Effects of Eucalyptus globulus wood autohydrolysis conditions on the reaction products

Eucalyptus globulus wood samples were reacted in aqueous media (hydrothermal treatments) at 160 degrees C for 30-66 min. Liquors from the several experiments were analyzed by spectrophotometry, high-performance liquid chromatography, or gas chromatography-mass spectrometry for monosaccharides, oligosaccharides, oligosaccharide substituents (arabinose moieties, uronic acids, and acetyl groups), acetic acid, furfural, hydroxymethylfurfural, and dichloromethane-soluble compounds. Individual components of this latter fraction were identified and quantified. The molecular weight distribution of oligosaccharides was studied by high-performance size exclusion chromatography. The kinetics of xylan conversion into high-, medium-, and low-molecular-weight products was assessed in terms of the severity factor and by pseudohomogeneous kinetic models.     

Productivity,nutrient immobilization and soil chemical properties in an Eucalyptus globulus plantation under different irrigation and fertilization regimes

To evaluate the influence of irrigation and fertilization on the productivity of E. globulus a field experiment was started in 1986 in Central Portugal. The nutrients accumulated in the biomass and their allocation to the various biomass components as well as the changes in soil chemical characteristics were also followed. Irrigation and fertilization resulted in a significant increase of biomass production during the first 2 yr. A similar trend occurred with the net primary production and leaf litterfall. The differences between treatments in the amounts of accumulated nutrients in the aboveground biomass were similar to those of biomass accumulation. However, there was a small but consistent effect related to the average concentration of nutrients in the plant tissues. This effect occurred essentially in the leaves and branches. The concentration of N and P in the leaf litterfall was higher in the fertilized treatments than in the others. Fertilization alone induced a slight increase in the soil pH values, C content, exchangeable Ca and available P levels. Such increase was more pronounced in the fertilized with dripping irrigation treatment. This was due to the accumulation of nutrients in the wetted soil volume.     

Contribution of decomposing harvest residues to nutrient cycling in a second rotation Eucalyptus globulus plantation in south-western Australia

Amounts of nutrients in harvest residues and their contribution to nutrient cycling were quantified following logging of a Eucalyptus globulus plantation in south-western Australia. An estimated 64 t ha^–1 of leaf, bark and branch material less than 3 cm in diameter was deposited on the forest floor during harvesting. Leaves contributed about one-third of the residue dry weight but accounted for almost three-quarters of residue-N stores (299 of 428 kg N ha^–1) and 36% to 52% of P, K, Ca, and Mg stores. Stores of nutrients in slash were significant in comparison to amounts in surface soil (0–20 cm). Residue-N amounted to 11% of total surface soil N and cations stored in residues were equivalent to 23–114% of surface soil exchangeable cations. Decomposition of the leaf fraction of slash was rapid with more than 90% of dry weight released during the 105-week study. Bark and branch fractions of diameters 0.5, 1 and 2 cm lost 39%, 37%, 32% and 29% of dry weight, respectively, during the same period. Single and double exponential decay models fitted to the data indicated half lives ranging from 20 weeks for leaves and from 3 to 4 years for bark and the branch fractions. During decomposition, K was leached rapidly from all residue fractions, Mg and P were released at similar rates to dry weight, and Ca and N were released more slowly than dry weight. In the 105-week study period, 250 kg ha^–1 of N, 20 kg ha^–1 of P, 213 kg ha^–1 of Ca, 298 kg ha^–1 of K, and 63 kg ha^–1 of Mg were returned to the soil from decomposing harvest slash. The leaf fraction was the major contributor to nutrient cycling, accounting for almost all of the N and Ca release and from half to three-quarters of the K, Mg and P released. Amounts of nutrients released from residues in the year following logging greatly exceeded quantities likely to be taken up by the newly established tree crop.     

