Characterization of hemicellulose in Cunninghamia lanceolata stem during xylogenesis

In this study, hemicellulose was isolated from the apical, middle and basal segments of C. lanceolata stem to investigate the dynamic change of its structure during xylogenesis. Results showed that the C. lanceolata hemicellulose is mainly consisted of O-acetylgalactoglucomannan (GGM) which backbone is alternately linked by β-d-mannopyranosyl (Manp) and β-d-glucopyranosyl (Glcp) via (1 → 4)-glycosidic bond, while the side chains are α-d-galactopyranosyl (Galp) and acetyl. In addition, 4-O-methylglucuronoarabinoxylan (GAX) is another dominant structure of C. lanceolata hemicellulose which contains a linear backbone of (1 → 4)-β-d-xylopyranosyl (Xylp) and side chains of 4-O-Me-α-d-glucuronic acid (MeGlcpA) and α-L-arabinofuranose (Araf). The thickness of the cell wall, the ratio of GGM/GAX and the molecular weight of hemicellulose were increased as the extension of growth time. The degree of glycosyl substitutions of xylan and mannan was decreased from 10.34 % (apical) to 8.38 % (basal) and from 15.63 % (apical) to 10.49 % (basal), respectively. However, the total degree of acetylation was enhanced from 0.28 (apical) to 0.37 (basal). Transcriptome analysis showed that genes (CSLA9, IRX9H1, IRX10L, IRX15L, GMGT1, TBL19, TBL25, GUX2, GUX3, GXM1, F8H1 and F8H2) related to hemicellulose biosynthesis are mainly expressed in mature part. This study is of great significance for genetic breeding and high-value utilization of C. lanceolata.

Response of Rhizosphere Bacterial Communities to Near-Natural Forest Management and Tree Species within Chinese Fir Plantations

Near-natural forest management plays an important role in the maintenance of the long-term productivity and soil fertility of plantations. We conducted high-throughput absolute quantitative sequencing of 16S rRNA genes to compare the structures and diversity of rhizosphere soil bacterial communities among a pure Chinese fir (Cunninghamia lanceolata) plantation (S), a Cunninghamia lanceolata-Castanopsis hystrix-Michelia hedyosperma mixed plantation (SHX), and a Cunninghamia lanceolata-Castanopsis fissa mixed plantation (SD). The results revealed that near-natural forest management improved the rhizosphere soil properties of Chinese fir, especially the phosphorus content. Rhizosphere soil bacterial communities of Chinese fir in SHX and SD contained higher total absolute abundances and more unique operational taxonomic units (OTUs) than the pure plantation forest. Planctomycetes and Actinobacteria were abundant in SD, and Actinobacteria were enriched in SHX. The tree species also had an impact on the rhizosphere soil bacterial communities. For the rhizosphere soils of different tree species of SHX, the available phosphorus (AP) content of the rhizosphere of Chinese fir significantly surpassed those of Castanopsis hystrix and Michelia hedyosperma. Bacteria related to nitrogen fixing, such as Burkholderiales and Rhizobiales, were more abundant in Chinese fir in SD than in Castanopsis fissa. Acdiobacteria and Proteobacteria underpinned the differences found in the compositions of soil bacteria. The pH and soil organic matter were key variables influencing the rhizosphere soil bacterial communities. Our results demonstrated that in Chinese fir plantations, 12 years of near-natural management of introduced broad-leaved tree species can drive alterations of the physicochemical characteristics, bacterial community structure, and composition of rhizosphere soil, with tree species identity further influencing the rhizosphere soil bacterial community. IMPORTANCE Near-natural forest management is an important way to change the soil fertility decline and productivity reduction of pure Chinese fir plantations. At present, many detailed studies have been carried out on the impact of near-natural forest management on Chinese fir plantations at home and abroad. However, there are still few studies on the response of rhizosphere bacterial communities to near-natural forest management. Our study determined absolute quantities of Chinese fir rhizosphere bacterial communities in different mixed patterns. The results underscore the importance of near-natural forest management for Chinese fir plantation rhizosphere bacterial communities and provide new information on soil factors that affect rhizosphere bacterial communities in South China.

