A provisional growth model with a size–density relationship for a plantation of <Emphasis Type="Italic">Paraserianthes falcataria</Emphasis> derived from measurements taken over 2 years in Pare,Indonesia

A growth model for a plantation of Paraserianthes falcataria was provisionally derived from measurements of 32 permanent plots taken over a period of 2 years in Pare, Indonesia. This model first predicts height growth with the polymorphic site index equation. Then density-related growth and mortality, that is, diameter and stand density, are calculated to satisfy the mathematical relationship for the reciprocal and self-thinning equations, both of which were based on the maximum size–density line with the slope of −1.759 identified in this study. Cumulative predictions on diameter and stand density, starting with each of three age classes, 3, 4, and 5 years after planting, and continuing for the next 2 years, agreed well with the observations of age-class mean. An exception was for stands that were 7 years old, which were marginal, but closest to the rotation age of 8 years. Contrasting height/diameter relationships among the three age classes were described reasonably well with this model, and the predicted basal growth area was found to agree fairly well with observations. These results suggest that the growth model presented here has good potential for applying size–density control for plantations of P. falcataria. However, measurements for an additional few years might be necessary to derive a model that will more accurately predict diameter size at the rotation age.     

广西马尾松经济材出材率表编制研究

以马尾松人工林作为研究对象,用伐倒木样木数据,经干形分析和多指标精度比较,选定最佳的削度方程;通过树皮率方程和树高曲线方程进行计算机理论造材,依据各经济材种规格,编制出马尾松胸径树高二元经济材出材率表。经检验,以该方法编制的出材率表达到林业数表模型编制的精度要求。     

Nonlinear mixed-effects modeling of variable-exponent taper equations for lodgepole pine in Alberta,Canada

Four variable-exponent taper equations and their modified forms were evaluated for lodgepole pine (Pinus contorta var. latifolia Engelm.) trees in Alberta, Canada. A nonlinear mixed-effects modeling approach was applied to account for within- and between-tree variations in stem form. Even though a direct modeling of within-tree autocorrelation by a variance–covariance structure failed to achieve convergence, most of the autocorrelation was accounted for when random-effects parameters were included in the models. Using an independent data set, the best taper equation with two random-effects parameters was chosen based on its ability to predict diameter inside bark, whole tree volume, and sectioned log volume. Diameter measurements from various stem locations were evaluated for tree-specific calibrations by predicting random-effects parameters using an approximate Bayesian estimator. It was found that an upper stem diameter at 5.3 m above ground was best suited for calibrating tree-specific predictions of diameter inside bark, whole tree volume, and sectioned log volume.     

国内外削度方程研究进展

削度方程在树干材积估算和森林碳汇规划中有着广泛的使用和重要的实际价值, 其模拟直径、材积、干形变化准确与否直接决定了木材交易的公平和森林规划系统方案的科学性。文中系统阐述了削度建模数据获取方法, 比较了削度方程的种类及优缺点, 分析了削度方程的精度要素, 并对未来相关研究趋势进行了预测。     

Derivation of two-way volume equation for bamboo, <Emphasis Type="Italic">Phyllostachys pubescens</Emphasis>

We derive a two-way volume equation for estimating the apparent culm volume of one of the largest bamboo species, Phyllostachys pubescens Mazel ex Houz. The volume equation was derived from the assumptions that (1) the relative culm form can be expressed by Kunze’s equation and (2) normal form-factors at two different relative heights are steady at constants independent of culm sizes. A total number of 200 sample culms were collected from a stand of P. pubescens in Mt. Toshima, Kumamoto Prefecture, western Japan, and were randomly bisected into two sets of data, i.e. modeling and test data. For the modeling data, normal form-factors at 0.6 and 0.9 in relative height were steady at 0.908 and 0.448, respectively. The coefficients of the volume equation were determined based on these steady values of the normal form-factors. For the test data, the apparent culm volume was estimated from diameter at breast height and culm height with the determined volume equation. The mean error and root mean square error of the estimated culm volume were, respectively, 8.120 × 10⁻⁵ and 3.291 × 10⁻³ m³, and there was no significant difference between estimated and actual volume. In conclusion, the two-way volume equation presented here appears to be convenient for predicting the apparent culm volume for P. pubescens.     

