以电导法配合Logistic方程确定不同冬青抗寒性

采用人工模拟低温处理技术测定了6种(含品种)冬青树种离体叶片的相对电导率,并用Logistic方程计算它们的半致死温度(LT50)。结果表明:6种(含品种)冬青耐低温能力有显著差异,由高到低依次为克恩氏冬青>欧洲冬青>大别山冬青>‘蓝少年’冬青>杂种冬青>‘蓝少女’冬青,其半致死温度值LT50在-11～-24℃之间。     

DA-6对不同品种北美冬青生长和生理特性的影响

以北美冬青'冬红'冬黄'格瑞'和'奥斯特'4个品种营养钵苗为试验材料,通过施用不同质量浓度(20,30,50 mg/L)的DA-6,研究其对北美冬青株高、冠幅、单株生物量、光合及可溶性糖等的影响.结果表明:30 mg/L DA-6处理下,'奥斯特单株'格瑞'的生长最好;20 mg/L DA-6处理下,'冬黄'冬红'生长最好.各品种株高、冠幅、单枝长及生物量最大,其中'奥斯特'单株鲜质量和干质量分别达到68.84,31.90 g.不同质量浓度的DA-6处理,各品种净光合速率、气孔导度、蒸腾速率与对照相比,均呈现出不同程度的增加,其中20 mg/L处理,'冬红'净光合速率最大,达到8.44μmol CO2/(m2.s).一定质量浓度的DA-6可促进北美冬青叶片可溶性糖积累,其中30 mg/L处理'冬红'格瑞',可溶性糖达到最大值,分别比对照增加了52.34％,36.09％.     

戴云山自然保护区冬青属野生植物资源调查与分析

文章采用标准样地方法调查戴云山保护区内冬青属野生植物资源,并观测其花期、花色、果期、果色、叶质、叶型特征。结果表明,该区冬青属野生植物共有15种,且具有较突出的观赏价值。花期3~7月,花朵较小,花色丰富;果期7~12月,果色以红色为主;叶以薄革质或厚革质为主。在本次调查所有样地出现野生冬青属植物频次最大的是钝齿冬青、梅叶冬青,最小的是尾叶冬青、黄毛冬青;大部分冬青属植物均分布在1 000~1 400 m海拔,钝齿冬青的海拔分布范围为最广;区内冬青属植物主要分布于黄山松阔叶混交林,在黄山松纯林、马尾松纯林和灌木林分布较少,且均为群落伴生种,重要值较低。     

柃木等5种地被植物的抗旱性研究

将柃木(Eurya japonica)、滨柃(E.emarginata)、厚叶石斑木(Raphiolepis umbellata)、赤楠(Syzygium buxifolium)、钝齿冬青(Ilex crenata)5种地被植物进行干旱胁迫处理,观察记录不同植物的外部形态、植株死亡等症状以及不同植物组织的含水率变化,并通过隶属函数的方法进行综合评价,结果表明:同等条件下,5树种抗旱性强弱依次排序为赤楠＞滨柃＞厚叶石斑木＞钝齿冬青＞柃木.     

呼吁保护和发展酸黄柏

在伊克昭盟准格尔旗分布着一种保持水土效果很高的好树种——酸黄柏。酸黄柏属小檗科。名叫鄂尔多斯小檗,是一种落叶灌木,树高1～2米,叶倒卵形或倒披针形,全缘或有齿,在刺掖两侧常成簇对生,每簇3～5个叶片,叶长3厘米左右,叶背白色。枝条灰褐色,细瘦枝条有棱。短枝基部外侧常有刺。花黄色。果实为长圆形浆果,9月成熟,鮮红色,每粒果实含有1～2粒种子。木料深黄色。在准格尔旗,酸黄柏分布在石质山区的山坡、荒沟及崖头。这些地方其他树种很难生长,而酸黄柏生长很好。笔者见到     

优良灌木沙棘林的营造技术

沙棘(Hippophae rhamnides L.)也叫酸刺(陕西)、醋柳(山西)、黑刺(青海)，是一种具有固氮能力的胡颓子科沙棘属野生落叶灌木，耐于旱、耐瘠薄，防风固沙，生态适应面宽。多年来沙棘主要作为营造水土保持林和薪炭林树种被广泛栽植，但随着营养价值和药用价值的综合开发，沙棘已成为一种集社会、生态与经济效益于一身的珍贵树种。     

三种紫胶虫寄主在海南岛的栽培技术

滇刺枣(Ziziphus mauritiana),苏门答腊金合欢(Acacia glauca),大叶千斤拔(Moghania macrophylla)是紫胶虫的优良寄主树。滇刺枣为小乔木,果实可作水果食用,果仁可入中药;苏门答腊金合欢和大叶千斤拔是灌木,既可生产紫胶,同时也可作为薪炭材。这三种树木适生性强,耐干旱贫瘠,生长较快。1984年初我们从云南引进了这三种树种在坝王岭乌烈林场和琼海上蛹区林场进行栽培试验,现将结果整理如下。一、育苗     

香樟新品种'涌金'

'涌金'系香樟种子变异种,叶、花呈金黄色;初生新枝为嫩黄色,半木质化后为浅红色,后转鲜红色;幼果果皮呈淡黄色,果柄果梗呈黄色.由于该品种叶、花艳丽,枝干夺目,并有季相的色彩变化,具有较高的观赏价值与园林应用前景,适宜作园林景观树、庭院树、行道树和四旁树种.     

几种常绿树种的介绍

在我国西部地区植树种草的热潮中，所用树种方面存在着落叶树种多，而常绿树种少的现象，这在一定程度上影响了绿化的效果，尤其冬春季节更加明显。现介绍几种适合于我国西部地区生长的耐旱、耐寒、耐风沙的常绿树种。一、沙冬青豆科沙冬青属，常绿阔叶灌木。叶多掌状3复叶，小叶菱状椭圆形，长2厘米～4厘米，宽0.6厘米～2厘米，总状花序顶生，花黄色，结荚果。产于内蒙古、新疆、陕西、甘肃、宁夏等省区。喜光、耐旱、耐寒、怕水湿。多生长于荒漠沙地，为绿化沙丘的优良树种。播种繁殖，不宜移植。移植树忌浇水，可用容器育苗克服移植难的…     

7个常见绿化树种的抗逆性研究

通过对花曲柳、黄栌、火炬树、山杏、复叶槭、卫矛、五角枫等7个树种进行不同程度的水分胁迫处理和遮阴胁迫处理，进行相关生理指标测定，初步探讨了这7个树种的耐旱性及耐阴性特点，结果表明：五角枫、花曲柳、复叶槭的抗脱水能力较强，是较为耐旱的树种；卫矛、花曲柳、复叶槭和火炬树表现出很好的耐阴性，黄栌和五角枫的耐阴性较差，山杏具有一定的耐阴性，但遮阴强度不宜过大。     

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.