18个杨树品系湖区对比试验初报

全国各地的杨树良种在洞庭湖区蜂拥而至的情况下,选择6个南方型黑杨、7个北方型黑杨、3个三倍体毛白杨以及由湖南省林业科学院等单位培育的2个湘林美洲黑杨新无性系,在洞庭湖垸内进行不同杨树品系的对比试验。根据5年生杨树的生长量分析,初步显示湘林-77、湘林-90两个新无性系最具生长优势,可在湖区推广应用;南林-1388、南林-895、转抗杨、南林-351、鲁山杨（辽宁杨）、南林-95杨6个黑杨派南方型无性系可作一般性生产用种在湖区应用;欧美杨108等7个黑杨派北方型无性系、白杨派3个三倍体毛白杨无性系5年生的材积仅为南林-95杨的54．7％-12．9％,不宜在湖区推广应用。     

湖南培育出美洲黑杨四个新品系

1979年以来,湖南省汉寿县林科所与中国林科院对美洲黑杨I-69×I-63杂交后代进行了新品系对比试验,经过多年的苗期和造林比较分析,筛选出了“中汉17”、中汉578”、“中汉592”、“中汉22”四个美洲黑杨杂交新无性系。与对照 I-69、I-63、I-72相比,其生长量、品质均明显提高,抗病虫及耐水湿能力亦有所增强。8年生“中汉592”平均树高23米,     

杨树优良无性系区域栽培研究

采用美洲黑杨后代I-69和I-63号作杂交组合,从杂种中选育出87个优良无性系在江汉平原进行适应性试验,并在4个不同气候和4种不同立地进行区域性栽培试验,结果表明:中汉17号表现最优,在中心区试验6年生平均单株材积分别比对照I-72号大55.2%,比亲本大57%以上;在区域栽培试验中,单株材积比亲本大14%～45%,比对照种大17%～29%,表现出其速生的特性.适宜在河南、安徽南部以南,广东中部、广西北部以北广大平原地区推广种植.     

湘林黑杨新无性系不同部位水培生根性状研究

对湘林-90等6个杨树新无性系及中汉-17、I-69杨1年生苗,自下而上按4部位分别裁截插穗,进行水培生根试验,探索杨树水培后皮层凸起、先期不定根数量、凸起成根率及根长在无性系、区分段间的分布规律及相关性。     

69杨×青杨杂种一代的性状研究

美洲黑杨(Populus deltoides Marsh.)是北美的一个重要杨树种,69杨(P.deltoid-es CV.‘I-69/55’或者 P.deltoides CV.‘L-ux’是意大利从美洲黑杨中选育出的一个优良无性系。各国杨树育种工作者用美洲黑杨与欧洲黑杨杂交培育出许多欧美杨品种,也用美洲黑杨与青杨派树种杂交培育出不少品种。近年来,一些国家对美洲黑杨与青杨派树种的杂交尤为重视,如比利时、新西兰等国用美洲黑杨与毛果杨(P.tricoca-pa)、滇杨(P.yunnanensis)等杂交,选出了一些较好的无性系。我国青杨派树种的种类多,分布广。育种工作者曾用小叶杨(P.simonii)、青杨(P.cathayana)等与欧洲黑杨(P.nigra)     

杨树无性系生长与材性遗传变异及综合选择研究

以6年生18个杨树无性系为材料，研究其生长与材性性状的遗传变异及性状问的相关性，结果表明：除纤维含量、纤维长度外，树高、胸径、材积、纤维宽度、长宽比、木材基本密度6性状在无性系间均存在显著差异，各性状重复力在0．6109～0．9053之间，生长性状受高度遗传控制，纤维宽度、长宽比、木材基本密度受中等至强度遗传控制；生长与材性性状遗传具有相对独立性，就杨树纸浆材而言，材性改良应以生长性状的改良为前提；利用灰色关联度分析法评选出XL-90、XL-77、XL-101、XL-75、XL-92共5个综合性状优异的美洲黑杨杂交新无性系，其中XL-90、XL-77表现尤为突出，与I-69比较，其单株材积生长量分别提高60．71％、46．45％，单株纤维产量分别提高51．43％、44．13％。     

美洲黑杨杂种无性系的抗旱性研究

本文研究了冬季休眼期苗杆水分蒸腾速率和水分饱和亏缺、春季起苗后自然曝晒条件下苗木失水状况及对展叶时间和造林成活率的影响、生长季节土壤干旱对苗木生长的影响。从这三方面综合评价美洲黑杨杂种无性系的抗旱性。结果是:69杨×美洲黑杨的杂种无性系抗旱性均优于69杨;69杨×青杨的杂种无性系的抗旱性也优于69杨,但不及青杨。其中69杨×美洲黑杨-52的抗旱性最强,69杨×青杨-1062、69杨×美洲黑杨-66和-65的抗旱性与Ⅰ—214杨相近,而69杨×青杨-1145不及Ⅰ—214杨。新引进的露易莎杨和西玛杨的抗旱性优于69杨,但不及Ⅰ—214杨。陕林1号杨是所有无性系中最抗旱的。被测验的杨树无性系的抗旱性可以大致排列如下顺序:陕林1号杨>青杨>69杨×美洲黑杨-52>69杨×青杨-1062、69杨×美洲黑杨-66和-65、Ⅰ-214杨>露易莎杨、西玛杨>69杨×青杨-1145>69杨。     

三个杨树无性系在湖区的优势与栽培

汉寿县1977年引进的杨树无性系中,以欧美杨72、美洲黑杨63、美洲黑杨69表现最好,优势显著,在洞庭湖区很有发展前途。县林科所1978年栽植的这三个无性系,7年生时,72杨平均单株材积1.234立方米,63杨平均单株材积0.974立方米,69杨平均单株材积1.323立方米。目前全     

美洲黑杨杂种无性系——陕林3号杨、陕林4号杨通过成果鉴定

省林业厅受省科委的委托,于今年5月8日至9日在杨陵科研协调中心召开研究成果鉴定会,对省林科所杂交培育出的杨树新无性系—陕林3号杨和陕林4号杨进行了鉴定。陕林3号杨是从Ⅰ—69杨×美洲黑杨杂交无性系中筛选出来的,原试验编号52号。陕林4号杨是从Ⅰ—69杨×青杨(长安)杂交无性系中筛选出来的,原试验编号1062号。它们的     

美洲黑杨PE-19-66、S.307-26材性测试报告

测试了美洲黑杨PE-19-66、S．307-26两个无性系的纤维长度、气干密度、干缩性、顺纹抗压强度、横纹抗弯强度及弹性模量、硬度等项指标，分析结果表明：美洲黑杨2个新无性系各项指标均优于对照I-69杨，是建筑材、胶合板材、家具材和制浆造纸用材的优良品种。     

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.