Estimation of taper rates and volume of smaller-sized logs in spotted gum saw timber plantations in Southeast Queensland,Australia

Spotted gum (Corymbia citriodora subsp. variegata) is a popular tree species for hardwood saw timber plantations in Southeast Queensland (SEQ), Australia. In many parts of the world, logs up to 10cm top diameter are considered to be merchantable logs and acceptable at sawmills. However, due to the higher handling costs of smaller-sized logs, sawmills in SEQ are only buying logs with a top diameter of 25cm and larger. This necessitates the determination of the volume of logs with top diameters between 10 and 25cm. This paper compares the taper rates of different sizes of spotted gum logs and estimates the stem volume of spotted gum logs between 10 and 24.94cm diameter. Analysis showed that there is a statistically significant difference between the mean taper rates of bottom (30.5–64.2cm diameter) and top parts of stems (10–24.94cm diameter) at harvesting age. Using only the average taper rate of large diameter logs would underestimate the log volume of smaller-diameter logs. The average length of spotted gum logs between 10 and 24.94cm was found to be 19.27 m. Therefore, by the sawmill declining to use 10–24.94cm diameter logs, approximately 0.55m³ of log volume per tree at harvesting age would be lost.     

Combined production of sawn timber and firewood billets at a birch sawmill in Finland: A simulation approach

Abstract

Growing markets for chopped firewood have created alternative uses for the by-products of sawmills. Based on empirical data and simulated results, the potential of birch (Betula pendula Roth, Betula pubescens Ehrh.) from commercial thinnings for combined industrial production of sawn timber and firewood billets was investigated. In the simulations, different sawing patterns were used for logs intended to combine production of sawn timber and billets for chopped firewood (‘sawlogs’), and for logs intended only to firewood production (‘firewood logs’). Finally, economical feasibility analysis was done concerning the differences between the sawmills’ traditional business concept and the novel concept combining sawn wood and firewood production. The bucking results for the volume yield of different timber assortments varied only slightly between the different bucking options, i.e. the combinations of timber assortments. The main differences in the volumes of timber assortments were due to the stand type where the birch trees were sampled (planted, naturally regenerated, mixed birch–spruce). In the sawing procedure, the output of sawn timber varied between 24% and 42% of the log volume in the sawlogs, depending on the log diameter class. As the volume yield of sawn timber and firewood billets was counted together in the case of sawlogs, the log consumption was c. 1.75 m³ of roundwood per 1 m³ of sawn timber and firewood billets. In the case of the firewood logs, the log consumption rate was considerably lower, only c. 1.35. The economic calculations showed that using the firewood approach in sawing may increase the net added value of products by €1.9–5.4 m^?3 of logs, depending on their diameter class. As a conclusion, parallel production of sawn timber and firewood from logs from the first and second commercial thinning of birch-dominated stands is a concept that could work as an alliance between a sawmiller and a firewood entrepreneur. The concept could be competitive compared with both traditional sawmilling and production of chopped firewood.     

Stem taper equation analysis for Larix kaempferi species in the Central Region of South Korea

Taper equation was developed to predict diameters at specific height for Larix kaempferi species in the Central Region of South Korea. The sampled trees that were collected through destructive sampling ranged from 0.60 to 47.90 cm DBH with total height ranging from 2.00 to 33.00 m. The dataset was randomly split into two: 80% for initial model fitting and 20% for model validation. The combined that means 100% dataset was used for final model fitting. Statistics of fit were used as criteria, including the coefficient of determination (R²), standard error of the estimate (SEE), bias (ē), the absolute mean difference (AMD), and the Akaike information criterion (AIC) values and weight (AICw), with a rank analysis being applied. Initial model fitting utilized a total of nine taper equations, with the three segmented taper equations and another three non-segmented determined for model validation and final model fitting. Kozak02 equation, which had not yet been evaluated for L. kaempferi species, indicated the best performance for the species in the Central Region of South Korea. Upon comparison, the ability of this study to predict diameters at specific height and stem volume was better than the existing taper equation for L. kaempferi in South Korea.     

