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1.

In order to obtain a more precise prediction of the distribution of each timber grade or log grade with regard to the volume of birch (Betula pendula Roth., B. pubescens Ehrh.) in models for long-term planning, ordered probit models were developed. These models were developed by using data from three mixed birch and Norway spruce stands in Norway. The data consisted of 168 stems. In Norway, three ordinary birch saw log grades are commonly used, with pulpwood as a fourth grade. In this study, these four grades were applied in addition to waste timber, which was treated as a fifth grade. The developed models showed that the grade distribution of birch trees of mixed birch and spruce stands was highly correlated with tree height (p<0.01) and height to first visible dry branch (p=0.081). The statistical significance of both models was good (p<0.0001), as measured by log likelihood test statistics. Classifying the 168 stems by saw timber or pulpwood in butt log led to greatly improved estimates (p<0.01). The developed models would allow the incorporation of timber grade in stand simulators, enabling more precise predictions regarding the economic implications of alternative management strategies for birch trees.  相似文献   

2.
Abstract

We modeled the technical relationships between volume of Pinus radiata D. Don structural lumber (with stiffness>8 GPa) and log attributes using a stochastic frontier approach. The production models were Cobb–Douglas and Translog, while the log attributes were small end diameter (SED), wood stiffness (STF), and largest branch (LBR); however, the effect of the latter trait was not significant (p>0.05). Economic values of log traits were represented by their values of marginal product (VMP). The coefficients for the Cobb–Douglas frontier were statistically significant and the model met most of the production theoretical properties. VMP derived from the Cobb–Douglas were 2.23 NZ$/cm for SED and 16.88 NZ$/GPa for STF. The Translog frontier coefficients were also significant (p<0.05) and VMP derived from this model were 1.67 NZ$/cm for SED and 9.15 NZ$/GPa for STF. Thus, for the analyzed production stage, changes to SED and STF were relevant for improving log value recovery above MSG8+. Technical efficiency derived from the frontiers allowed to identify and characterize the best logs to produce structural grades with stiffness of 8 GPa or higher.  相似文献   

3.
Abstract

Volume equations for poplars growing on farmland in Sweden. The aim of the study was to construct a simple volume equation for poplar and to evaluate the equation together with seven published equations. Data from 72 poplars were collected from 37 stands in central and southern Sweden (lat. 55–60°N). The stands’ mean age and density was 21 years and 940 stems ha?1, respectively and the trees’ mean diameter at breast height (DBH) was 25 cm. One simple volume equation with three parameters to be estimated for poplar was constructed with DBH and total height (H) as independent variables. This equation was analyzed and compared to seven published simple equations. The best performance, in terms of low values of Root Mean Square Error (RMSE) and Absolute Bias, was achieved by the equations developed by Eriksson and by Scott. However, due to these equations high level of multicollinearity an alternative recommendation was made where the constructed equation is recommended.  相似文献   

4.
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.  相似文献   

5.
ABSTRACT

Tree-stem volumes constitute critical measurements for forest management. We propose a general two-criterion procedure for choosing the most reliable and robust volume equation(s), among a set of them previously fitted in a forest. Also, the proposal can be used as an additional criterion when fitting new equations to a single sample. Through simulated volumes, we considered how well a model estimates the volume generated by itself (the more accurate estimation, the better) and measured a model’s variability of the mean errors when it estimates volumes rebuilt by other models (the lower variability, the better). The procedure is exemplified with volume equations of Pinus patula in the Forestry Management Unit 1302 in Hidalgo, Mexico. In the example, we found that a linearized form of the combined-variable equation results reliable and robust. This selection coincided with the one made with data of a recent 150 trees sample (validation), where the rebuilt-estimated mean volume differs 0.034 m3 from the observed mean volume; it represents around US$2.6. Therefore, it is shown that simulation becomes an effective tool to identify equations that do not reproduce the volume of trees well in the current forest and helps to choose reliable and robust equations.  相似文献   

6.
Abstract

A survey was conducted at nine sawmills in Japan to evaluate and compare the sawing of sugi (Cryptomeria japonica D. Don) logs of 30 cm and more in diameter. The purpose was fourfold: (1) to document sawing patterns appropriate to the large-diameter logs; (2) to examine the composition of wood components (structural, nonstructural, and fixtures) produced from those patterns; (3) to investigate log and product prices; and (4) to ascertain distances to the log supplier and product markets. Impetus for the study arose from a forecasted shift in the diameter distribution of plantation trees in Japan; from small and medium-sized logs to large-diameter logs. With an overabundance of large-diameter domestic logs forecasted within the next decade, the need to understand how to best utilize and effectively process the large-diameter resource is of utmost importance.  相似文献   

