Kinetics of acid-catalysed delignification of Eucalyptus globulus wood by acetic acid

Summary The kinetics of HCl-catalysed delignification of Eucalyptus globulus wood by 70% (w/w) acetic acid solution were satisfactorily explained by a model in which 5% of the lignin fraction could not be eliminated and the remaining 95% was eliminated by a single process which, in view of the activation energy calculated from the data was attributed to the hydrolysis of -aryl ether bonds. The selectivity of the process was effectively independent of HCl concentration and operating temperature for pulp yields >50%. At high temperature (160 °C) and catalyst concentration (0.027 MHCl), lignin condensation and precipitation became significant and the data were better fitted by a model comprising two consecutive processes: lignin solubilization followed by lignin condensation.The authors are grateful to the CICYT for financial support of this work (Project AGF93-0605) and also to the DGICYT for a research grant awarded to J. González     

European hardwoods versus Eucalyptus globulus as a raw material for pulping

The importance of eucalypt as a raw material for pulping is steadily growing. Eucalyptus globulus was compared with European hardwood species using two alkaline pulping processes, kraft and alkaline sulfite, anthraquinone pulping (ASA), which is a recently developed modified alkaline sulfite process. All cooks were performed to similar kappa numbers. Poplar cooks resulted in the highest yields followed by eucalypt and birch which were on the same level. Yield of beech pulps was definitely lower. ASA pulps show a moderate higher yield due to the less alkaline pH-profile of the cooking liquor. This yield advantage was maintained and even enhanced after TCF-bleaching. The bleaching response of all pulps was excellent. The birch pulps had the highest tensile strength followed by the poplar and beech pulps. Surprisingly eucalypt pulps had the lowest tensile strength. But this was compensated by the very good tear index of eucalypt pulps. The runnability factor, as an index for the overall strength potential, was on the same level for all pulps. Due to the higher hemicellulose content of the ASA pulps their tensile strengths were higher, but tear strengths lower compared to the kraft pulps. The different morphology of the hardwoods investigated resulted in different volumes and light scattering coefficients of the corresponding pulps. Dedicated to Prof. Dr. Dr. h. c. mult.Walter Liese on the occasion of his 80th birthday.     

蓝桉组织培养的研究

用蓝桉（Ｅｕｃａｌｙｐｔｕｓｇｌｏｂｕｌｕｓ）离体芽器官诱导培养，分化形成丛生芽，年繁殖系数３￣（１２）。０．１～０．５ｍｇ／Ｌ的６－ＢＡ或０．５～０．８ｍｇ／Ｌ的ＫＴ诱导外植体（带节茎段）腋芽萌动的效果最佳，诱导率分别达８０．３％和８１．５％。１．５～２０ｍｇ／Ｌ的６～ＢＡ或２０～２．５ｍｇ／Ｌ的ＫＴ分别与０．５～１．０ｍｇ／Ｌ的ＮＡＡ组合，对于促进腋芽分化形成丛生芽及继代培养中芽的增殖具有最佳效果。培养基中的无机盐浓度、蔗糖含量对蓝桉试管苗的生根具有显著影响；ＩＢＡ促进蓝桉试管苗的生根。至目前为止，在１／２ＭＳ无机盐培养基＋ＩＢＡ１．２～１．４ｍｇ／Ｌ＋Ｓ５ｇ／Ｌ中诱导生根，生根率最高可达２６．４％。     

蓝桉人工纯林土壤肥力研究

本项研究历时４年,研究结果显示,营造蓝桉纯林会引起林地土壤肥力明显降低,有机质、全Ｎ、有效Ｎ、Ｐ、Ｋ、交换性Ｃａ２＋、Ｍｇ２＋等７项指标均直接受影响。蓝桉人工林,经造林初期林地施肥能提高其生长量,但不能阻止林地土壤肥力下降。由于施肥促进了林木的生长,故也加强了对土壤肥力的消耗。     

