dbh, H₁₀₀ and site index and explained 66% of the total variation. Expansion factors decreased from 1.8–2.0 in small trees (dbh < 10 cm) to 1.1–1.2 for large trees (dbh > 25 cm), but differed among species. The overall model explained 86% of the variation and included quadratic mean diameter and dbh.     

苏柳932等5个柳树优良无性系幼林生长及干形的初步研究

为进一步了解柳树优良无性系的生长特点,为无性系的合理利用提供依据,对苏柳932,799,795,797和172等5个柳树优良无性系2年生幼林的树高、胸径、材积等生长指标以及生物量和形率进行了测定分析。结果表明,苏柳5个无性系的胸径平均值为4．28cm,其中苏柳172的平均胸径最大（4．71cm）;树高平均值为6．97m,其中苏柳795平均树高最高（7．75m）。苏柳795的形率qo．5、q0．7值分别为0．68,0．44,是各无性系中形率的最高值,主干生物量占单株地上部分总生物量的比例最高（76．02％）,出材率高,是优良的用材林树种;而苏柳932的总生物量最高,为12．35kg／株,枝量、叶量占总生物量的比例最大,为42．0％,14．4％,属于防风防浪和生物能源林的造林良种。     

广东乳源19个枫香自由授粉家系在东江林场的生长表 现与初步评估

以广东乳源 19 个枫香 Liquidambar formosana 自由授粉家系为研究对象,调查不同家系苗期苗 高和 10.5 年生测定林的生长指标,并分析两个阶段生长指标的相关性,以期为枫香种质早期评价提供理 论依据。分析结果表明：枫香苗高在不同家系间存在显著差异（P<0.05）,且随着年龄的增长,差异呈逐 渐减小的趋势;枫香幼龄林树高、胸径、材积和干形质量在不同家系间存在显著差异,而分枝数、枝下 高和叶色等级无显著差异,19 个家系的单株树高、胸径、材积、枝下高、分杈数、干形质量和叶色等级 的平均值分别为 6.07 m、6.07 cm、0.012 2 m3、1.90 m、0.41 个、2.36 和 4.75;幼龄苗高与测定林的枝下 高、分杈数、叶色等级间的相关不显著,而与树高、胸径和材积的相关较强,且幼龄苗高与测定生长指 标间的相关性随苗龄增长呈增强趋势。因此,采用苗高对枫香优良家系进行早期选择具有一定的可行性。     

Long-term effects of superphosphate fertilization on stem form, taper and stem volume estimation of Pinus radiata

The long term effects of superphosphate fertilization on stem form, taper and stem volume estimation of Pinus radiata on a phosphorus-deficient site was examined using data from a fertilizer experiment which had been maintained for 30 years. The application of superphosphate resulted in long term and statistically significant changes in stem form. Mean cylindrical form factor ranged from 0.33 for the control trees up to 0.40 for trees fertilized with 100 kg P ha⁻¹. Stem form was also examined through taper curves which provided detailed depiction of average relative stem profiles. The increase in cylindrical form factor of fertilized trees was largely attributed to a significantly broader profile of the lower third of the stem. In comparison with the control trees, the fertilized trees also had a broader, although not statistically significant, profile of upper and middle stem which could also contribute to the increase in their cylindrical form factor. With increased form factor a greater proportion of the stem became merchantable because of increased log length to tree height ratio. Mean average taper of trees did not show a consistent trend with increasing lelevels of superphosphate application. It largely reflected the differential response of DBH and height growth to the treatments. The volume equation based on control trees underestimated the underbark stem volume of fertilized trees by 5–12% on average. Developing separate volume equations for the fertilized trees is warranted.     

