落羽杉属种源研究：种子和苗期变异

对落羽杉、池杉31个种源研究结果表明,种源间种子、芽苗、苗期生长和落叶期等性状变异显著。变异存在于种源、林分、家系和个体间。但无明显的地理趋势。按苗期生长节律可以分为3种类型:一般型、速生型和江苏池杉。苗期生长以速生型中的6个种源即:落羽杉304,601,41764以及池杉6,15,江苏池杉表现较好,比种源平均值大20％以上。     

落羽杉赤枯病防治药剂筛选研究

随着落羽杉大量栽植,加之气候条件及栽植技术等原因,落羽杉赤枯病逐渐成为危害落羽杉的主要病害之一。为筛选落羽杉赤枯病有效防治药剂,选用6种药剂,通过室内测试和室外药效测定,研究了6种药剂的抑菌率和防治效果。结果表明：6种药剂均能够对落羽杉赤枯病起到一定的防治作用,其中,30%苯甲·丙环唑抑菌率最高,防治效果最好,稀释500倍防治效果达到83.52%;其次是50%多菌灵可湿性粉剂和45%甲硫·腈菌唑乳油,抑菌率分别为72.45%、70.67%。为此,提出了在杉木防护中,可应用这3种药剂稀释500倍液对落羽杉赤枯病进行防治。     

落羽杉属种源研究：生长和生物量变异

对落羽杉属不同种源,家系和树种苗期,幼林期生长量（高,胸径,冠幅）,保存率和生物量及其分配（总生物量、干,枝,根生物量及其比值）进行了５年研究,发现落羽杉不同种源,家系间、内均存在显著的性状变异,变异系数以种源,家系间最大,个体间其次。     

落羽杉地理种源变异与选择

从落羽杉原产地美国6个州引进19个落羽杉(包括4个池杉)种源,以国内早期引种的河南鸡公山落羽杉(CK1)和池杉(CK2)为对照,于1993年3月在江苏东海进行种源试验造林.在苗期和幼林期测定基础上,对13 a种源试验林生长测定结果表明:种源间树高、胸径和材积生长存在显著变异,其遗传变异系数分别为12.91%、23.51%和48.51%,广义遗传力分别为0.51、0.65和0.60.在同一区域,既有生长表现较好的种源,也有生长表现较差的种源,种源生长变异未见明显的地理趋势.落羽杉种源苗期(1 a)与13 a生长没有相关性,3 a开始与13 a生长相关性显著.落羽杉种源早期选择的合适年龄为3-5 a初选,8 a决选.按单株材积比CK1增加50%的选择强度,选出路易斯安娜Q.R.(1600号)、密西西比R.F.(503号)、阿肯色O.M.(304号)和佛罗里达N.L.(701号)4个优良种源.其树高、胸径和材积的平均表型增益为13.86%、21.78%和61.11%,遗传增益达7.07%、14.16%和36.67%;与CK2相比,平均表型增益和遗传增益分别达14.29%、59.89%、148.64%和7.29%,38.93%、89.18%,丰产性十分显著.     

美国落羽杉育苗,造林技术研究

研究出了简单易行、经济实用的落羽杉种子处理技术,可保证有胚种子全部发芽,场圃发芽率达70%以上,比对照发芽率提高30000%,开始发芽提早3～40d,发芽持续期减少35～53d。分析了落羽杉不同种源、家系、树种在种子千粒重,发芽率和苗期、幼林期生长的遗传变异。系统地掌握了落羽杉种子温床播种,芽苗移栽和容器育苗、造林的关键技术,苗木产苗量比文献高产记录增产3136%,总经济效益提高50%以上,容器苗造林成活率达100%。摸索出落羽杉无性繁殖的有效技术———夏季嫩技扦插,10～15d愈合,30～45d生根,平均成活率达90%以上。同时分析了落羽杉不同种源、家系和树种扦插成活率和生根力的遗传变异。     

