农桐间作经营技术中的几个问题

中国林科院林研所泡桐组,对农桐间作经营技术进行了系统地调查研究,得出如下结论1.农桐间作初植密度以5×20m 为宜,间作后6—7年,泡桐已经成材,对作物产量有一定的影响,应及时进行隔行间伐,使     

农桐间作对小麦产量效应的评价方法探讨

农桐间作对小麦产量的影响,国内曾作过较为广泛的研究报道,确认农桐间作对小麦有明显的增产作用,其增产的幅度为0.8—38.8％。这样宽的增产幅度引起了我们的思考:除了客观条件诸如桐行走向、栽植密度、树龄、土壤肥力、管理水平及气象条件等的影响外,在主观评价方面,测算方法的不同和对照点选择上的差异,也必然在某种程度上给调查结果带来偏差和误差、影响农桐间作小麦产量效应的正确评价。 目前江苏农桐间作一般是按50×6米规格种植。若在间作地内人为地确定对照点是不科学的;若在间作地外选择一块不受泡桐     

渭北旱原农桐间作营造技术要点

农桐间作是我国劳动人民为了改造自然,充分挖掘生产潜力,合理利用土地,提高经济效益,实行科学种田的一项创举。大量事实证明:农作物和泡桐生长在一起,不仅不会影响粮食产量,而且能够发挥农桐相互依存、彼此促进的作用,达到粮桐双丰收的目的。据观测,实行农桐间作,可降低风速,增加空气湿度,调节光照,有利于小麦灌浆,对御防小麦干热风效果显著。农作物平均增产6.39％。近年来,由于农村实行经     

农桐间作光和作物产量关系的研究

该项研究应用常规方法探讨了农桐间作光分布和农作物产量的关系。结果表明:光照条件是农桐间作影响农作物产量的主要因子;在一定的范围内,间作地光照强度越大农作物产量越高,5×40米农桐间作地,距树行15米处,光照条件和作物产量均与对照区农田接近;相对光强0.6和0.9分别是间作区小麦、玉米增减产的临界值。     

桐棉间作光照条件的初步研究

农桐间作是平原绿化的重要内容之一。从1971年以来,德州地区农桐间作不断发展,到“六五”期末已达105万亩。关于农桐间作的效益,特别是对小麦增产效益问题,国内已有不少研究。笔者为了摸清泡桐对棉花产量的影响,探讨合理的桐棉配置结构,于1982年进行了桐棉间作光照条件的测定分析,现将测定结果总结如下。     

莎车县泡桐区域性引种和农桐间作试验

泡桐属于玄参科泡桐属,是我国最速生的优质用材落叶阔叶树种之一。它具有生长快、分布广、适应性强、材质好、用途广的优点。 在河南一带,农桐间作6年生兰考桐;胸径48公分,年生长量为8公分,河南省睢县梁庄11年生兰考桐胸径66,材积2.04立方米,在山东一带农桐间作8年生泡桐树高13.7米,胸径46公分,材积近半立方米,在我国南方4年生白花泡桐胸径35公分,年平均生长量为8.8公分。泡桐适合农桐间作,大力发展泡桐是迅速解决农村四料(木料、肥料、饲料、燃料)来源的捷径。中国林科院林研所,对泡桐叶、花、花蕾进行了分析,(见表1)。泡桐的叶、     

银杏-小麦间作系统水热效应的研究

对黄淮海平原农区银杏 -小麦间作系统的热量效应 (白天 )和水分效应进行了研究。结果表明 :(1)小麦抽穗　乳熟期 ,晴天间作系统总辐射量比单作 (麦田 )系统低 7.6 % ,阴天时二者差别不大 ;晴天间作系统净辐射通量比单作系统高 5 .6 % ,阴天时比单作系统低 1.9% ;晴天间作系统潜热通量比单作系统低 6 .8% ,阴天时二者相差极小 ;晴天和阴天间作系统的感热通量均低于单作系统 ,分别约低 5 2 .6 %和 11.1% ;晴天间作系统土壤热通量比单作系统高 2 1.8% ,阴天时比单作系统低2 5 .0 %。(2 )小麦拔节　腊熟期 ,间作系统小麦日蒸腾速率比单作麦田低 18.4 % ;小麦抽穗　腊熟期 ,实际区域面积 (1.4 3hm2 )内系统总蒸腾耗水量为 36 .4 5m3·d- 1,其中小麦占 91.7% ,银杏占 8.3% ,说明整个系统蒸腾耗水以小麦蒸腾耗水为主 ;系统内麦田土壤贮水量随带距的变化呈抛物线状分布 ,对比单作麦田 ,间作系统总体平均可使麦地 0　 10 0cm土壤贮水量提高 6 .84 % ;间作系统小麦叶片水分利用率比单作麦田约高 4 .0 %。     

农桐间作中光辐射分量实测分析

在田间实测基础上,分析了农桐间作中总辐射、反射辐射、净辐射、直接辐射、散射辐射及生理辐射的时空变化特征、分布规律及影响因素,为认识间作田中小气候形成原因和农田遮荫情况提供依据,对提高作物生产潜力,扩大农桐间作面积有参考意义。     

泡桐病虫害研究进展

泡桐病虫害研究进展赵忠懿钱振国田野刘俊磊（河南省林业科学研究所）王帮磊（南阳市林业调查设计管理站）泡桐是我国重要的速生用材树种之一，具有生长快、产量高、适应性广等特点。至今我国已发展农桐间作面积３５０多万ｈｍ２，栽植泡桐１２亿株，但由于经常遭受泡桐丛...     

扶沟县农桐间作形式及效益

<正> 扶沟县实行农桐间作开始于1965年,主要间作类型有以农为主间作型(南北行,株距5—6m,行距30—50m,主要品种兰考泡桐)农桐并重闻作型(南北行,株距5—6m,行距15—25m,主要品种豫杂一号)和以桐为主间作型(南北行,株距4—5m,行距8—10m,主要品种豫杂一号或豫林一号)。到     

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.