扫螨净对国槐叶螨的防治研究

使用扫螨净乳油对国槐叶螨的防治效果表明，在喷施２０００倍和３０００倍扫螨净乳油１２小时后，叶螨校正杀虫率分别为９６．７％和９５．６％，有效防治时间长达３０－５０天，是目前防治国槐叶螨的理想药物。     

苹果园山楂叶螨田间药剂防治试验

山楂叶螨的发生与高温干旱气候有关，叶螨繁殖盛期在7月上句。选用5种药剂进行叶螨防治试验，20％螨死净乳油2500倍液、40％水胺硫磷乳油1000倍液、灭扫利3000倍液防治效果较好；40％氧化乐果1000倍液和20％三氯杀螨醇乳油800倍液防治效果较差。     

3种杀螨剂防治山楂叶螨试验

扫螨净，尼索朗、三氯杀螨醇３种杀螨剂对山楂叶螨的防治试验表明：扫螨净３０００倍液对山楂叶螨的卵、幼若螨、成螨均有极强的触杀效果，其田间有效期长达５０天，一次用药可基本控制全年危害，效果优于尼索朗、三氯杀螨醇。     

四种杀虫剂对梨上瘿螨的田间药效试验

应用4种药剂进行了梨上瘿螨的田间药剂防治，结果表明：施药14d后，0．2％爱诺虫清EC2000倍液、10％哒四螨悬浮液、15％哒螨灵EC和20％灭扫利EC2000、3000倍液可取得良好的防治效果，其防效均达99．1％以上。     

国槐截形叶螨的生物学特性及防治

北京地区国槐普遍受截形叶螨（ＴｅｔｒａｎｙｃｈｕｓｔｒｕｎｃａｔｕｓＥｈａｒａ）危害，从５月下旬至１１月上旬均有发生，危害盛期在７—８月份，有螨叶率市区达７０％，近郊区可达９０％以上。根据有效积温及气象资料推算，截形叶螨在北京地区每年发生１５—１７代。在２８℃、ＲＨ６７℃条件下，室内饲养，发育一代平均６．７天，在２７℃、Ｒｈ７２％条件下，雄成螨平均寿命７．５天，雌成螨１０．７天。截形叶螨以成螨越冬，其场所主要在树干及粗枝树皮裂缝内，极少部分在小校、树冠下草地及根际土壤中。早春用生物制剂—２．５％日光霉素１０００倍，１０％增效浏阳霉素２０００倍７３％克螨特乳油２０００倍及洗衣粉４００倍，碳酸氢铵颗粒剂１００倍防治，均能取得很好的效果。     

枸杞锈螨无公害防治试验研究

选择适宜枸杞锈螨无公害防治的吡螨胺、劲克、锐螨净和齐螨素等药剂,进行药剂筛选和防治试验,喷施齐螨素2000倍、吡螨胺、锐螨净和劲克1000倍液,均能达到95%左右的防治效果。     

螺螨酯等药剂防治苹果二斑叶螨田间试验

应用24%螺螨酯悬浮剂、40%阿维·炔螨特悬浮剂、15%哒螨灵乳油、1.8%阿维菌素微乳剂、0.3%苦参碱水剂杀虫剂5种药剂防治苹果二斑叶螨的结果表明:24%螺螨酯悬浮剂4 000倍液、40%阿维·炔螨特悬浮剂2 000倍液、1.8%阿维菌素微乳剂5 000倍液、0.3%苦参碱水剂杀虫剂600倍液4种药剂,喷药后7天防效分别为98.06%、95.01%、98.19%、97.46%,药剂处理后20天防效分别为96.34%、99.04%、92.76%、96.39%,用以上4种药剂防治二斑叶螨速效性好、持效期长、防效高;而15%哒螨灵乳油3 000倍液药后7天的防效仅有56.61%,原因是多年来一直使用15%哒螨灵乳油防治二斑叶螨,导致二斑叶螨产生抗药性。     

枸杞瘿螨防治农药室内筛选及大田防治技术

用6种药剂对枸杞瘿螨幼虫进行室内毒力测定及大田防治技术研究的结果表明,齐螨素对枸杞瘿螨的毒力最高,LC50为1.8651 μg/ml,其次为敌杀死、阿耳发特、哒螨灵、安民乐,灭扫利最低.1.8%齐螨素乳油在田间的使用剂量为3 000倍液喷雾,施药间隔期为14～23天.     

毛竹叶螨防治技术的研究

在室内试验的基础上,用多种药剂在林间开展竹腔注射和根施竹螨灵药肥防治毛竹叶螨,结果表明,两种防治方法对毛竹叶螨均有显著防治效果。竹腔注射５０％甲胺磷、４０％氧化乐果见效最快,３ｄ后害螨减退率达１００％。竹腔注射２０％杀灭菊酯、２０％快灵、５％抑太保和２０％灭扫利,１０ｄ后害螨减退率达８６．０％～９８．９％;３０ｄ后除灭扫利外,各处理害螨减退率达１００％。根施药肥１０ｄ后害螨减退率达９６．３％以上。从防治后受害毛竹林叶片长势、返青及新竹产量、质量上看,防治方法优先选择依次为综合治理、根施竹螨灵＋有机肥药肥、根施竹螨灵＋复合肥药肥、竹腔注射甲胺磷＋营养剂、根施竹螨灵＋尿素药肥、竹腔注射甲胺磷。     

枸杞锈螨、瘿螨药剂防治试验

枸杞锈螨、瘿螨是我国枸杞的重要害虫，普遍分布于国内枸杞各产区，为害严重时可使果实品质显著下降，产量减少30％以上。应用锐螨特、吡螨胺、哒螨酮等药剂进行防治试验，对锈螨、瘿螨的平均最高防效分别达到87．9％～95％和87．3％～98％；在单剂农药中添加增效剂后可显著提高防治效果。     

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.