尾叶桉人工林二元材积表的研制

通过收集福建省永安市不同林龄、立地、密度的尾叶桉人工林林分的样木资料,采用多模型优选法和逐步回归法研制尾叶桉人工林二元立木材积表,并用相关指数、剩余标准差、平均系统误差、平均相对误差绝对值、预估精度作为评价指标,应用灰色关联分析法建立综合评价指数,评价模型优劣。经检验,所编的材积表完全符合生产上的精度要求,且理论基础扎实,编表结果可靠,可在森林资源调查中推广应用。     

贡嘎山冷杉林土壤CO_2释放的模拟研究

利用贡嘎山冷杉林1998年和1999年土壤CO_2通量对生物地球化学循环模型Forest-DNDC进行校准和验证,通过调整温度和湿度对土壤根呼吸影响的计算公式和对模型参数的本土化,提高了模拟值与真实值之间的吻合程度,尤其是提高了冬季土壤CO_2释放模拟的准确性.校准后使土壤CO_2日释放量模拟结果的平均误差((-e))和相对平均误差((-e)')分别下降了3.81 kg/hm~2和13.49%,绝对平均误差(M)和相对绝对平均误差(M')也同时降低;模型效率的Nash-Sutcliffe系数(Me)和冷模拟(利用默认参数)相比,也由0.651提高到0.683.模型验证结果表明,冷杉林土壤CO_2释放通量模拟值大体上能够与实际观测值的季节变化和日变化保持一致,在释放的量上也与实际观测值相当.     

Knot attributes and occlusion of naturally pruned branches of Fagus sylvatica

The aim of this study was to develop models on occluded branch characteristics for Fagus sylvatica (beech) based on 41 sample trees. A total of 717 beech branches were sampled; this information was then used to predict (1) the time for a complete occlusion, (2) the total radius of the occluded branch inside the trunk, (3) the branch insertion angle at the year of its death and during branch development, and (4) the dead branch portion of the occluded branch (loose knot). Generalized hierarchical mixed models with nonlinear forms were used in this analysis. The models explained between 6.3 and 52.2% of the total variance (including random effects 23.8–77.1%). The diameter of the occluded branch and the stem radial increment played dominant roles as predictors. Larger branches showed a significantly longer occlusion time, a larger occluded branch radius, a steeper insertion angle, and a higher loose knot portion. Simulations showed a biologically reasonable overall behavior of the models. The residual variation was tolerable for integrating the models into a growth simulation system.     

瓦斯浓度红外检测噪声消除方法研究

将数学方法与实验方法相结合,通过测量信号和参考信号的比值,消除由于光源的不稳定及其他因素引起的检测误差、外界环境引起的误差等,并利用数学方法推导得到计算方程。实验结果验证此类方法的可行性,可有效消除井下复杂恶劣环境带来的一系列噪声干扰,包括检测系统固有的性能误差和外部环境引起的干扰误差。     

Rapid assessment of wood chemical properties and pulp yield of Eucalyptus camaldulensis in Thailand tree plantations by near infrared spectroscopy for improving wood selection for high quality pulp

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.     

快速检测木材微纤丝角的近红外光谱分析技术

介绍了一种新的测量木材微纤丝角的无损检测技术--近红外光谱分析,并详细阐述了测量时木材样品的选择及制备,测量工作包括X射线衍射和近红外光谱采集、多变量数据分析与模型建立的方法及步骤.证明了近红外光谱分析技术可以用于快速准确地预测木材的微纤丝角.     

小兴安岭谷地云冷杉林叶面积指数的季节动态及空间格局

应用半球摄影技术对小兴安岭谷地云冷杉林落叶季节(7-11月)的有效叶面积指数进行动态监测.为准确估测谷地云冷杉林的叶面积指数(LAI),对叶凋落末期(11月初)的有效叶面积指数(LAIe)进行木质部分及集聚效应(包括冠层水平集聚和针簇内集聚效应)的合理校正,以校正值作为该时期常绿树种的真实叶面积指数(LAIt),结合凋落物法,反推得到LAIt的季节动态并分析LAIt最大时期(7月)和最小时期(11月)的空间格局特征.结果表明:谷地云冷杉林11月初木质部分所占比例(α)均值为0.10±0.06,冠层水平集聚指数(ΩE)均值为0.90±0.04,常绿针叶树种的针簇内集聚指数(针簇比,γE)为红松(1.77)＞云杉(1.28)＞冷杉(1.10);LAIt随季节变化呈递减趋势,7月达到峰值(3.97),11月值最小(2.71);相对而言,光学仪器法测定的LAIe各调查期的低估范围为28.81％ ～43.24％,平均低估值为32.98％;变异函数分析表明,LAIt大的月份其空间异质性程度也大,7和11月LAIt的空间异质性主要由空间自相关引起,其引起的空间异质性分别占总空间异质性的99.8％,66.9％.     

Nondestructive determination of paper properties of Populus × euramericana with near infrared spectroscopy

Five Populus x euramericana wood samples representing three different sites were selected and nearinfrared （NIR） spectra were obtained. For these sections, basis weight, brightness and three mechanical properties （tensile index, tearing index and bursting index） were determined by standard analytical methods. Calibrations were developed for each paper property using the NIR spectra, data on paper properties, using partial least squares （PLS） regression. The results show that the coefficients of correlation of calibration and validation for basis weight were 0.8824 and 0.8299, respectively; the standard error of calibration （SEC） and prediction （SEP） were 1.150 and 1.170, respectively. In testing for brightness, the correlation coefficient of calibration was 0.9621 and for validation 0.9612, while the SEC and SEP were 0.997 and 1.300, respectively; paper brightness and NIR spectroscopy were highly correlated. NIR spectroscopy can be used to predict tensile, tearing and bursting indices of paper samples rapidly. We found that the paper properties fitted by NIR and GB methods were highly correlated. The coefficients of correlation of calibration and validation for basis weight exceeded 0.8000, while the SEC and SEP were very small. These results reveal that the five paper properties of Populus x euramericana and those predicted by the NIR model were highly correlated. We conclude that the NIR models can be used for the prediction of paper properties.     

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.     

A jack pine survival model for spring-lifting and planting delays in Ontario

The general problem of developing a model capable of exploring the survival response of seedlings to tradeoffs in the timing of spring lifting, planting and cold storage was investigated. After the construction of an overall model framework, one general and three specific functions to predict first-year survival for batches of 2 + 0 jack pine seelings were developed. The independent variables required by the functions include: cold storage duration (days), average air and soil temperature during planting (°C), cumulative degree days at time of planting (°C), ratio of terminal-to-top length at time of lifting, and cumulative degree days at time of lifting (°C). A brief example of the type of use to which such functions could be put, and an indication of the expected level of confidence that may be placed in such a prediction, is presented. The survival functions developed in this study were not designed for widespread use throughout the Province of Ontario. At most they should be limited to 2 + 0 jack pine planting stock originating from Swastika Nursery, and planted nearby.Approved for publication as Journal Article No. J-7315 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University.