杉木优良无性系造林增产显著

1990年开始，广西林科院和区林业技术推广总站等单位，分别在融安县西山林场等十多个单位推广杉木优良无性系造林。至1996年，共造杉木无性系林409．8公顷，其中试验林、示范林2098公顷，面上推广造林（这丰杯）200公顷。试验统一未用分组随机区组设计，每组一般为20个无性系，用杉木良种（融水白云糖杉）实生前作对照。整地方法、造林时间、抚育措施等均与对照相同。据1997年测定分析，在初选参加试验的927个无性系中，有230个无性系表现较为优良，其材积总平均比对照增益451％；最优的无性系”个，村积总平均比对照增益53．5％；较优的无…     

杉木无性系改良增产效益的研究

据对14片试验林102个无性系的调查分析，8年生（含苗龄）以上的82个无性系，平均单株材积比对照（开化1代种子园或那坡优良种源实生苗）增产35．8％，从中筛选出15个优良无性系，平均比对照增产87.1％，其中三个增产1倍以上。试验表明，从杉木优良家系（合优良种源的优良家系）、优良杂交组合和2代种子园的优良种苗营造的幼、中龄林中进行无性系选优，增产效果以优良杂文组合较好，2代种子园次之，1代种子园和优良种源更次之。在增产水平高且后代分化大的优良家系中选择，以选育单系为好；在增产水平高，但后代分化不大的优良家系中选择，以选育多系为好。     

湘林—90等5个美洲黑杨新无性系速丰性能研究

在引进国内外优树材料、优良无性系、人工杂交及天然实生苗230多份种质材料中，经过苗期选择、无性化繁殖，在湖区分3地、共71个无性系参加对比试验造林；经过7～8年的定位观测，选定美洲黑杨55／65×W07杂交组合FI的湘林-90、湘林-75、湘林-101，美洲黑杨W10×2KEN8杂交组合F1的湘林-77、湘林-92共5个美洲黑杨杂交新无性系为优良、速生杨树无性系。5—8年生，湘林-90等5个杨树新无性系的胸径、材积均大于试验林平均数＋标准差，且生长量排序均位居参试无性系前列，显著高于对照I-69杨、中汉-17杨。8年生，湘林-90、湘林-77材积比I-69分别增产50．1％和44．8％，比中汉-17增产32．8％和28．1％，生长优势显著；湘林-101、湘林-92、湘林-75材积比I-69增产29．1％-25．3％，比中汉-17增产14．3％～10．9％，均达新种审定增产10％以上的增产标准。诸多无性系试验表明，新无性系的生长性状，需5～6年后才稳定。     

杉木无性系的遗传变异及优良无性系选择

试验揭示了杉木无性系在树高、胸径、单株材积和开花结果等方面有巨大的遗传差异。从99个参试无性系中选出了6个优良无性系，与种子园实生苗相比较，树高增益19％－26％，胸径增益17％－34％，单株材积增益50％－114％。分析了杉木家系选择和无性系选择的遗传改良潜力。无性系树高、胸径和单株材积的遗传变异系数分别是家系遗传变异系数的2．6倍、3．1倍和3．1倍。在入选率相同的条件下，无性系树高、胸径和单株材积的选择响应分别是家系选择响应的2．8倍、3．6倍和3．5倍。     

几种杨树优良无性系耐盐测定及其盐渍区的生长表现

本文对当前大力推广的几个杨树优良无性系进行了耐盐、耐水湿和盐渍土实地栽培测定，结果表明：中驻8号杨、中林46杨耐盐能力达0．2％－0．3％，耐水湿，是适于沿黄背河洼地与盐碱地栽培的2个优良无性系。中驻6号杨、中林23杨、中林34杨和中林115杨也有较强的适应性，可适当发展。     

长白落叶松种子园优良无性系选择方法研究

本研究以长白落叶松各子园子代测定结果品质优良、结实量多、种子发芽率高达３项指标为依据，对种子园优良无性系进行选择，共选出优质、高产、品质优良无性系１０个。以方差分析结果为依据，估算出树高、胸径、材积的遗传力分别为０．７２８、０．７１３和０．６８７；遗传增益分别为７．６％、１１．７％和８．２％；材积生长量超过对照６４４．０％，超过各一系均值１３１．１％。这些优良无性系是增产经二代种子园的理想材料，同     

思茅松高产脂优良无性系选育研究

对40个思茅松高产脂无性系产脂力测定的结果表明，所有无性系的产脂力均大于对照，较对照产脂力平均提高迭210％；无性系间产脂力存在极显著差异，其遗传力为0．83。初步筛选出8个高产脂的优良无性系，入选无性系产脂力的对照遗传增益为281％。     

油茶湘林系列6个无性系嫁接苗生长调查

对湘林系列5、14、15、18、40、166等6个油茶优良无性系的芽苗砧嫁接苗生长情况进行了调查。调查结果为：6个无性系平均成活率和抽梢率的变化范围分别为74．6％-96．2％和71．3％-93．6％，平均苗高和地径的变化范围分别为13．5-19．8cm和0．303-0．356cm，平均叶片数和冠幅值变化范围分别为8．7-12．7片／株和7．3-8．6cm，平均根长和根幅变化范围分别为6．0-6．8cm和4．7-6．5cm。6个无性系平均成活率和抽梢率分别为85．O％和88．5％，分别大于对照5．0％和2．1％；平均苗高和地径分别为15．8cm和0．33cm，分别大于对照1．4cm和0．022cm；平均叶片数为10片／株，大于对照0．8片／株；平均冠幅、根长和根幅分别为8．0cm、6．5cm和5．4cm，分别大于对照0．43cm、0．25cm和0．78cm。湘林166和湘林5的芽苗砧嫁接苗生长表现较好，其平均成活率、抽梢率及苗高、地径、叶片数量、冠幅与根长等均较大；湘林15和湘林40则生长表现较差，其平均成活率、苗高、叶片数量等均略低于混合优良无性系（对照）苗。     

长沙市召开杉木优良无性系推广现场会

一月底，长沙市林业局在浏阳县如开发全市杉木优良无性系科技推广现场会。对全市全面推广应用杉木优良无性系进行了规划和部署。长沙市从1990年开始推广杉木优良无性系，现已建采穗园19亩，造林5000亩。其中浏阳市建采穗园17亩，造林4500亩。在张坊林场营造的杉木优良无性系示范林，二年生平均高228．2cm，比一般生产用种高78．2cm基树高生长量大52．1％。三年生优良无性系平均高130cm，最高达550cm。参加现场会的代表参观了连云山林场的杉木无性系采重田、扦插田、及张坊林场-杉木无性系示范林。通过现场参观，与会同志看到了杉木优良无性…     

欧美杨优良无性系选择

经过5年欧美杨优良无性系选育研究，综合生长性状及独立淘汰法，初步选择出适于吉林省中东部河流冲积平地和四旁绿化造林的欧美杨优良无性系为N2、N12。平均单株材积分别是对照的414．9％和398．5％；最大单株树高、胸径分别为7．80m和7．6cm，在造林地表现出明显的生长优势。     

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.