霍须盾蚧的研究

霍须盾蚧Kuwanaspis howarai(Cooley)是为害毛竹干部的一种重要蚧虫,主要分布于安徽、江苏、云南、浙江等地。该虫在马鞍山地区一年发生2代,以受精雌虫越冬,翌年5月上旬开始产卵繁殖。对此虫的防治应抓住竹材检疫和疏伐等环节,对为害严重的林分,可在6月上、中旬若虫期用50％马拉松和25％亚胺硫磷800倍液进行防治。     

密竹链蚧生物学特性研究

密竹链蚧Bambusaspismiliaris（Boisduval）是为害毛竹秆部的一种新害虫。该蚧在福建三明中村、尤溪一年发生二代。第一代产卵、孵化盛期为7月下旬与8月中下旬，第二代产卵、孵化盛期为11月中旬和翌年5月上中旬。卵量7～165粒。每年5月上中旬和8月中下旬为危害高峰期。     

氧化乐果防治竹蚧初步试验

宜兴毛竹林遭受多种蚧类危害.其中拟白须盾蚧、竹灰球粉蚧为危害较严重、发生较普遍的种类.拟白须盾蚧寄生竹秆、竹枝,被害严重时虫体将竹、秆包裹一层,剥去虫层,竹青褐色,竹材变脆发臭,降低利用价值,竹林出笋产竹量减少,终至衰败.竹灰球粉蚧寄生竹新抽枝基部及隐芽,使竹叶发黄,早地脱落,隐芽死亡,不能抽枝,严重时整株枯死.1983年6—10月对两种竹蚧用氧化乐果进行内吸传导防治试验,都取得了良好的效果.     

皱绒粉蚧生物学特性的观察

皱绒粉蚧(Eriococcus rugosus wang)属蚧总科,绒蚧属。我市现有毛竹林4,500多亩,受皱绒粉蚧为害较重的成园毛竹林达1,000多亩,严重地影响竹林的正常生长。1980—1984年,我们在青山蚕桑场进行了此虫生物学特性的观察。现将资料整理于下: 一、寄主及危害 皱绒粉蚧在我市主害毛竹,亦能危害刚竹。 此虫以若虫寄生于1—2年生竹嫩梢叶鞘内,初期每叶鞘可寄生多头,最后成活只1—2头。被害后的嫩梢先发黄,抽新梢少,严重受害的枯死,一般受害的竹林,出现霉污     

华北地区杨树蚧害研究

华北地区为害杨树的蚧虫有４科２９种，其中１４种可造成严重为害。以白杨派和青杨派树种受害较重；在不同林分中，以密度大、生长在不良立地条件上的中幼龄林受害最重。本文还给出了为害杨树的主要蚧虫田间识别检索表，并对杨树蚧害的防治提出了探讨性建议。     

怎样防治枣龟蜡蚧

枣龟蜡蚧又名日本龟甲蚧,俗称枣虱子,我省枣区均有分布。主要为害枣、柿等树,以若虫、成虫固着于枣树叶片和1—2年生枝上,刺吸树液,并能分泌粘液,导致煤污病菌寄生,可造成严重落果和枝条干枯,为枣树的一种危险性害虫。该虫在山西1年发生1代,以受精雌虫固着在1—2年生枝上越冬。雌成虫椭圆形,体长2毫米,宽1.5毫米,紫红色,背覆白色蜡质介壳,介壳背中央隆起,周缘有8个小突起。翌年5     

岷县国槐桑白盾蚧危害调查

为了掌握桑白盾蚧为害国槐行道树的规律和危害状况,用田间连续观察和室内饲养相结合的方式、样地调查的方式开展研究。结果表明,在岷县县城,桑白盾蚧1年发生2代,5月中、下旬是化学药物防治该虫的关键期;国槐行道树桑白盾蚧危害比较普遍严重,呈扩散蔓延加重趋势;桑白盾蚧主要为害国槐2~6年生枝条,其间随枝龄增加为害程度有加重趋势;桑白盾蚧具有隐蔽寄生为害的习性。     

华北地区经济树种蚧害研究

对华北地区经济树种蚧虫的种类区系、发生和分布规律及为害特点进行了系统研究。据调查，现已知华北经济树种蚧虫共有９科１２２种。随纬度增高、立地条件恶化、植物群落简单、人为活动频繁、管理水平粗放，蚧虫种类增多，为害严重。一般情况下，观赏树木受害普遍，温室植物受害严重，果树及平原地区林木部分受害，山地森林受害轻微。     

江西发现台松副长蛎蚧为害

1999年 8月 ,在横峰县莲荷发现蚧壳虫危害湿地松。经调查 ,发生面积有 33hm2多。湿地杉被害后 ,针叶枯黄 ,提早落叶 ,生长日趋衰弱 ,受害严重的松树 ,针叶一片枯黄 ,秋后干枯而死。经中科院上海昆虫研究所胡金林先生鉴定为同翅目盾蚧科的台松副长蛎蚧Parainsulaspis phtysophila( Takagi)。据报道 ,该虫国内分布在浙江、湖南 ,江西属首次发现 ,主要危害树种有湿地松、火炬松、马尾松、黑松、长叶松和华山松等江西发现台松副长蛎蚧为害$江西省横峰县森防站@刘发照     

桑盾蚧在国槐上的发生与防治

严重为害桃等核果类果树的桑盾蚧,近年来在唐山市主要行道树——国槐上大发生。该虫每年2代,以受精雌虫越冬。防治措施以发芽前喷柴油乳剂,初孵若虫爬出分散结蜡前喷触杀剂效果好。     

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.