蓝桉、直干桉综合丰产技术试验示范

试验林采用正交设计，因素为树种、整地方式、密度、施肥，各因素取３个水平，３次重复。用生长量、生物量与投入产出进行评价。试验结果：３．５年生蓝桉、直干桉幼林最佳处理平均高９．５ｍ，平均胸径８．９ｃｍ，每ｈｍ２蓄积量７０．５１２６ｍ３，最佳处理比最差处理树高大２８．４％，胸径大３４．９％，蓄积量大１８３％。用已取得的技术成果营造的示范林，３．５年生平均高９．８ｍ，平均胸径６．５ｃｍ，累计产桉叶２．４３万ｋｇ／ｈｍ２，３年生左右，通过桉油及薪柴的收入可以回收全部造林及加工成本。     

Origins and diversity of the Portuguese Landrace of Eucalyptus globulus

The Portuguese Landrace of Eucalyptus globulus is of unknown origin, with the earliest plantings of this tree species dating back to the early 19th century. In Portugal it is currently a major seed source for plantations and is also used in breeding programs. Eucalyptus globulus is native to south-eastern Australia. The substantial genetic differentiation of chloroplast and nuclear DNA markers between different native geographic races of this species allowed us to uncover the Australian origins of the Portuguese Landrace and to study its genetic diversity. To achieve this, we sequenced a highly polymorphic region of chloroplast DNA from 47 Portuguese Landrace individuals, and genotyped 34 of these using seven nuclear microsatellites. We compared these individuals to those in a database comprising chloroplast DNA sequence profiles from 292 native trees and seven nuclear microsatellites from 372 native trees. The majority of the Portuguese Landrace samples had closest affinities, in both marker systems, to native trees from south-eastern Tasmania, but some had affinities to trees from south-eastern Victoria. The discrepancies in the affinities indicated by chloroplast versus nuclear DNA markers could be explained by inter-race hybridisation after introduction. The genetic diversity in the Portuguese Landrace was less than that found in native E. globulus at the species level, but was similar to the average diversity found in native races of the species. This study demonstrates the power of using independent marker systems to identify the origins and diversity of domesticated populations, by comparison with variation in native stands.     

Integrating revenues from carbon sequestration into economic breeding objectives for Eucalyptus globulus pulpwood production

A system where carbon sequestration was directly dependent upon biomass production in a plantation was modelled to assess whether economic breeding objectives for the genetic improvement of Eucalyptus globulus were sensitive to potential revenues from carbon sequestration. Carbon dioxide equivalent accumulation in the biomass (CO₂e) of the Australian E. globulus plantation estate established between 2004 and 2012 was estimated. Total carbon dioxide equivalent (CO₂e) accumulation was in the order of ～146 t CO₂e ha^?1, of which 62 t CO₂e ha^?1 were tradable in 2012 (the 1st Kyoto Protocol commitment period) and a further 30 t CO₂e ha^?1 were tradable in 2016 (a hypothetical second Kyoto protocol commitment period). The correlated response of breeding objectives with and without carbon revenues (ΔcG _{h 1}) never fell below 0.86 in sensitivity analysis, and the mean was 0.93. Where economic breeding objectives for the genetic improvement of Eucalyptus globulus for pulpwood plantations are based on maximizing net present value by increasing biomass production, the consideration of carbon revenues in economic breeding objectives will have no significant effect on the relative economic weights of the key economic traits, wood basic density and standing volume at harvest.     

蓝桉子代测定

本文对云南省一平浪蓝桉实生种子园的子代测定林进行初期评价。该子代测定采用α-循环设计,21个重复,每个重复有18个不完全区组,每个区组分为15个小区,每小区2株树。全部270个家系均为自由授粉的半同胞家系,按来源分为3个类型(原产地天然林、云南地方品种和种子园),11个地区。调查和分析的数据包括造林后2年时的树高、胸径、冠幅、干形、抗寒性和存活率等性状。分析结果如下:1. 不同的类型在生长表现上存在显著差异,来自种子园的类型为最好。2. 自不同地区的蓝桉在各性状上都表现出显著差异。在生长表现上,来自维克多利亚东部、西部和各种子园的子代比其它地区的好。云南当地蓝桉子代的耐寒性和两年时的保存率为最好,在生长、干形和抗病方面与塔斯马尼亚东部和南部的蓝桉子代表现相似。采用两株小区,明显比单株小区降低小区缺失率,提高分析的可靠性。表3参7。     

Kinetics of polysaccharide hydrolysis in the acid-catalysed delignification of eucalyptus globulus wood by acetic acid