The effect of ultrasonic intensity on physicochemical properties of Chinese fir

Cavitation intensity is affected by ultrasonic intensity (UI) and is a key parameter to describe experimental results during ultrasonic treatment. The relationship between the UI and physicochemical properties of Chinese fir was investigated. In this study, four frequencies (25, 28, 40, and 59 kHz) were used at the same intensity of 240 W and the same duration of 35 min. The UI during the ultrasonic treatment was determined, and the chemical components were determined. The chemical structure, crystallinity, morphology, and extractives of wood were respectively analyzed by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and gas chromatography-mass spectrometry (GC-MS). The results showed that higher crystallinity was associated with a larger integrated area under the curve of the ultrasonic intensity (UIA). The largest UIA was observed at 25 kHz, followed by those at 40, 59, and 28 kHz. The relative content of hemicellulose was strongly affected by the ultrasonic treatment. No chemical reactions were observed in the wood, whereas the ultrasonic treatment affected the torus of the bordered pits and facilitated the migration of extractives. In general, the higher the UIA, the stronger the effect of the cavitation was. The most significant changes in the physicochemical properties were observed at 25 kHz. The instantaneous ultrasonic intensity (IUI) changed over time, and the UIA was closely associated with changes in the physicochemical properties of the wood. The results of this study demonstrate that UI has a significant influence on the physicochemical properties of wood.

Sesquiterpenoids and Diterpenoids from the Wood of Cunninghamia konishii and Their Inhibitory Activities against NO Production

Three new sesquiterpenoids, 2α-hydroxy-3,3,6α,9β-tetramethyltricyclo[4,3,2(1,4)]undecane (1), 11-acetoxyeudesman-4β-ol (4), and 2α,3β-dihydroxy-4β-methyl-6,8,10-cadinatriene (6), four known sesquiterpenoids (2, 3, 5, and 7), together with eight known diterpenoids (8-15), were isolated from the wood of Cunninghamia konishii. Their structures were determined by detailed analysis of spectroscopic data and comparison with the data of known analogues. Four sesquiterpenoids (1, 4, 5, and 6) and all the diterpenoids (8-15) were evaluated for inhibition of nitric oxide production in lipopolysaccharides (LPS)-activated RAW 264.7 macrophages and the results showed that compounds 10 and 15 exhibited moderate inhibitory activities against nitric oxide production.

Isolation of High-Quality Total RNA from Chinese Fir (Cunninghamia lanceolata (Lamb.) Hook)

RNA isolation with RNA in a high quantity is a basic analytical method in plant genetics, molecular biology and related physiological investigations. To understand the genetic and molecular biology of Chinese fir, sufficient high-quality total RNA must be obtained for cDNA library construction and other downstream molecular applications. However, extracting RNA from Chinese fir is difficult and often requires the modification of existing protocols. Chinese fir tissues containing large amounts of polysaccharides and polyphenol compounds and are one of the most difficult plant tissues for RNA isolation. Therefore, we developed a simple method for extracting high-quality RNA from Chinese fir tissues. RNA isolations were performed within two hours, RNA quality was measured for yield and purity. Total RNA obtained from this procedure was successfully used for cDNA library construction, RT-PCR and transcriptome sequencing. It was proven that extracted RNA was intact and suitable for downstream molecular applications, including RT-PCR and qPCR, and other downstream molecular applications. Thus, this protocol represents a simple, efficient, and low-cost method.

