Nail Holding Performance of Self-Tapping Screws on Masson Pine and Chinese Fir Dimension Lumbers

Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures.

Preparation and Properties of HBS Lignin from Masson Pine

In order to establish a new method for making cellulose and lignin from Masson pine, a high boiling solvent(HBS) pulping process with an aqueous solvent of 1,4-butanediol was investigated. Masson pine chips were pulped with a 70%—90% aqueous solution of 1,4-butanediol containing a small amount of a catalyst at 200—220 ℃ for 60—180 min. HBS Masson pine cellulose is suitable for making paper. Water-insoluble HBS lignin was separated from the liquor reaction mixture by water precipitation. The recovered high boiling solvent(RHBS) is able to be recycled as a pulping solvent, indicating that the HBS method is a pulping process of Masson pine which is energy saving, resources saving and pollution free. HBS lignin has a better chemical reactivity and a lower ash content than lignin sulfonate.

A preliminary study on the characteristics of fogwater in the masson pine forest in Chongqing, China

The masson pine (Pinns massoniana Lamb.) forest of 2000 ha situated on Nanshan, the south bank of the Yangtze River near Chongqing, China. From 1982, some trees began to die. Since then, half of the trees have died and the whole forest is in danger. Prom November 1986 to January 1987, a study dealt with the characteristics of fogwater in that area was carried out, in order to explain the relationship between acid fog and masson pine decline. The results of our study showed that the acid fog might be responsible in part for the decline of the masson pine forest.

Studies on Electrolyte Conductivity and Activity of Dehydrogenase of Chinese Fir and Masson Pine Bare-Root Seedling under Water and Cold Stress

The electrolyte conductivity and activity of dehydrogenase of bare-root seedlings of both Chinese fir (Cunningha-mia lanceolata (Lamb.) Hook.) and Masson pine (Pinus massoniana Lamb.) under freezing and desiccation treatments were studied. The results showed that needle electrolyte conductivity of both species increase significantly after freezing treatment and there are no significant differences in needle electrolyte conductivity between the two species. The dehydrogenase activity (ARD) of fine roots of both Chinese fir and Masson pine was negatively correlated with increasing freezing and desiccation. The results suggest that both electrolyte conductivity and dehydrogenase activity could be used as quick indicators of Chinese fir and Masson pine bare-root seedling quality.

Microfibril angle variability in Masson Pine (Pinus massoniana Lamb.) using X-ray diffraction

The microfibril angle of fiber walls is an ultra-mieroscopic feature affecting the performance of wood products. It is therefore essential to get more definitive information to improve selection and utilization. X-ray diffraction is a rapid method for measuring microfibril angles. In this paper, the variability of microfibril angle in plantation-grown Masson pine was investigated by peak-fitting method. This method was compared with the traditional hand-drawn method, 40% peak height method and half peak height method. X-ray diffraction measurements indicated that the microfibril angle changed as a function of the position in the tree. The mean microfibril angle decreased more gradually as the distance increased from the pith and reached the same level in mature wood. The microfibril angle also seemed to decrease clearly from the base upward. Differences of angle-intensity curves between heartwood and sapwood were also examined.

Simulation of the biomass dynamics of Masson pine forest under different management

TREE submodel affiliated with TREEDYN was used to simulate biomass dynamics of Masson pine （Pinus massoniana） forest under different managements （including thinning, clear cutting, combining thinning with clear cutting）. The purpose was to represent biomass dynamics involved in its development, which can provide scientific arguments for management of Masson pine forest. The results showed the scenario that 10% or 20% of biomass of the previous year was thinned every five years from 15 to 40 years made total biomass of pine forest increase slowly and it took more time to reach a mature community; If clear cutting and thinning were combined, the case C （clear cutting at 20 years of forest age, thinning 50% of remaining biomass at 30 years of forest age, and thinning 50% of remaining biomass again at 40 years of forest age） was the best scenario which can accelerate speed of development of Masson pine forest and gained better economic values.