Segmented taper equations with crown ratio and stand density for Dahurian Larch (<Emphasis Type="Italic">Larix gmelinii</Emphasis>) in Northeastern China

Segmented taper equation was selected to model stem profile of Dahurian larch (Larix gmelinii Rupr.). The data were based on stem analysis of 74 trees from Dailing Forest Bureau in Heilongjiang Province, Northeastern China. Two taper equations with crown ratio and stand basal area were derived from the Max and Burkhart’s (1976) taper equation. Three taper equations were evaluated: (1) the original equation, (2) the original equation with crown ratio, and (3) the original equation with basal area. SAS NLIN a...     

COMPATIBLE STEM TAPER AND VOLUME RATIO EQUATION FOR KOREAN PINE

INTRODUCTIONWiththedevelopl11entofecono111yandoPeninghn1berInarket.thehlnbersizeiscaredaboutmorea11dl11ol'e.otl1ermse,l11uIhpleproductinventonesrequlresaccurateeshmatesofproductsizes(dial11eteral1dlengths)andvolume.Koreanpine(PinIisko1nIensisSib.etZucc.)isararehn1bersPeciesil1Heilol1roial1gProvince.ItisnecessarynotonlytopredicttI1evolumebasedonvolumetablebutalsotoas-sesstheassotheent.Accordingtothenahol1alhmbercritenonandthewoodqt1ality,thestandqualityisdetenl1i11ed.ThemainPOintofco…     

Comparison of taper functions between two planted and coppiced eucalypt clonal hybrids, South Africa

In addition to regeneration through seed, certain eucalypts are able to regenerate via the production of coppice shoots following felling, which can then be selectively thinned over time and managed as a coppice stand for the commercial production of timber. Little information could be found if tree form differs between coppiced (where one or two stems had been left per stump) and planted eucalypts, or whether different volume taper models would need to be developed. To determine if this was necessary, rotation-end stem taper data was collected from an Eucalyptus grandis × E. urophylla and an E. grandis × E. camaldulensis trial to compare volume taper equations for planted versus coppiced commercially grown Eucalyptus clonal hybrids. For treatment comparisons, taper data were collected from the parent crop (1R), the replanted crop (2R), as well as from coppiced stands where either a single (Cop_Sngl) or double stem (Cop_Dbl) had been left per stump. Stem taper functions used for treatment comparisons indicated differences between clones, as well as between treatment, with the models based on single stems (1R, 2R or Cop_Sngl) being significantly different from those containing two stems (Cop_Dbl). Despite any non-significant model differences (for example between 1R, 2R and Cop_Sngl single stem crops) the percentage magnitude of any bias in utilizable volume differences when comparing the individual models (between a 6.31% over-prediction to a 3.8% under-prediction) still needs to be taken into account as these differences may have importance in terms of the volume and product prediction.     

理论造材:削度方程和出材率表的编制

本文提出了计算机理论造材仅根据削度方程和单株带,去皮胸径的转换关系式两个模型,可不必由削度方程推导材长方程和材积比方程。比相关指数,均方程为指标,结合残差图分析,选择了杉木、落叶松的削度方程;结合标准树高曲线,是可仅根据优势高为任一具体林分编制（一元）单株出材率表（特称之为自动调整出材率表）。     

Variation in log quality and prediction of sawing yield in oak wood (Quercus robur)

Context

The commercial feasibility of sawmilling depends on the expected volume and value of sawn planks. Models that predict the volume of sawn timber of a particular quality and produced from logs of known characteristics are therefore very useful.

Aims

The objectives were to study variation in sawing yield and to obtain models that predict lumber volume and grade recovery on the basis of easy-to-measure predictor variables of saw logs.

Methods

Forty-six oak trees growing in Galicia (NW Spain) were felled and cut into logs. The logs were visually graded and sawn mainly into quartersawn planks, which were dried, planed and visually graded for structural purposes.