Biomedical molecular of woody extractives of Cunninghamia Lanceolata biomass

Extractives, important compounds from wood, provide abundant resources for woody medicine. In this study, the three extractives from Cunninghamia lanceolata wood were removed by method of three-stage extraction with alcohol, petroleum ether, and alcohol/petroleum ether and their chemical components were analyzed by gas chromatography-mass spectrometry (GC-MS). Thirteen chemical components were discovered in the first-stage extractives, including: 4-((1e)-3-hydroxy-1-propenyl)-2-methoxyphenol (36.80%), α-(2-phenylethenyl)-1-piperidineacetonitrile (15.39%). One-hundred chemical components were discovered in the second-stage extractives, including: [1s-(1α,4aα,10aβ)]-1, 2,3,4,4a,9,10,10a-octahydro-1,4a- dimethyl-7-(1-methylethyl)-1- phenanthrenecar-boxylic acid (15.16%), 1,3-dimethoxy-5-[(1e)-2- phenylethenyl]-benzene (6.99%). Seven chemical components were discovered in the third-stage extractives, including: 1,3-dimethoxy -5-[(1E)-2-phenylethenyl]-benzene (32.88%), stigmasta-4,6,22-trien-3α-ol (17.83%). And both the main retention time of the first-stage and which of third-stage extractives are 20-30 minutes, and the main retention time of the second-stage extractives is <10 minutes. Besides, the three extractives contained many biomedical molecular, such as [1s-(1α,4aα,10aβ)]-1,2,3,4,4a,9,10,10a-octahydro-1,4a-dimethyl-7-(1-methylethyl)-1-phenanthrenecar-boxylic acid, squalene, stigmast-4-en-3-one and γ-sitosterol and so on, which means that the three extractives from Cunninghamia lanceolata wood have huge potential in biomedicine.

Two new labdane-type diterpenes from the wood of Cunninghamia konishii

Phytochemical investigation of the methanol extract of the wood of Cunninghamia konishii resulted in the isolation of two new acidic labdane-type diterpenoids, 12(S)-hydroxy-15,16-epoxylabda-8(17),13-dien-19-oic acid (1) and 12(S)-hydroxy-15,16-epoxylabda-8(17),13-dien-18-oic acid (2), along with one known labdane-type diterpene, 7,13E-labdadien-15-ol (3). Their structures were determined by analysis of spectroscopic data and comparison with the data of known analogues.

Insecticidal activities of Cunninghamia konishii Hayata against Formosan subterranean termite, Coptotermes formosanus (Isoptera: Rhinotermitidae)

BACKGROUND

Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), is a major urban pests in many countries throughout the world. In an attempt to find natural products that could be employed in the effective and environmentally friendly control of the termite, this study investigates, for the first time, the insecticidal activities of the wood and leaf essential oils and ethanolic extracts from Cunninghamia konishii Hayata against C. formosanus according to direct contact application.

RESULTS

Wood and leaf essential oils and wood ethanolic extract showed the excellent antitermitic activities. Among the four fractions of wood ethanolic extract, the hexane-soluble fraction showed the strongest antitermitic activities. In addition, β-elemol and α-cadinol showed excellent inhibitory action against C. formosanus.

CONCLUSION

The results clearly reveal that the wood and leaf essential oils and ethanolic extract from C. konishii, and their effective constituents, served as potential, eco-friendly termite-control agents.

Co-pelletization of sewage sludge and biomass: the density and hardness of pellet

In the present study, the effects of process parameters on pellet properties were investigated for the co-pelletization of sludge and biomass materials. The relaxed pellet density and Meyer hardness of pellets were identified. Scanning electron microscopy, FT-IR spectra and chemical analysis were conducted to investigate the mechanisms of inter-particular adhesion bonding. Thermogravimetric analysis was applied to investigate the combustion characteristics. Results showed that the pellet density was increased with the parameters increasing, such as pressure, sludge ratio and temperature. High hardness pellets could be obtained at low pressure, temperature and biomass size. The optimal moisture content for co-pelletization was 10-15%. Moreover, the addition of sludge can reduce the diversity of pellet hardness caused by the heterogeneity of biomass. Increasing ratio of sludge in the pellet would slow down the release of volatile. Synergistic effects of protein and lignin can be the mechanism in the co-pelletization of sludge and biomass.

