山杏壳木醋液的精制及抑菌活性研究

以山杏壳木醋液为原料,经活性炭前处理,采用常压蒸馏和减压蒸馏方法进行精制分离,通过气相色谱-质谱联用技术(GC-MS)对精制的馏分进行成分组成分析,并对精制后木醋液的抑菌活性进行测试。试验结果表明,原山杏壳木醋液经过5%的活性炭前处理后再经常压蒸馏精制,主要成分由8种减少到4种,有助于山杏壳木醋液的精制;与常压蒸馏方法相比较,减压蒸馏收集0.1 MPa下,小于70℃的馏分,可以有效去除有害成分,精制效果好且后处理简单。精制山杏壳木醋液对6种供试细菌均表现出抑菌活性,抑菌效果比浓度为0.4 mg/mL的对照品硫酸链霉素提高了1.6~6.7倍,最大抑菌圈直径可达42.33 mm。研究表明,精制山杏壳木醋液作为纯天然物质,在食品、医药、化妆品等领域应用前景广阔。     

柞树木醋液酚类物质的组分分析

采用常规方法测定了柞树木醋液的基本参数，所得木醋液为黑褐色且带有烟焦味，pH值4.06，有机酸含量（以醋酸计）5.20％，密度（20℃）1．0260g／cm^3，木炭粉吸附法精制得率90.7％。采用分配法将柞树木醋液系统地划分为酸性物、酚类物和中性物，并利用GC—MS联用仪对酚类物进行了组分分析。结果表明，酚类物中的主要组分是苯酚3．60％、2-甲基苯酚1．20％、1，2,3-三甲氧基苯12．82％、2,6-二甲氧基苯酚34．41％和4,6-二（1，1-二甲基乙基）-2-甲基-苯酚35．97％。该分析对柞树木醋液产品品质基准的制订具有重要意义。     

柳杉木材边材木醋液中的成分研究

用毛细管气相色谱法对日本柳杉木材边材炭化得到的木醋液中的37种成分进行定性和定量分析.结果表明,醇类、酮类、羧酸类、呋喃类、苯酚类及愈创苯酚类是其主要成分.用溶剂萃取-硅胶柱层析法进一步分离处理木醋液,纯化出炭化过程中产生的手性脱水内醚糖-左旋葡聚糖(LGA,1,6-脱水-β-D-葡萄糖),但其不能被毛细管气相色谱法检...     

柞树木醋液酚类物质的组分分析

采用常规方法测定了柞树木醋液的基本参数,所得木醋液为黑褐色且带有烟焦味,pH值4.06,有机酸含量(以醋酸计)5.20%,密度(20℃)1.026 0 g/cm3,木炭粉吸附法精制得率90.7%.采用分配法将柞树木醋液系统地划分为酸性物、酚类物和中性物,并利用GC-MS联用仪对酚类物进行了组分分析.结果表明,酚类物中的主要组分是苯酚3.60%、2-甲基苯酚1.20%、1,2,3-三甲氧基苯12.82%、2,6-二甲氧基苯酚34.41%和4,6-二(1,1-二甲基乙基)-2-甲基-苯酚35.97%.该分析对柞树木醋液产品品质基准的制订具有重要意义.     

冷冻处理对日本柳杉边材炭化的影响

将冷冻处理前后的日本柳杉边材在 4 0 0℃下进行炭化 ,得到了木醋液、木焦油和木炭。与没有处理相比 ,虽然处理过边材的木焦油的收率几乎不变 ,木醋液的收率显示增加倾向 ,但是木炭的收率有减少迹象。用毛细管气相色谱法对得到的木醋液中的 11种成分进行了定量分析。与无处理相比较后 ,发现处理过边材木醋液中的甲醇、脂肪酸及糠醛 (呋喃甲醛 )的收量有了变化 ,但是 5 -羟甲基糠醛、麦芽酚、苯酚、邻苯二酚及愈创苯酚的收量几乎没有变化。     

醋酸水溶液预处理对柳杉木材炭化的影响

杉木(日本柳杉)经醋酸水溶液处理后，重量减少。将处理前后柳杉木材在4℃下进行炭化，得到了木醋液、木焦油和木炭。与未处理材相比，处理材木醋液的收率增加，而木焦油和木炭的收率减少。处理液的醋酸浓度增加后，木醋液和木焦油的收率几乎不变，但木炭的收率稍微减少了。用毛细管气相色谱法对木醋液的成分进行了定量分析。与未处理材相比，处理材木醋液中糠醛(呋喃甲醛)及5-羟甲基糠醛的收量增加，而羧酸类、苯酚类、邻苯二酚、愈创木酚类及麦芽酚的收量几乎不变。当醋酸浓度从0增至3％时，糠醛的收量随着增加，但是当醋酸浓度从3％增至30％时，其收量却几乎不变。     

木醋液的制备、精制与应用研究进展

从原料、热解工艺、催化剂几方面阐述了对木醋液理化性质及组成成分的影响,概述了静置法、蒸馏法、萃取法、活性炭吸附法、膜过滤法等常用精制工艺及其应用特性,着重介绍了木醋液在农业、林业、畜牧业、医药和食品领域的应用研究进展。     

