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1.
用常规方法测定了104个速生桉木样品的综纤维素、聚戊糖、酸不溶木素及苯醇抽出物含量并采集了样品的近红外光谱。对原始光谱进行多元散射校正后,运用偏最小二乘法和交互验证的方法,确定最佳主成分数并建立样品相关化学成分含量的校正模型。独立验证中综纤维素、聚戊糖、酸不溶木素和苯醇抽出物模型的决定系数 Rval2分别为0.9067、0.9033、0.9504、0.9570;预测均方根误差(RMSEP)分别为0.33%、0.50%、0.31%、0.17%;相对分析误差(RPD)值分别为3.22、3.20、4.43、4.73;绝对偏差(AD)分别为?0.53%~0.60%、?0.95%~0.77%、?0.55%~0.52%、?0.22%~0.29%,4个校正模型较好地预测了验证集样品的化学成分含量,基本满足制浆造纸工业中快速测定速生桉木原料的需求。  相似文献   

2.
Near-infrared (NIR) spectroscopy has been demonstrated as a means for rapid nondestructive determination of the chemical composition and final pulp yield of Eucalyptus camaldulensis in Thailand tree plantations. Multiple linear regression (MLR) analysis and partial least squares (PLS) analysis were introduced to develop statistical models in terms of calibration equations for total pulp yield, screened pulp yield, and contents of -cellulose, pentosans, and lignin in wood. In MLR analysis, a reasonably good calibration equation was found only for pentosans (standard error of prediction (SEP): 0.98%). The PLS analysis improved the accuracy of prediction for every criterion variable, especially for pentosans (SEP: 0.91%) and lignin (SEP: 0.52%). Also, in the case of screened pulp yield, we were able to use such a statistical result as an indicator of the characteristics of the pulp and paper. Thus, NIR spectroscopy could be satisfactorily used as an effective assessment technique for Eucalyptus camaldulensis plantation trees.  相似文献   

3.
基于近红外光谱与BP神经网络预测落叶松木屑的含水率   总被引：2，自引：0，他引：2  
利用近红外光谱(NIR)技术结合BP神经网络定量预测了落叶松木屑的含水率。首先对采集的落叶松木屑原始近红外光谱进行9点平滑及多元散射校正预处理,然后利用主成分分析法提取光谱数据主成分作为BP神经网络的输入,最后建立BP神经网络预测模型并采用交叉验证法对模型进行验证。所建模型校正集的相关系数R为0.98,校正集的均方根误差RMSEC为0.001 7;预测集的相关系数R为0.99,预测集的均方根误差RMSEP为0.001 5。研究表明,此方法可以实现对落叶松木屑含水率的快速预测。  相似文献   

4.
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.  相似文献   

5.
The orientation of the tracheid cells with respect to the stem axis (grain angle, spiral grain) exerts a strong influence on numerous material properties. Therefore, several methods have been developed to assess this wood anatomical feature. The current study compares SilviScan spiral grain measurements, which uses X-ray diffractometry, with direct goniometer readings. The correlation between these two methods yielded an r2 of 0.874 and a root mean square error of prediction (RMSEP) of 1.21 clearly demonstrating that X-ray diffractometry can provide accurate and rapid information on the grain orientation in Norway spruce (Picea abies (L.) Karst.) or similar structured softwoods.  相似文献   