Results

The total volumetric sawing yield was 47.6 %. The sawing yield for planks of structural dimensions (cross-section, 70?×?120 or 70?×?170 mm) was 43.4 %, but decreased to 8.4 % for structural sized and quality grade beams because of wane and biotic damage in many pieces. Log grade did not significantly affect sawing yield in the sample analysed, despite the wide range of diameter over bark at the smallest end in the sampled logs (22–77 cm). The sawing pattern affected total sawing yield (F?=?4.913; p value?=?0.001) and the sawing yield for structural planks (F?=?6.142; p value?=?0.0002); radial sawing with one cut and live sawing of half logs provided the highest yields. Three models were proposed for estimating sawn volume in timber products, with the small-end log diameter over bark as the predictor variable and R _adj ² between 0.31 and 0.78 (p value?<?0.01).

Conclusion

For the purpose of producing oak timber destined for structural use, the presence of bark and sapwood in planks must be reduced in the sawing process; this would decrease the total lumber recovery but increase the timber value yield. Air drying must be accelerated to reduce biotic damage in sawn planks. Geometric mean diameter over bark at the smallest end (d) outperforms other measures as a predictor variable for total or structural sawn timber volume.     

Simulated yield and quality distribution of sawn timber from final felling in a Norway spruce [Picea abies (L.) Karst.] stand with varying thinning regimes: A case study

Abstract

An integrated simulation tool, formed by integrating the InnoSIM sawing simulation system with the RetroSTEM simulator, was used to convert available wood raw materials from final felling into sawn timber, allowing for calculation of the three-dimensional wood properties of individual stems (stem geometry, heartwood formation, knottiness) as well as the volume, quality and value of sawn timber in a Norway spruce stand with different thinning regimes (unthinned, normal and intensively thinned). Based on the input data of sawing patterns, the simulations indicate that there are relatively small differences (<8%) in the volume yield (m³ha^?1) of sawn goods resulting from sawlogs available from final felling with different thinning practices. However, intensive thinning yielded the largest stem diameters and the greatest volumes (m³ha^?1) of large-sized centre goods (thickness: 50, 63, 75 mm) of rather poor quality. Normal thinning yielded the largest volume of A-grade side boards and centre goods (m³ha^?1), as well as the best total value ([euro]ha^?1) of sawn timber. Differences observed in sawn timber quality distribution can contribute to even more significant variation in value yields, if pricing mechanisms of timber products change to favour higher grade timber products.     

Total and Merchantable Volume Equations for Tectona grandis Linn. f. Plantations in Karnataka,India

Tectona grandis (teak) is one of the most important timber species worldwide and India is one of the major teak growing countries. Though some volume equations were developed in the past in India, merchantable volume equations (any top diameter or bole length) are not available. Moreover, the models developed were neither quantitatively and qualitatively evaluated nor validated with independent data sets. Hence, the objective of this study was to develop appropriate volume equations to predict total tree volume and merchantable volume for teak in Karnataka.

Linear and non-linear equations were used to model the relationship of the volume with respect to diameter at breast height (dbh) and total height. Merchantable volume equations for estimating merchantable volume to any minimum top diameter or bole length have also been constructed. The equations tested mostly fitted well to the data. Other models developed elsewhere tended to underestimate the volume, especially at dbh ≥ 23 cm. The geometric cylinder volume equation, in combination with a stem form factor of .40, is widely used for teak in Karnataka but they were found to be less precise compared to regression equations when applied to the present data set. Model validation indicated that models should be calibrated with local data for greater accuracy in the prediction.     

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.     