[Long-term effects of thinning on carbon storage in Cunninghamia lanceolata plantations]

The stand environment and tree growth could be changed as well as carbon storage be affected by thinning. Thus it is important to conduct the research on changes of carbon stock in plantations after thinning for assessing the dynamics of forest ecosystem carbon pool. The carbon storage and its distribution of various components in 22-year-old Cunninghamia lanceolata plantations were studied with control and different treatments such as moderate and heavy thinning. Moderate (thinning intensity was 35%) and heavy (thinning intensity was 50%) thinning treatments were conducted twice at the age of 7 and 14 years, respectively. The stand of control was thinned 15% in the 14th year. The results showed that the proportion of stem carbon storage increased with the increasing thinning intensity, while the proportion of carbon storage in branches, leaves and roots slightly decreased, which suggested that thinning was beneficial for carbon stocking in stem. However, the carbon storage in arbor layer decreased with the thinning intensity in C. lanceolata plantation under moderate and heavy thinning treatments, accounted for 89.0% and 83.1% of the control, respectively. The arbor carbon storage decreased in followed two years after the first thinning. The carbon storage in arbor layer had a fast recovery rate within eight years after the second thinning, and the increment of carbon storage in arbor layer had no difference with the control for the heavy thinning treatment. The carbon storage in understory vegetation, litter and soil layers also had no significant difference under the different thinning treatments. Generally total ecosystem carbon storage under the control, moderate and heavy thinning treatments reached 169.34, 156.65 and 154.37 t x hm(-2), respectively. There was no significant difference among the three treatments. Therefore, it could be concluded that the carbon storage in C. lanceolata plantation did not reduce after thinning in more than 15 years.

New Lignans from the Heartwood ofCunninghamia lanceolata

Two new lignans, including the aryltetralin-type lignan, lanceoline (1), and the diaryl butyrolactone-type lignan, 5-methoxytrachelogenin (2), together with 5-methoxywikstromol (3), were isolated from the low-polar layer of a heartwood extract of Cunninghamia lanceolata as their acetylated derivatives 1a, 2a and 3a, respectively, and were identified by spectroscopic analyses. The (13)C-NMR data for 3a are reported for the first time in this paper.

[Effects of Chinese fir litter on soil organic carbon decomposition and microbial biomass carbon]

By using 13C stable isotope tracer technique, this paper studied the effects of Chinese fir litter addition on the soil organic carbon (SOC) decomposition, microbial biomass carbon, and dissolved organic carbon in 0-5 cm and 40-45 cm layers. The decomposition rate of SOC in 40-45 cm layer was significantly lower than that in 0-5 cm layer, but the priming effect induced by the Chinese fir litter addition showed an opposite trend. The Chinese fir litter addition increased the soil total microbial biomass carbon and the microbial biomass carbon derived from native soil significantly, but had less effects on the soil dissolved organic carbon. Turning over the subsoil to the surface of the woodland could accelerate the soil carbon loss in Chinese fir plantation due to the priming effect induced by the litters.

Composition, anticancer, and antimicrobial activities in vitro of the heartwood essential oil of Cunninghamia lanceolata var. konishii from Taiwan

This study investigated the chemical composition, anticancer, and antimicrobial activities in vitro of the essential oil isolated from the heartwood of Cunninghamia lanceolata var. konishii from Taiwan. The essential oil was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. Thirty-seven compounds were identified, representing 100% of the oil. The main components identified were cedrol (58.3%), alpha-cedrene (11.8%), alpha-terpineol (4.2%) and beta-cedrene (3.5%). The oil exhibited cytotoxic activity against human lung, liver and oral cancer cells. The active source compound was cedrol. The antimicrobial activity of the oil was tested by the disc diffusion and micro-broth dilution methods against ten microbial species. The oil exhibited strong growth suppression against Gram-positive bacteria and yeast with inhibition zones of 42-50 mm to MIC values of 31.25-62.5 microg/mL, respectively. For the antimicrobial activities of the oil, the active compound was determined to be cedrol.