Inhomogeneities in the chemical structure of sugarcane bagasse lignin

Sequential treatments of dewaxed bagasse with distilled water, 0.5 M NaOH, 0.5, 1.0, 1.5, 2.0, and 3.0% H(2)O(2) at pH 11.5, and 2 M NaOH at 55 degrees C for 2 h solubilized 2.8, 52.5, 14.9, 3.3, 5.5, 5.0, 2.8, and 2.2% of the original lignin, respectively. The eight isolated lignin fractions were subjected to a comprehensive structural characterization by UV, FT-IR, and (1)H and (13)C NMR spectroscopies and thermal analysis. The nitrobenzene oxidation method was also applied to the in situ lignins. The seven lignin fractions, isolated successively with alkali and alkaline peroxide, were all SGH-type lignins, with a small amount of esterified p-coumaric acid and mainly etherified ferulic acid. No significant differences were found in the weight-average molecular weights (1680-2220 g/mol) of the seven alkali and alkaline peroxide dissolved lignins. However, the first four lignin fractions, isolated with 0.5 M NaOH and 0.5, 1.0, and 1.5% H(2)O(2) at pH 11.5, were rich in syringyl units and contained large amounts of noncondensed ether structures, whereas the last three lignin fractions, isolated sequentially with 2.0 and 3.0% H(2)O(2) at pH 11.5 and 2 M NaOH at 55 degrees C for 2 h, had a higher degree on condensation and were rich in guaiacyl lignins.     

Solution-state nuclear magnetic resonance study of the similarities between milled wood lignin and cellulolytic enzyme lignin

The structures of milled wood lignin (MWL) and cellulolytic enzyme lignin (CEL) have been analyzed using traditional chemical methods and solution-state NMR techniques. Comparisons of the results obtained reveal that subtle differences exist between the two lignin preparations. Thioacidolysis produced higher monomer yields from CEL than MWL, suggesting MWL has a more condensed structure. Quantitative (13)C NMR determined the degree of condensation in MWL to be 0.43 unit per aromatic moiety as compared to 0.36 in CEL. The MWL also contained a lower amount of beta-O-4' substructures per aromatic ring than CEL, 0.41 versus 0.47, respectively. Carbohydrate analysis revealed that the MWL may contain a higher proportion of middle lamella material as compared to the CEL. Because the middle lamella is considered to have a more condensed lignin structure, on the basis of the bulk polymerization theory, these results could explain the differences in beta-O-4' and degree of condensation.     

Toward a better understanding of the lignin isolation process from wood

The recently developed protocol for isolating enzymatic mild acidolysis lignins (EMAL) coupled with the novel combination of derivatization followed by reductive cleavage (DFRC) and quantitative (31)P NMR spectroscopy were used to better understand the lignin isolation process from wood. The EMAL protocol is shown to offer access at lignin samples that are more representative of the overall lignin present in milled wood. The combination of DFRC/(31)P NMR provided a detailed picture on the effects of the isolation conditions on the lignin structure. More specifically, we have used vibratory and ball milling as the two methods of wood pulverization and have compared their effects on the lignin structures and molecular weights. Vibratory-milling conditions cause substantial lignin depolymerization. Lignin depolymerization occurs via the cleavage of uncondensed beta-aryl ether linkages, while condensed beta-aryl ethers and dibenzodioxocins were found to be resistant to such mechanical action. Condensation and side chain oxidations were induced mechanochemically under vibratory-milling conditions as evidenced by the increased amounts of condensed phenolic hydroxyl and carboxylic acid groups. Alternatively, the mild mechanical treatment offered by ball milling was found not to affect the isolated lignin macromolecular structure. However, the overall lignin yields were found to be compromised when the mechanical action was less intense, necessitating longer milling times under ball-milling conditions. As compared to other lignin preparations isolated from the same batch of milled wood, the yield of EMAL was about four times greater than the corresponding milled wood lignin (MWL) and about two times greater as compared to cellulolytic enzyme lignin (CEL). Molecular weight distribution analyses also pointed out that the EMAL protocol allows the isolation of lignin fractions that are not accessed by any other lignin isolation procedures.     

