韶关市6个桉树无性系试验初报

通过对参试的尾巨桉（DH．33．27、DH．33．29、广林9号）、尾赤桉（201号、201．2号）和尾叶桉（U6）6个桉树无性系早期人工林的生长量和抗逆性进行调查和综合评价。结果表明：参试无性系20个月生林分平均胸径6．30～7．72cm,平均树高为5．87～9．18m,都表现出速生特性。6个无性系间的树高生长存在极显著差异,胸径生长量存在显著差异。尾赤桉和尾巨桉5个无性系间树高生长也存在极显著差异,胸径生长量差异不显著。尾叶桉U6和尾巨桉DH．33．29耐寒性较差,尾赤桉系列幼龄林存在易风倒现象。尾巨桉系列（DH-33-27、广林9号）速生性、适应性较强,可作为目前韶关市桉树人工林建设的主栽品种。     

巨尾桉无性系山地引种造林效果的研究

通过对引进巨尾桉无性系与巨桉,尾叶桉进行山地造林试验３年的研究结果表明,巨尾桉无性系不仅能适宜本地区山地栽培,而且,生长快,３年生平均树高１２．１ｍ,胸径１２．３ｃｍ,单株带皮材积０．０７２８ｍ＾３,去皮材积０．０５７４ｍ＾３,比尾叶桉分别增长２３．５％,２８．１％,９２．１％和１４０．２％,比巨桉分别增长１３．１％,１９．４％,５６．６％和５１．５％。它还具有树干通直圆满,树皮较薄,冠径比小,出     

重庆地区不同桉树无性系生长对比试验及经济效益分析

6个桉树无性系和1个对照品种(巨桉实生苗)在相同立地条件下的造林对比试验结果表明:6个桉树无性系和1个对照品种在本区生长均表现良好,不同桉树无性系之间、各无性系与对照之间的胸径、树高、单株材积生长量差异性显著,只是2年生时生长量差异性更大,6年生时生长量差异性变小;适宜本区发展的桉树无性系首选巨尾桉GU9,其次为尾巨桉DH32-29、尾巨桉DH33-27,在6年生时这3个无性系的单株材积量分别达到0.249875 m3、0.189 312 m3、0.188 103 m3,其种植经济效益显著优于其它无性系和对照实生苗。     

尾叶桉及其杂交种无性系早期生长变异分析

本文对9个尾叶桉、巨尾桉、尾巨桉无性系0.5~2.5年生试验林生长率、差异性及林分直径结构分析,发现林龄0.5~1.5 a是无性系树高生长高峰期,此时树高生长率达79.20%~96.27%,是林龄1.5~2.5 a树高生长率的3~4倍;林龄1.5~2.5 a时,各无性系林分胸径、树高、单株材积生长率分别为19.66%~25.67%、18.58%~27.96%、52.57%~62.54%,生长率最大的是E7号无性系(胸径、单株材积)和E6号无性系(树高);秩次相关分析表明：各无性系胸径、单株材积生长量在不同林龄时排序变动不大,而无性系树高生长量排序在不同林龄时变动较大;差异性分析表明：无性系间胸径、树高、单株材积生长差异显著,但随林龄增加有差异减小趋势;林龄2.5年生时,E5号无性系胸径、单株材积生长量最大,分别达11.39 cm、0.0736 m3;各无性系林分树木径阶范围为6~14 cm或8~14 cm,以10 cm或12 cm径阶树木占最大比例,除E8号无性系外,其余8个无性系树木径阶分布总体上近似正态分布。     

巨尾桉无性系山地引种造林效果的研究

通过对引进巨尾桉无性系与巨桉、尾叶桉进行山地造林试验３年的研究结果表明,巨尾桉无性系不仅能适宜本地区山地栽培,而且生长快,３年生平均树高１２１ｍ,胸径１２３ｃｍ,单株带皮材积００７２８ｍ３,去皮材积００５７４ｍ３,比尾叶桉分别增长２３５％、２８１％、９２１％和１４０２％,比巨桉分别增长１３１％、１９４％、５６６％和５１５％。它还具有树干通直圆满、树皮较薄、冠径比小、出材率高、丰产性好等特点,可以大面积发展,并总结出栽培上的关键技术。     