6.
Eucalyptus camaldulensis Dehnh. (red river gum; Myrtaceae) is an invasive tree in riparian habitats of the Western Cape, South Africa, where it replaces indigenous vegetation and affects ecosystem functioning. These invasions lead to changes in river geomorphology and reduction in stream flow. The mechanisms that drive these effects are poorly understood. The potential for allelopathic effects of aqueous extracts of E. camaldulensis tissues and of soil and litter collected beneath E. camaldulensis trees on the germination and seedling growth of four selected native plant species was investigated in a greenhouse experiment. Soils collected beneath E. camaldulensis trees were used in three treatments: untreated soils, sterilised soils and sterilised soils overlaid with a eucalypt litter layer. In addition, soils collected from underneath native species were used in two treatments: untreated soils and soils overlaid with a eucalypt litter layer. All soil treatments were watered with three E. camaldulensis leaf, bark and root aqueous treatments. Compounds present in the aqueous extracts and fresh samples were identified using gas chromatography. Soil and aqueous treatments showed varying effects on germination and seedling growth of the four native species. Germination and seedling growth of Olea europaea subsp. africana and Dimorphotheca pluvialis were significantly reduced by E. camaldulensis root and bark aqueous extracts as well as by the soils treatments. The addition of eucalypt litter to native and sterilised soils reduced shoot and root growth of all four native species. Compounds such as -phellandrene, eucalyptol, p-menth-1-en-8-ol and -pinene, which have the potential to inhibit germination and plant growth, were identified in E. camaldulensis aqueous extracts and fresh samples. Although the methods applied in this study had limitations (e.g. lack of control treatment to litter addition), the results provide an additional motivation to prioritise removal of invasive E. camaldulensis stands from riparian ecosystems. Restoration initiatives should target native species that are not negatively affected by allelopathy.  相似文献   

7.
The use of furfuryl alcohol (FA) as a wood modification agent has been known for decades. An independent and reliable analytical method to determine the level of furfurylation is not available. This article reports the use of near infrared spectroscopy (NIR) and thermogravimetric analysis (TGA) to make partial least square prediction models for determining the furfurylation level (the percentage of FA polymer formed within the wood structure). A total of 115 individual samples of furfurylated Scots pine (Pinus sylvestris) originating from 115 production batches were used for modelling. As much as 81 samples were randomly selected for the calibration set and 34 samples for the validation set. Both NIR and TGA gave good predictions when validated by a separate test set. The r 2 for NIR and TGA are 0.93 and 0.94, respectively, and the root mean square errors of predictions are 1.025 and 0.958, respectively. However, the number of principal components for the NIR and TGA models is two and six, respectively. The NIR method is preferred because only two principal components are used and sampling is fast.  相似文献   

8.
Three models for the prediction of bamboo culm length and two for culm volume were fitted from data of 303 guadua bamboo (Guadua angustifolia Kunth) culms. Data are from 101 temporary inventory plots systematically distributed over the coffee region of Colombia (inventory area about 1,029,525 ha). Linear and non-linear regression models were used, and the precision of the models was evaluated by cross-validation. The models were compared by studying the adjusted coefficient of determination, the bias, mean square error and Akaike’s information criterion and by the F-test that compares predicted and observed values. For culm length, the best fit showed models that included predictor variables related to stand characteristics such as quadratic mean diameter and number of culms per ha. For culm volume prediction, the inclusion of culm length improved the model significantly. For the simple form factor model, precision of prediction was least. The models developed are useful in facilitating the estimation of stand characteristics that are relevant for the silvicultural management of Guadua stands and also for the assessment of their environmental services (such as carbon sequestration).  相似文献   

9.
Determination of quality parameters such as lignin and extractive content of wood samples by wet chemistry analyses takes a long time. Near-infrared (NIR) spectroscopy coupled with multivariate calibration offers a fast and nondestructive alternative to obtain reliable results. However, due to the complexity of the NIR spectra, some wavelength selection is generally required to improve the predictive ability of multivariate calibration methods. Pinus brutia Ten. is the most growing pine species in Turkey. Its rotation period is around 80 years; the forest products industry has widely accepted the use of Pinus brutia Ten. because of its ability to grow on a wide range of sites and its suitability to produce desirable products. Pinus brutia Ten. is widely used in construction, window door panel, floor covering, etc. Determination of lignin and extractive content of wood provides information to tree breeders on when to cut and how much chemicals are needed for the pulping and bleaching process. In this study, 58 samples of Pinus brutia Ten. trees were collected in Isparta region of Turkey, and their lignin and extractive content were determined with standard reference (TAPPI) methods. Then, the same samples were scanned with near-infrared spectrometer between 1,000 and 2,500 nm in diffuse reflectance mode, and multivariate calibration models were built with genetic inverse least squares method for both lignin and extractive content using the concentration information obtained from wet standard reference method. Overall, standard error of calibration (SEC) and standard error of prediction (SEP) ranged between 0.35% (w/w) and 2.40% (w/w).  相似文献   