Assessment of tree-ring mercury radial translocation and age effect in Masson pine:Implications for historical atmospheric mercury reconstruction

The tree ring has been regarded as an emerging archive to reconstruct historical atmospheric mercury(Hg)trends,but with the large knowledge gaps in the reliability.In this study,we comprehensively evaluated the Hg source,radial translocation and age effect of Masson pine(Pinus massoniana)tree ring at Mt.Jinyun in Chongqing,to assess the suitability of such tree ring as the archive of atmospheric Hg.Results showed that distinct variabilities among Masson pine tree-ring Hg concentration profiles.The Hg concentration significantly increased along with stem height(P<0.05),indicating the Hg in tree rings mainly derived from foliage uptake atmospheric Hg.We found a distinct age effect that the tree ring of young trees had the higher Hg concentration.Besides,we used the advection-diffusion model to demonstrate how Hg concentration shifted by the advection or/and diffusion in tree rings.The modeling results showed that the advection induced radial translocation during the young growth period of tree was a plausible mechanism to result in the tree-ring Hg record largely different from the trend of anthropogenic Hg emissions in Chongqing.We finally suggest that in further Hg dendrochemistry,better discarding the tree-ring Hg profile of the young growth period to reduce impacts of the radial translocation and age effect.

In Situ Generation of Copper Nanoparticles in Heat-Treated Copper-Containing Masson’s Pine as a Preservative Process for Sawn Timber

Heat-treated wood has good dimensional stability,durability,and color,but its susceptibility to fungal growth affects its commercial value.In this study,lumber harvested from mature Masson’s pine(Pinus massoniana Lamb.)was vacuum impregnated with a basic copper salt solution(copper hydroxide,diethanolamine,and polyethylene glycol 200)prior to heat-treatment at 220℃ for 3 h.Antifungal properties,surface chemistry,crystal structure and sugar contents were tested,compared with heat treatment alone.The results showed that the samples treated by heating without copper salt treatment showed poor suppression of fungal growth,the copperimpregnated heat-treated wood suppressed(100%)the growth of Botryodiplodia theobromae Pat.,Aspergillus niger V.Tiegh.,Penicillium citrinum Thom,and Trichoderma viride Pers.The combined results of X-ray photoelectron spectroscopy,X-ray diffraction and sugars analysis suggested that fungal inhibition by the heat-treated copper-bearing Masson’s pine was mainly due to the reduction of the metal salt by PEG200 at high temperature to generate copper nanoparticles.In addition,the reduced sugar content of the treated timber,and hence the nutrient substrate for spoilage microbes,reduced in the presence of the metal salts at high-temperature.This study has demonstrated an effective method of increasing low-grade wood’s utility and commercial value.

Fertilization and clear-cutting effects on greenhouse gas emissions of pinewood nematode damaged Masson pine plantation

Introduction:Management practices are essential for maintaining forest ecological functions under increasing diseases and pest disasters.The effects of nitrogen fertilization(NF)and clear-cutting(CC)on the soil microbial community structure and greenhouse gases emission were investigated of pinewood nematodes(Bursaphelenchus xylophilus)-infected Masson pine(Pinus massoniana)plantations.Outcomes:CC increased the soil microbial biomass carbon(SMBC)and soil microbial biomass nitrogen(SMBN)contents relative to the control(CK).NF increased the SMBN but had no significant effect on the SMBC content.The total fungal and bacterial abundances increased in the CC treatment compared with the CK,but there was no significant difference between the NF and CK.The cumulative soil CO_(2)emission(-2.35 t C·hm^(-2))was higher than that of CK(1.65 t C·hm^(-2))in summer,and the cumulative annual N_(2)O emission(16.90 kg N·hm^(-2)yr^(-1))of NF was approximately 47 times of CK(0.36 t N·hm^(-2)·yr^(-1)).CC increased the CO_(2)flux(-2.21 t C·hm^(-2))in summer but have no significantly effects on N_(2)O emission.Conclusion:These results indicated that NF and CC practices changed forest soil microbial community structure and affected soil greenhouse gas emissions in pinewood nematodes-infected Masson pine plantations.The CO_(2)emission rates increased in the NF and CC treatments,which reduced the carbon sequestration function of forests and had a negative impact on climate change.