Anti-inflammatory and analgesic activity of total flavone of Cunninghamia lanceolata

The present study was undertaken to investigate the anti-inflammatory and analgesic activity of total flavone of branches and leaves of Cunninghamia lanceolata (TFC) to provide a scientific basis for its clinical use and resource development. TFC was evaluated for anti-inflammatory and analgesic activity in mice or rats using chemical and thermal models of nociception, including acetic acid-induced writhing test, hot plate latency test, formalin test and carrageenan induced paw oedema test. Results showed that TFC given orally can significantly attenuate acetic acid-induced writhing in mice in a dose-dependent manner. In the hot plate latency test, TFC showed common activity in prolonging duration time only at the highest dose (400 mg/kg). Each dose of TFC could not significantly inhibit the first phase but was active in the later phase of formalin-induced pain, whereas morphine showed notable activity in the two phases. In the carrageenan-induced paw oedema model, TFC could significantly and dose-dependently reduce the carrageenan-induced paw edema at the third and fifth hour, and decrease the content of PEG₂ in paw edema tissue and that of COX-2 in blood serum. It may be concluded that TFC showed both anti-inflammatory and analgesic effects, showing that it can be of importance in drug development, especially in the field of pain and inflammation.

Phytochemicals from Cunninghamia konishii Hayata act as antifungal agents

The aims of the present study were to isolate and identify the antifungal compounds from the ethanolic extract of Cunninghamia konishii wood and to evaluate their antifungal activities against wood decay fungi. The results showed that the n-Hex soluble fraction of the ethanolic extract from C. konishii wood had an excellent inhibitory effect against Lenzites betulina, Trametes versicolor, Laetiporus sulphureus, and Gloeophyllum trabeum, with IC(50) values of 33, 46, 62, and 49 μg/mL, respectively. By following the bioactivity-guided fractionation procedure, four sesquiterpenes, T-cadinol, cedrol, T-muurolol, and (-)-epi-cedrol, and three diterpenes, 13-epi-manool, cis-abienol, and isoabienol, were identified from the active subfractions. Among the main constituents of the ethanolic extract from C. konishii, T-cadinol, cedrol, and T-muurolol efficiently inhibited the growth of four wood-rot fungi at the concentration of 100 μg/mL, with antifungal indices of 51.4-100.0%, 68.3-100.0%, and 39.5-100.0%, respectively. Results of this study show that the ethanolic extract of C. konishii wood may be considered as a potent source of T-cadinol, cedrol, and T-muurolol as new natural antifungal agents.

[Effects of UV-B radiation on the decomposition of Cunninghamia lanceolata leaf litter]

A litterbag experiment was conducted to study the decomposition of Cunninghamia lanceolata leaf litter under ambient and reduced UV-B radiation (22.1% below ambient). Comparing with ambient treatment, the reduced treatment decreased the decomposition rate of C. lanceolata leaf litter by 69.6% (P<0.001), making the relative contents of nitrogen (N), phosphorus (P), and lignin in the litter increased by 150%, 83.3%, and 13.8%, respectively, and the release of potassium (K) and carbon (C) slowed down. In the process of litter decomposition, photo-degradation of lignin didn't play crucial role. The results suggested that UV-B radiation could accelerate the decomposition rate of C. lanceolata leaf litter, promote the release of N, P, K, and C from it, and increase the nutrients turnover rate in litter layer as well as the carbon flux on the ground, giving potential effects on the function of C. lanceolata forest as a carbon source or sink in humid subtropical China.

[Litter fall production and carbon return in Cunninghamia lanceolata, Schima superba, and their mixed plantations]

From March 2005 to April 2007, an investigation was made on the litter fall production and carbon return of Cunninghamia lanceolata, Schima superba, and their mixed plantations in the Jian' ou Science and Education Park of Soil and Water Conservation, Fujian. In these three plantations, the mean annual litter fall production was from 2470.85 kg x hm(-2) x a(-1) to 4285.99 kg x hm(-2) x a(-1), and dominated by leaf litter, accounting for 68.62%-87.26% of the total production. In C. lanceolata plantation, the litter fall production peaked in April-May, July, and December; while in S. superba and mixed plantations, this production only peaked in March. Comparing with pure plantations, mixed plantation had a higher litter fall production per tree of broadleaved S. superba while a lower litter fall production per tree of coniferous C. lanceolata. Leaf litter in the three plantations was the main body of the litter falls carbon return, and the total amount of the carbon return was the largest (2.12 t C x hm(-2) x a(-1)) in mixed plantation and the smallest (1.19 t C x hm(-2) x a(-1)) in C. lanceolata plantation, which was in accordance with the annual litter fall production of the plantations. This study demonstrated that comparing with pure coniferous or broadleaved plantation, coniferous-broadleaved mixed plantation had higher annual litter fall production and carbon return, and thus, higher potential of C sequestration.

