樗蚕的发生规律与综合防治

樗蚕Ｐｈｉｌｏｓａｍｉａｃｙｎｔｈｉａ危害椿树及泡桐，石榴，在河间市一年可发生２～３代，１代历期为８０～９０天，以幼虫危害寄生叶片，总食叶量可达到４０６．８６ｃｍ＾２／头，樗蚕的发生程度主要取决于气候条件，特别是温，湿度适宜与否，其次是受越冬蛹基数，寄主树种的多寡以及天敌数量的影响，在防治上应采取综合防治的措施，如人工消灭越冬蛹和大龄幼虫法，灯光诱杀成虫法，以减少幼虫发生量，药剂防治必须掌握在幼虫     

樗蚕生物学特性与防治

樗蚕在荆州市1年发生2代,以蛹越冬.第一代幼虫期6月上旬～7月中旬,危害盛期为6月下旬;第二代幼虫期8月下旬～10月上旬,危害盛期为9月中旬.人工剪除越冬茧蛹,成虫羽化盛期使用黑光灯和杀虫灯诱杀,可降低虫口基数.在低虫口密度时,采取生物制剂防治和保护利用天敌的措施,可以有效控制樗蚕的发生和危害;在高虫口密度时,使用高效、低毒、低残留的无公害药剂喷雾防治,可以迅速压低虫口密度.     

樗蚕生物学特性的研究

樗蚕（ＰｈｉｌｏｓａｍｉａｃｙｎｔｈｉａＷａｌｋｅｒｅｔＦｅｌｄｅｒ）在保定１ａ发生２～３代,以２代为主,以蛹在茧内于树上越冬。越冬代成虫羽化高峰期为５月８日,第１代成虫羽化高峰期为７月１６日。４龄幼虫排粪量为２６粒／头。４龄幼虫期平均抓着力为４２ｇ,５龄幼虫平均抓着力为１９５ｇ。樗蚕性比为雌∶雄＝１∶１０３。在河北省主要寄主植物有臭椿、臭檀、花椒、枣树、泡桐等,另外有１３种植物,共１８种,分别隶属于１６科。     

樗蚕生物学特性研究

樗蚕属磷翅目大蚕蛾科 ,是一种食量大、食性杂的暴发性害虫。通过 3年的试验研究 ,弄清了该虫在沧州市椿树上 1年发生 2～ 3代 ,且 8月 18日前化蛹的樗蚕可产生第 3代 ,以后化的蛹可直接越冬 ;枣树和其它寄主植物上的樗蚕 1年仅发生 2代 ,没有世代分化现象 ;同时摸清了各世代卵、幼虫、成虫的发生时期和历期 ,为科学防治提供了依据     

桦三节叶蜂的发生规律与综合防治

桦三节叶蜂Ａｒｇｅ ｓｉｍｉｌｉｓ Ｖｏｌｌｅｎｈｏｖｅｎ危害桦树。在互助县北山林区一年发生１代，以幼虫危害叶片，总食叶量可达４７．１ｃｍ＾２／头，桦三节叶蜂发生程度主要取决于气候条件，特别是温湿度适宜与否。其次是受越冬蛹茧基数、寄主树种的多寡以及天敌数量的影响，在防治上应采取综合防治措施，如人工消灭越冬蛹茧、营造混交林，保护天敌等方法，以减少幼虫发生量，药剂防治在卵刚孵化后的幼虫期效果最佳。     

樗蚕生物学特性及防治方法

樗蚕（PhicosamiacynthiaWalkeret.）属鳞翅目，天蚕蛾科。在河南省主要危害臭椿苗木及幼树叶片，受害苗木提前40d左右落叶。1989年在信阳地区有零星发生，苗木叶片被食20％。199年虫口密度大增，每株多达40余头，苗木叶片被食6O％以上。为了掌握樗蚕生物学特性和防治方法，我们于1989～1991年在息县城关镇和八里岔乡进行了室内饲养和野外观察。现将结果报导如下。l生物学特性1．l生活史根蚕在淮河流域，l年发生3代，以蛹在茧内越冬，翌年5月上旬成虫羽化、交尾、产卵，卵期15d；5月下旬孵化出第】代幼虫，幼虫期25d36月中旬开始结虽，蛹…     

美国白蛾的发生规律与综合防治

美国白蛾Ｈｙｐｈａｎｔｒｉａ ｃｕｍｅａ（Ｄｒｕｒｙ）在秦皇岛市１年发生２～３代,其幼虫为害百余种植物的叶片,以蛹的枯枝落叶下、建筑物缝隙、树皮裂缝、土石块下等处越冬,具有食性杂、繁殖力强、适生范围广、传播速度快、危害严重特点。通过１０ａ的防治试验,总结出了一套综合防治措施,如人工、生物及化学等防治方法,可有效地控制美国白蛾的发生。     

桦三节叶蜂的发生规律与综合防治

桦三节叶蜂 Arge similis Vollenhoven危害桦树。在互助县北山林区一年发生 1代 ,以幼虫危害叶片 ,总食叶量可达 47.1 cm2 /头 ,桦三节叶蜂发生程度主要取决于气候条件 ,特别是温湿度适宜与否。其次是受越冬蛹茧基数、寄主树种的多寡以及天敌数量的影响 ,在防治上应采取综合防治措施 ,如人工消灭越冬蛹茧、营造混交林 ,保护天敌等方法 ,以减少幼虫发生量 ,药剂防治在卵刚孵化后的幼虫期效果最佳     

杨小舟蛾生物学特性研究

杨小舟蛾［Ｍｉｃｒｏｍｅｌａｌｏｐｈａ ｔｒｏｇｌｏｄｙｔａ（Ｇｒａｅｓｅｒ）］在陕西关中平原１年发生５代，以蛹越冬，翌年４月中旬羽化，７～８月为危害盛期，１０月上、中旬化蛹越冬。选用灭幼脲Ⅲ２０００倍液防治第２、３代功虫效果良好。     

华竹毒蛾生物学特性及防治方法的初步研究

华竹毒蛾是毛竹的食叶害虫，在安福武功山区一年发生３代，以蛹在竹杆上的地面灌木杂草叶背越冬，翌年４月中旬开始羽化产卵。１、２、３代幼虫发生危害期分别为：４月下旬－６月下旬，７月上旬－８月上旬，８月中旬－１０月中旬。以第２代发生整齐且危害最烈。在幼虫１－３龄期用ＤＤＶＰ插和烟雾剂进行熏杀，效果可达８０％，蛹期寄生虫较多，可利用于防治。     

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.