Study Situation of Properties and Modification of Masson pine in China

Masson pine(Pinus massoniana) is one of the main pine species in China.It is the most extensively distributed,it is the largest in number,and its use is extensive.This paper deals with the study situation of the property variation of the tree and the effect of external conditions on its properties in China,including pine wood modification(degreasing,mould prevention and improvement of dimensional stability).

Colorimetric Assay to Determine In Vitro Antibacterial Activity Against Clinical Isolates： Enhanced Activity in Damaged Chinese Masson Pine Needles

A colorimetric assay for antibacterial susceptibility testing of clinical isolates （Escherichia coli, Pseudomonas aeruginosa, Shigella dysenteriae, Staphylococcus aureus, Bacillus cereus, and Streptococcus pneumoniae） is described based on the reduction of a novel tetrazolium salt, 3-（4,5-dimethylthiazol-2-yl）-5-（3-carboxymethoxyphenyl）-2-（4-sulfophenyl）-2Htetrazolium （MTS）, in the presence of phenazine methosulfate （PMS） as an electron-coupling agent. The combination of 200 μg/mL MTS with 25 μmol/L PMS resulted in production of large amounts of formazan within 1 h of exposure. In this setting, fractions extracted from Chinese Masson pine （Pinus massoniana Lamb.） needles damaged by the pine caterpillar Dendrolimus punctatus Walker were found to have enhanced levels of antibacterial activity. These fractions, which were designated ＂Master＂, ＂Technique＂, and ＂Strength＂, were isolated and identified by reverse-phase C18 cartridge concentration, gel filtration, and affinity chromatography. Two fractions purified from healthy and undamaged needles were designated H1 and H2, respectively. For all test bacteria species. Technique produced the lowest minimal inhibitory concentrations （MICs）, ranging from 2 to 32 μg/mL, and H2 produced the highest values, with four of the six M ICs being higher than 128 μg/mL. We found that the Rmax model fitted the data well in that the r^2 ranged between 0.87 and 0.96 （median, 0.92） and no statistically significant deviations from the model were found （P= 0.23）. The median coefficient of variation of the log RC50 values and the slope m of the fitted model for all six strains among the replicates were 38 and 41%, respectively. In the course of the investigation, the physiological and functional factors involved in pest damage to plants were also explored. In summary, the MTS-PMS colorimetric assay has advantages over existing methods for the examination of antibacterial activity, and could be developed further such that it would be suitable for screening new antibiotic molecules.

Study on Longitudinal Gas Permeability of Air-dried Masson Pine Sapwood

Measurement of the longitudinal gas permeability was made for air-dried sapwood specimens from Masson pine (Pinus massoniana). Results showed that air-dried Masson pine sapwood was one of the most permeable softwoods. The investigated specimens had an average longitudinal gas permeability of 4.60 ×10-13 m3/m, and the permeability ranged from 1.06 ×10-13 to 1.12 ×10-12 m3/m. The Kruskal- Wallis Test indicated that, generally, there was no correlation between the longitudinal gas permeability and the trees from which specimens were prepared, and tree height had no significant effect on the longitudinalgas permeability.

投加石灰石和菱镁矿对酸化土壤上马尾松(Pinus massoniana)林的影响

为了确定酸化森林生态系统的修复效果,在重庆铁山坪的马尾松林内设立了6个10m×10m的样地,其中2个作为对照样地,另外4个分别在土壤表面施撒石灰石和菱镁矿粉末,各有2个重复。在处理前和处理1a后的生长季末各进行了一次植被观测,协方差分析和多重比较的结果显示投加修复剂对马尾松生长的影响已经初步显现,马尾松的胸径增量和针叶平均长度都有显著的增加,而针叶中Ca、Mg元素含量也表现出显著的差别。另外,立木更新的变化、细根生物量的增加和物种多度的变化也较明显,总体来说生态系统有恢复的趋势。土壤上层细根的增加较快,这与在土壤表面施撒修复剂,上层土壤的化学变化较显著是一致的。而两种修复剂对生态系统的影响也表现出明显的差异,相对而言,施撒菱镁矿的效果可能会更好。由于土壤修复的效果是长期的,其影响观测还将继续下去。