种植密度对尾叶桉木材细胞形态结构影响的研究

对不同种植密度的尾叶桉（Eucalyptus urophylla)木材细胞形态结构进行测试和分析，探讨种植密度与木材纤维、导管分子和薄壁细胞的作用规律和相关模型。结果表明：种植密度与木纤维宽度、导管分子长度之间存在着显著的正相关，与导管分子的双壁厚之间存在着显著的负相关；种植密度对其余测试的指标影响不大。     

基于红外光谱的不同农作物秸秆磨木木质素差异表征

木质素是植物细胞壁中主要组分之一,其苯丙烷结构单元的单体结构和连接方式的复杂性直接影响木质素脱除和利用效果,了解不同农作物秸秆中木质素的差异,对提高秸秆的综合利用效率是非常必要的。该文选取代表性棉秆、玉米秸和小麦秆,分别提取磨木木质素,利用傅里叶变换中红外技术对棉秆、玉米秸和小麦秆三类秸秆磨木木质素进行红外表征,分析比较三类秸秆磨木木质素的差异,结果表明:1)三类秸秆磨木木质素G/S相对比值差别不大,并无明显规律;2)三类秸秆磨木木质素中,对羟基结构单元:玉米秸小麦秆棉秆;愈创木基结构单元:棉秆玉米秸小麦秆;紫丁香基结构单元:玉米秸小麦秆棉秆;3)玉米秸和小麦秆磨木木质素相似度较高,而棉秆磨木木质素则更加接近于木本植物。     

Effect of water and nutrient supply on root distribution in anEucalyptus globulus plantation

Water and nutrients were supplied to anEucalyptus globulus plantation in a controlled experiment in west central Portugal. The trees were planted in a sandy soil at a spacing of 3 × 3 m. The experiment consisted of four treatments: irrigation, irrigation plus fertilization, fertilization without irrigation, and a rain fed and unfertilized control. The quantification of root biomass was carried out 13 mo after planting. When the plantation was 31 mo old, a trench was dug in the soil to uncover the distribution of the roots of individual trees. In the irrigated treatments root biomass was higher than in the control and in the fertilized plots. Differences in fine and coarse root distribution along the soil profile were also observed. In both irrigated treatments roots were concentrated along tree rows, where the irrigation tubes were dripping water or water plus nutrients.     

Characterization of residual lignin after SO(2)-catalyzed steam explosion and enzymatic hydrolysis of Eucalyptus viminalis wood chips

The lignin component found in both water insoluble (WI) and water and alkali insoluble (WIA) fractions derived from SO(2)-impregnated steam-exploded eucalyptus chips (SEE) was isolated and characterized. Dioxane lignins with a sugar content lower than 2% (w/w) were obtained after each material was treated with commercial cellulases. The C9 formulas of both SEE-WI and SEE-WIA dioxane lignins were C(9)H(6.83)N(0.04)O(2.24)(OCH(3))(1.21)(OH(aro))(0.56)(OH(ali))(0. 77) and C(9)H(8.65)N(0.29)O(1.97)(OCH(3))(0.90)(OH(aro))(0. 46)(OH(ali))(1.02), respectively. The weight-average molecular weight (M(w)) of the SEE-WI lignin corresponded to 3.85 kDa, whereas the SEE-WIA lignin had an M(w) of 3.66 kDa for the same polydispersity of 2.4. The SEE-WIA lignin was shown to be more thermally stable than the SEE-WI lignin, requiring temperatures in the range of 520 degrees C for complete degradation. FTIR and (1)H NMR analyses of both untreated and peracetylated lignin fractions showed that (a) the alkali insoluble lignin contained a relatively higher degree of substitution in aromatic rings per C9 unit and that (b) alkaline extraction removed lignin fragments containing appreciable amounts of phenolic hydroxyl groups.     

Effect of water and nutrient supply on root distribution in an eucalyptus globulus plantation

Water and nutrients were supplied to an Eucalyptus globulus plantation in a controlled experiment in west central Portugal. The trees were planted in a sandy soil at a spacing of 3 × 3 m. The experiment consisted of four treatments: irrigation, irrigation plus fertilization, fertilization without irrigation, and a rain fed and unfertilized control. The quantification of root biomass was carried out 13 mo after planting.When the plantation was 31 mo old, a trench was dug in the soil to uncover the distribution of the roots of individual trees. In the irrigated treatments root biomass was higher than in the control and in the fertilized plots. Differences in fine and coarse root distribution along the soil profile were also observed. In both irrigated treatments roots were concentrated along tree rows, where the irrigation tubes were dripping water or water plus nutrients.     