Summary The influence of operating conditions (temperature, HCl catalyst concentration and time) on the percentage of xylose solubilized in the acid-catalysed delignification of Eucalyptus globulus wood by acetic acid was studied using an incomplete 3 × 3 × 3 factorial design. Regression analysis afforded an equation satisfactorily correlating the experimental results. A kinetic model of polysaccharide hydrolysis is proposed which involves two parallel first order reactions: one the fast hydrolysis of hemicellulose and the other the slower hydrolysis of cellulose. Under mild operating conditions (i.e. at low temperatures and HCl concentrations) only the fast reaction occurs, leaving the cellulosic fraction as the unhydrolysed residue. The authors are grateful to the CICYT for financial support of this work (Project AGF93-0605) and also to the DGICYT for a research grant awarded to J. Gonzalez     

Studies on the delignification of spruce wood by organosolv pulping using SEM-EDXA and TEM

Summary Samples of spruce wood derived from various stages of organosolv pulping were studied by SEM-EDXA and TEM. During the first stage (methanol-water) the lignin content of the secondary walls decreased slowly, whereas in the compound middle lamellae only the reactivity of lignin increased. During the subsequent stage (methanol-NaOH) the delignification proceeded fast in both layers but the residual lignin content in the compound middle lamellae remained higher than in the secondary walls.     

Leaf orientation,light interception and stomatal conductance of Eucalyptus globulus ssp. globulus leaves

Juvenile and adult leaves of the heteroblastic species Eucalyptus globulus Labill. ssp. globulus did not show active diurnal orientation toward or away from incident radiation. Juvenile leaves of a late-maturing sapling of a Tasmanian provenance were evenly distributed in all azimuth sectors. In contrast, an early-maturing sapling of the same age from Wilsons Promontory, Victoria had a predominance of adult leaf blades facing east and west. Mid-vein and blade angles of juvenile and adult leaves were non-random with an overall vertical declination of the leaves. Both leaf types intercepted a greater irradiance during the morning than at midday. Sub-horizontal juvenile leaves intercepted 22% more irradiance than vertical adult leaves during the middle of the day. The amphistomatal and isobilateral adult leaves intercepted sunlight equally on both leaf surfaces. Stomatal conductance was variable during the period of measurement but was similar for the Tasmanian juvenile (0.4 to 0.9 cm s(-1)) leaves and Wilsons Promontory adult (0.5 to 1.2 cm s(-1)) leaves. Greater light interception by the sub-horizontal juvenile leaves would confer a growth advantage to saplings and regenerating canopies. Reduced light interception and leaf temperature of vertical adult E. globulus leaves would assist in water conservation, particularly at high solar angles.     

Studies on Dual Mycorrhizas of Eucalyptus globulus and E

This paper represents the first part of the results from a glasshouse experiment designed to compare the competition of ECM and VAM fungi on root colonization and effects on growth of two Eucalyptus species　（E．globulus and E．urophylla）．One ECM fungus（Laccaria lateritia）　and three VAM fungi belonging to genera Glomus，Acaulospora and Scutellospora，along with field soil as well，were used to inoculate Eucalyptus seedlings alone or in combination．Both ECM and VAM fungi colonized and formed mycorrhizal associations on roots of inoculated seedlings，though infective rates of VAM and ECM tips per meter varied according to inoculant fungi and plant ages． There were some regressive interactions for colonization between the two fungi，as a general trend for ECM root colonization levels to increase with time at the expense of VAM colonization was observed during 16 weeks． The effect of phosphorus levels in soils on mycorrhizal formation was discussed．     

Leaf growth of Eucalyptus globulus seedlings under water deficit

Eucalyptus globulus Labill. seedlings grown under field conditions in Portugal were watered either daily (control) or every 6 days (drought-treated). Relative to those of control plants, rates of leaf production and leaf biomass accumulation were reduced by almost half in drought-treated plants. However, whereas expansion of new leaves on control plants slowed toward the end of the 30 day experiment, expansion of leaves of the same age on drought-treated plants accelerated as a change in weather conditions resulted in midday plant water potentials above -3.0 MPa. In plants that were left unwatered until they wilted and were then watered daily, expansion of the fifth leaf pair from the apex was slower than that of the same pair of leaves of plants watered daily throughout; but it continued for about twice as long and resulted in the same final leaf area. Drought treatment also caused a substantial reduction in the rate of leaf production, which, in part, accounted for the effect of drought on leaf biomass production. In a greenhouse study, witholding water for 15 days had only a slight effect on the length or width of adaxial epidermal cells, and the effect was quickly reversed on rewatering.     

