环斑猛猎蝽生物学特性的研究*

据北京室内饲养观察，环斑猛猎蝽一年发生一代，以４龄若虫越冬。卵期９．９±１．１ｄ。若虫共５龄，历期３１５．０±４．９ｄ。成虫羽化后７－２５ｄ交配，交配后２２－２３ｄ开始产卵。描述了各虫态形态特征。记述了生物学特性。试验表明该虫是杨扇舟蛾、黄刺蛾、杨叶蜂、舞毒蛾、油松毛虫、黄褐天幕毛虫、刺槐蚜等多种林木害虫的捕食性天敌。     

褐菱猎蝽生长学特性的研究

据在北京室内饲养观察，褐菱猎蝽一年发生一代，以成虫越冬。卵期 １２．１±１．０天。若虫５龄，历期６１－８３天。成虫羽化后８－３０天交配，次年开始产卵。描述了各虫态形态特征。记述了生物学特性。试验表明该虫表明该虫对舞毒蛾、杨扇舟蛾、杨叶蜂、榆毒蛾、黄刺蛾等多种林木食叶害虫有明显捕食作用。     

茶翅蝽对植原体的传播能力

经１９９６年至１９９８年室内接种试验,分别比较了人工饲养带毒和自然带毒的杀翅蝽成虫和若虫的传病特点。结果显示：室内人工饲养带毒的３龄、４龄若虫接种泡桐发病率分别达６１．７％和４６．５％,高于自然带毒的若虫１６％的传病率。室内饲带毒成虫的接种发病率为１４．１％,高于自然带毒成虫４．５％的传病率。寄主体内病原的最短潜育期（ＭＩＰ）室内饲毒３龄若虫为３４ｄ,４龄为４５ｄ,成虫处理为２１９ｄ;自然带毒若虫     

化学药剂防治舞毒蛾幼虫试验研究

舞毒蛾是世界性害虫。用２．５％溴氰菊酯乳剂、４０％久效磷乳油和４０％氧化乐果乳油，对舞毒蛾幼虫进行喷杀试验，平均死亡率分别为９９．４％、９８．２５％及８８．２５％。用２．５％溴氰菊酯乳油制成毒绳，对舞毒蛾２～３龄虫和４～５龄幼虫进行扎毒绳试验，平均死亡率分别为９６．７％及７６．６％。扎毒绳田间防治示范，平均杀虫效果达９１．３％。     

拟异尾华枝的取食量研究

拟异尾华枝ＳｉｎｏｐｈａｓｍａｐｓｅｕｄｏｍｉｒａｂｉｌｅＣｈｅｎ雌、雄性的个体取食量：雌性一生总食叶量为１７．８８ｌｇ，其中１～４龄低龄若虫期的占５．４８％，５～７龄老龄若虫期的占２２．７１％，成虫期的占７１．８１％；雄性为７．２１５ｇ，其中１～４龄低龄若虫期的占６．２０％，５～６龄老龄若虫期的占３１．１０％，成虫期的占６２．７０％，老龄若虫期和成虫期是主要的危害期；并分别建立了雌、雄性个体食叶量、个体日均食量指数增长模型，胸径为８～１２ｃｍ的寄主，其防治指标为１５８．４头。     

褐菱猎蝽生物学特性的研究

据在北京室内饲养观察,褐菱猎蝽一年发生一代,以成虫越冬。卵期12.1±1.0天。若虫5龄,历期61-83天。成虫羽化后8-30天交配,次年开始产卵。描述了各虫态形态特征。记述了生物学特性。试验表明该虫对舞毒蛾、杨扇舟蛾、杨叶蜂、榆毒蛾、黄刺蛾等多种林木食叶害虫有明显捕食作用。     

黄杨粕片盾蚧生物学特性,发生动态及其防治研究

黄杨粕片盾蚧在北方严重为害小叶黄杨，１ａ发生２代，多以成虫、部分以２龄若虫越冬。第１代１龄若虫高峰日为５月１２日－６日，第２代１龄若虫盛期为７天下旬，以第１代发生较为整齐。该蚧虫在小叶黄杨上主要分布于１ａ生枝叶，并以１龄若虫逐年向新生枝呈主动扩散，在较大范围内扩展较快，在３－４ａ内可造成严重为害。对其防治的关键时期是１龄若虫活动期和雄成虫期。喷洒４０％氧化乐果１０００倍液、洗衣粉５００倍液防治１龄     

黄带犀猪蝽的生物学及应用研究

黄带犀猎蝽在广州室内饲养年发生2代，以4－5龄若虫于杂草丛生的石块、土块下或枯枝落叶层中越冬，卵成块，12．5－16．5天孵化。若虫5龄，历期48．0－223．5天。成虫羽化后5．0－12．5天交配，交配后11．5－25．5天产卵。成虫寿命一般在36．0天以上。若虫和成虫有较强的耐饥力，在缺少猎物时3－5龄若虫和成虫寿命分别为8．9－13．2天和17．3－20．2天，室内外捕食试验表明，对马尾松毛虫，纵带球须刺蛾，录刺蛾、细皮夜蛾和竹虫有较好的抑制作用。     

广斧螳螂生物学特性观察与保护建议

广斧螳螂Ｈｉｅｒｏｄｕｌａｐａｔｅｌｉｆｅｒａ（Ｓｅｒｖｉｌｅ）在山东日照沿海地区１年发生１代，以卵鞘在树干、枝或石块上越冬，５月中旬孵化若虫，若虫经８龄，于８月中旬羽化，成虫９月中旬产卵。若虫生活历期平均９３．３天，成虫历期平均５５．８天，雌雄性比为７∶３。成虫日取食量平均１．４８ｇ，每只成虫平均共可食虫８２．５８４ｇ，若虫期平均可食虫３４．９６６ｇ，每头螳螂一生平均可食虫１１７．５５ｇ。该螳螂发生与外界温度、食料、天敌等关系密切     

叉角厉蝽生物学特性研究

叉角厉蝽是黑荆树林中害虫的一种生长的天敌昆虫,在福建省长泰县一年多代,饲养为不完整的３代,以第二代成虫于枯落叶下越冬,第三代若虫未完成发育。卵期平均９．０６ｄ,若虫５龄,平均历期２１．３ｄ,１龄植食,２－５龄及成虫捕食,仍观察到植食。     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.