Proteome profiling of early seed development in Cunninghamia lanceolata (Lamb.) Hook

Knowledge of the proteome of the early gymnosperm embryo could provide important information for optimizing plant cloning procedures and for establishing platforms for research into plant development/regulation and in vitro transgenic studies. Compared with angiosperms, it is more difficult to induce somatic embryogenesis in gymnosperms; success in this endeavour could be increased, however, if proteomic information was available on the complex, dynamic, and multistage processes of gymnosperm embryogenesis in vivo. A proteomic analysis of Chinese fir seeds in six developmental stages was carried out during early embryogenesis. Proteins were extracted from seeds dissected from immature cones and separated by two-dimensional difference gel electrophoresis. Analysis with DeCyder 6.5 software revealed 136 spots that differed in kinetics of appearance. Analysis by liquid chromatography coupled to tandem mass spectrometry and MALDI-TOF mass spectrometry identified proteins represented by 71 of the spots. Functional annotation of these seed proteins revealed their involvement in programmed cell death and chromatin modification, indicating that the proteins may play a central role in determining the number of zygotic embryos generated and controlling embryo patterning and shape remodelling. The analysis also revealed other proteins involved in carbon metabolism, methionine metabolism, energy production, protein storage, synthesis and stabilization, disease/defence, the cytoskeleton, and embryo development. The comprehensive protein expression profiles generated by our study provide new insights into the complex developmental processes in the seeds of the Chinese fir.

Inhibition of the growth of Alexandrium tamarense by algicidal substances in Chinese fir (Cunninghamia lanceolata)

The wood sawdust from Chinese fir (Cunninghamia lanceolata) exhibited stronger inhibition on the growth of Alexandrium tamarense than those from alder (Alnus cremastogyne), pine (Pinus massoniana), birch (Betula alnoides) and sapele (Entandrophragma cylindricum). The water extract, acetone-water extract and essential oil from fir sawdust were all shown to inhibit the growth of A. tamarense. The inhibition of fir essential oil was the strongest among all the above wood sources while the half effective concentration was only 0.65 mg/L. These results suggested that the fir essential oil may play an important role in the algicidal effect of Chinese fir.

Prediction of wood property in Chinese Fir based on visible/near-infrared spectroscopy and least square-support vector machine

A method for the quantification of density of Chinese Fir samples based on visible/near-infrared (vis-NIR) spectrometry and least squares-support vector machine (LS-SVM) was proposed. Sample set partitioning based on joint x-y distances (SPXY) algorithm was used for dividing calibration and prediction samples, it is of value for prediction of property involving complex matrices. A stepwise procedure is employed to select samples according to their differences in both x (instrumental responses) and y (predicted parameter) spaces. For comparison, the models were also constructed by Kennard-Stone method, as well as by using the duplex and random sampling methods for subset partitioning. The results revealed that the SPXY algorithm may be an advantageous alternative to the other three strategies. To validate the reliability of LS-SVM, comparisons were made among other modeling methods such as support vector machine (SVM) and partial least squares (PLS) regression. Satisfactory models were built using LS-SVM, with lower prediction errors and superior performance in relation to SVM and PLS. These results showed possibility of building robust models to quantify the density of Chinese Fir using near-infrared spectroscopy and LS-SVM combined SPXY algorithm as a nonlinear multivariate calibration procedure.