Advances in reproductive biology and seed production systems of Eucalyptus: the case of Eucalyptus globulus

Eucalyptus globulus is the main eucalypt species grown in Australian plantations. The focus on seedling deployment systems, coupled with exploitation of large, open-pollinated base populations for breeding purposes over the last two decades, has required a detailed understanding of the reproductive biology of this species. We review our research on the reproductive biology of E. globulus, with a focus on its breeding system and advances made in seed production systems. While most improved seed is still obtained from open-pollinated seedling or grafted seed orchards, the development of the one-stop/single-visit pollination procedure has revolutionised the breeding and deployment of this species. The reduced costs of controlled pollination has meant full pedigree-control can now be maintained in large advanced-generation breeding populations and E. globulus is one of the few eucalypt species where large-scale production of manually pollinated seed for family forestry is being undertaken.     

蓝桉幼林施肥效应研究

在云南省保山市石灰岩红壤地区进行了历时4年的蓝桉幼林N、P、K不同配比的10种处理施肥试验。结果表明，施肥能明显促进蓝桉（Eucalyptusglobulus）幼林的生长；其中处理6、9、10增产效果极显著，树高增加16．31％～20．40％，胸径分别增加18．78％～19．21％，材积增加65．04％～70．19％。有机肥对蓝桉生长有促进作用，施过有机肥的处理10生长始终保持优势；磷肥是蓝桉增产的主要因素，每株施430g钙镁磷肥做底肥能使树高、胸径分别增加14．67％、15．87％，每株施215g钙镁磷肥则树高、胸径分别增加11．44％、7．83％；氮肥各水平间无差异，增产效果不明显；钾肥1、2水平间无差异，3水平可能过量，阻碍了肥效发挥。施肥能提高蓝桉生产的经济效益，较好的几个处理依次为6、9、2、10、3产出投入比值均大于对照。综合以上几个因素，N2P3K2为蓝桉幼林的最佳施肥方案。     

Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations of Tasmania,Australia

The genus Mycosphaerella Johanson contains many pathogens capable of causing a severe impact on the growth of susceptible eucalypt species. The lack of knowledge about which species are present in Tasmania and their potential risk to the plantation industry prompted this study into the Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations in Tasmania. A total of 36 plantation and five road verge sites of E. globulus and E. nitens were sampled. Five Mycosphaerella species and three species from associated anamorph genera were isolated and identified in Tasmania; Mycosphaerella nubilosa, Mycosphaerella cryptica, Mycosphaerella tasmaniensis, Mycosphaerella grandis, Mycosphaerella vespa, Coniothyrium ovatum, Sonderhenia eucalypticola and Sonderhenia eucalyptorum. The most frequently isolated species with the highest incidence and severity of infection were M. cryptica and M. nubilosa. These two species appear to have the greatest potential to damage juvenile eucalypt plantations in Tasmania. A link between Mycosphaerella vespa and Coniothyrium ovatum is described for the first time.     

Flexural and visual characteristics of fibre-managed plantation Eucalyptus globulus timber

ABSTRACT

The main goal of this study was to investigate the visual characteristics, recovery rate, and flexural properties of sawn boards from a fibre-managed plantation Eucalyptus globulus resource as a potential raw material for structural building applications. The impacts of the visual characteristics, strength-reducing features, and variation in basic density and moisture content on the bending modulus of elasticity (MOE) and modulus of rupture (MOR) of the boards were investigated. The reliabilities of different non-destructive methods in predicting MOE and MOR of the boards were evaluated, including log acoustic wave velocity measurement and numerical modellings. The MOE and MOR of the boards were significantly affected by the slope of grain, percentage of clear wood, and total number of knots in the loading zone of the boards. The normal variation in basic density significantly influenced the MOE of the boards while its effect on the MOR was insignificant. The numerical models developed using the artificial neural network (ANN) showed better accuracies in predicting the MOE and MOR of the boards than traditional multi-regression modelling and log acoustic wave velocity measurement. The ANN models developed in this study showed more than 78.5% and 79.9% success in predicting the adjusted MOE and MOR of the boards, respectively.     