杨树木醋液的化学成分分析及抑菌试验

对于馏法制取、不同温度段采集到的杨树木醋液的抑菌效果进行研究,并对高温度段的化学成分用GC-MS进行分析.结果表明:150～300 ℃温度段木醋液除对大肠杆菌抑制效果差于对照庆大霉素外,对其他细菌的抑制作用均强于抗菌素;300～510℃温度段木醋液抑菌效果均好于对照庆大霉素,说明高温度段的木醋液具有很强的抑菌作用.300～510℃收集的木醋液约含有41种化学成分,其中主要成分为酸类、酚类、酮类、醇类、醛类和酯类等.在所有化合物中,乙酸含量最高,占总量的17.10%,其次为苯酚,含量为11.36%.初步分析确定其抑菌活性成分为乙酸和酚类物质.     

木醋液的制造及其应用

本文叙述了木醋液的理化性质及其制造方法；重点介绍了日本的木醋液精制工艺和科研成果，以及将木醋液作为促进林木和农作物生长材料的经验。作者认为，木醋液在我国具有广阔的发展前景，是一种可获得巨额收入的产业，林业部门不可等闲视之。     

热解工艺对木醋液制备及性质的影响

以杉木屑为原料,在固定床反应器上探讨了热解条件对杉木屑制备木醋液及其性质的影响,结果表明:热解温度是主要影响因素,在热解温度450℃、升温速率10℃/min、氮气流量100 mL/min的热解工艺下,粗木醋液产率可达57.13%,精制醋液产率可达38.20%。杉木屑热解制备得到的木醋液的6类主要化学成分中,酸类和酚类物质为主要成分,约占总含量的2/3,其次是醇类、酮类和醛类,酯类含量较少。热解工艺条件对木醋液的组成和含量有显著影响,热解温度影响酸类、酚类和醇类含量,升温速率影响酸类和醇类含量,氮气流量影响酚类和醇类含量,酮类、醛类和酯类含量基本不受影响。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.     

Tree planting for dryland salinity control in Australia

Dryland salinity is emerging as a major form of land and water degradation in southern Australia, particularly in Western Australia, South Australia and Victoria, and to a lesser extent in New South Wales, Tasmania and Queensland.Tree planting, in combination with other vegetation treatments, is regarded as a leading solution to dryland salinity. Research has now shown that planting trees can significantly lower groundwater tables, and thereby reverse the causal process of salinisation. Substantial progress has been made towards answering the basic questions of which species to grow, how to plant, where to plant, at what density and configuration to plant, and how much area to plant. The economic potential for commercial tree planting has given impetus to partial reforestation in higher rainfall (> 600 mm yr^–1) areas. Even so, serious constraints are apparent, relating primarily to cost, uncertainty and attitude. The future should bring increasing community input and control, technical refinement and gradual adoption, provided all aspects of the issue are well researched, relevant information is well communicated and programmes are well administered. Some specific requirements for future research are identified in this review.     

Effect of Cuttings on the Scenic Beauty of a Tree Stand

The opinions of 207 respondents on the visual effects of seven different cutting types were asked using a nine-point verbal scale ranging from ''worsens very much'' to ''improves very much''. Other estimates were obtained by letting the same respondents evaluate photographs of stands which had been treated with different cuttings. The direct questions gave results quite similar to the evaluations of photographs for all but young respondents, indicating that most respondents were able to imagine the effect of the treatment correctly. The results based on the evaluation of photographs indicated that the effect of regenerative cuttings is negative while the impact of thinnings is positive. After a few years of cutting the stand is already regarded as clearly more pleasant than immediately after the cutting. Natural regeneration with seed trees seems to be a way to avoid the very negative immediate impact of clear-felling, especially in the case of Scots pine. Women, young, urban people and those who do not own forest or have work related to forests tended to experience thinnings less positively and saw regenerative cuttings as more harmful than the other test groups did.     

Pinus contorta growth in northern Sweden as affected by soil scarification

The aim of this study was to quantify the effects of different soil scarification methods on tree growth. Soil scarification influenced stem volume and stem biomass yield of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) in a 17-year-old field trial in boreal Sweden. Soil scarification (disc trenching, mounding and ploughing) resulted in an average stem volume yield of 3.1 and 34.2 m³ ha^–1 on the poor and intermediate sites, respectively, while corresponding values for no soil scarification were 0.9 and 16.7 m³ ha^–1. In comparison to no scarification, ploughing increased volume yields by 500% on the poor site and by 200% on the intermediate sites. The ranking according to stem volume yield was ploughing > disc trenching = mounding no soil scarification. Averaged over the two sites, the mean annual increment of stem biomass was 219% and 145% higher (in d.w., 0.26 kg and 0.34 kg per sample tree) after ploughing compared with no soil scarification, for the average and dominant sample trees, respectively. Although not significant, the increased growth rate after soil scarification decreased the average stem basic wood density of the sample trees with 1.6% and 5.3%, at the poor and intermediate sites, respectively. In conclusion, soil scarification significantly increased the 17-year stem volume yield compared with no scarification. The results also indicate that the difference in stem biomass yield between ploughing and the other methods, especially no soil scarification, will increase even more in the near future.