10.
We exposed the roots of nine Myrtaceae species (Melaleuca bracteata F. Muell., Melaleuca cajuputi Powell, Melaleuca glomerata F. Muell., Melaleuca leucadendra [L.] L., Melaleuca quinquenervia [Cav.] S.T. Blake, Melaleuca viridiflora Sol. ex Gaertner, Eucalyptus camaldulensis Dehnh., Eucalyptus deglupta Bl., and Eucalyptus grandis W. Hill ex Maiden) to 1 mM Al in a nutrient solution for either 24 h or 20 days to evaluate their sensitivity to excess Al and to determine whether callose and lignin formation can be used as interspecific indicators of Al sensitivity. Inhibition of root elongation by Al varied among the species. Melaleuca leucadendra, M. cajuputi, E. grandis, M. quinquenervia, and E. deglupta were tolerant to 1 mM Al, whereas M. viridiflora, E. camaldulensis, M. glomerata, and M. bracteata were sensitive to 1 mM Al. We found that Al induced callose formation in the root tips of each species, but lignin was formed only in the root tips of the most sensitive species, M. bracteata. Root elongation at 1 mM Al was negatively correlated with Al-induced callose formation but not with the Al-induced lignin formation in the root tips. These results suggest that Al-induced callose formation, rather than lignin formation, can be used as an interspecific indicator of Al sensitivity.  相似文献   

11.
The effect of alkali extraction on the lignin monomeric composition was examined inEucalyptus camaldulensis andE. globulus by thioacidolysis using extractive-free samples as a control. Results showed that the effect onEucalyptus is different among species and among sample positions in the trunk, although a small amount of lignin is solubilized during the extraction in all samples. In addition, it was proved that lignin extracted by the alkali extraction is not always guaiacyl-rich, probably relating to the original lignin monomeric composition, which depends on the sample species or the sample position in the trunk.  相似文献   

12.
Density and fiber length belong to the parameters that are used by the pulping industry as indicators of wood quality for different industrial processes and final paper products. The feasibility of Fourier transform near-infrared (FT-NIR) spectroscopy for the non-destructive evaluation of fiber length and air-dry density of fast-growing E. camaldulensis from Thailand was investigated using 50 samples. NIR spectra taken from solid wood and air-dry density as well as fiber length were used for partial least squares (PLS) regression analyses. It is the first time that the fiber length of E. camaldulensis solid wood could be predicted with high accuracy and precision and that the ratios of performance to deviation (RPD) obtained are the first that fully fulfill the requirements of AACC Method 39-00 (AACC 1999) for screening in breeding programs (RPD?≥?2.5). The RPDs for cross-validation (test set validation) of the NIR-PLS-R models of 3.3 (3.8) for air-dry density and 3.5 (3.9) for fiber length allow drawing the conclusion that the models are at least applicable for screening in breeding programs as they lie in-between screening (RPD?≥?2.5) and quality control (RPD?≥?5). Even when 40% of the samples were removed in cross-validation of the air-dry density model, the RPD is 3.2, which confirms that the model is robust, stable, and well qualified for prediction. The good model statistics obtained in this study might be due to the fact that measurement sites for the measurement of NIR spectra, air-dry density, and fiber lengths were strictly coincided.  相似文献   

13.
Feasibility of near-infrared (NIR) spectroscopy for developing multi-species model for plantation timber was explored for estimation of holocellulose in un-extracted milled wood samples. Six commonly planted species of Eucalyptus tereticornis, E. camaldulensis, E. grandis, Leucaena leucocephala, Dalbergia sissoo and Populus deltoides from a wide range of locations and varying age groups were taken for the present study. Few samples of E. hybrid between E. tereticornis and E. camaldulensis were also included in the study to make the model useful for practical application. NIR models were evaluated using partial least squares regression (PLSR-1—full cross-validation, PLSR-2—cross-validation which leaves more than one out) and by dividing the samples into calibration and prediction (test) sets and interchanging them from calibration to prediction sets. The predictive ability of the model was assessed by calculating four ratios of multivariate statistics for individual species model and combined species models. A final combined model for all the species having component range of 76.14–63.03 % and standard deviation of 2.586 % was developed in the spectral range of 7502–4246 cm?1 wave number using 1st derivative plus multiplicative scatter correction using factor of nine by removing samples with outliers found in all the PLSR-2 evaluation steps and in most of the models. The model remained stable even when 30 % of the samples were left out with no outlier detected.  相似文献   