尾巨桉等桉树无性系生长特性分析及选择

对尾巨桉(Eucalyptus urophylla×E.grandis)、巨尾桉(E.grandis×E.urophylla)、尾叶桉(E.urophylla)无性系试验林生长性状和干形进行了分析,为选择优良无性系提供科学依据。结果表明,不同无性系及同一无性系在不同林龄时的胸径、树高、单株材积生长率均有所不同,总体上QL4、QL7无性系生长率较大,而QL1、QL2无性系的生长率则较小;林龄1.5年及6.5年时无性系间胸径、单株材积均有显著差异,而无性系间树高仅在林龄1.5龄时差异显著;其余林龄无性系间的差异均不显著。用6.5年生参试无性系胸径、树高、单株材积、干形观测值对各无性系进行综合评定,结果QL7无性系的综合评定结果最佳,被评为优良无性系,其6.5年生时平均胸径、树高、单株材积分别是16.83 cm、21.42 m、0.233 1 m~3;而QL1无性系综合评定排最后一位;因此,不同无性系及同一无性系在不同阶段的生长表现均有所不同,无性系间胸径、单株材积在其生长的早期及后期均存在显著差异,而树高则在早期差异显著,所选择的QL7优良无性系可在试验地所在区域推广种植。     

尾叶桉无性系生长比较研究

对12个尾叶桉无性系的生长性状差异分析和比较结果表明：各性状在无性系间差异均极显著，各性状的无性系重复力75．24％～94．32％，单株重复力为43．18％～80．57％。冠幅的重复力最小，材积最大。5．5年生时共有4个无性系生长量超过总体家系平均值，生长最优的无性系平均单株材积达0．1684m^3，是最差无性系的253．78％，是平均值的58．38％，比最优对照U6无性系高79．33％。应用主成分分类方法，将无性系分成6类。速生型无性系较慢生型无性系的树高、胸径和材积分别高出30．40％、57、74％和221．64％，增产效果十分显著。     

巨桉无性系生长早期选择

对26个巨桉无性系人工林生长性状的调查分析表明：胸径、材积在无性系间呈极显著差异,相关性分析结果表明胸径、树高、材积三者间存在极显著的正相关关系。变异系数最大的是材积,达到78.82%,其次为树高和胸径,分别为52.23%、23.13%。胸径、树高、材积的重复力分别为0.5744、0.5469、0.3453。利用综合评定方法评选出5个优良的巨桉无性系,分别为20、18、25、9和5号。5个优良无性系胸径、树高、材积的遗传增益分别为11.60%、11.09%和2.05%。     

不同桉树无性系造林对比试验

通过7个桉树无性系在3个不同立地条件的造林对比试验研究,结果表明:7个桉树无性系在本区表现良好,不同桉树无性系间在胸径、树高、蓄积量生长方面均存在显著差异;适宜本区发展的桉树无性系首选为尾赤桉201-2,其次为尾巨桉3229和尾圆桉184-1;海拔在300 m以下的适宜种尾赤桉201-2、尾圆桉184-1、尾巨桉3229等,海拔在300~460 m的适合种尾赤桉201-2和巨桉。     

海南岛东部地区桉树树种/种源试验*

在海南岛东部进行的桉树１１个树种７９个种源试验，５年的结果表明，不同树种种源间生长差异极显著，来自印度尼西亚Ｍｔ．ｍａｎｄｉｒｉ的尾叶桉１２８９５种源是所有参试树种／种源中表现最好的，树高、胸径和每公顷材积分别为１３．８２ｍ、１２．５４ｃｍ和１２８．３４ｍ３。同一树种种源间生长差异也极显著，最佳种源的每公顷材积与最差种源相比，尾叶桉为８．４６：１，细叶桉５．８６：１，赤桉５．３２：１和巨桉３．０４：１。细叶桉、赤桉和巨桉种源树高、胸径和材积生长与原产地纬度显著负相关，尾叶桉种源与原产地海拔高极显著负相关。本文提出了适合海南岛东部地区生长的树种和种源。     

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.