A simple stem taper model with mixed effects for boreal black spruce

We simplified Kozak’s taper model by setting the inflection point at 1.3 m (dbh) without losing accuracy and precision. The simplification was required to facilitate the estimation of the covariance parameters when using a mixed-effects method. This method was necessary to take into account the correlation among multiple diameter measurements on an individual stem. The simple stem taper model was fitted to an extended data set collected across the province of Quebec, Canada. Comparison of the predicted stem taper and the derived stem volume with those obtained using existing models showed a comparable predictive power for the simple model. Including a prediction of the tree random effects based on supplementary diameter measurements of the bole improves the predictive ability of the model around the extra diameter observation. This model offers welcome simplicity as a means of predicting tree taper at coarse resolution for planning tree harvesting.     

特呈岛3种生境条件下白骨壤天然林的生长与树冠特征

文章以广东省湛江特呈岛高潮带、中潮带、低潮带白骨壤纯林为研究对象,调查了其树高、地径、冠长、冠幅以及分枝角度等,揭示了其生长及树冠特征.结果表明:不同潮带间白骨壤冠幅及树冠面积差异不显著(P＞0.05),而树高、地径、冠长及树冠体积均存在显著差异(P＜0.05),中潮带、高潮带与低潮带的树冠体积分别达31.522,15...     

马尾松实生种子园五年生的植株生长与分枝

本文研究了马尾松实生种子园建立第五年时植株的生长与分枝状况,研究的性状包括树高、胸径、枝条总数、年高生长、 年枝条生长量、年分枝数、不同分枝处树干直径等。对总的生长与分枝性状(含树高、胸径、枝条总数)分析表明:家系间只在胸径方面存在显著差异。对分年度的生长与分枝性状的研究表明:家系间在年高生长、年枝条生长量、年枝条直径方面无显著差异;年分枝数在刚建立的前两年家系间没有显著差异,后两年则差异显著;不同分枝处树干直径在连续的四年内,家系间均存在显著差异。不同年度的生长与分枝的趋势分析结果发现,大部分家系的年高生长与年枝条生长呈递增型,而大部分家系每年的分枝数却为波动型。这些研究结果表明,该马尾松实生种子园到建立的第五年时,家系间的差异大部分都不显著。究其原因,一方面可能是马尾松初期生长节律;另一方面可能是因为建园家系复杂的父本构成。因此,这个时期进行家系选择不太有效,建议在利用优树自由授粉子代建立实生种子园时,对他们先期进行苗期选择,而不是采用所有的子代。图1表4参20。     

厚朴药用林的生长特性及人工培育技术

采用标准地调查、生物量测定、树干解析等方法对福建省明溪县不同年龄的厚朴药用林的生长特性及人工培育技术进行分析研究。结果表明,厚朴适应性强、早期速生,造林后10 a即可间伐采收树皮。21年生的厚朴树干解析木分析表明:树高速生期在4～12年生,胸径速生期为6～14年生,材积速生期为4～18年生,18年生以后为厚朴剥皮的最佳年龄。树皮生长与胸径、树高呈极显著的正相关,即胸径越粗、树越高、树皮也越厚。药用林栽培关键技术为选用小凸尖厚朴等优良品种,Ⅰ、Ⅱ立地级造林,结合整地施足基肥,合理的造林密度,适时造林,强化抚育,适当选留萌条,及时间伐控制密度等。     

A flexible stem taper and volume prediction method based on mixed-effects B-spline regression