Contribution of Arbuscular Mycorrhizal and Saprobe Fungi to the Aluminum Resistance of Eucalyptus globulus

Aluminum in acidic conditions is toxic to plants. Aluminum tolerance in some plant species has been ascribed to arbuscular mycorrhizal fungal symbiosis. In this study, the application of aluminum was found to inhibit mycelia development of saprobe fungi Fusarium concolor and Trichoderma koningii and the hyphal length of the arbuscular mycorrhizal fungi Glomus mosseae and Glomus deserticola in vitro. Several levels of aluminum were applied to Eucalyptus globulus plants and inoculated with arbuscular mycorrhizal fungi alone or together with both saprobe fungi. The application of 1,500 mg kg^?1 decreased the shoot and root dry weight, chlorophyll content and total P, Mg, and Ca concentrations in the shoot of E. globulus. However, both mycorrhizal fungi G. mosseae and G. deserticola inoculated alone increased the shoot dry weight of Eucalyptus, compared with a non- arbuscular mycorrhizal inoculated control treated with 1,500 mg kg^?1 of aluminum. When 1,500 mg kg^?1 of aluminum was applied, T. koningii increased the effect of G. deserticola on the shoot weight of eucalyptus, whereas with 3,000 mg kg^?1, shoot weight and arbuscular mycorrhizal colonization decreased in all treatments. With 1,500 mg kg^?1, the highest accumulation of aluminum in the shoot was obtained when G. deserticola was inoculated together with T. koningii. The possibility of manipulating an arbuscular mycorrhizal inoculation together with a saprobe fungus confers a high aluminum resistance in E. globulus. The effect of such combined inoculation is particularly important in some Chilean volcanic acid soils, mainly those which have been intensively cropped and are without lime addition, which facilitates the increase of phytotoxic aluminum species and limits their agricultural use. Therefore, such dual inoculation in field conditions deserves further investigation. Overall, the arbuscular mycorrhizal and saprobe fungi contribute to the increase in resistance of E. globulus to aluminium.     

Estimation of chlorophyll content in Eucalyptus globulus foliage with the leaf reflectance model PROSPECT

This communication presents the performance of the PROSPECT leaf optical model to derive chlorophyll content (Cab) estimates from reflectance and transmittance spectra of Eucalyptus globulus foliage. Estimates were compared to measured chlorophyll of 100% acetone extractions. The analysis showed that recent modifications to the absorption coefficients used in the PROSPECT model resulted in improved estimates of chlorophyll for both adult and juvenile leaves. Results were better for adult leaves, with estimates within 5 μg cm^?2 for the juvenile data set and 3 μg cm^?2 for adult leaves. Accurate estimates of canopy chlorophyll content in eucalypt plantations through the numerical inversion of leaf-level radiative transfer (RT) models such as PROSPECT coupled to canopy RT models would improve our ability to assess and monitor eucalypt plantation growth, health and condition.     

广西山茶属木材解剖构造研究

对采自广西的山茶属9个组43种的木材进行解剖研究，结果表明，管孔类型为散孔材至似半环孔材；射线以2列为主．次为1列。偶3列；射线组织全为异形，以异形Ⅰ型为主，稀Ⅰ型和Ⅱ型；结晶体和树胶常见，含晶细胞多呈异形．在某些组木材细胞中富含细胞核及细胞质。由此可知，山茶属是比较原始的种系。此外，从解剖构造角度讨论了山茶属木材的构造特点和山茶属木材中细胞核的分布特点及其与生境的关系。     

Non-linear impacts of Eucalyptus plantation stand age on soil microbial metabolic diversity

Purpose

Although it is generally accepted that planting exotic plant species alters metabolic function of soil microbial communities, its temporal dynamic is often ignored when evaluating ecological effects of associated land use changes. To investigate the dynamic impacts of successive Eucalyptus planting on carbon metabolic activities of soil microbial communities, we studied community-level physiological profiles of soil microbial communities in different generations of Eucalyptus plantations.