Comparisons of carbon storages in Cunninghamia lanceolata and Michelia macclurei plantations during a 22-year period in southern China

Tree species composition was important for carbon storage within the same climate range. To quantify the dynamics of ecosystem carbon allocation as affected by different tree species, we measured the above- and below-ground biomass accumulation in 22 years, as well as the tissue carbon concentrations of trees in Cunninghamia lanceolata plantation and Michelia macclurei plantation. Results indicated that M. macclurei plantation significantly stored more carbon (174.8 tons/hm2) than C. lanceolata plantation (154.3 tons/hm2). Most of the carbon was found in the soil pool (57.1% in M. macclurei plantation, 55.2% in C. lanceolata plantation). Tree and soil component of M. macclurei plantation possessed significantly higher carbon storage than that of C. lanceolata plantation (p <0.05). No significant difference was found in the carbon storage of understory and forest floor. These results suggest that the broadleaved species (M. macclurei) possesses greater carbon sequestration potential than the coniferous species (C. lanceolata) in southern China.

[Determination of holocellulose and lignin content in Chinese fir by near infrared spectroscopy]

The contents of holocellulose and lignin of wood are important determinants of the pulping quality of wood. The determination of holocellulose and lignin contents using traditional chemical methods is a costly and time-consuming process. Near infrared reflectance (NIR) analysis offers a fast, nondestructive testing and low cost alternative for prediction of wood quality. In the present article, the total amounts of holocellulose and lignin contents of 48 samples were analyzed according to standard wet-chemical method. All samples were milled using a Standard Wiley knife mill with a 2 mm screen. The 2 mm material was sieved with a 40-60 mesh sieve. Then, near infrared (NIR) spectra were collected in diffuse reflectance from samples of meal contained in a spinning cup by an analytical spectral devices (ASD) Lab Spec at wavelengths between 350 nm and 2 500 nm. The raw spectra were pretreated by the second derivative and smoothing, then the NIR model was built using partial least-squares statistical analysis and full cross validation. The coefficients of correlation (r) of calibration and validation for holocellulose were 0. 96 and 0.93, respectively; the standard error of calibration (SEC) and the standard error of prediction (SEP) were 0.39 and 0.50, respectively. For lignin, the values for r of calibration and validation were 0.99 and 0.90, while the SEC and SEP were 0.10 and 0.28, respectively. It was concluded that NIR analysis is a reliable, fast and nondestructive testing predictor of holocellulose and lignin content of wood in Chinese fir.

[Effects of Cunninghamia lanceolata-broadleaved tree species mixed leaf litters on active soil organic matter]

With incubation test, this paper studied the effects of Cunninghamia lanceolata leaf litter and its mixture with the litters of main broadleaved tree species in subtropical China, such as Alnus cremastogyne, Kalopanax septemlobus and Michelia macclurei on active soil organic matter. The results showed that adding leaf litters into soil could significantly increase soil microbial biomass C and N, respiration rate and dissolved organic C, and mixed leaf litters were more effective than C. lanceolata leaf litter in increasing soil dissolved organic C. By the end of the incubation, the increment of soil microbial biomass C and N, respiration rate, and dissolved organic C in treatments C. lanceolata leaf litter and C. lanceolata-broadleaved tree species mixed leaf litters was 49% and 63%, 35% and 75%, 65% and 100%, and 66% and 108%, respectively, compared with control. The addition of leaf litters had no significant effects on soil microbial quotient and microbial biomass C/N ratio.

Properties of resorcinol-tannin-formaldehyde copolymer resins prepared from the bark extracts of Taiwan acacia and China fir

Resorcinol-tannin-formaldehyde copolymer resins (RTF) were prepared by using the bark extracts of Taiwan acacia (Acacia confusa) and China fir (Cunninghamia lanceolata) to substitute part of the resorcinol. From the results, the content of reactive phenolic materials in Taiwan acacia and China fir bark extracts were 51.6% and 46.5%, respectively. Aromatic compounds were the main components in the bark extracts showed by FT-IR analysis. The conventional synthesis condition used for RF resin was certainly not suitable for the RTF copolymer resin. It should be formed the novolak RF prepolymer by reacting the resorcinol with formaldehyde at the first stage, and then the bark extracts added and underwent the copolymerization reaction under acidic condition at the second-stage. The RTF copolymer resins prepared had cold-setting capability. They had higher viscosity, shorter gel time as compared with the RF resin. The RTF copolymer resins could be carried out the gluing application immediately after the hardener was added and had bonding strength the same as RF resin. But the RTF copolymer resins had worse stability and shorter shelf life than RF resin.