7.
ABSTRACT

Stem form information can enhance rapid estimation of stem volume. Studies on important determinants of stem form in pure stands are scanty. This study aimed at identifying determinants of stem form using Tectona grandis stands in Omo Forest Reserve, Nigeria. Twenty 0.04 ha square plots were randomly selected across four stand ages. Crown diameter, total and merchantable heights (MH), diameters at breast height (DBH), at 5.27 m tree height and at midpoint from breast height to tip of tree were measured in each plot. Measured trees were classified into four canopy layers (CL)—dominant, codominant, intermediate, and suppressed. Merchantable volume, basal area (BA), form factor (Ff), normal form quotient (Qn), Girard form class (QG), absolute form quotient (Qa), ratio of diameter at merchantable limit to diameter at the base (Dt/Db), and tree slenderness coefficient were derived from the data. Analysis of variance, correlation, and regression analyses were used to analyze the data. Significant differences were observed in stem form and tree size variables under different canopy layers. The DBH, BA, MHT, and CL were identified as important variables associated with stem form. Inclusion of Qa improved most the predictive ability of the selected stem volume equation.  相似文献   

8.
Abstract

A micropropagation process was developed for Anogeissus latifolia-a tree of fragile ecosystems. Multiple shoots were regenerated from cotyledonary node and epicotyl explants on Murashige and Skoog's (MS) medium containing 0.1 mgl-1 indole-3-acetic acid (IAA) + 1.5 mgl -l 6-benzylaminopurine (BAP) + additives (25 mgl -l each of adenine sulphate, L-arginine, ascorbic-, citric acids and 1.0 mM L-asparagine) + 200 μM Fe-EDTA (ferric-ethylenediaminetetraacetic acid) salt. The shoots differentiated in vitro were subcultured and repeatedly transferred onto fresh medium but with 1.0 mgl-1 of BAP to achieve 4-5 fold rate of shoot multiplication. After every 4th week of culture, from each culture bottle 8-10 shoots could be harvested for rooting. The shoots produced in culture were rooted in vitro on half strength MS medium with 1.0 mgl -l either of IBA (indolebutyric acid) or NAA (naphthaleneacetic acid). The shoots were pulse treated with combination (100 mgl -l each) of IBA and NOA (2-naphthoxy acetic acid) rooted ex vitro. The ex vitro root induction method is highly efficient and plantlets so generated could be acclimatized and pot transferred. The process developed can be used for large scale production of plants of A.  相似文献   

9.
Accurate estimates of lumber volume become an important indicator of production and monetary value for a sawmill. However, such estimates are only obtained directly after logging, and no accurate predictions are made for the Amazonian commercial species. In this sense, the objective was to generate equations of lumber volume for commercial species in Amapá (a state in northern Brazil) by adjusting and selecting regression models. The data of 50 logs processed from 10 commercial species were collected, as well as the quantity and volume of sawn products. Sixteen (16) statistical models were adjusted and statistical weights were performed to evaluate the quality of the estimates and to select the best equation by species. In summary, precise estimates of lumber volume can be obtained by the nº16 model for Carapa guianensis, while the models nº13 and nº15 are the most recommended for Dinizia excelsa and Hymenolobium petraeum, respectively. Model 7 presented the best adjustments for Hymenaea courbaril and Vochysia guianensis. Equations using only the log diameter variable suggest less precise estimates. Also, the log volume should be considered as an important predictor variable to obtain the serrated/lumber volume for the different Amazonian commercial species.  相似文献   

10.

Properties of 200 poorly debarked softwood logs were studied in order to examine how different log characteristics affect drum debarking of mixed pine (Pinus sylvestris L.) and spruce [Picea abies (L.) Karst] pulpwood during the summer. The definition of a poorly debarked log and the sampling criterion was that >10 dm2 bark remained on the log surface. The average share of poorly debarked logs was 8% and the most frequent log type was breakage logs. The main species among the poorly debarked logs was spruce and the mean wood moisture content was considerably lower than for the pulpwood chips. Many logs were affected by root rot or were damaged by harvesting equipment, resulting in reduced moisture content and, consequently, in increased bark/wood shear strength. Bark from the poorly debarked logs contributed to approximately 68% of the bark content in the chips. By avoiding air-drying of pulpwood, or by sorting pulpwood prior to debarking, the bark content in chips might be substantially reduced, which would improve the purity of the pulp and decrease production costs.  相似文献   