Materials and methods

We studied community-level physiological profiles of soil microbial communities, using the Biolog? Ecoplates incubation, in adjacent first (G1), second (G2), third (G3), and fourth (G4) generation Eucalyptus plantations that were, respectively, aged 3, 8, 14, and 19 years in Guangxi province, southern China. We used the ‘space-for-time substitution’ approach to investigate the impact of stand age of exotic Eucalyptus plantations on carbon metabolic diversity and activities of soil microbial communities. For each Eucalyptus plantation generation, three experimental plots were randomly selected. In each plot, one composite soil sample from 0 to 10 cm in depth was obtained for the analyses.

Results and discussion

Single carbon source utilization varied with Eucalyptus plantation stand age. Among preselected 31 carbon sources, utilization of 17 carbon sources changed significantly, which was best described by a quadratic function (ten carbon sources) and an exponential function (seven carbon sources). As a result, cumulative averaged metabolic activity and metabolic diversity of soil microbial communities showed quadratic and exponential changes relative to Eucalyptus plantation stand age. The order of cumulative averaged carbon metabolic activity and metabolic diversity were G1?>?G4, G3?>?G2 and G1?>?G2?>?G3, G4 (p?<?0.05), respectively. The factors contributing to carbon source utilization structure of soil microbial communities for different stand ages of Eucalyptus plantations were shrub richness, soil organic carbon content, microbial biomass carbon, C-to-N ratio, and N-to-P ratio.

Conclusions

Eucalyptus plantation stand age has inconsistent non-linear impacts on two aspects of soil microbial metabolic function: (1) quadratic impacts on carbon metabolic efficiency and (2) exponential impacts on carbon metabolic diversity. The decreasing carbon metabolic diversity has no significant impact on carbon metabolic efficiency during successive Eucalyptus plantings. The results show that the importance of assessing long-term impacts of land use changes on soil microbial communities from exotic plantations by quantifying multi-aspect non-linear changes on soil microbial metabolic function.     

Contribution of Arbuscular Mycorrhizal and Saprobe Fungi to the Tolerance of Eucalyptus globulus to Pb

The application of Pb inhibited the development of mycelia of the saprobe fungi Fusarium concolor and Trichoderma koningii and the hyphal length of the arbuscular mycorrhizal fungi (AM) Glomus mosseae and G. deserticola in vitro. The application to soil of 1500 mg kg^?1 of Pb decreases the dry weight, total N, P, Mg and Fe concentration and chlorophyll content of the shoot of E. globulus no inoculated with AM fungi. However, G. deserticola increased the dry weight, total nutrient concentration and chlorophyll content of the shoot, and the percentage of AM root length colonization and the succinate dehydrogenase activity of AM mycelia of E. globulus in presence of 1500 mg kg^?1 of Pb, and these increases were higher when G. deserticola was inoculated together with T. koningii. The application to soil of 3000 mg kg^?1 of Pb decreased the shoot dry weight and AM colonization of E. globulus in all treatments tested. Pb was accumulated in the stem more than in the leaves of E. globulus. In presence of 1500 mg kg^?1 of Pb the highest accumulation of this metal in the stem took place when E. globulus was colonized with G. deserticola. In conclusion, the possibility to increase Lead accumulation in stem is very attractive for phytoextraction function, the saprobe fungi, AM and their interaction may have a potential role in elevating phytoextraction efficiency and stimulate plant growth under adverse conditions such as lead contaminated soil.     

钙对化学诱抗剂诱导番茄叶片木质素合成的影响

为探索钙对化学诱抗剂水杨酸（SA）、 茉莉酸甲酯（MeJA）、 龙胆酸（GA）和 -氨基丁酸（BABA）诱导番茄木质素合成的影响,在番茄六叶期用上述诱抗剂分别处理第3 叶片,然后喷施CaCl2、 蒸馏水、 乙二醇-双-(2-氨基乙醚)四乙酸（EGTA）或LaCl3,处理后0、 1、 2、 3、 5 d 测定各处理番茄第3 叶片（诱导叶）和第5 叶片（非诱导叶）中木质素含量的变化。结果表明, （1）用上述化学诱抗剂处理番茄第3 叶片,诱导叶及其上位非诱导叶中木质素含量均升高;（2）外源Ca2+ 进一步促进上述诱抗剂诱导番茄叶片中木质素含量的增加;而Ca2+ 螯合剂EGTA和质膜钙通道抑制剂LaCl3,则不同程度地抑制这些诱抗剂对木质素含量的诱导作用。这些结果表明,钙对上述4 种诱抗剂诱导番茄叶片中木质素的合成具有正调控作用。     

