影响湿地松粉蚧种群密度因子的初步研究

影响湿地松粉蚧种群密度因子的初步研究＊顾茂彬陈佩珍关键词湿地松粉蚧、种群密度、环境因子湿地松粉蚧（ＯｒａｃｅｌａａｃｕｔａＦｅｒｉｓ）［１］于１９８８年由美国传入广东省台山市红岭种子园后，迅速繁殖并向四周扩散，目前此虫已分布到开平、新会、恩平、鹤山、...     

湿地松粉蚧外引寄生天敌室内繁殖试验

在广东省森林病虫害防治与检疫总站昆虫繁育室,用接种了湿地松粉蚧的湿地松和火炬松盆栽幼树,繁殖从美国引进的湿地松粉蚧寄生天敌——火炬松短索跳小蜂、迪氏跳小蜂和粉蚧广腹细蜂,连续10年成功繁殖出子代蜂,并长期保持一定的种群数量。释放的亲代寄生蜂数量与检查到的子代寄生蜂数量的比例为6：1。     

蜡蚧轮枝菌防治湿地松粉蚧的研究

应用蜡蚧轮枝菌防治湿地松粉蚧的试验结果，用其２．５×１０７／ｍｌ和１．７×１０７／ｍｌ的孢子液室内防治湿地松粉蚧，校正死亡率分别为８６．７％和６５．９％；林地用其每公顷喷孢量为３３×１０１２和１６．５×１０１２个孢子防治湿地松粉蚧，校正死亡率分别为９２．７％和９９．５％。     

湿地松粉蚧林间种群量消长规律研究

应用定点观察和跟踪调查的方法，研究了湿地松粉蚧林间种群数量消长规律。结果显示，湿地松粉蚧种群在疫区边缘存在８～１０ｋｍ宽的高密度区，虫口密度达６０～７０头／松梢；粉蚧侵入的季节不同，种群密度高峰出现时间也不同，一般粉蚧侵入半年后种群密度达到最大，之后锐减；林间种群数量消长主要受湿地松新梢的影响，现有天敌无法有效控制种群数量的增长。     

湿地松粉蚧蛹寄生蜂火炬松短索跳小蜂生物学特性

火炬松短索跳小蜂Acerophagus coccois Smith是湿地松粉蚧Oracella acuta(Lobdell)的原产地重要天敌。观察了火炬松短索跳小蜂羽化、交配、产卵、活动、成虫寿命和繁殖等生物学习性。结果表明,火炬松短索跳小蜂成虫寿命受温度和营养条件影响很大,雌雄蜂均需要补充营养,补充营养亦可显著延长成虫的寿命。以喂食5%蜜糖水、4~6℃保存的成虫寿命最长,雌虫平均寿命9.17d,雄虫平均寿命8.32 d;其次是供带寄主的松梢,雌雄虫平均寿命分别为5.50 d和5.43 d;平均寿命最短的是仅喂食5%蜜糖水的处理,雌雄虫平均寿命分别为4.12 d和3.98 d。室内繁殖试验表明,火炬松短索跳小蜂在广东省室内条件下能够寄生湿地松粉蚧,但子代蜂数量较少,寄生效能需进一步研究。     

芽枝状枝孢霉和蜡蚧轮枝菌防治湿地松粉蚧研究初报

用芽枝状枝孢霉ＣｌａｄｏＳｐｏｒｉｕｍｃｌａｄｏｓｐｏｒｉｄｅｓ（Ｆｒｅｓ．）Ｄｅｒｒｕｅｓ和蜡蚧轮枝菌Ｖｅｒｔｉｃｉｌｌｉｕｍｌｅｃａｎｉｉ的孢子液２．５×１０７／ｍｌ和１．７Ｘｌ０７／ｍｌ防治湿地松粉蚧Ｏｒａｃｅｌｌａａｃｕｌａ（Ｌｏｂｄｅｌｌ），试验结果为：在室内，用芽枝状枝孢霉的校正死亡率分别为８２．７％和８５．ｏ％，用蜡蚧轮枝菌的校正死亡率分别为８６．７％和６５．９％；林地每公顷喷孢量为３３×１０１２和１６．５×１０１２个孢子防治湿地松粉蚧，用芽枝状枝孢霉的校正死亡率分别为４５．２％和８１．０％，用蜡蚧轮枝菌的校正死亡率分别为９２．７％和９９．５％。初步认为上述两种菌在湿地松粉蚧防治上具有应用前途。     

化学药剂防治湿地松粉蚧的研究

选择了３种化学药剂对湿地松粉蚧进行室内杀虫试验及林间防治，结果表明：在室内低浓度１以速扑杀效果最好，平均校正死亡率达８４．４７％；林间用速扑杀能较快地降低当代虫虫口密度，对湿地松粉蚧的扩散蔓延起到一定的抑制作用。     

湿地松粉蚧林间种群量消长规律研究

应用定点观察和跟踪调查的方法，研究了湿地松粉蚧林间种群数量消长规律。结果显示，湿地松粉蚧种群在疫区边缘存在８－１０ｋｍ宽的高密度区，虫口密度达６０－７０头／松梢；粉蚧侵入的季节不同，种群密度高峰出现时间了不同，一般粉蚧侵入半年后种群密度达到最大，之后锐减；林间种群数量消长主要受湿地松新梢的影响，现有天敌无法有铲控制种群数量的增长。     

芽技状枝孢霉防治湿地松粉蚧的试验初报

用牙枝状枝孢霉Ｃｌａｄｏｓｐｏｒｉｕｍｃｌａｄｏｓｐｏｒｉｓｉｄｅｓ（Ｆｒｅｓ）Ｄｅｒｒｕｅｓ的孢子液防治近年新传入广东的湿地松粉蚧Ｏｒａ－ｃｅｌｌａａｃｕｔａ（Ｌｏｂｄｅｌｌ）。室内试验的校正死亡率为８２．７％～９２．７％；林间试验，每公顷喷孢子量１６．５×１０　个，２０天的防治效果８０％以上。因此，芽枝状枝孢霉防治湿地松粉蚧是一种安全有效的防治方法。     

湿地松粉蚧蔓延进入广西

2000年5～6月,经调查,在与广东交界的玉林市、梧州市的北流、陆川、容县、博白、岑溪5个县(市)的18个乡镇发现湿地松粉蚧,证明湿地松粉蚧已于今年上半年进入广西,有蚧虫面积0.49万hm2,这将对广西现有13.3万hm2湿地松林构成威胁。目前,广西区林业局和有关市、县林业局及森防站正在采取有力措施,防止湿地松粉蚧扩散蔓延。一是继续实行监测和加强检疫;二是调查天敌,了解自控能力;三是做好小面积的防治试验;四是对湿地松进行林分改造。湿地松粉蚧蔓延进入广西$广西壮族自治区森林病虫害防治站@吕送枝     

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.