11.
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.  相似文献   

12.
 The amounts of CO2 that are absorbed and emitted by forest in a model stand area were determined using two calculation methods, namely the flow approach and the stock approach for emission trading, to understand the relationships between the cutting age for the highest profit rate (CAHPR; optimum tree ages to be cut so as to maximize the profit) and (1) the prices of CO2 and (2) the balance between CO2 emission and absorption. The resultant CAHPR differed between these two CO2 accounting methods, which give different tree ages for maximum log volume yield. A rise in CO2 price caused the CAHPR to approach the tree age of maximum log volume in the flow approach method, and to deviate from the tree age of maximum log volume in the stock approach method. Even at the same CO2 price, the CAHPR differed between the CO2 accounting methods. At low CO2 prices, the CAHPR did not affect situations where the difference of average profit is large by cutting age. On the other hand, the CAHPR was greatly affected at low CO2 prices when the mean log volume growth changed with tree age. These trends were found to be universal. Received: September 18, 2001 / Accepted: October 25, 2002 Acknowledgments This study is one of the fifth science study subsidy projects of the Japan Forest Technology Association. Correspondence to:K. Sakata  相似文献   

13.

Studies on rearing and development of the Peach Buprestid,Capnodis tenebrionis L. (Col., Buprestidae).

The composition of a semisynthetic medium for rearing the Peach Buprestid,C. tenebrionis, and the techniques for handling the insects and their eggs in the laboratory are described.

The period required for the biological cycle using this medium and the techniques described are about the same as the required on natural hosts. However the medium is not yet a perfect substitute for the natural food of the larvae and further experiments is carried out at present to reconsider it.

  相似文献   

14.
[目的]研究建立地上生物量与地下生物量、立木材积之间相容,以及地上生物量与各分量之间可加的一体化生物量模型系统,为准确估计森林生物量提供定量依据。[方法]以新疆自治区的云杉(Picea spp.)为研究对象,基于230株和78株样木的实测地上生物量、树干材积和地下生物量数据,综合利用误差变量联立方程组方法和哑变量建模方法,研究建立集地上生物量、树干材积和地下生物量为一体,兼具相容性和可加性的二元和一元生物量模型系统,并分析一元模型是否受地域的影响。[结果]所建云杉一元和二元一体化生物量模型系统,地上生物量方程的平均预估误差在7%以下,干、皮、枝、叶各分项生物量方程的平均预估误差在10%左右,地下生物量方程的平均预估误差在15%以下,均达到了相关技术规定的预估精度要求。除了干材和树皮生物量的估计效果不如二元模型外,一元模型对其它各项生物量的估计均要优于二元模型。比例控制法和代数控制法均能解决地上生物量与干、皮、枝、叶各分项生物量之间的可加性问题,且两种方法得出的模型预估结果无显著差异。[结论]将哑变量引入误差变量联立方程组,不仅能解决地上生物量和地下生物量样本单元数不相等时如何联合建模的问题,还能同时解决地上生物量与地下生物量和立木材积之间的相容性问题及地上生物量与各分量之间的可加性问题,方法切实可行;对地上生物量、地下生物量及立木材积的估计,含区域因子的哑变量模型均要优于总体平均模型。  相似文献   

15.
Abstract

The objective of this study was to compare volume growth and external timber quality properties of lodgepole pine (Pinus contorta Dougl. var. latifolia) stands planted in different spacings (1.41×1.41, 2.00×2.00, 2.83×2.83, 4.00×4.00) in southern Sweden. In northern Sweden lodgepole pine has been grown for a long time and shows superior volume production compared to Scots pine (Pinus Sylvestris L.). The Swedish Forestry Act restricts establishment of lodgepole pine plantations in southern Sweden. However, it is important to increase the knowledge about lodgepole pine and its potential use also in this part of the country. Two experiments in southern Sweden were studied. Each trial was designed as a random block experiment with two blocks. Both investigated stands had an age of 23 years at the time of assessment. The mean diameter and the volume production differed significantly between the spacings. The highest volume production was found in the narrowest spacing, 313% compared to the widest spacing. Significant differences between spacings were also found concerning external quality traits. The frequency of dominant and co-dominant trees without defects was 24% in the most open spacing compared to 46% in the narrowest one. Under current circumstances approximately 2500 seedlings/ha in the initial stand seems to be a reasonable compromise between growth, diameter development and timber quality.  相似文献   

16.
Abstract

Quality sorting of sawlogs based on three-dimensional (3D) or X-ray scanning or a multivariate combination of variables from both methods may be used to decrease the production of off-grade products carrying unwanted combinations of dimension and grade. There is, however, potential for further improving the sorting accuracy if 3D and X-ray raw data are combined at an early stage using path length compensation. From the measured 3D shape, a good estimate of the length of each X-ray path through the log can be made, enabling the calculation of a log density profile from the measured X-ray attenuation. The effect of this technique on heartwood diameter measurements of 423 Scots pine (Pinus sylvestris L.) logs was evaluated. By the addition of 3D data to the X-ray data it was possible to raise the predictability of the heartwood diameter from R 2=0.84 to 0.95 and to improve the root mean square error from 17 mm to 9.3 mm, primarily because of the enhanced contrast between heartwood and sapwood.  相似文献   

