矮化银杏林杂草发生和化学除草剂的应用

矮化银杏林易遭杂草为害，采用化学除草剂除草，省工省本，除草效果好。试验结果表明，进行了土壤封闭除草，以２５％敌草降４．５ｋｇ／ｈｍ＾２，４８％氟乐灵１．８７５公升／ｈｍ＾２敌草隆、氟乐灵各半量混配的３各药剂，防效最佳，控制期可达４５ｄ；进行灭一性除草，草第１高峰生长盛期，用１０％草甘膦１５公升／ｈｍ＾２，兑水７５ｋｇ，喷头向下定向喷雾，防除效果达９４．６４％，控制期可达３０display status     

油茶林用草甘膦除草试验

在油茶林地内使用草甘膦杀除黄茅，五节芒等恶生杂草试验结果，草甘膦最佳用量１．５ｋｇ／ｈｍ２，较好用量１．８ｋｇ／ｈｍ＾２，和１．２ｋｇ／ｈｍ＾２；进行两次喷药可以彻底除草，间隔期２个月；杂草内吸传导草甘膦破坏杂草生长优势致死时间为６ｈ，１５天后草根枯死。     

杉松育苗应用果尔化学除草试验研究

通过应用不同剂量的果尔（ＧＯＡＬ）在杉苗于播后苗前、苗期，松苗（芽苗切根移栽）苗期的除草试验，认为杉木育苗于播后出苗前商品用量为７５０ｍｌ／ｈｍ２，除草效果可达９８％，苗木出土不受影响。苗期商品用量为６００～７５０ｍｌ／ｈｍ２，除草效果可达９５％以上。松类育苗苗期商品用量为９００ｍｌ／ｈｍ２，除草效果可达９５％以上。杉松苗期施用果尔对苗木生长无不良影响，与人工除草相比，降低费用８９．３％。     

桧柏育苗化学除草试验

在桧柏育苗地应用精禾草克进行化学除草试验，结果表明，施用精禾草克以０．０９－０．１２ｍｌ／ｍ＾２，对防除禾本科杂草有良好效果；施用精禾草克＋西马津各０．０６ｍｌ／ｍ＾２可防除全部杂草。化学除草与人工除草相比，不仅节省劳力、降低育苗成本而且大大提高苗木质量。     

火炬松幼林化学抚育试验初报

以茅草为主的人工火炬松幼林地用草甘膦、草甘膦加二甲四氯进行化学除草,不但除草效果好(除草率可达87.3%—99.4%),而且除草成本低(约占人工除草费用的33.8—66.1%)。     

三滩幼林地化学除芦和除草技术研究

１９９８～１９９９ 年在望江县江外滩的杨树幼林地内进行了８８ 个小区的化学除芦和除草试验。结果表明：２０％ 克无踪和４１％ 草甘膦药液商品用量分别为２ ２５０ ｍｌ／ｈｍ２ 和５ ７００ ｇ／ｈｍ２ ；用药时间分别为３ 月２５ 日～４ 月２０ 日、４ 月２５ 日～５ 月３０ 日，除芦和除草效果分别达８１ ％和８３ ％ 以上。每公顷分别节约费用５６３ 元和５０５ 元。     

开辟林内防火线方法对比试验

化学除草与火烧法相结合开辟林内防火线，优于火烧法及石棉铝铂隔离燃烧法。前者的关键是利用草甘膦在植物生长期内即将草、灌木致以干枯并根除，点燃时，不易引发周围草、灌及林木燃烧，安全可靠。草甘膦的经济用药量为：１年生杂草４．５ｋｇ／ｈｍ＾２，多年生杂草７．５ｋｇ／ｈｍ＾２，多年生木１１．２５ｋｇ／ｈｍ＾２，配制药液每公顷加水５２５ｋｇ；最佳施药期为８月上旬－８月中旬，避开降雨天气，防止降雨减效。     

特效生物杀虫剂—“苏力精”林间防治马尾松毛虫研究

使用不同剂型，不同用量的苏力精防治１，２代马尾松毛虫幼虫试验结果表明，１２００ｍｌ／ｈｍ＾２悬浮剂防治效果９０．１％－９０．４％；７５０ｇ／ｈｍ＾２可湿性粉剂防治效果９５．０％－９６．４％，１８７５ｇ／ｈｍ＾２粉剂喷粉防治效果７９．２％－８６．５％，而且残存害虫化蛹后继续死亡，成虫产卵量显著减少，对松毛虫天敌无显著不良影响。     

北京温泉苗圃化学除草试验初报

经采用几种除草剂防除苗圃杂草试验。于播种后出苗前采用不同药剂及剂量喷雾油松圃地，结果以果尔（５２５ｍｌ／ｈｍ２）＋扑草净（１．１２５ｋｇ／ｈｍ２）混合剂效果最好，防除效果达９７．２％。采用１０％草甘膦水剂１：３０～４０倍液喷雾，加入药剂量０．１％洗衣粉，在侧柏苗圃地防除１年生和多年生杂草地上部分，效果达９１．３％～９３．７％；对多年生杂草的地下根茎，根除效果在７７．２％～８９．６％。     

20%杀铃脲（氟幼灵）悬浮剂防治松毛虫试验

本文通过使用２０％杀铃脲悬浮剂不同剂量防治松毛虫的试验，并与同类药剂相比较，得出以６０ｇ／ｈｍ＾２的用药量防治效果可达９６．４％，是一种经济适用，防效高又有利于保护天敌和环境的仿生农药。     

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.