14.
为研究巨尾桉人工林林木根径、胸径与树高数学模型,在滇西南的双江县选取138株（其中建模样本103株,检验样本35株）树干健全、通直圆满、无分杈的巨尾桉人工林样木,采集其根径与树高、胸径与树高成对数据。利用SPSS 21.0回归分析,分别建立线性方程、对数曲线、指数曲线和Logistic曲线等11个数学模型,以决定系数（R2）、估计值的标准误（SEE）、均方差（RMSE）、平均绝对偏差(MAD)、相对误差（RS）、模型预估精度（P）、显著性(Sig)P值作为模型评价指标,对比11个模型的拟合效果。结果表明,11个根径—树高模型显著性（Sig）P<0.001,其中有9个模型的预估精度大于97%,回归方程达到极显著水平,拟合效果较好;11个胸径—树高模型显著性（Sig）P<0.001,其中9个模型的预估精度大于97%,回归方程达到极显著水平,拟合效果也较好。通过对各项评价指标进行比较分析,确定三次项曲线H=a0+a1DR+a2DR2+a3DR3是拟合效果最好的根径—树高数学模型,代入拟合参数后的根径—树高数学模型表达式为H=11.069901-0.729389DR+0.096782DR2-0.001984DR3;线性方程H=a0+a1D是拟合效果最好的胸径—树高数学模型,代入拟合参数的胸径—树高数学模型表达式为H=4.818702+0.891217D。  相似文献   

15.
The aim of this study was to develop a method for segment-based forest inventory and determine whether segment-level inventories can be used in forest management planning. The study area covered 76 ha located in two different aerial photographs in eastern Finland. The study area was segmented into 220 segments with the aid of aerial photographs and the segment-level forest characteristics were assessed in the field using relascope sample plots and a field computer which displayed the aerial photographs, segment borders and surveyor's location on the screen. The segment estimates were calculated as weighted averages of k nearest neighbours (kNN) for the segments and the sample plots. The estimates were tested with a cross-validation technique. The averages and the standard deviations of the spectral values of aerial images extracted for the segments and the sample plots were used in the kNN estimation. The relative root mean square error of the mean volume was 58.1% (bias –6.4%) at the segment level and 57.9% (bias –0.9%) at the sample plot level. The segment-based approach studied here needs further research and improvement before it can be applied to forest management planning.  相似文献   

16.
以东北小兴安岭林区带岭林业局东方红林场的土壤为研究对象,对120个土壤样品近红外光谱做去噪、Savitzky-Golay平滑和多元散射校正预处理,利用偏最小二乘（PLS）法建立关于土壤碳含量和吸光度之间的定量分析模型,并进行模型校、验证及部分预测集样品碳含量预测.结果表明：主成分数为4时,模型最优.校正模型的决定系数R2和均方根误差（RMSE）分别为0.784和5.752;验证模型的决定系数R2和均方根误差（RMSE）分别为0.621和7.521,预测集样品的实测值和预测值的决定系数R2达到0.735,均方根误差RMSE为7.202,预测标准差SEP为10.356.应用近红外技术可以实现对小兴安岭次生林土壤碳含量的有效预测,为大面积快速测定土壤碳含量提供理论依据与技术支撑,进而为林分土壤碳循环的相关研究提供新的思路.  相似文献   

17.
采用偏最小二乘法(PLS)建立测定八角茴香中莽草酸含量的近红外(NIR)光谱定量分析模型.应用多种光谱预处理方法分别对八角茴香固体粉末样品的NIR光谱进行预处理,并采用预处理后的光谱建立定量分析模型,每个模型均经过选择最有效的光谱区域和最适主因子数进行优化.经过比较各个模型的内部交互验证均方根误差(RMSECV)和交互验证预测值与真实值间的相关系数(RV),外部预测均方根误差(RMSEP),选取最优的模型,结果表明定量分析模型稳健性好和测定精度高,在中药有效成分定量分析方面有很好的应用前景.  相似文献   