盐胁迫对‘中山杉405’及其亲本叶绿体结构的影响

对不同浓度盐胁迫下‘中山杉405’及其亲本墨西哥落羽杉和落羽杉的叶肉细胞叶绿体结构进行透射电镜观察.结果表明:随着盐浓度的增加,3种材料叶绿体中的淀粉粒数目增多、体积增大,嗜锇体数量增多,类囊体片层结构呈现不同程度的肿胀、松散变形.4 g/kg盐浓度胁迫条件下,‘中山杉405’叶绿体结构基本保持完整,未出现明显的盐胁迫症状,而墨西哥落羽杉和落羽杉叶绿体的类囊体片层出现不同程度的分解现象.     

墨西哥落羽杉优良单株无性系苗期测定

以897个墨西哥落羽杉优良单株无性系(包括速生型、奇特株型和金叶类型)为试验材料,开展无性系苗期比较试验。方差分析结果显示,苗高、地径无性系间差异均达到极显著水平,苗高、地径的广义遗传力分别为0.267 3和0.202 9,表明开展速生型无性系选择是可行的。通过构建包括地径、苗高两生长性状的选择指数,以10%的入选率,复选出墨西哥落羽杉速生型无性系77个,奇特株型无性系8个,叶色金黄型无性系5个。     

4个落羽杉属树种引种造林试验

为丰富沿海围垦滩涂和平原绿化造林乔木树种,对墨西哥落羽杉(Taxodium mucronatum)、中山杉(As-cendens mucronatum)、落羽杉(Taxodium distichum)和池杉(Taxodium ascendens)等4个落羽杉属树种开展引种造林试验,结果表明:绿叶期,墨西哥落羽杉>中山杉>落羽杉与池杉;耐盐性,墨西哥落羽杉>落羽杉>中山杉>池杉;抗风性,中山杉>池杉>落羽杉与墨西哥落羽杉;耐水性,落羽杉>池杉>墨西哥落羽杉与中山杉;生长速度,中山杉>落羽杉与墨西哥落羽杉>池杉。     

江汉平原水杉、池杉、落羽杉物理力学性能比较研究

对江汉平原水杉、池杉、落羽杉人工林物理力学性能进行了研究,结果表明:落羽杉的密度和硬度最大;落羽杉、水杉、池杉的抗弯强度差异不大;水杉的弹性模量最大,约为落羽杉的2.3倍,落羽杉的弹性模量与池杉的比较接近。南北方向对水杉、池杉、落羽杉的密度、顺纹抗压强度在5%水平上差异均不显著,对池杉、水杉抗弯强度在5%水平上差异不显著,对落羽杉抗弯强度在1%水平上差异显著,对落羽杉、池杉的弹性模量在1%水平上差异显著,对水杉的弹性模量在5%水平上差异不显著。三杉南北面近树皮处木材的密度、抗弯强度、弹性模量、顺纹抗压强度均大于髓心处。对水杉、池杉、落羽杉物理力学性能比较研究,旨在为其培育及合理利用提供依据。     

落羽杉中山杉系列新品种选育初报

报道了落羽杉属(Taxodium)中山杉系列‘Zhongshansha’杂交新品种选育结果。以经国家林木良种审定委员会审定推广的优良品种中山杉302‘Zhongshansha302’为母本,与父本墨西哥落羽杉(T.mucronatum)回交,获得回交代杂种200个以上。通过苗期实生初选和无性系复选以及不同立地的栽植试验,初选出优于或相似于亲本中山杉302的系列新品种中山杉1号、9号、24号、27号、46号、86号、91号、102号、118号、136号、146号、149号等12个。其中中山杉1号、24号、27号、86号、102号、118号、136号、146号具有一定的耐盐碱能力,可在池杉(T.ascen-dens)、落羽杉(T.distichum)不宜栽植的盐碱地上绿化造林。     

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.