新技术文摘

２３个柳树品系比较试验分析甘肃省临夏州林科所对引种的２３个柳树品系,经过３年苗期、５年造林比较试验结果分析,以从江苏省林科所引种的Ｊ１７２柳品系表现最好,造林９年平均高１７９２ｍ,平均胸径２５４７ｃｍ,显著高于当地优良品种旱柳１４。其次是Ｊ１９４...     

柳树优良品系区域性试验

在柳树引种对比试验的基础上,对所选出的５个生长快,干形好,抗逆性强的品（系）种于１９９６￣１９９８年在全省４个气候类型区进行了区域性试验。结果表明：Ｊ１７２、Ｊ１９４、Ｊ３６９柳除武威试点外,其余各点均表现出极强的速生性,定植３年后最大单株高９．９ｍ,最大胸径１２．８ｃｍ;准噶尔柳和青刚柳在武威和临夏表现出良好的速生性。５个品系在临夏杨柳蛀干害虫为害区,经１０年观察未见蛀干害虫为害。     

短轮伐期杨,柳材的制浆性能研究

对３年生杨柳无性系木材的纤维素含量和纤维形态的测定分析表明，各无性系之间无显著差异，而同一无性系木材纤维长度则随密度提高而变长，其中Ｉ—７２杨的５个造林密度，Ｉ—６９杨的１ｍ×１．５ｍ、１ｍ×３ｍ、２ｍ×２ｍ，Ｊ—１７２柳和Ｊ—１９４柳的１ｍ×１．５ｍ、１ｍ×２ｍ、１ｍ×３ｍ以及Ｊ—３３３柳的１ｍ×１．５ｍ、１ｍ×２ｍ等１６个处理的木材均达到中级优质造纸纤维原料要求。     

滩地柳树无性系人工林密度试验研究

长江滩地４年生苏柳１７２等无性系密度试验结果表明，造林密度对蓄积量生长和林木干形影响显著，１ｍ×１．５ｍ密度林分，蓄积年生长量达２７．５ｍ＾３／ｈｍ＾２，滩地柳林造林密度应不低于１６６７株／ｈｍ＾２。     

马尖相思多点栽培试验阶段报告

本文报道了在景洪、普文、思茅、河口、瑞丽５个地点所同时进行的马尖相思多点栽培试验２，５年生林分的测定结果。初步证实云南北热带及南亚热带南部，年均温１８℃以上，＞１０℃积温６３００℃以上，年降水量１２００ｍｍ以上，土壤ｐＨ值４～６，无霜或偶有轻霜的地区是马尖相思的适生区。在此区域内马尖相思表现出初期速生，年平均树高生长量达１．４６～１．７２ｍ，胸径生长量１．１７～１．５３ｃｍ。育苗造林措施与幼林管理质量对其生长影响很大。     

17个杨树无性系造林对比试验初报

１９９１年春由中国林科院引进２９个杨树新杂交Ｆ１无性系，经２年苗期对比试验，选出鲁克斯杨×（箭杆杨×黑杨）－４，鲁克斯杨×（箭杆杨×黑杨）－３等１５个比较适宜本地生长的无性系，又以锦县小钻杨和沙兰杨为对照，于１９９３年春进行造林对比试验。结果表明：鲁克斯杨×（箭杆杨×黑杨）－４是表现最好的无性系，平均高生长达３５１．７ｃｍ，平均胸径达２．３３ｃｍ，与对照呈极显著差异。鲁克斯杨×（箭杆杨×黑杨）－３、鲁克斯杨×天然杂种是表现较好；鲁克斯杨×青杨１３、鲁克斯杨×青杨－２、鲁克斯杨×青杨１２，对杨树灰斑病具有免疫力，但生长量与对照沙兰杨无显著差异。     

大叶相思种源选择试验

对从昆士兰引进的５个大叶相思种源及１个本地种源，在琼海试点和花都试点进行试验，结果表明，引进种源在前者的生长表现均比后者好，不同种源在同一试验点比较，以１５６９７和１５４８３种源生长快，产量高，年平均生长琼海试点和花都试点分别为胸径２．０ｃｍ和１．３树高，树高２．３ｍ和１．３ｍ，生物量２５．３６ｔ／ｈｍ＾２和１３．６３ｔ／ｈｍ＾２以上，明显地优于其余各种源。花都试点５个引进种源树高，胸径生长量及生     

马尖相思造林技术研究

通过持续６年，面积达２３．６７ｈｍ＾２的造林试验，初步探索出适于云南引种区采用的马尖相思育苗、造林技术。在普文引种试区马尖相思生长迅速，６年生树高年均生长量达２．３１ｍ，胸径年龄生长量为２．９ｃｍ，活立木蓄积２８９．０４１４５ｍ＾３／ｈｍ＾２，年均生长量４８．１７３５７５ｍ＾３／ｈｍ＾２；４．５年生的马尖相思林，地上部分生物量达１０５．６ｔ／ｈｍ＾２，有效高的经济和生态效益。     

马尖相思造林技术研究

通过持续６年，面积达２３．６７ｈｍ￣２的造林试验，初步探索出适于云南引种区采用的马尖相思育苗、造林技术。在普文引种试区马尖相思生长迅速，６年生树高年均生长量达２．３１ｍ，胸径年均生长量为２．９ｃｍ，活立木蓄积２８９．０４１４５ｍ￣３／ｈｍ￣２，年均生长量４８．１７３５７５ｍ￣３／ｈｍ￣２；４．５年生的马尖相思林，地上部分生物量达１０５．６ｔ／ｈｍ￣２，有较高的经济和生态效益。     

巨尾桉无性系林分生长的研究

对１９９１～１９９３年定位连续调查的资料作了统计分析表明，巨尾桉无性系林分树高，胸径，胸高断面积，材积连年生长量峰值分别出现在１，２，３，３年；平均生长量除材积的推迟１．３年，其它林木因子都在同一龄期达到高峰；４年生林分平均树高达１５．８ｍ，平均胸径１１．６ｃｍ（带皮）年平均蓄积生长量达３１．２９７９ｍ＾３／ｈｍ＾２。可见巨尾桉无性系林分生长快速，适宜于短轮伐期集约经营利用。     

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.