Stem Volume Equations for Valuable Timber Species in Mozambique

Development of stem volume for umbrella-shaped crown trees remains a big challenge for efficient use of forest resources in Mozambique. In this study, species-specific stem volume equations were developed for the first time for three of the most important timber species in Mozambique: Afzelia quanzensis Welw. (Chanfuta), Millettia stuhlmannii Taub. (Jambire), and Pterocarpus angolensis D.C. (Umbila). The study was carried out at three locations in Mozambique: Inhaminga, Mavume, and Tome covering 58 trees from which, 24 of Chanfuta, 15 of Jambire, and 19 of Umbila. The volume of the sampled stem sections (logs) was calculated using Smalian’s formula, where stem volume total was obtained through the sum of the respective defined sections. Using a nonlinear procedure, different volume models were tested for each tree species independently. The coefficient of the determination of the tested equations in the tree species ranged from .90 to .95, making the equations potential candidate models for the stem volume equations object of the study. Based on statistical parameters analysis, the best fit nonliner power equation was Equation 2 with the lowest AICc and lowest average absolute bias. The stem volume for the studied species is better explained by models including both diameter and height as explanatory variables.     

Volume equations and biomass estimates for three species in tropicalmoist forest in the Orientale province,Democratic Republic of Congo

Volume equations predict the volume of the stem of a tree from dendrometrical characteristics that are easy to measure, such as diameter and/or height. These equations can serve as a surrogate for biomass equations, by converting the stem volume to stem biomass, and then expanding it to the total aboveground biomass. This is especially important for Central Africa where biomass equations are scarce, whereas volume equations are common. We measured the stem volume of 459 trees in the Yoko forest, Orientale province, Democratic Republic of Congo. These trees belonged to three species: Gilbertiodendron dewevrei (limbali), Guarea thompsonii (bossé foncé) and Scorodophloeus zenkeri (divida). Species-specific volume equations were fitted using these data, and biomass estimates were derived from these volume equations. The fitted volume equations were consistent with other location-specific volume equations for the same species. The biomass estimates derived from the fitted volume equations were also found to be consistent with multispecies pantropical biomass equations.     

Stand basal area as an index of tree competitiveness in timber intercropping

To derive optimal benefits from intercropping timber, farmers should make important initial decisions on tree species and planting density with a good understanding of their tradeoffs. Complex and data-intensive models used by researchers should be supplemented with simpler models based on easily measured parameters and easily understood competition functions. In experiments in the Philippine uplands, growth parameters of three popular farm-forestry species (Eucalyptus deglupta, E. torelliana, and Paraserianthes falcataria) were measured, along with intercropped and non-intercropped yields of maize and vegetables. The commonly used forestry parameter of stand basal area had a significant negative correlation with intercrop yields (as a percentage of non-intercropped yields). The slope of the regression line differed between species; in this study, percent yield loss per unit stem basal area growth was in the order E. deglupta > E. torelliana > P. falcataria. The relationship between stand basal area and intercrop-yield decline was tested on an independent data set from China. Intercrop yields had significant negative correlations with stand basal area of Paulownia elongata. We propose that adaptive tree-screening trials evaluate competitiveness in addition to evaluating growth and mortality. Stand basal area may be better suited to this task than more mechanistic indices such as leaf-area index as it is easy to measure, calculate, and understand, and it may serve as a better index of total (aboveground + belowground) competition. Basal area is also directly related to tree volume, and allows farmers to more easily evaluate the economic tradeoffs between tree growth and intercrop-yield declines. This revised version was published online in June 2006 with corrections to the Cover Date.     

Enzymatic saccharification and ethanol production of <Emphasis Type="Italic">Acacia mangium</Emphasis> and <Emphasis Type="Italic">Paraserianthes falcataria</Emphasis> wood,and <Emphasis Type="Italic">Elaeis guineensis</Emphasis> trunk

We examined the saccharification and fermentation of meals from Acacia mangium wood, Paraserianthes falcataria wood, and Elaeis guineensis trunk. The levels of enzymatic hydrolysis of cellulose and ethanol production were highest for P. falcataria wood and lowest for A. mangium wood. Ultrasonication pretreatment of meal further increased the rates of hydrolysis and ethanol production in meal from P. falcataria wood. Through this pretreatment, hemicelluloses (xylan and xyloglucan) and cellulose were released in the meal from P. falcataria wood. Loosening of hemicellulose associations can be expected to make P. falcataria wood more useful for bioethanol production.