我国邓恩桉抗寒性研究进展

邓恩桉具有生长快、材性好、耐寒的特点，成为我国桉树北移种植的优良树种。本文概述了国内有关邓恩桉抗寒性的研究动态，讨论了邓恩桉抗寒性与细胞膜系统、保护酶系统等方面的相关性，参考其他植物抗寒性研究方法与思路，对邓恩桉抗寒性的进一步研究提出了一些设想。     

几种不同桉树在福建省中部区域引种适应性探讨

在福建省中部地区永安市分别进行尾巨桉、邓恩桉、尾细桉、赤桉等几种不同桉树引种栽植试验,调查它们当年的成活率、生长量、保存率、冻害状况和病虫害危害以及两年生和三年生的胸径和高生长量,比较分析上述几种树种3年生胸径、树高的生长。结果表明：邓恩桉在该地区有较好的年生长量和抗寒能力,尾巨桉、尾细桉生长量较高,但抗寒性较差,赤按有良好的抗寒性,但生长量较差。对于桉树北移栽植而言,极端低温是该树种的限制因子。在比较速生性状的同时,应考虑它的抗寒性状。该试验结果表明,邓恩桉在该区域引种栽培是较理想的选择树种,可减少按树在该区域投资风险,为生产提供科学的理论依据。     

南平市延平区桉树引种适应性试验研究

在福建省南平市延平区进行纸浆林阔叶树种尾赤按DH184、尾赤桉DH201、柳窿按、邓恩桉引种试验.通过对以上树种的速生性、适应性的调查分析,研究结果表明:尾赤按DH201、柳窿桉、邓恩桉适合在南平市延平区300m以下海拔山地栽植,为该地区发展速生桉树选择提供了参考.     

广西桉树大径材培育前景

桉树天然分布于澳大利亚,是广西主要速生丰产造林树种。桉树中的大花序桉(Eucalyptus cloeziana)、斑皮桉(E.maculata)、柠檬桉(E.citriodora)等树种的木材密度更大、硬度更高,适合培育大径材,是广西近年来重点研究的桉树种;一些国家已利用桉树培育大径材,加工成锯材,制作家具、木地板等,大径材价值高,市场需求大;此外,广西桉树发展的基础雄厚,培育桉树大径材前景好。     

韦塔桉母本选择与控制授粉技术

桉树为纸浆材重要树种,其新品种培育已成为研究热点,韦塔桉作为桉树中的速生和适生种而备受育种家的关注.总结了韦塔桉常规育种程序和技术,内容包括选择韦塔桉为亲本的原因,亲本选择原则,亲本物候观察,亲本育种前高度控制方法,花粉收集、处理及保存方法,用于授粉的花粉活力测定、控制授粉中去雄处理及套袋授粉方法,割柱授粉法,种子的采收和贮藏方法等.韦塔桉育种总结可为其它桉树人工杂交及乔木树种的控制授粉提供技术及方法上的借鉴.     

科学改良桉树杉木人工纯林

正桉树和杉木是中国人工造林的两大重要树种。桉树原产于澳大利亚,目前中国桉树人工种植面积已达150万公顷,仅次于巴西和印度,居世界第三位。其中广东30万公顷、广西20万公顷、海南18万公顷、云南17万公顷,其他地区65万公顷。此外,四川、湖南等地已尝试在寒冷地区种植桉树,桉树有北移的趋势。杉木是我国人工种植面积最广、最重要的速生用材树种之     

耐寒桉树播种育苗技术

耐寒桉树是湖南省“十五”期间重点发展的工业用材林树种，它具有生长快、材质好、用途广以及适应性强等特点。种植桉树具有较高的经济效益，在适宜的地区值得大力推广。1.适于在我省推广的耐寒桉树种类适于在我省推广的耐寒桉树主要有邓恩桉、赤桉和柳桉等。其中赤桉和柳桉因其种子繁殖苗木生长分化较大，一般采用无性系育苗。而邓恩桉因其在原产地分布范围较窄，种子繁殖苗木生长分化相对较小，所以邓恩桉可用种子进行繁殖。2.播种时间耐寒桉树造林最好在6月中旬以前进行，因此，播种时间在当年的2~3月为宜。3月份以前播种，要在保护地进…     

广西耐寒桉树研究进展

广西耐寒桉树改良和栽培技术研究项目实施 3年来 ,着重开展了下面几个方面的工作 :(1)对 1991年建立的邓恩桉 (E dunnii)种源 /家系试验林进行了观测研究 ,包括种源及家系的生长表现 ,开花物侯与种子生产能力的研究 ,促进邓恩桉开花结实试验、邓恩木材基本密度的分析测定 ;(2 )从澳大利亚引进多枝桉、邓恩桉等 10多个耐寒桉树种 /种源 ,建立了新的耐寒桉品种试验林 ;(3)扩大邓恩桉栽培范围 ,在广西、江西以及湖南建立起邓恩桉种源试验与示范林 ;(4)开展了邓恩桉、柳窿桉 (E saligna×E exserta)组培无性繁殖研究 ,建立了 8个无性系无菌体系 ;(5 )对栽培耐寒桉树的柳州、桂林两地试验点的立地进行了评估。此外 ,还指出了项目存在问题及下一步的工作展望。     

广西桂林耐寒桉树引种试验研究

本文概述了桂林1984年、1986年、1991年以来桉树引种概况。共引种22个树种(种源)现存20个。经过4—11年观察,能安全越冬、渡过-4℃低温、冰冻持续5天之久的恶夯天气。筛选出柳窿桉、邓恩桉、圆角桉、尾叶桉、巨桉等几个速生、适应性较强的树种,可在本地区适宜范围内引种推广,扩大栽培面积。邓恩桉可作为耐寒树种在桂北地区引种推广。     

桉树基因组研究进展

桉属的一些树种在全世界的热带和亚热带地区广为种植。该属树种生长快,工业性能好,适应范围广,引起了许多国家的种植兴趣。据估计,1985年全球桉树种植面积约6百万hm~2。现在,全世界引种的绝大多数硬材林树种是桉树,桉树已成为一个主要的生物资源树     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.