Modelling stem taper and volume is crucial in many forest management and planning systems. Taper models are used for diameter prediction at any location along the stem of a sample tree. Furthermore, taper models are flexible means to provide information on the stem volume and assortment structure of a forest stand or other management units. Usually, taper functions are mean functions of multiple linear or nonlinear regression models with diameter at breast height and tree height as predictor variables. In large-scale inventories, an upper diameter is often considered as an additional predictor variable to improve the reliability of taper and volume predictions. Most studies on stem taper focus on accurately modelling the mean function; the error structure of the regression model is neglected or treated as secondary. We present a semi-parametric linear mixed model where the population mean diameter at an arbitrary stem location is a smooth function of relative height. Observed tree-individual diameter deviations from the population mean are assumed to be realizations of a smooth Gaussian process with the covariance depending on the sampled diameter locations. In addition to the smooth random deviation from the population average, we consider independent zero mean residual errors in order to describe the deviations of the observed diameter measurements from the tree-individual smooth stem taper. The smooth model components are approximated by cubic spline functions with a B-spline basis and a small number of knots. The B-spline coefficients of the population mean function are treated as fixed effects, whereas coefficients of the smooth tree-individual deviation are modelled as random effects with zero mean and a symmetric positive definite covariance matrix. The taper of a tree is predicted using an arbitrary number of diameter and corresponding height measurements at arbitrary positions along the stem to calibrate the tree-individual random deviation from the population mean estimated by the fixed effects. This allows a flexible application of the method in practice. Volume predictions are calculated as the integral over cross-sectional areas estimated from the calibrated taper curve. Approximate estimators for the mean squared errors of volume estimates are provided. If the tree height is estimated or measured with error, we use the “law of total expectation and variance” to derive approximate diameter and volume predictions with associated confidence and prediction intervals. All methods presented in this study are implemented in the R-package TapeR.     

Modeling internode length and branch characteristics for Pinus radiata in New Zealand

It is recognized that estimation of internode length and maximum branch size is important for the prediction of clearwood in unpruned timber stands, as well as for evaluating the quality and value of logs in general. A review of existing branch models reveals a diversity of approaches as well as a tendency for results to be species specific. Here, a branch model is developed for Pinus radiata in New Zealand, capable of predicting successive internode lengths, the number of branches on each branch cluster, and the size of each branch up to the green crown (GC) at site index age 20. Inputs to the model include tree height and diameter at breast height (dbh) (both at age 20) and basal area per hectare of the top 100 stems. Further optional inputs are an ocular count of the number of branch clusters up to the green crown, and branch factor (BF)—the size of the biggest branch in the first cluster encountered above 6 m. The vertical distributions of internode length and maximum branch diameter are found to reach maxima around 0.3–0.4 of relative height. Internode length and the number of branches per whorl were found to be independent of tree size, site index and stand density. Stems per hectare is not required as an explicit predictor variable but it appears implicitly through tree dbh. Some model output is given and the results are discussed.     

钻天柳嫩枝扦插苗生长特性研究及优良单株选择

对6年生钻天柳嫩枝扦插苗生长特性及优良单株选择进行研究的结果表明,6年生钻天柳嫩枝扦插苗高生长平均4.8578 m,最高6.5 m;胸径生长平均31.3079 mm,最大58.24 mm。胸径、树高分布基本遵循正态分布;钻天柳扦插苗初期栽植苗木等级对钻天柳树高生长影响较大,栽植密度对钻天柳胸径生长影响较大;初步选出优良单株15株,初选优良单株树高平均值5.84 m,超过3块地树高平均值的20.22%,最优个体超过树高平均值的33.81%;初选优良单株胸径平均值50.97 mm,超过3块地胸径平均值的62.80%,最优个体超过胸径平均值的86.02%。     

陕西红花椒树冠结构对产量的影响

根据花椒树冠结构与产量的关系,确定影响花椒产量的主要结构因素,为丰产管理提供依据.对4个品种('大红袍'豆椒'黄盖狮子头'小红袍')的树龄、地径、树高、冠幅、标准枝(结果枝)数和产量进行调查,分析产量与树冠结构因子的关系.结果表明:(1)花椒适宜栽植密度约50株/666.7m2,栽植后树高应控制在2.50 m左右...     

降香黄檀不同家系测定试验初报

通过对福建省华安县西陂国有林场降香黄檀不同家系的胸径、树高、平均冠幅以及冻害程度等指标的测定与分析,结果表明:降香黄檀不同家系间胸径和树高生长差异极显著,造林后1 a胸径为1.22~2.38 cm,树高为1.55~2.27 m;而冠幅生长差异不显著,平均冠幅为0.30~0.58 m。综合考虑胸径、树高和冻害3个因素初步判断,21、118、8、49、39、43、90、14、115、46、55、16、19等13个家系在福建华安表现较好。     