Wood anatomy and biometric parameters variation of Eucalyptus globulus clones

Variation in wood anatomy and biometric variables was studied in 14 7-year-old Eucalyptus globulus clones grown in a clonal trial in Arauco, Bio-Bio Region, Chile. Biometric characteristics were measured for each tree and the anatomical variables were measured at three radial positions by image analysis on transverse microsections cut from radial increment cores sampled at breast height. Results showed, that among clones wide ranges of variation were found for vessel frequency, vessel area and vessel coverage. However, narrow ranges of variation were found for fiber wall thickness, fiber diameter and lumen diameter. From pith to bark, mean vessel area and vessel coverage increased gradually, whereas the vessel frequency decreased. The fiber wall thickness did not differ significantly from pith to bark. Mean fiber and lumen diameters showed the same radial pattern, increasing from pith to the midpoint of the radius to reach a plateau close to the bark. Furthermore, important commercial volume gains that can exceed 100% were found. Considering the commercial importance of tree volume, vessel and fiber anatomy in the pulping and papermaking process, it is suggested that the information given in this study may be used as an additional criteria for the selection of E. globulus.     

Extraction of antioxidants from eucalyptus (Eucalyptus globulus) bark

The extraction of phenolic compounds from eucalyptus (Eucalyptus globulus) bark was examined with the aim of analyzing the potential of the extracts as natural antioxidants. Experiments were planned according to a 2³ factorial design to analyze the influence of temperature and Na₂SO₃ and NaOH concentrations in aqueous solutions on extraction yield, extract total phenols content, ferric reducing antioxidant power (FRAP), and number- and weight-average molecular weights. Extract total phenols content and FRAP antioxidant activity in the ranges 0.91–2.58?g gallic acid equivalent (GAE)/100?g oven-dried bark and 4.70–11.96?mmol ascorbic acid equivalent (AAE)/100?g oven-dried bark, respectively, demonstrated the potential of eucalyptus bark as a source of antioxidant compounds. Extraction at the highest temperature (100°C), the lowest Na₂SO₃ concentration (1.5% on oven-dried bark), and without NaOH provided the highest extract total phenols content and FRAP antioxidant activity. Those eucalyptus bark extracts with lower molecular weight showed higher antioxidant activity. Matrix-assisted laser desorption ionization time-of-flight and reverse-phase high-performance liquid chromatography electrospray ionization time-of-flight mass spectrometry revealed the presence of polygalloyl glucoses, catechin, epicatechin, ellagic acid, quercetin-3-o-rhamnoside, and isorhamnetin in eucalyptus bark aqueous extracts.     

Impacts of Teratosphaeria leaf disease on plantation Eucalyptus globulus productivity

The effects of Teratosphaeria leaf disease (TLD) on Eucalyptus globulus are varied, and it is currently poorly understood whether infection by TLD can cause long‐term growth effects. Such information would greatly assist disease management and pruning regimes on E. globulus plantation sites, resulting in both financial and ecological benefits. Two trials were established to quantify the effects of TLD on long‐term growth. The first was a 2‐year fungicide exclusion trial that aimed to determine initial growth losses between trees treated with fungicide and untreated trees. It was found that tree growth was not affected until a threshold value of 20% damage was reached. Volume was reduced by 17% between treated and untreated trees over the course of the 2‐year trial. The second trial, a 5‐year growth study, used differentially affected adjacent stands (one infected and the other unaffected) to look at the longer term effects of more severe defoliation (44–60%) caused by an epidemic of TLD. Results recorded 5 years after the epidemic showed that trees recovered to regain normal growth trajectories after the epidemic, but growth was retarded by ca. 1.2 years for both height and diameter compared with that of the adjoining unaffected stand. As the growth of trees was not permanently reduced by the epidemic, it is concluded that the financial impacts of TLD are more likely to be associated with the loss of income resulting from extensive branch death in the lower crown after leaf and stem infection, which makes the affected stands not suitable for pruning and hence prevents them from being managed as a higher value solid wood crop.