18.
A total of 910 maritime pine (Pinus pinaster Aiton) wood discs, belonging to a genetic trial of 80 families with 11–12 trees per family, were used in this study. A near infrared (NIR) partial least squares regression (PLSR) model for the prediction of Kappa number of Pinus pinaster Aiton pulps obtained from samples pulped under identical conditions was calculated. Very good correlations between NIR spectra of maritime pine pulps and Kappa numbers in the range from 58 to 100 were obtained. Besides the raw spectra, spectra pre-processed with ten methods were used for PLS analysis (cross validation with 57 samples), showing that even after test set validation (with 34 samples) no model decision could be made due to almost identical statistics. The final evaluation that proved the predictive power of the models by predicting pulps with unknown Kappa numbers allowed choosing a model according to a minimal number of outliers found during this process. The minimum–maximum normalized spectra in the wave number range from 6,110 to 5,440 cm−1 used for the calculation gave the best model with a root mean square error of prediction of 2.3 units of Kappa number, a coefficient of determination of 95.9%, and one PLS component. The percentage of outliers during evaluation was 0.9%.  相似文献   

19.
【目的】确保立木材积和树皮材积预测的一致性并提高预测精度。【方法】以大兴安岭兴安落叶松为研究对象,分别采用控制法和分解法研建了可加性模型系统。利用SAS统计软件模型模块proc model中的NSUR法进行拟合及参数估计。拟合结果采用确定系数(R2)和均方根误差(RMSE)进行评价;检验结果则通过确定系数(R2)、均方根误差(RMSE)、平均相对误差(MRE)、平均误差绝对值(MAB)和相对误差绝对值(MPB)进行评价。【结果】从模型的整体评价结果来看,两种方法的拟合和检验效果均很好,基于分解法构建的模型略优于基于控制法构建的模型;不同径阶的检验表明,对于中等径阶的树木(20≤D<36 cm),基于控制法的模型相对较好,而对于小径阶(5≤D<20 cm)和大径阶的树木(D≤36 cm),基于分解法的带皮、去皮、树皮材积模型的预测精度要比基于控制法的各立木材积模型要稍好。【结论】总的来说,两种可加性模型系统均能很好地预测单木带皮材积、去皮材积和树皮材积,并确保得到满足一致性的预测结果,在具体应用时可根据实际情况选择适合的可加性材积模型系统。  相似文献   

20.
《Southern Forests》2013,75(3-4):181-189
Near-infrared (NIR) scanning technology is regarded as a potential tool for rapid determination of wood properties, which can substitute time-consuming and costly traditional methods. Pinus patula is the most important softwood species in South Africa, and this study is aimed at developing NIR calibration models for quick prediction of its pulp yield and chemical composition. A total of 85 trees from 17 plots, covering the range of site conditions in the Mpumalanga escarpment area, were sampled. Two samples were taken from each tree: a 1 m billet above breast height and a 20 mm disc at breast height. The billet was pulped using the kraft pulping process to determine pulp yield. The disc was ground into sawdust and the chemical composition was determined using conventional wet chemistry. Sawdust was scanned on a NIR spectrophotometer to produce NIR spectra. Calibration models to predict pulp yield, cellulose and lignin content were developed by applying chemometrics and partial least squares regression. Validation and determination of prediction accuracy of the models were performed using independent data. The prediction of cellulose and lignin were acceptable with correlations of determinations (r 2) of 0.71 and 0.70 respectively. Standard errors of prediction were generally low (less that 0.86) for all the models. The prediction r 2 for both total and screened pulp yield were only 0.62. Although the cellulose and lignin models can be used with confidence, the expansion of the sample size for follow-up research must be considered in order to increase the variability of tested wood properties and improve the prediction strength of the models. The NIR calibration provided in this study can contribute to the efficient examination of forest site-to-wood quality relationships that would enhance precision forest management and wood processing efficiency.  相似文献   

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