[Chemical components and antimicrobial activity of essential oils in Cunninghamia lanceolata heartwood]

In this study, the essential oils in Cunninghamia lanceolata heartwood were water-steam distilled, and their chemical components were analyzed by column chromatography and GC-MS, with their antimicrobial activity tested. The results showed that the essential oils content was 1.794-2.076 (w/w), and 47 peaks were separated. 27 compounds, accounted for 99% of crude essential oils, were identified. The essential oils had an obvious antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus sabtills and Salmonella typhi, and cedrol, occupying 76.27% of essential oils, was the major component with antimicrobial activity.

[Degradation mechanism of Chinese fir plantation]

Chinese fir (Cunninghanzia lanceolata) is a fast-growing species native to China, and has a very important status in production of commercial timber. In response to the growing need for timber, pure Chinese fir plantations have been extensively replanted on the same site in successive rotations, which has resulted in serious problems of soil fertility degradation and productivity decline, and these problems have caused considerable attention from foresters, microbiologists, soil scientists and ecologists. They have also done a lot of work on these problems and studied the mechanism of productivity decline of replanted Chinese fir plantation. In this article, the author described the characteristics of productivity decline and soil degradation, and summed up the factors caused lower productivity, and analyzed the degradation mechanism of replanted Chinese fir plantation. In sum, productivity decline and soil physical and chemical characteristics deterioration were the main properties of replanted Chinese fir plantation. The factors summarized primarily as two kinds of reasons. One was the unreasonable management that was the edogenic factor, and another was the biotic self-characteristics of Chinese fir that was the intrinsic factor of poor establishment of replanted Chinese fir plantation. The combination of the edogenic and intrinsic factors reduced the productivity decline and soil degradation of the replanted Chinese fir plantation.

[Degradation mechanism of Chinese fir plantation]

Chinese fir (Cunninghanzia lanceolata) is a fast-growing species native to China, and has a very important status in production of commercial timber. In response to the growing need for timber, pure Chinese fir plantations have been extensively replanted on the same site in successive rotations, which has resulted in serious problems of soil fertility degradation and productivity decline, and these problems have caused considerable attention from foresters, microbiologists, soil scientists and ecologists. They have also done a lot of work on these problems and studied the mechanism of productivity decline of replanted Chinese fir plantation. In this article, the author described the characteristics of productivity decline and soil degradation, and summed up the factors caused lower productivity, and analyzed the degradation mechanism of replanted Chinese fir plantation. In sum, productivity decline and soil physical and chemical characteristics deterioration were the main properties of replanted Chinese fir plantation. The factors summarized primarily as two kinds of reasons. One was the unreasonable management that was the edogenic factor, and another was the biotic self-characteristics of Chinese fir that was the intrinsic factor of poor establishment of replanted Chinese fir plantation. The combination of the edogenic and intrinsic factors reduced the productivity decline and soil degradation of the replanted Chinese fir plantation.

[Gas chromatographic analysis of fatty acids in phosphatidylglycerol from needles of two crosses of Chinese Fir]

This paper reports a method for determination of fatty acids in phosphatidylglycerol from needles of two crosses of Chinese Fir with different cold-resistance. Some simplifications and improvements for analytical method of DEAE CL-6B column chromatography and of silica thin layer chromatography were also discussed. After being extracted with chloroform and methanol, phosphatidylglycerol was isolated from the general lipid extract by using DEAE CL-6B IEC and Silica TLC. Quantitative analysis was conducted by gas chromatography on a DB-FFAP (30m x 0.32mm i.d.) column. The results showed that there was a difference in the ratio of fatty acid (18:1+18:2+18:3)/[16:0+16:1(3t)] between the two crosses of Chinese Fir with different cold-resistance, 1.12 for that with higher cold-resistance and 1.25 for that with lower cold-resistance. A special fatty acid 16:1(3t) was found in both of the two crosses.