Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber

This study was carried out to investigate the possibility of calibrating a prediction model for the moisture content and density distribution of Scots pine (Pinus sylvestris) using microwave sensors. The material was initially of green moisture content and was thereafter dried in several steps to zero moisture content. At each step, all the pieces were weighed, scanned with a microwave sensor (Satimo 9,4GHz), and computed tomography (CT)-scanned with a medical CT scanner (Siemens Somatom AR.T.). The output variables from the microwave sensor were used as predictors, and CT images that correlated with known moisture content were used as response variables. Multivariate models to predict average moisture content and density were calibrated using the partial least squares (PLS) regression. The models for average moisture content and density were applied at the pixel level, and the distribution was visualized. The results show that it is possible to predict both moisture content distribution and density distribution with high accuracy using microwave sensors.     

Assessment of wood surface roughness: comparison of tactile roughness and three-dimensional parameters derived using a robust Gaussian regression filter

Japanese oak and Japanese beech were sanded by hand with abrasive papers of varying grit number. Two three-dimensional parameters selected to characterize their surface roughness – one parameter for the distribution of roughness-profile peaks and the other for the relative area of the roughness-profile peaks above the threshold height – were compared against tactile roughness. The parameters were obtained from roughness profiles as determined by a robust Gaussian regression filter (RGRF) using seven cutoffs. The RGRF filtering process was adjusted specifically for the evaluation of wood surface roughness. Except for a cutoff wavelength of 0.25mm, the RGRF lent itself well to the determination of roughness profiles. No distortion of roughness profiles occurred around deep valleys, and there was a good correlation between the parameters and tactile roughness.Part of this study was presented at the 2002 Kansai Branch Office lecture meeting of the Japan Society for Precision Engineering, Kyotanabe, August 2002     

热带山地雨林生态系统水文化学循环规律的研究

根据５ａ定位观测，对尖峰岭热带山地雨林更新林生态系统的水文化学循环规律的数据分析表明，年均降雨量为２６６８．３ｍｍ，其中总径流量占４６．７％，蒸散量５３．３％，冠层截留量１４．０％。Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ的年均降雨输入量为７８．４ｋｇ／（ｈｍ２·ａ），总径流输出５６．７ｋｇ／（ｈｍ２·ａ），净积累２１．６ｋｇ／（ｈｍ２·ａ）；Ｓｉ、有机Ｃ、Ａｌ、Ｍｎ的年均降雨输入量为２５．０ｋｇ／（ｈｍ２·ａ），总径流输出为１１２．３ｋｇ／（ｈｍ２·ａ），净损失８７．３ｋｇ／（ｈｍ２·ａ），更新林系统仅处于更新进展过程中，同时证实了冠层对降水化学的淋溶效应，净淋溶系数达４．１１；提出了降雨、林内净降雨、总径流的各水化学物含量与其相应水量的回归模式     

黄土高原半干旱区油松人工林林冠截留模型及其参数特征研究

利用2008—2011年定位观测数据,采用回归分析方法对黄土高原半干旱区油松人工林林冠截留与林外降雨之间的关系进行建模研究,并运用Bootstrap方法,对模型参数特征进行分析。结果表明:林冠截留量(I)与林外降雨量(P)可用非线性模型I=a Pb进行回归模拟,回归方程为I=0.584P0.576;该模型不仅具有较高的拟合精度,且拟合方程参数稳定性良好,经检验,方程均达到显著性要求,可在该区域油松人工林应用。     

Studies on Heavy Metal Pollution in Soil—Plant System：A Review

Heavy metal pollution in soil-plant system is of major environmental concern on a world scale and in China in particular with the rapid development of industry.The heavy metal pollution status in soil-plant system in China,the research progress on the bioavailability of heavy metals (effecting factors,extraction methods,free-ion activity model,adsorption model,multivariate regression model,Q-I relationship,and compound pollution),and soil remediation are reviewed in paper.Future research and monitoring is also discussed.     

Heat budget and statistical analysis of the relationship between stream temperature and riparian forest in the Toikanbetsu River basin, northern Japan

Riparian forests greatly influence aquatic ecosystems by providing shade cover, which controls water temperature and limits primary production. We examined the relationship between forest cover and summer stream temperature in northernmost Japan. Heat budget and statistical analyses were employed and the results were compared. Heat budget analysis revealed that the water temperature would decrease almost linearly from 29°C to 25°C with an increase in forested reaches along a 3.2 km stretch of the river. Multiple regression analysis by the stepwise method chose only open channel length as a variable to explain the variation in maximum stream temperature. A sharp increase in stream temperature was noted when riparian forest cover was removed in short lengths, of up to 1.0km; this increasing trend gradually flattened as the length of open stretch increased. Thus, even small openings in the riparian canopy resulted in drastic rises in summer stream temperature. The maximum summer temperatures estimated by the two methods were coincided, and can therefore be accurately estimated by regression analysis. Retrospective analysis based on the regression equation showed that the maximum summer temperature in 1947 was 6°C lower than at present, and that a sharp increase occurred from 1947 to 1960, a period of rapid expansion of agricultural land development in the watershed.     

辽东山地混牧林经济分析

混牧林业是森林生态系统开发利用的一个重要组成部分。发展混牧林业直接关系到山地农村经济发展与环境改善和农民收入的提高。通过对辽东山地主要树种的林牧结合经营模式的实地观察调查,并采取回归分析和净现值计算,结果证实:混牧林业可以直接提高森林资源经营的经济效益,并且有较高的经济阈值,但对林分蓄积增长有负面影响,应适度控制载畜量和禁止在幼林下放牧。     

Modeling to assess growth respiration of stems inPinus densiflora trees

Multiple regression analyses were applied to the respiration data obtained by an excision method to distinguish between maintenance and growth respiration in stems ofPinus densiflora. Among several types of regression models, a few models showed marked stability of coefficient of growth related respiration that are independent of degrees of correlation between predictors and any combinations of predictors. These models predicted growth respiration as 0.45 g CO₂ g (dry weight)⁻¹. At 15°C, sapwood maintenance respiration rate was estimated to 0.72 mg CO₂ g⁻¹ day⁻¹. These estimates were not different from the results obtained with standing trees.     

Use of Near Infrared Spectroscopy to Measure Mechanical Properties of Solid Wood

The visible and near infrared （NIR） （350-2500 nm） spectra and the MOE of 438 small clear wood samples from Chinese fir, eucalyptus and poplar 72 were measured. Using partial least-square （PLS） modeling, the NIR spectra could be used to predict MOE and MOR of the clear-wood samples from Chinese fir and eucalyptus solid wood. NIR spectra could only be used to Predict MOE but not MOR of poplar clear-wood samples. With the exception of MoR of poplar clear-wood samples, the correlations between NIR and the mechanical properties are very strong, and the calibration and test correlation coefficients are both above 0.80.     

Intratree Variability of Tensile Strength Parallel to Grain in Chinese Fir and 1-214 Poplar from Plantation

The variation of tensile strength parallel to grain in Chinese fir and 1-214 poplar wood from plantations was studied in this paper. Aaccording to the national standards The Testing Methods for Physical and Mechanical Properties of Wood （GB 1927 to 1943 -- 1991）, the small clear wood samples were cut and tested, which represent the south and north of trees with heights of 1.3, 3.3, 5.3 and 7.3 m. The results showed： the tensile strength parallel to grain of the north wood was higher than that of south wood. ANOVA shows that the tensile strength parallel to the grain with height is of significant difference （at 0.05 level）.