17.
Abstract

Multiple shoots and plantlets were developed in vitro from cotyledonary nodal segments of in vitro raised seedlings of Anogeissus rotundifolia (syn. A. sericea var. nummularia)-a rare and endemic tree species of the Thar Desert. About 15-20 shoots differentiated from a single cotyledonary node within four weeks on Mu-rashige and Skoog's (MS) basal medium containing 0.1 mg l?1 indole-3-acetic acid (IAA) + 2.0 mg l?1 6-benzylaminopurine (BAP) + additives (25 mg l?1 each of adenine sulphate, L-arginine, and citric acid, and 50 mg l?1 of ascorbic acid) at 26 ± 2°C temperature and 36 μmol m?2 s?1 photon flux density with a 12 h/day photoperiod. The shoots produced in vitro were further multiplied by subculturing on fresh medium. The original cotyledonary nodal segment was repeatedly transferred (5 to 6 times) onto fresh medium containing 1.0 mg l ?1 BAP + 0.1 mg I ?1 IAA + additives to yield fresh crops of multiple shoots. These shoots were rooted on half-strength MS medium supplemented with 0.1 mg l?1 indole-3-butyric acid (IBA). Plantlets were transferred to pots containing sand-dune soil and ver-miculite it the ratio of 4:1 (v/v) and hardened in a growth chamber for two weeks and finally transferred to a greenhouse. From a single cotyledonary node about 1500 plantlets could be developed within four months. The method developed is useful for mass multiplication and for the conservation of germplasm of Anogeissus rotundifolia.  相似文献   

18.
Abstract

The volume of a tree's crown represents the accumulated historic crown surfaces integrated over time and environmental conditions. As such the crown volume of a tree should be correlated to the stem diameter, which represents accumulated historic wood increment. This study examines the relationship between crown and stem metrics of four tree species, Macaranga peltata, Schumacheria castaneifolia, Shorea megistophylla, and Shorea trapezifolia, from an evermoist forest in southwestern Sri Lanka. Shorea megistophyllahad the highest correlation between crown volume and stem diameter of the four species (r2 = 0.55). The addition of an inverted parabola, to represent historic crown surfaces not included by the current crown volume, improved correlations with stem diameter significantly, especially in the flat-topped pioneer species, Macaranga peltata. Schumacheria castaneifoliashowed poor correlations between stem and crown dimensions, suggesting that allocation to fruit and flower production may receive higher priority than diameter growth. The relative importance of current crown volume and cumulative crown volume in explaining variation in stem diameter offers insight into species life-history patterns.  相似文献   

19.
Abstract

Wood density is an important quality variable, closely related to the mechanical properties of the wood. Precise wood density measurements in the log sorting would enable density sorting of logs for products such as strength-graded wood and finger-jointed wood. Density sorting of logs would also give more homogeneous drying properties and thus improve the quality of the final products. By compensating the radiographs from an X-ray log scanner for the varying path lengths using outer shape data from a three-dimensional (3D) scanner, it is possible to make precise estimates of both green and dry density. Measurements on simulated industrial data were compared with densities measured in computed tomographic (CT) images for 560 Scots pine (Pinus sylvestris L.) logs. It was found that green sapwood density could be measured with predictability R 2=0.65 and root mean square error (RMSE) of 25 kg m?3. Green and dry heartwood densities were measured with similar precision: R 2=0.79 and RMSE=32 kg m?3 for green density and R 2=0.83 and RMSE=32 kg m?3 for dry density.  相似文献   

20.
Abstract

The Sierra Madre Occidental ecoregion accommodates some of the richest biodiversity anywhere in North America and contains about two-thirds of the standing timber biomass in Mexico. Worldwide forest trees provide an industrial output of about 363 million cubic meters, with the volume of bark accounting for an estimated 10% of total tree volume, so that bark is a very important nonwoody product. In this study, the proportion of bark volume (PBV) and its correlation with selected tree characteristics as well as the relationship between total tree volume and wood volume (WV) and total volume and bark volume (BV) were calculated for the first time for the 16 common and commercially most important tree species in the temperate pine-oak forest region of El Salto (Durango) on the Sierra Madre Occidental, Mexico. Measurements were made on 2,027 felled trees. The PBV in the species investigated ranges from 0.129 to 0.260 depending on the species and genus, with a mean value of 0.175. BV and WV can be accurately estimated. The approach used in this study is simple and effective, and very user-friendly. The method is recommended for researchers wishing to develop bark models for other tree species.  相似文献   

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