杨树天牛为害程度的聚类分析

根据３０块天牛为害标地的调查，采用平均虫口密度和有虫株率作为标准地指标，运用最短距离法进行被害程度的聚类分析，并划分为５类，为天牛的综合治理决策提供依据。     

陆川县白僵菌防治松毛虫重复感染效果好

陆川县清湖镇官冲村陆类屯有一片9年生的湿地松人工林，连片面积约4000亩。今年5月底发现有轻微松毛虫危害（平均虫口密度未达1条／株），该县森防站根据虫情的发生趋势，于6月3～6日会同清湖镇林业站一起对该片松林施放了白僵菌粉300公斤（预防作业面积1200亩）。由于当时虫口密度低，加上天气晴朗湿度低，效果不甚明显。7月中旬进行松毛虫第二代虫情调查时，该片湿地松林有500亩虫口密度大大上升，平均虫口密度为20．9条／株，有虫株率达IOO％。该县森防站及当地林业站、村委会准备采取化学药杀时，却发现该林区白僵菌二次感染率较高，…     

应用聚集信息素监测与防治纵坑切梢小蠹

监测和防治试验结果表明：最好的诱芯9诱集效果是对照诱集效果的7706．8倍，是饵木的20．49倍；效果中等的诱芯1的诱集量是对照的4288．4倍，是饵木的11．4倍；效果最差的诱芯5诱集量为对照的830倍，是饵木的2．19倍。这一结果肯定了聚集信息素诱虫灵敏度高、效果好的特性。同时虫口密度、有虫株率和梢被害率3项指标的减退率证实了应用聚集信息素防治纵坑切梢小蠹的效果显著可靠。其虫口密度减退率平均为94．35％，有虫株率减退率平均为87．7％，被害梢减退率为88．39％。     

利用黄斑星天牛有虫株率估计株虫口密度方法研究初报

本文通过黄斑星天牛有虫株率、株虫口密度相关性调查分析，提出了不同种群密度下有虫株率与株虫口密度之间的回归式，并对利用有虫株率估计株虫口密度的方法进行了评价，同时对黄斑星天牛株虫口密度林间调查方法进行了初步探讨。     

宁夏银北二代林网抗虫性分析及应用

采用虫口密度，被害株率，林分结构和生长量指标对宁夏银北区二代林网防护林体系各种混交林及纯林的主要害虫进行数量动态和空间动态分析，将其划分为四类，进行方并分析检验，从中筛选出最优抗虫林分，包括抗蛀干和抗枝梢害虫两种林分，为营造和改建天虫灾林分提供依据。     

侧柏毒蛾的发生与防治

寿县八公山林场现有侧柏纯林面积约7000亩,是八公山森林公园的主要森林景观。1997年八公山林场突发大面积侧柏毒蛾虫害,发生面积1640亩,至第1代扩散到3973亩,占全场侧柏总面积的57%,虫株率100%,平均虫口密度1016条/株,最高株率3438条,被害树木鳞片凋落,形如火烧,严重影响生长,     

应用管氏肿腿蜂防治双条杉天牛技术研究

2001—2005年北京市密云县进行了管氏肿腿蜂防治双条杉天牛技术的研究与推广,5 a放蜂1200万头,累计防治面积3000 hm^2。管氏肿腿蜂5 a平均寄生率达69.68%,寄生率随着放蜂密度的增加而增加。林内放蜂后侧柏的被害率由放蜂前22.78%下降到0.49%;被害木虫口密度由25.4头/株下降到3头/株,下降率88.2%;被害木管氏肿腿蜂密度由放蜂前的0.2头/株上升到2005年的2.5头/株,基本达到有虫不成灾。     

滩地抬田造林对杨树蛀干害虫天牛生态控制效果的初探

抬田造林杨-农（油）-渔复合经营模式对杨树蛀干天牛虫口密度和有虫株率都有明显下降作用。其生态控制的综合效益有以下几方面：（1）促进了杨树的快速生长，提高了杨树迅速生长的经济效益；（2）增加了抬田垛面林下套种农作物和沟内养殖水产品的收入；（3）增加了杨树林内有益生物的多样性；（4）对天牛类蛀干害虫起到了有效地控制作用；（5）天牛严重危害区可合理间种柳树（诱集天牛），并在天牛虫口密度达到饱和时，及时集中防治或？肖灭高虫口密度虫源诱集树（柳树）上的蛀干害虫天牛，可达到控点保面的作用。     

释放花绒寄甲防治危害白蜡的云斑天牛

在地处黄河三角洲的山东省东营市和滨州市,选取8个受害严重的白蜡林作为试验样地,在云斑天牛幼虫期释放花绒寄甲卵和成虫,然后调查和统计天敌释放前后白蜡树的被害株率、天牛的株虫口数,计算出花绒寄甲对云斑天牛的防治效果.结果表明:林间释放花绒寄甲卵和成虫对云斑天牛均有良好的控制作用.在释放花绒寄甲卵的5个试验林中,释放后第2年的平均株虫口校正减退率为73.16％,平均被害株校正减退率为72.36％;在释放花绒寄甲成虫的3个试验林中,释放后第2年的平均株虫口校正减退率为77.20％,平均被害株校正减退率为69.68％.对释放花绒寄甲卵和成虫的防治效果进行比较表明,释放花绒寄甲成虫的防治效果略高于释放卵的林分,但二者差异不显著,说明在云斑天牛生物防治中,释放花绒寄甲2种虫态的天敌均不失为有效和良好的技术,而卵的成本低,值得在生产防治中大力推广应用.     

杨干象对杨树生长的影响和防治指标的研究

1995～2000年，对杨干象对杨树生长的影响和防治指标进行了研究。结果认为，不同虫口密度对杨树生长的影响明显，通过建立虫口密度与杨树生长(树高、胸径、材积)损失率回归预测模型表明，随着虫口密度的增加，胸径、材积生长明显下降，其关系呈直线、对数回归关系；高生长总的趋势是下降的，呈多项式回归关系；杨干象防治指标确定为：5年生以下杨树为2头／株，6～8年生杨树为3头／株，9年生以上杨树为4头／株。     

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.