Realized genetic gain observed in second-generation seedling seed orchards of <Emphasis Type="Italic">Acacia mangium</Emphasis> in South Kalimantan,Indonesia

Realized genetic gains brought by the first-generation tree improvement of Acacia mangium were evaluated by analyzing the 1-year growth performance of growth (height, dbh) and form (stem straightness, multi-stem) traits using data collected from three second-generation orchards: groups B, C, and D. Each orchard was composed of improved families derived from open-pollinated seed of plus trees selected from the first-generation seed orchards and newly added unimproved families collected from the same geographic region. The number of improved families and that of the unimproved in each orchard were 31 and 23 for group B, 28 and 39 for group C, and 24 and 30 for group D. Gains were calculated as percentage increase of improved families over unimproved ones. Improved families performed better than unimproved ones in 11 out of 12 comparison cases: four traits each in the three orchards. Averages of the realized genetic gain across the three seedling seed orchards were 3.1%, 5.2%, 4.3%, and 0.5% for height, dbh, stem straightness, and multi-stem, respectively. Except for multi-stem, the performances of improved families were significantly better than those of unimproved families in all the three orchards for dbh and in two out of three orchards for height and stem straightness.     

Growth of native forest species planted on abandoned pasture land in Costa Rica

Many forest plantations in the humid neo-tropics are established on degraded soils in abandoned pasture land and, with some exceptions, the species planted have not grown successfully. Studies of adaptability and growth under these conditions are scarce, particularly for native species. In this paper we present data on growth and tree form at 3 years of age for 11 species planted in abandoned pastures. The research plantation was established at La Selva Biological Station, in the Atlantic lowlands of Costa Rica (10° 26′N, 83° 59′W). Survival, diameter at breast height (DBH), total height, basal area, volume index and tree form were used to evaluate the species performance. After 3 years, Vochysia guatemalensis displayed a survival significantly higher (98%) than that of the other species. The lowest survival was 75% for Pinus tecunumanii. There were significant differences in growth measures among species. Acacia mangium exhibited significantly higher growth rates than the other species. Although this species grew rapidly, it did not develop straight single stems. About 14% of trees of A. mangium had bifurcation below DBH and more than 50% showed multiple axes or branches as large in diameter as the principal axis. The native species with the highest growth rate was Vochysia guatemalensis (DBH 12.7 cm, total height 7.5 m, volume index 55 m³ ha⁻¹ at 3 years of age). Vochysia ferruginea exhibited a slightly lower growth rate. Both Vochysia species were ranked highly with regard to tree form, with more than 80% straight single stemmed trees. The lowest growth rates were exhibited by Pentaclethra macroloba, Pithecellobium macradenium and Virola koschnyi; however, the latter two species formed straight single terms. Pentaclethra macroloba and Inga edulis failed to form straight single stems. In general, the growth rates of the species studied were high in comparison with results reported from other tree plantations in the tropics. In spite of this, it is not prudent to draw final conclusions on the basis of these 3 year measurements.     

Effects of wide spacing and thinning strategies on wood quality in Norway spruce (Picea abies) stands in southern Sweden

Abstract

The initial density of a stand influences both the prethinning growth and the quality of the harvested trees. This study investigated the effects of different square spacings (2.0, 2.5 and 3.0 m) with thinning from above and thinning from below on stand development and tree characteristics in a 33-year-old Norway spruce [Picea abies (L.) Karst.] plantation in southern Sweden. Before thinning the total standing volume was not significantly different between treatments. Diameter at breast height (dbh) and diameter of the thickest branch were positively correlated. Before thinning, dbh of the trees and their thickest branches were significantly higher in the stands with 3.0 m spacing. After thinning, the dbh and the diameter of the thickest branch did not significantly differ between the 3.0 m spacing with thinning from above and 2.0 and 2.5 m spacing with thinning from below. Spacing did not significantly influence the presence or size of spike knots. The results suggest that a combination of wide spacing with thinning from above may yield timber of similar quality to denser spacing with thinning from below.