马尾松人工林碳储量密度控制图研建及应用研究

[目的]马尾松是我国重要的人工林树种,不但发挥着重要的经济效益,而且在固碳释氧,应对气候变化等生态服务方面发挥着重要的作用。开展抚育间伐,调控林分密度是人工林经营过程中的重要手段,而当前马尾松人工林抚育间伐存在“定性”不“定量”的问题,制约着经营目标的实现。本研究拟构建马尾松人工林碳储量密度控制图,实现马尾松人工林抚育间伐过程中的精准化。[方法]首先,以湖南省马尾松人工纯林为研究对象,基于森林资源连续清查(一类清查)数据,以Reineke自然稀疏模型为基础,构建湖南省马尾松基本密度控制图。其次,将碳储量等高线加入到基本密度控制图上,构建了碳储量密度控制图,增加了以碳储量调控为目标的密度调控功能。再次,基于所构建的密度控制图,以湖南慈利县为例,对马尾松人工林的林分密度合理性进行诊断,生成密度诊断图,并提出相关经营建议。[结果]湖南省慈利县(1)绝大部分马尾松人工林的密度高于合理密度区间,林木对有限的光照、温度、水分等自然资源产生强烈竞争,甚至有些林分会产生严重的自然枯死现象,亟待开展抚育间伐,降低林分密度;(2)少部分林分位于合理密度区间范围内,此时的林分能够充分利用自然资源,林木个体之间处于互相促进的状态;(3)少部分林分密度低于最优密度下限,此时的林地空间没有得到充分的利用,造成林地资源的浪费,亟待开展林下补植作业。[结论]本研究所构建的马尾松林分密度控制图,能够精准指导森林抚育,此外还能够对森林经营单位的林分密度合理性进行诊断,形成林分密度诊断图,进而为合理经营措施的制定提供依据。

Physiological responses of needles of Pinus massoniana elite families to phosphorus stress in acid soil

Pinus massoniana Lamb. is a major timber species widely planted in the South China, where the soil is acidic and deficient in phosphorus （P） due to fixation by aluminum and iron. Understanding the physiological responses to rhizospheric insoluble P is essential for enhancing plantation productivity. Thus, a sand culture experiment was conducted with four levels of P treatment （0, 5, 20 g insoluble P and 10 g soluble P）, and 11 P. massoniana elite families. Physiological responses were measured after two months of stress. Compared to the normal soluble P treatment, the insoluble P treatment significantly reduced the proline content and the APase activity in the needles, while it significantly increased the catalase activity by 1.3-fold and malondialdehyde content by 1.2-fold. Soluble protein content was unaffected by the treatments, but chlorophyll content was significantly lower in P-deprived treatment compared with soluble and insoluble P treatments. These physiological responses also exhibited highly significant variation among families （p 〈 0.01）. The findings suggest that increased catalase activities in the presence of insoluble P might be involved in the activation of an anti-oxidation defense mechanism that scavenges the reactive oxygen species elicited by the stress. And this response has a strong genetic control that can be exploited to identify desirable genotypes.

Microwave vacuum drying characteristics of Pinus massoniana wood

Microwave-vacuum （MV） drying characteristics of plantation Masson pine （Pinus massoniana） were studied experimentally for various levels of microwave radiation time, initial moisture content 0VIC）, vacuum level and wood thickness. The results show that the process of MV drying for wood can be significantly divided into a short accelerating rate drying period, a long constant rate drying period and falling rate drying period, and the second drying period can extend to levels of mean MC below the fiber saturation point. With the increase of initial MC and microwave radiation time, the drying rate of wood increases significantly. The vacuum level affects the drying rate in a slightly positive way. Within the range of 2 to 6 cm, the effects of sample thickness on the drying rate can be negligible.

