甘肃干旱荒漠区纸浆林三倍体毛白杨营建试验

本文分析了2001年作为纸浆林发展引种的10个三倍体毛白杨系号在石羊河流域造林的生长适应性。结果表明:在同一立地类型和同等抚育条件下,A129、A128、B330、A125、B1008、BT85、A122等7个无性系杂种三倍体毛白杨幼林在石羊河流域速生、抗寒、耐盐碱、抗黄斑星天牛,在石羊河流域表现出较强的适应性和抗逆性,生长量显著高于普通毛白杨、群众杨、新疆杨;由于其速生性使黄斑星天牛不能完成生活史而不至于造成危害;在专用纸浆林方面大力推广具有良好的发展前景。     

毛白杨的无性繁殖措施

毛白杨是我国特有的速生用材树种之一，它高大挺拔，生长快，材质好，寿命长，分布广。特别是近些年培育出的毛白杨新品种对黄斑星天牛和光肩星天牛表现出特殊的抗性。巴盟作为上述“二牛”发生的重灾区，引入和推广毛白杨具有非常重要的意义。 一、毛自杨在巴盟的引种试验情况 １９９８年毛白杨在巴盟临河小召乡采取伐根嫁接的方式进行引种试验。经两年观察试验，发现伐根嫁接的毛白杨长势良好，安全过冬，无不良反应。１９９９年大面积引进，主要品种有从河北选育的优良品种二倍体毛白杨和从山西调入的三倍体毛白杨，经过巴盟林场站在临河…     

几种混交林对黄斑星天牛的抗虫性研究

在青海西宁的黄斑星天牛危害核心区,以青杨、旱柳、新疆杨、毛白杨、三倍体毛白杨、杜梨、沙枣、海棠、山楂为造林树种营造了7种混交试验林,以观测研究不同混交林(纯林)对黄斑星天牛的抗性.结果表明:多树种混交林比纯林对该虫害的抗性强;青杨与其他杨树的混交林对其抗虫性有明显的差异,该树种在林分中起到了诱虫作用.     

河西走廊三倍体毛白杨引种造林研究初报

本文分析了引种的7个三倍体毛白杨系号在河西走廊的适应性。结果表明：供试的7个三倍体毛白杨系号（BT85、B1008、A129、A128、A122、B330、BM18)在土壤贫瘠、中度盐渍化的土壤上能正常生长，树高、胸径年增长量是当地乡土树种二白杨的数倍至数十倍，可作为温度较高的同类地区造林的主要树种。供试的7个三倍体毛白杨系号中BT85抗冻性较强，基本上能够安全越冬，可作为河西走廊绿洲内部造林的主要树种之一，B1008在有林带庇护小气候的区域内造林可望获得成功。     

河西走廊三倍体毛白杨引种造林研究初报

本文分析了引种的 7个三倍体毛白杨系号在河西走廊的适应性。结果表明 :供试的 7个三倍体毛白杨系号 (BT85、B10 0 8、A12 9、A12 8、A12 2、B330、BM18)在土壤贫瘠、中度盐渍化的土壤上能正常生长 ,树高、胸径年增长量是当地乡土树种二白杨的数倍至数十倍 ,可作为温度较高的同类地区造林的主要树种。供试的 7个三倍体毛白杨系号中BT85抗冻性较强 ,基本上能够安全越冬 ,可作为河西走廊绿洲内部造林的主要树种之一 ,B10 0 8在有林带庇护小气候的区域内造林可望获得成功     

三倍体毛白杨引种繁育试验研究

引进三倍体毛白杨8个无性系,通过对其生态适应性观测,证明能适应当地的气候条件,今后可推广栽植;通过育苗试验,选择出三倍体毛白杨嫁接繁育的最佳砧木、嫁接时间和嫁接方法;通过生长特性观测,掌握了三倍体毛白杨的物候期、速生性能和生长规律,提出了丰产栽培的关键管理时期。     

杨树天牛类害虫的成灾原因及防治措施

杨树是河北省平原地区主要造林树种,构成了全省平原地区速生丰产林、农田防护林的基本框架。河北省主要杨树品种有三倍体毛白杨、中林46、107、108杨等,由于树种单一,极易遭受光肩星天牛、桑天牛、青杨天牛等杨树枝干害虫的猖獗危害。一、灾害成因分析(一)近年来,随着退耕还林、速生丰产林、农田防护林、风沙源治理等     

三倍体毛白杨无性系苗期生长特性初步探讨

2000年引进的三倍体毛白杨无性系B301、B302、B303、B304、B305、B306、B331，以易县毛白杨作对照，对其物候期、生长量、生长节律和生物量进行观测、分析。结果表明：引种的7个三倍体毛白杨优良无性系在山东自然条件下均能正常完成年生育周期；各无性系苗木的高度和地径生长量均明显高于对照，且高度和地径生长节律基本相同。三倍体毛白杨无性系的总生物量均大于对照，且各无性系之间的生物量差别不大。     

杨树天牛类害虫防治措施

目前,严重危害我省杨树的天牛主要是星天牛、光肩星天牛、黄斑星天牛、桑天牛、云斑白条天牛等。其防治措施如下: 1.在造林设计上,可用主栽树种、辅栽树种、引诱树、驱避村及隔离林带等不同功能的林分合理搭配,确保主栽树种速生、丰产、优质。 2.利用出孔成虫大多有补充营养的习性防治。     

噻虫啉微胶囊剂在河西地区防治黄斑星天牛试验

黄斑星天牛在河西地区发生防治概况1、黄斑星天牛危害状况黄斑星天牛属鞘翅目天牛科,主要危害杨属、柳属、榆树和槭树,是西北地区危害杨树的一种毁灭性蛀干害虫,以幼虫蛀食韧皮部后钻入木质部危害,严重时破坏树木束导组织,切断了养分的传输,导致树木死亡。在河西地区2年1代,     

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。     

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.     

Key Habitats in the Norwegian Production Forest: A Case Study

This study investigated the forest history, structural characteristics, the presence of fungal species suggested to indicate ecological continuity in old-growth forest, and the species composition of saproxylic beetles in 30 old forest ''woodland key habitats'' (WKHs), and compared them with production forest in the same age-class in south-eastern Norway. No statistically significant differences in forest characteristics, community of saproxylic beetles or number of red-listed beetles were found between the WKHs and the production forest, probably owing to a combination of profound long-term logging and a lack of will to delineate sufficiently large WKHs in the one area with significantly less forestry impact. The study indicates the advantage of including forest history information in WKH selection where such data exist, and the importance of restoring habitats in heavily exploited forest landscapes.