Chemical composition and structural features of the macromolecular components of plantation Acacia mangium wood

The wood of Acacia mangium, a prominent fast-growing plantation species used in the pulp-and-paper industry and, so far, poorly investigated for its chemical structure, was submitted to a detailed characterization of its main macromolecular components. Lignin (28% wood weight) isolated by mild acidolysis and characterized by permanganate oxidation, 1H and 13C NMR, and GPC, showed a very low content of syringylpropane-derived units (S:G:H of 48:49:3), a high degree of condensation, a low content of beta-O-4 ( approximately 0.40-0.43 per C6) structures, and a Mw of 2230. Glucuronoxylan (14% wood weight) isolated by alkaline (KOH) or by dimethyl sulfoxide extraction was characterized by methylation analysis, 1H NMR, and GPC. About 10% of the xylopyranose (Xylp) units constituting the linear backbone were substituted at O-2 with 4-O-methylglucuronic acid residues. Almost half of the Xylp units (45%) were O-2 (18%), O-3 (24%) or O-2,3 (3%) acetylated. X-ray diffraction analysis of cellulose (46% wood weight), isolated according to the Kürschner-Hoffer method, showed a degree of crystallinity of 67.6%.     

基于SWAT模型茶园化肥减施增效配比研究

茶园化肥减施技术是改善茶园土壤环境、降低茶区地表水体富营养化的主要措施之一,有助于茶园生态环境的改善。利用云南省西双版纳自治州勐海县勐邦库区曼真村2018年3—9月大田试验数据及勐海县勐邦库区2011—2016年气象水文资料,基于SWAT模型建立区域尺度茶园化肥减施模型,构建环境效益评价体系(土壤肥力指标、水环境指标和经济效益指标),采用模糊综合评价法定量计算茶园不同施肥方式(常规化肥、70%化肥+有机肥配施、70%化肥+缓释肥配施、70%化肥+土壤改良剂配施)的环境综合效益指数,系统研究勐海茶园化肥减施增效配比方案。结果表明:1)勐邦库区流域月尺度径流与水质的模拟和实测结果趋势相同,决定系数R2=0.895,纳什系数Ens=0.837,模型拟合度高;2)综合效益权重计算结果表明,水环境指标(0.412)土壤肥力指标(0.317)经济效益指标(0.271),水环境对综合效益存在显著影响;3)勐海茶园最优的化肥减施配比方案为70%化肥+缓释肥配施,其土壤肥力效益指数为0.96,水环境效益指数为0.97,经济效益指数为0.99,综合效益评价指数为0.97。综上, 70%化肥+缓释肥配施能有效降低茶园地表水体富营养化产生的风险,同时能够提高茶园土壤肥力而不影响茶园的经济效益。因此,配施缓释肥是现阶段较为适合勐海茶园的环境友好型施肥技术。     

落叶松人工林结构对土壤水文特性的影响

为了解落叶松人工林结构对土壤水文特性的影响,对黑龙江省尚志市帽儿山地区不同结构类型下落叶松人工林的土壤水分物理性质、贮水能力及入渗性能进行研究。结果表明：1）土壤密度平均值由大到小依次为均匀结构、六行结构、四行结构、二行结构,分别为1.33、1.22、1.19和1.10 g/cm^3,总孔隙度变化趋势与土壤密度相反,分别为26.36%、48.99%、54.49%、56.00%;2）初渗速率变化范围为1.20-2.27 mm/min,10℃时的渗透系数K10大小依次为二行结构（1.04 mm/min）〉四行结构（0.81 mm/min）〉六行结构（0.67 mm/min）〉均匀结构（0.61 mm/min）,30 min累计入渗量表现出相应的变化趋势;3）40 cm土层范围内,土壤的饱和贮水量在1 054.20-2 239.80t/hm^2之间,其中二行结构的土壤贮水量最大。因此,二行结构的落叶松人工林土壤水文效益较高,是落叶松人工林营建时的首选方式。