Patterns of biomass,carbon,and nitrogen storage distribution dynamics after the invasion of pine forests by Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) in the three Gorges Reservoir Region

Masson pine stands infected by Pine wilt disease(PWD) in the Three Gorges Reservoir Region of central China were surveyed to quantify the immediate responses and subsequent trajectories of biomass,carbon(C),and nitrogen(N) in stand-level major ecosystem compartments.The biomasses of above-and belowground tree components,as well as of the understory,forest floor,and mineral soil(0–40 cm),were determined within each stand.C and N storage were also estimated for each ecosystem compartment.Overstory biomass decreased steadily with the extent of PWD infection.Understory biomass ranged from1.97 to 4.16 Mg ha,and the observed value for forest floor biomass was 12.89–22.59 Mg ha.The highest mean C and N concentrations were found in the stem bark and needles of Masson pine,respectively,while the lowest were found in the semi-to fully decomposed layer of the forest floor and stem wood of Masson pine,respectively.The C and N storage of aboveground trees,tree roots,and the aboveground ecosystem decreased with the extent ofPWD infection.However,the C and N contents of the understory,forest floor,and total mineral soil initially declined after PWD infection before recovering over the following several years.Those result concluded that the biomass,C,and N storage of different forest ecosystem compartments have experienced certain variations following the PWD epidemic.This is vital to understand the shifts in stand-level C and N allocation in PWD-damaged forest stands,as well as for predicting the responses of regional and global C and N cycling.

Early Monitoring of Pine Wilt Disease in Pinus massioniana based on Hyperspectral Data

We selected healthy Pinus massioniana for pine wood nematode inoculation experiments to get the spectral reflectance of healthy and infected Pinus mas- sioniana in different infection stages via a ground spectrometer （ wavelength in 350 - 2 500 nm）, and analyzed the changes in chlorophyll content at various periods. The original spectral reflectance of healthy and infected P. massoniana was significantly different in the middle and late infection stages, and the reflection peak and absorption valley in visible light region and near infrared region gradually weakened and even disappeared to a straight line. There was significant correlation rela- tionship between chlorophyll content of infected plants and spectral reflectance at the wavelength of 1 405 nm, and the quantitative inversion model of chlorophyll content was correspondingly established as follows： Car = - 1.74（X1~ ）2 ＋ 4. 72X1,~ - 0. 76. Through first-order derivative spectra at the wavelength of 593 nm, combined with quantitative inversion of the corresponding chlorophyll content, we can discriminate whether P. massoniana is infected by pine lt disease or not, especially in the early stages before disease features are visible to the naked eyes it has a good quantitative monitoring effect.

马尾松和杉木人工林细根碳氮磷化学计量特征随土层深度的变化

为探究马尾松和杉木人工林细根碳(C)、氮(N)、磷(P)浓度及其化学计量比随土层深度变化的特征,于2011年4月在福建省三明市金丝湾森林公园陈大林业采育场内测定马尾松和杉木人工林五个土层深度(0—10 cm、10—20 cm、20—40 cm、40—60 cm、60—80 cm)细根的C、N、P浓度、比根长(SRL)及其土壤养分浓度,结果表明:林分类型显著影响细根C浓度,但对细根N、P浓度无显著影响,马尾松人工林细根C浓度显著大于杉木人工林。土层深度显著影响马尾松和杉木人工林细根N、P浓度,对C浓度无影响,细根N、P浓度随土壤深度的增加呈指数下降。马尾松和杉木人工林细根N、P浓度与土壤全氮(TN)、全磷(TP)浓度以及SRL均呈正相关。拟合直线表明马尾松人工林和杉木人工林细根N养分获取能力的不同,马尾松对N养分的获取能力更强,而杉木通过SRL获取养分的能力比马尾松更强,可能体现了两种人工林细根N获取策略的差异。马尾松和杉木人工林在不同土层细根N∶P比值(33.5±2.81、30.18±2.10)均大于16,表明两者均受P限制,但细根N∶P不受土壤N∶P和SRL的影响。马尾松和杉木人工林细根N和P浓度受土层深度的影响,与土壤养分和细根形态特征变化有关。

营造马尾松-桉树混交林防治松材线虫病研究进展

马尾松人工纯林结构简单,生态系统极不稳定,容易引起一系列生态问题。随着功能定位的转变,需要对马尾松纯林结构进行相应改造,而松材线虫病对松林造成的毁灭性危害毫无疑问地加剧了马尾松纯林改造的紧迫性。本文综述松材线虫病及其防治方法、马尾松混交林、马尾松与桉树挥发性物质等方面的研究进展,并对营造马尾松-桉树混交林防治松材线虫病的可行性进行论证,认为营造马尾松-桉树混交林防治松材线虫病具有很强的可行性和广阔应用前景。